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Sample records for carlo dose mapping

  1. Monte Carlo dose mapping on deforming anatomy

    Science.gov (United States)

    Zhong, Hualiang; Siebers, Jeffrey V.

    2009-10-01

    This paper proposes a Monte Carlo-based energy and mass congruent mapping (EMCM) method to calculate the dose on deforming anatomy. Different from dose interpolation methods, EMCM separately maps each voxel's deposited energy and mass from a source image to a reference image with a displacement vector field (DVF) generated by deformable image registration (DIR). EMCM was compared with other dose mapping methods: energy-based dose interpolation (EBDI) and trilinear dose interpolation (TDI). These methods were implemented in EGSnrc/DOSXYZnrc, validated using a numerical deformable phantom and compared for clinical CT images. On the numerical phantom with an analytically invertible deformation map, EMCM mapped the dose exactly the same as its analytic solution, while EBDI and TDI had average dose errors of 2.5% and 6.0%. For a lung patient's IMRT treatment plan, EBDI and TDI differed from EMCM by 1.96% and 7.3% in the lung patient's entire dose region, respectively. As a 4D Monte Carlo dose calculation technique, EMCM is accurate and its speed is comparable to 3D Monte Carlo simulation. This method may serve as a valuable tool for accurate dose accumulation as well as for 4D dosimetry QA.

  2. Gamma irradiator dose mapping: a Monte Carlo simulation and experimental measurements

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Rogerio R.; Ribeiro, Mariana A.; Grynberg, Suely E.; Ferreira, Andrea V.; Meira-Belo, Luiz Claudio, E-mail: rrr@cdtn.b, E-mail: marianaalmeida@ufmg.b, E-mail: seg@cdtn.b, E-mail: avf@cdtn.b, E-mail: lcmb@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Sousa, Romulo V.; Sebastiao, Rita de C.O., E-mail: romuloverdolin@yahoo.com.b, E-mail: ritacos@ufmg.b [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Inst. de Ciencias Exatas. Dept. de Quimica

    2009-07-01

    Gamma irradiator facilities can be used in a wide range of applications such as biological and chemical researches, food treatment and sterilization of medical devices and products. Dose mapping must be performed in these equipment in order to establish plant operational parameters, as dose uniformity, source utilization efficiency and maximum and minimum dose positions. The isodoses curves are generally measured using dosimeters distributed throughout the device, and this procedure often consume a large amount of dosimeters, irradiation time and manpower. However, a detailed curve doses identification of the irradiation facility can be performed using Monte Carlo simulation, which reduces significantly the monitoring with dosimeters. The present work evaluates the absorbed dose in the CDTN/CNEN Gammacell Irradiation Facility, using the Monte Carlo N-particles (MCNP) code. The Gammacell 220, serial number 39, was produced by Atomic Energy of Canada Limited and was loaded with sources of {sup 60}Co. Dose measurements using TLD and Fricke dosimeters were also performed to validate the calculations. The good agreement of the results shows that Monte Carlo simulations can be used as a predictive tool of irradiation planning for the CDTN/CNEN Gamma Cell Irradiator. (author)

  3. Monte Carlo dose computation for IMRT optimization*

    Science.gov (United States)

    Laub, W.; Alber, M.; Birkner, M.; Nüsslin, F.

    2000-07-01

    A method which combines the accuracy of Monte Carlo dose calculation with a finite size pencil-beam based intensity modulation optimization is presented. The pencil-beam algorithm is employed to compute the fluence element updates for a converging sequence of Monte Carlo dose distributions. The combination is shown to improve results over the pencil-beam based optimization in a lung tumour case and a head and neck case. Inhomogeneity effects like a broader penumbra and dose build-up regions can be compensated for by intensity modulation.

  4. Monte Carlo dose distributions for radiosurgery

    Energy Technology Data Exchange (ETDEWEB)

    Perucha, M.; Leal, A.; Rincon, M.; Carrasco, E. [Sevilla Univ. (Spain). Dept. Fisiologia Medica y Biofisica; Sanchez-Doblado, F. [Sevilla Univ. (Spain). Dept. Fisiologia Medica y Biofisica]|[Hospital Univ. Virgen Macarena, Sevilla (Spain). Servicio de Oncologia Radioterapica; Nunez, L. [Clinica Puerta de Hierro, Madrid (Spain). Servicio de Radiofisica; Arrans, R.; Sanchez-Calzado, J.A.; Errazquin, L. [Hospital Univ. Virgen Macarena, Sevilla (Spain). Servicio de Oncologia Radioterapica; Sanchez-Nieto, B. [Royal Marsden NHS Trust (United Kingdom). Joint Dept. of Physics]|[Inst. of Cancer Research, Sutton, Surrey (United Kingdom)

    2001-07-01

    The precision of Radiosurgery Treatment planning systems is limited by the approximations of their algorithms and by their dosimetrical input data. This fact is especially important in small fields. However, the Monte Carlo methods is an accurate alternative as it considers every aspect of particle transport. In this work an acoustic neurinoma is studied by comparing the dose distribution of both a planning system and Monte Carlo. Relative shifts have been measured and furthermore, Dose-Volume Histograms have been calculated for target and adjacent organs at risk. (orig.)

  5. Monte Carlo dose distributions for radiosurgery

    International Nuclear Information System (INIS)

    The precision of Radiosurgery Treatment planning systems is limited by the approximations of their algorithms and by their dosimetrical input data. This fact is especially important in small fields. However, the Monte Carlo methods is an accurate alternative as it considers every aspect of particle transport. In this work an acoustic neurinoma is studied by comparing the dose distribution of both a planning system and Monte Carlo. Relative shifts have been measured and furthermore, Dose-Volume Histograms have been calculated for target and adjacent organs at risk. (orig.)

  6. Optimizing dose prescription in stereotactic body radiotherapy for lung tumours using Monte Carlo dose calculation

    NARCIS (Netherlands)

    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

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

    Science.gov (United States)

    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.

  8. Monte Carlo dose calculation in dental amalgam phantom

    OpenAIRE

    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...

  9. 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

  10. Dose-mapping distribution around MNSR

    CERN Document Server

    Jamal, M H

    2002-01-01

    The aim of this study is to establish the dose-rate map through the determination of radiological dose-rate levels in reactor hall, adjacent rooms, and outside the MNSR facility. Controlling dose rate to reactor operating personnel , dose map was established. The map covers time and distances in the reactor hall, during reactor operation at nominal power. Different measurement of dose rates in other areas of the reactor buildings was established. The maximum dose rate, during normal operation of the MNSR was 40 and 21 Sv/hr on the top of the reactor and near the pool fence, respectively. Whereas, gamma and neutron doses have not exceeded natural background in all rooms adjacent to the reactor hall or nearly buildings. The relation between the dose rate for gamma rays and neutron flux at the top of cover of reactor pool was studied as well. It was found that this relation is linear.

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

    Science.gov (United States)

    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.

  12. Dose rate mapping of VMAT treatments.

    Science.gov (United States)

    Podesta, Mark; Popescu, I Antoniu; Verhaegen, Frank

    2016-06-01

    Human tissues exhibit a varying response to radiation dose depending on the dose rate and fractionation scheme used. Dose rate effects have been reported for different radiations, and tissue types. The literature indicates that there is not a significant difference in response for low-LET radiation when using dose rates between 1 Gy min(-1) and 12 Gy min(-1) but lower dose rates have an observable sparing effect on tissues and a differential effect between tissues. In intensity-modulated radiotherapy such as volumetric modulated arc therapy (VMAT) the dose can be delivered with a wide range of dose rates. In this work we developed a method based on time-resolved Monte Carlo simulations to quantify the dose rate frequency distribution for clinical VMAT treatments for three cancer sites, head and neck, lung, and pelvis within both planning target volumes (PTV) and normal tissues. The results show a wide range of dose rates are used to deliver dose in VMAT and up to 75% of the PTV can have its dose delivered with dose rates  <1 Gy min(-1). Pelvic plans on average have a lower mean dose rate within the PTV than lung or head and neck plans but a comparable mean dose rate within the organs at risk. Two VMAT plans that fulfil the same dose objectives and constraints may be delivered with different dose rate distributions, particularly when comparing single arcs to multiple arc plans. It is concluded that for dynamic plans, the dose rate range used varies to a larger degree than previously assumed. The effect of the dose rate range in VMAT on clinical outcome is unknown.

  13. Dose rate mapping of VMAT treatments

    Science.gov (United States)

    Podesta, Mark; Antoniu Popescu, I.; Verhaegen, Frank

    2016-06-01

    Human tissues exhibit a varying response to radiation dose depending on the dose rate and fractionation scheme used. Dose rate effects have been reported for different radiations, and tissue types. The literature indicates that there is not a significant difference in response for low-LET radiation when using dose rates between 1 Gy min-1 and 12 Gy min-1 but lower dose rates have an observable sparing effect on tissues and a differential effect between tissues. In intensity-modulated radiotherapy such as volumetric modulated arc therapy (VMAT) the dose can be delivered with a wide range of dose rates. In this work we developed a method based on time-resolved Monte Carlo simulations to quantify the dose rate frequency distribution for clinical VMAT treatments for three cancer sites, head and neck, lung, and pelvis within both planning target volumes (PTV) and normal tissues. The results show a wide range of dose rates are used to deliver dose in VMAT and up to 75% of the PTV can have its dose delivered with dose rates  <1 Gy min-1. Pelvic plans on average have a lower mean dose rate within the PTV than lung or head and neck plans but a comparable mean dose rate within the organs at risk. Two VMAT plans that fulfil the same dose objectives and constraints may be delivered with different dose rate distributions, particularly when comparing single arcs to multiple arc plans. It is concluded that for dynamic plans, the dose rate range used varies to a larger degree than previously assumed. The effect of the dose rate range in VMAT on clinical outcome is unknown.

  14. Establishment Of Dose Correlation During Dose Mapping On Medical Devices

    International Nuclear Information System (INIS)

    This paper explains the work done during product dose mapping in order to get the correlation between doses at MINTec-Sinagama plant. Product used was medical devices in aluminium tubes packaged in cardboard kegs packaging with average weight of 12 kg per carton. 12 cartons were loaded in every one tote to give 0.2 g/ cm3 of density. Ceric cerous dosimeters were placed at specific locations as indicated in SP14: Product Dose Mapping, QMS of MINTec-Sinagama around three planes. Three processes were made at different days as a three replicates to show the reproducibility of measurements. (author)

  15. Dose mapping for documentation of radiation sterilization

    DEFF Research Database (Denmark)

    Miller, A.

    1999-01-01

    The radiation sterilization standards EN 552 and ISO 11137 require that dose mapping in real or simulated product be carried in connection with the process qualification. This paper reviews the recommendations given in the standards and discusses the difficulties and limitations of practical dose...

  16. Monte Carlo dose calculation in dental amalgam phantom.

    Science.gov (United States)

    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

  17. Monte Carlo dose calculation in dental amalgam phantom.

    Science.gov (United States)

    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.

  18. 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.

  19. Monte Carlo N Particle code - Dose distribution of clinical electron beams in inhomogeneous phantoms

    OpenAIRE

    H A Nedaie; Mosleh-Shirazi, M. A.; Allahverdi, M.

    2013-01-01

    Electron dose distributions calculated using the currently available analytical methods can be associated with large uncertainties. The Monte Carlo method is the most accurate method for dose calculation in electron beams. Most of the clinical electron beam simulation studies have been performed using non- MCNP [Monte Carlo N Particle] codes. Given the differences between Monte Carlo codes, this work aims to evaluate the accuracy of MCNP4C-simulated electron dose distributions in a homogenous...

  20. Investigation of Nonuniform Dose Voxel Geometry in Monte Carlo Calculations.

    Science.gov (United States)

    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.

  1. Skin dose mapping for fluoroscopically guided interventions

    International Nuclear Information System (INIS)

    Purpose: To introduce a new skin dose mapping software system for interventional fluoroscopy dose assessment and to analyze the benefits and limitations of patient-phantom matching. Methods: In this study, a new software system was developed for visualizing patient skin dose during interventional fluoroscopy procedures. The system works by translating the reference point air kerma to the location of the patient's skin, which is represented by a computational model. In order to orient the model with the x-ray source, geometric parameters found within the radiation dose structured report (RDSR) are used along with a limited number of in-clinic measurements. The output of the system is a visual indication of skin dose mapped onto an anthropomorphic model at a resolution of 5 mm. In order to determine if patient-dependent and patient-sculpted models increase accuracy, peak skin dose was calculated for each of 26 patient-specific models and compared with doses calculated using an elliptical stylized model, a reference hybrid model, a matched patient-dependent model and one patient-sculpted model. Results were analyzed in terms of a percent difference using the doses calculated using the patient-specific model as the true standard. Results: Anthropometric matching, including the use of both patient-dependent and patient-sculpted phantoms, was shown most beneficial for left lateral and anterior-posterior projections. In these cases, the percent difference using a reference model was between 8 and 20%, using a patient-dependent model between 7 and 15%, and using a patient-sculpted model between 3 and 7%. Under the table tube configurations produced errors less than 5% in most situations due to the flattening affects of the table and pad, and the fact that table height is the main determination of source-to-skin distance for these configurations. In addition to these results, several skin dose maps were produced and a prototype display system was placed on the in

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

    CERN Document Server

    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...

  3. Monte Carlo study of radiation dose enhancement by gadolinium in megavoltage and high dose rate radiotherapy.

    Directory of Open Access Journals (Sweden)

    Daniel G Zhang

    Full Text Available MRI is often used in tumor localization for radiotherapy treatment planning, with gadolinium (Gd-containing materials often introduced as a contrast agent. Motexafin gadolinium is a novel radiosensitizer currently being studied in clinical trials. The nanoparticle technologies can target tumors with high concentration of high-Z materials. This Monte Carlo study is the first detailed quantitative investigation of high-Z material Gd-induced dose enhancement in megavoltage external beam photon therapy. BEAMnrc, a radiotherapy Monte Carlo simulation package, was used to calculate dose enhancement as a function of Gd concentration. Published phase space files for the TrueBeam flattening filter free (FFF and conventional flattened 6MV photon beams were used. High dose rate (HDR brachytherapy with Ir-192 source was also investigated as a reference. The energy spectra difference caused a dose enhancement difference between the two beams. Since the Ir-192 photons have lower energy yet, the photoelectric effect in the presence of Gd leads to even higher dose enhancement in HDR. At depth of 1.8 cm, the percent mean dose enhancement for the FFF beam was 0.38±0.12, 1.39±0.21, 2.51±0.34, 3.59±0.26, and 4.59±0.34 for Gd concentrations of 1, 5, 10, 15, and 20 mg/mL, respectively. The corresponding values for the flattened beam were 0.09±0.14, 0.50±0.28, 1.19±0.29, 1.68±0.39, and 2.34±0.24. For Ir-192 with direct contact, the enhanced were 0.50±0.14, 2.79±0.17, 5.49±0.12, 8.19±0.14, and 10.80±0.13. Gd-containing materials used in MRI as contrast agents can also potentially serve as radiosensitizers in radiotherapy. This study demonstrates that Gd can be used to enhance radiation dose in target volumes not only in HDR brachytherapy, but also in 6 MV FFF external beam radiotherapy, but higher than the currently used clinical concentration (>5 mg/mL would be needed.

  4. Monte Carlo study of radiation dose enhancement by gadolinium in megavoltage and high dose rate radiotherapy.

    Science.gov (United States)

    Zhang, Daniel G; Feygelman, Vladimir; Moros, Eduardo G; Latifi, Kujtim; Zhang, Geoffrey G

    2014-01-01

    MRI is often used in tumor localization for radiotherapy treatment planning, with gadolinium (Gd)-containing materials often introduced as a contrast agent. Motexafin gadolinium is a novel radiosensitizer currently being studied in clinical trials. The nanoparticle technologies can target tumors with high concentration of high-Z materials. This Monte Carlo study is the first detailed quantitative investigation of high-Z material Gd-induced dose enhancement in megavoltage external beam photon therapy. BEAMnrc, a radiotherapy Monte Carlo simulation package, was used to calculate dose enhancement as a function of Gd concentration. Published phase space files for the TrueBeam flattening filter free (FFF) and conventional flattened 6MV photon beams were used. High dose rate (HDR) brachytherapy with Ir-192 source was also investigated as a reference. The energy spectra difference caused a dose enhancement difference between the two beams. Since the Ir-192 photons have lower energy yet, the photoelectric effect in the presence of Gd leads to even higher dose enhancement in HDR. At depth of 1.8 cm, the percent mean dose enhancement for the FFF beam was 0.38±0.12, 1.39±0.21, 2.51±0.34, 3.59±0.26, and 4.59±0.34 for Gd concentrations of 1, 5, 10, 15, and 20 mg/mL, respectively. The corresponding values for the flattened beam were 0.09±0.14, 0.50±0.28, 1.19±0.29, 1.68±0.39, and 2.34±0.24. For Ir-192 with direct contact, the enhanced were 0.50±0.14, 2.79±0.17, 5.49±0.12, 8.19±0.14, and 10.80±0.13. Gd-containing materials used in MRI as contrast agents can also potentially serve as radiosensitizers in radiotherapy. This study demonstrates that Gd can be used to enhance radiation dose in target volumes not only in HDR brachytherapy, but also in 6 MV FFF external beam radiotherapy, but higher than the currently used clinical concentration (>5 mg/mL) would be needed.

  5. Monte Carlo simulations of dose distributions with necrotic tumor targeted radioimmunotherapy

    International Nuclear Information System (INIS)

    Radio-resistant hypoxic tumor cells are significant contributors to the locoregional recurrences and distant metastases that mark failure of radiotherapy. Due to restricted tissue oxygenation, chronically hypoxic tumor cells frequently become necrotic and thus there is often an association between chronically hypoxic and necrotic tumor regions. This simulation study is the first in a series to determine the feasibility of hypoxic cell killing after first targeting adjacent areas of necrosis with either an α- or β-emitting radioimmunoconjugate. - Highlights: • A representative necrotic tumor geometry was created in the Geant4 Monte Carlo toolkit. • Custom designed particle tracking was performed allowing for separation of deposited doses from different decay particles. • Post-processing of the data included relative biological effectiveness of the different decay particles and effects of cell oxygenation. • Physical and equivalent doses resulting from 177Lu and 212Pb were compared by means of dose maps and dose profiles. • 212Pb appears to be a promising isotope for necrotic tumor targeted α-therapy and will be pursued in future in vivo studies

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  7. 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

  8. Monte Carlo calculation of 60Co γ-ray's albedo-dose rate from the air

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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.

  10. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  12. Monte Carlo verification of IMRT dose distributions from a commercial treatment planning optimization system

    Science.gov (United States)

    Ma, C.-M.; Pawlicki, T.; Jiang, S. B.; Li, J. S.; Deng, J.; Mok, E.; Kapur, A.; Xing, L.; Ma, L.; Boyer, A. L.

    2000-09-01

    The purpose of this work was to use Monte Carlo simulations to verify the accuracy of the dose distributions from a commercial treatment planning optimization system (Corvus, Nomos Corp., Sewickley, PA) for intensity-modulated radiotherapy (IMRT). A Monte Carlo treatment planning system has been implemented clinically to improve and verify the accuracy of radiotherapy dose calculations. Further modifications to the system were made to compute the dose in a patient for multiple fixed-gantry IMRT fields. The dose distributions in the experimental phantoms and in the patients were calculated and used to verify the optimized treatment plans generated by the Corvus system. The Monte Carlo calculated IMRT dose distributions agreed with the measurements to within 2% of the maximum dose for all the beam energies and field sizes for both the homogeneous and heterogeneous phantoms. The dose distributions predicted by the Corvus system, which employs a finite-size pencil beam (FSPB) algorithm, agreed with the Monte Carlo simulations and measurements to within 4% in a cylindrical water phantom with various hypothetical target shapes. Discrepancies of more than 5% (relative to the prescribed target dose) in the target region and over 20% in the critical structures were found in some IMRT patient calculations. The FSPB algorithm as implemented in the Corvus system is adequate for homogeneous phantoms (such as prostate) but may result in significant under- or over-estimation of the dose in some cases involving heterogeneities such as the air-tissue, lung-tissue and tissue-bone interfaces.

  13. 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)

  14. Patient-specific CT dose determination from CT images using Monte Carlo simulations

    Science.gov (United States)

    Liang, Qing

    Radiation dose from computed tomography (CT) has become a public concern with the increasing application of CT as a diagnostic modality, which has generated a demand for patient-specific CT dose determinations. This thesis work aims to provide a clinically applicable Monte-Carlo-based CT dose calculation tool based on patient CT images. The source spectrum was simulated based on half-value layer measurements. Analytical calculations along with the measured flux distribution were used to estimate the bowtie-filter geometry. Relative source output at different points in a cylindrical phantom was measured and compared with Monte Carlo simulations to verify the determined spectrum and bowtie-filter geometry. Sensitivity tests were designed with four spectra with the same kVp and different half-value layers, and showed that the relative output at different locations in a phantom is sensitive to different beam qualities. An mAs-to-dose conversion factor was determined with in-air measurements using an Exradin A1SL ionization chamber. Longitudinal dose profiles were measured with thermoluminescent dosimeters (TLDs) and compared with the Monte-Carlo-simulated dose profiles to verify the mAs-to-dose conversion factor. Using only the CT images to perform Monte Carlo simulations would cause dose underestimation due to the lack of a scatter region. This scenario was demonstrated with a cylindrical phantom study. Four different image extrapolation methods from the existing CT images and the Scout images were proposed. The results show that performing image extrapolation beyond the scan region improves the dose calculation accuracy under both step-shoot scan mode and helical scan mode. Two clinical studies were designed and comparisons were performed between the current CT dose metrics and the Monte-Carlo-based organ dose determination techniques proposed in this work. The results showed that the current CT dosimetry failed to show dose differences between patients with the same

  15. Local dose enhancement in radiation therapy: Monte Carlo simulation study

    International Nuclear Information System (INIS)

    The development of nanotechnology has boosted the use of nanoparticles in radiation therapy in order to achieve greater therapeutic ratio between tumor and healthy tissues. Gold has been shown to be most suitable to this task due to the high biocompatibility and high atomic number, which contributes to a better in vivo distribution and for the local energy deposition. As a result, this study proposes to study, nanoparticle in the tumor cell. At a range of 11 nm from the nanoparticle surface, results have shown an absorbed dose 141 times higher for the medium with the gold nanoparticle compared to the water for an incident energy spectrum with maximum photon energy of 50 keV. It was also noted that when only scattered radiation is interacting with the gold nanoparticles, the dose was 134 times higher compared to enhanced local dose that remained significant even for scattered radiation. (author)

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

    Science.gov (United States)

    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.

  17. 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

  18. 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.

  19. Feasibility Study of Neutron Dose for Real Time Image Guided Proton Therapy: A Monte Carlo Study

    OpenAIRE

    Kim, Jin Sung; Shin, Jung Suk; Kim, Daehyun; Shin, EunHyuk; Chung, Kwangzoo; Cho, Sungkoo; Ahn, Sung Hwan; Ju, Sanggyu; Chung, Yoonsun; Jung, Sang Hoon; Han, Youngyih

    2015-01-01

    Two full rotating gantry with different nozzles (Multipurpose nozzle with MLC, Scanning Dedicated nozzle) with conventional cyclotron system is installed and under commissioning for various proton treatment options at Samsung Medical Center in Korea. The purpose of this study is to investigate neutron dose equivalent per therapeutic dose, H/D, to x-ray imaging equipment under various treatment conditions with monte carlo simulation. At first, we investigated H/D with the various modifications...

  20. Monte Carlo estimation of photoneutrons spectra and dose equivalent around an 18 MV medical linear accelerator

    Science.gov (United States)

    Alem-Bezoubiri, A.; Bezoubiri, F.; Badreddine, A.; Mazrou, H.; Lounis-Mokrani, Z.

    2014-04-01

    A fully detailed Monte Carlo geometrical model of an 18 MV Varian Clinac 2100C medical linear accelerator, lodged at Blida Anti-Cancer Centre in Algeria, was developed during this study to estimate the photoneutrons spectra and doses at the patient table in a radiotherapy treatment room, for radiation protection purposes.

  1. Organ doses for reference adult male and female undergoing computed tomography estimated by Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Choonsik; Kim, Kwang Pyo; Long, Daniel; Fisher, Ryan; Tien, Chris; Simon, Steven L.; Bouville, Andre; Bolch, Wesley E. [Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institute of Health, Bethesda, Maryland 20852 (United States); Department of Nuclear Engineering, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, Florida 32611 (United States); Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institute of Health, Bethesda, Maryland 20852 (United States); Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, Florida 32611 (United States)

    2011-03-15

    Purpose: To develop a computed tomography (CT) organ dose estimation method designed to readily provide organ doses in a reference adult male and female for different scan ranges to investigate the degree to which existing commercial programs can reasonably match organ doses defined in these more anatomically realistic adult hybrid phantomsMethods: The x-ray fan beam in the SOMATOM Sensation 16 multidetector CT scanner was simulated within the Monte Carlo radiation transport code MCNPX2.6. The simulated CT scanner model was validated through comparison with experimentally measured lateral free-in-air dose profiles and computed tomography dose index (CTDI) values. The reference adult male and female hybrid phantoms were coupled with the established CT scanner model following arm removal to simulate clinical head and other body region scans. A set of organ dose matrices were calculated for a series of consecutive axial scans ranging from the top of the head to the bottom of the phantoms with a beam thickness of 10 mm and the tube potentials of 80, 100, and 120 kVp. The organ doses for head, chest, and abdomen/pelvis examinations were calculated based on the organ dose matrices and compared to those obtained from two commercial programs, CT-EXPO and CTDOSIMETRY. Organ dose calculations were repeated for an adult stylized phantom by using the same simulation method used for the adult hybrid phantom. Results: Comparisons of both lateral free-in-air dose profiles and CTDI values through experimental measurement with the Monte Carlo simulations showed good agreement to within 9%. Organ doses for head, chest, and abdomen/pelvis scans reported in the commercial programs exceeded those from the Monte Carlo calculations in both the hybrid and stylized phantoms in this study, sometimes by orders of magnitude. Conclusions: The organ dose estimation method and dose matrices established in this study readily provides organ doses for a reference adult male and female for different

  2. Monte Carlo angular dose distribution of the microselectron HDR 192Ir brachytherapy source

    International Nuclear Information System (INIS)

    Polar dose profiles around the Nucletron MicroSelectron high dose rate (HDR) 192Ir brachytherapy source were calculated using the Monte Carlo radiation transport code MCNP (Monte Carlo N Particle) version 4A. The geometry modeled consisted of an identical simulation of the construction of the MicroSelectron HDR source located at the centre of a spherical water phantom of 100cm radius. Doses were calculated using a spherical coordinate system at 5 degree intervals (measured relative to the cable) at radii of 0.25, 0.5,1.0, 3.0, 5.0 and 7.0cm. These polar doses were compared to equivalent profiles from the Nucletron PLATO Brachytherapy Planning System (BPS) version 13.X. At 3.0, 5.0 and 7.0cm radii, the Monte Carlo and BPS profiles are generally within 3%. The near field polar dose profiles however, are in significant disagreement. At 1.0cm radius, the discrepancy can exceed 5%. At 0.5cm this figure rises to 15%, and even 60% at 0.25cm radius

  3. Impact of photon cross section systematic uncertainties on Monte Carlo-determined depth-dose distributions

    CERN Document Server

    Aguirre, Eder; David, Mariano; deAlmeida, Carlos E

    2016-01-01

    This work studies the impact of systematic uncertainties associated to interaction cross sections on depth dose curves determined by Monte Carlo simulations. The corresponding sensitivity factors are quantified by changing cross sections in a given amount and determining the variation in the dose. The influence of total cross sections for all particles, photons and only for Compton scattering is addressed. The PENELOPE code was used in all simulations. It was found that photon cross section sensitivity factors depend on depth. In addition, they are positive and negative for depths below and above an equilibrium depth, respectively. At this depth, sensitivity factors are null. The equilibrium depths found in this work agree very well with the mean free path of the corresponding incident photon energy. Using the sensitivity factors reported here, it is possible to estimate the impact of photon cross section uncertainties on the uncertainty of Monte Carlo-determined depth dose curves.

  4. 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...

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

    CERN Document Server

    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...

  6. Comparison of internal dose estimates obtained using organ-level, voxel S value, and Monte Carlo techniques

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, Joshua, E-mail: grimes.joshua@mayo.edu [Department of Physics and Astronomy, University of British Columbia, Vancouver V5Z 1L8 (Canada); Celler, Anna [Department of Radiology, University of British Columbia, Vancouver V5Z 1L8 (Canada)

    2014-09-15

    Purpose: The authors’ objective was to compare internal dose estimates obtained using the Organ Level Dose Assessment with Exponential Modeling (OLINDA/EXM) software, the voxel S value technique, and Monte Carlo simulation. Monte Carlo dose estimates were used as the reference standard to assess the impact of patient-specific anatomy on the final dose estimate. Methods: Six patients injected with{sup 99m}Tc-hydrazinonicotinamide-Tyr{sup 3}-octreotide were included in this study. A hybrid planar/SPECT imaging protocol was used to estimate {sup 99m}Tc time-integrated activity coefficients (TIACs) for kidneys, liver, spleen, and tumors. Additionally, TIACs were predicted for {sup 131}I, {sup 177}Lu, and {sup 90}Y assuming the same biological half-lives as the {sup 99m}Tc labeled tracer. The TIACs were used as input for OLINDA/EXM for organ-level dose calculation and voxel level dosimetry was performed using the voxel S value method and Monte Carlo simulation. Dose estimates for {sup 99m}Tc, {sup 131}I, {sup 177}Lu, and {sup 90}Y distributions were evaluated by comparing (i) organ-level S values corresponding to each method, (ii) total tumor and organ doses, (iii) differences in right and left kidney doses, and (iv) voxelized dose distributions calculated by Monte Carlo and the voxel S value technique. Results: The S values for all investigated radionuclides used by OLINDA/EXM and the corresponding patient-specific S values calculated by Monte Carlo agreed within 2.3% on average for self-irradiation, and differed by as much as 105% for cross-organ irradiation. Total organ doses calculated by OLINDA/EXM and the voxel S value technique agreed with Monte Carlo results within approximately ±7%. Differences between right and left kidney doses determined by Monte Carlo were as high as 73%. Comparison of the Monte Carlo and voxel S value dose distributions showed that each method produced similar dose volume histograms with a minimum dose covering 90% of the volume (D90

  7. Poster — Thur Eve — 14: Improving Tissue Segmentation for Monte Carlo Dose Calculation using DECT

    Energy Technology Data Exchange (ETDEWEB)

    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.

  8. Development and validation of Monte Carlo dose computations for contrast-enhanced stereotactic synchrotron radiation therapy

    International Nuclear Information System (INIS)

    Contrast-enhanced stereotactic synchrotron radiation therapy (SSRT) is an innovative technique based on localized dose-enhancement effects obtained by reinforced photoelectric absorption in the tumor. Medium energy monochromatic X-rays (50 - 100 keV) are used for irradiating tumors previously loaded with a high-Z element. Clinical trials of SSRT are being prepared at the European Synchrotron Radiation Facility (ESRF), an iodinated contrast agent will be used. In order to compute the energy deposited in the patient (dose), a dedicated treatment planning system (TPS) has been developed for the clinical trials, based on the ISOgray TPS. This work focuses on the SSRT specific modifications of the TPS, especially to the PENELOPE-based Monte Carlo dose engine. The TPS uses a dedicated Monte Carlo simulation of medium energy polarized photons to compute the deposited energy in the patient. Simulations are performed considering the synchrotron source, the modeled beamline geometry and finally the patient. Specific materials were also implemented in the voxelized geometry of the patient, to consider iodine concentrations in the tumor. The computation process has been optimized and parallelized. Finally a specific computation of absolute doses and associated irradiation times (instead of monitor units) was implemented. The dedicated TPS was validated with depth dose curves, dose profiles and absolute dose measurements performed at the ESRF in a water tank and solid water phantoms with or without bone slabs. (author)

  9. 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

  10. Pre-treatment radiotherapy dose verification using Monte Carlo doselet modulation in a spherical phantom

    CERN Document Server

    Townson, Reid W

    2013-01-01

    Due to the increasing complexity of radiotherapy delivery, accurate dose verification has become an essential part of the clinical treatment process. The purpose of this work was to develop an electronic portal image (EPI) based pre-treatment verification technique capable of quickly reconstructing 3D dose distributions from both coplanar and non-coplanar treatments. The dose reconstruction is performed in a spherical water phantom by modulating, based on EPID measurements, pre-calculated Monte Carlo (MC) doselets defined on a spherical coordinate system. This is called the spherical doselet modulation (SDM) method. This technique essentially eliminates the statistical uncertainty of the MC dose calculations by exploiting both azimuthal symmetry in a patient-independent phase-space and symmetry of a virtual spherical water phantom. The symmetry also allows the number of doselets necessary for dose reconstruction to be reduced by a factor of about 250. In this work, 51 doselets were used. The SDM method mitiga...

  11. Monte Carlo simulation of glandular dose in a dedicated breast CT system

    Institute of Scientific and Technical Information of China (English)

    TANG Xiao; WEI Long; ZHAO Wei; WANG Yan-Fang; SHU Hang; SUN Cui-Li; WEI Cun-Feng; CAO Da-Quan; QUE Jie-Min; SHI Rong-Jian

    2012-01-01

    A dedicated breast CT system (DBCT) is a new method for breast cancer detection proposed in recent years.In this paper,the glandular dose in the DBCT is simulated using the Monte Carlo method.The phantom shape is half ellipsoid,and a series of phantoms with different sizes,shapes and compositions were constructed. In order to optimize the spectra,monoenergy X-ray beams of 5-80 keV were used in simulation.The dose distribution of a breast phantom was studied:a higher energy beam generated more uniform distribution,and the outer parts got more dose than the inner parts.For polyenergtic spectra,four spectra of Al filters with different thicknesses were simulated,and the polyenergtic glandular dose was calculated as a spectral weighted combination of the monoenergetic dose.

  12. A Graphical review of radiogenic animal cancer data using the 'dose and dose-rate map'

    International Nuclear Information System (INIS)

    We have been investigating the effects of low dose or low dose rate irradiation on mice, using our low dose-rate irradiation facilities. In these studies, we found that the effects were highly dependent on both total dose and dose rate. To show this visually, we proposed the 'dose and dose-rate map (DDR map),' and plotted the results of our laboratory and our co-workers. The map demonstrated that dose and dose rate plane could be divided into three areas; an area where harmful effects are observed, an area where no harmful effects are observed and another area, between previous two areas, where certain protective functions are enhanced As this map would be a powerful tool to find some trend among the vast numbers of data relating the biological effects of ionizing radiation, we have developed a computer program which plots the collected data on the DDR map sorting by experimental conditions. In this study we graphically reviewed and analyzed the data relating to the lifespan studies of animals with a view to determining the relationships between doses and dose rates of ionizing radiation and cancer incidence. The data contains about 800 sets of experiments, which concerns 187,000 animals exposed to gamma ray or X-ray and their 112,000 controls, and total of about 30,000 cancers in exposed animals and 14,000 cancers in controls. About 800 points of data were plotted on the DDR map. The plot showed that the divided three areas in the DDR map were generally confirmed by these 800 points of data, and in some particular conditions, exempli gratia (e.g.) sarcoma, the biologically effective area is extended to relatively high dose and dose rate area. (author)

  13. Radiation doses in volume-of-interest breast computed tomography—A Monte Carlo simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Chao-Jen, E-mail: cjlai3711@gmail.com; Zhong, Yuncheng; Yi, Ying; Wang, Tianpeng; Shaw, Chris C. [Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030-4009 (United States)

    2015-06-15

    Purpose: Cone beam breast computed tomography (breast CT) with true three-dimensional, nearly isotropic spatial resolution has been developed and investigated over the past decade to overcome the problem of lesions overlapping with breast anatomical structures on two-dimensional mammographic images. However, the ability of breast CT to detect small objects, such as tissue structure edges and small calcifications, is limited. To resolve this problem, the authors proposed and developed a volume-of-interest (VOI) breast CT technique to image a small VOI using a higher radiation dose to improve that region’s visibility. In this study, the authors performed Monte Carlo simulations to estimate average breast dose and average glandular dose (AGD) for the VOI breast CT technique. Methods: Electron–Gamma-Shower system code-based Monte Carlo codes were used to simulate breast CT. The Monte Carlo codes estimated were validated using physical measurements of air kerma ratios and point doses in phantoms with an ion chamber and optically stimulated luminescence dosimeters. The validated full cone x-ray source was then collimated to simulate half cone beam x-rays to image digital pendant-geometry, hemi-ellipsoidal, homogeneous breast phantoms and to estimate breast doses with full field scans. 13-cm in diameter, 10-cm long hemi-ellipsoidal homogeneous phantoms were used to simulate median breasts. Breast compositions of 25% and 50% volumetric glandular fractions (VGFs) were used to investigate the influence on breast dose. The simulated half cone beam x-rays were then collimated to a narrow x-ray beam with an area of 2.5 × 2.5 cm{sup 2} field of view at the isocenter plane and to perform VOI field scans. The Monte Carlo results for the full field scans and the VOI field scans were then used to estimate the AGD for the VOI breast CT technique. Results: The ratios of air kerma ratios and dose measurement results from the Monte Carlo simulation to those from the physical

  14. Effects of CT based Voxel Phantoms on Dose Distribution Calculated with Monte Carlo Method

    Science.gov (United States)

    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.

  15. 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.

  16. Dose conversion coefficients for ICRP110 voxel phantom in the Geant4 Monte Carlo code

    Science.gov (United States)

    Martins, M. C.; Cordeiro, T. P. V.; Silva, A. X.; Souza-Santos, D.; Queiroz-Filho, P. P.; Hunt, J. G.

    2014-02-01

    The reference adult male voxel phantom recommended by International Commission on Radiological Protection no. 110 was implemented in the Geant4 Monte Carlo code. Geant4 was used to calculate Dose Conversion Coefficients (DCCs) expressed as dose deposited in organs per air kerma for photons, electrons and neutrons in the Annals of the ICRP. In this work the AP and PA irradiation geometries of the ICRP male phantom were simulated for the purpose of benchmarking the Geant4 code. Monoenergetic photons were simulated between 15 keV and 10 MeV and the results were compared with ICRP 110, the VMC Monte Carlo code and the literature data available, presenting a good agreement.

  17. Dose prediction and process optimization in a gamma sterilization facility using 3-D Monte Carlo code

    International Nuclear Information System (INIS)

    A model of a gamma sterilizer was built using the ITS/ACCEPT Monte Carlo code and verified through dosimetry. Individual dosimetry measurements in homogeneous material were pooled to represent larger bodies that could be simulated in a reasonable time. With the assumptions and simplifications described, dose predictions were within 2-5% of dosimetry. The model was used to simulate product movement through the sterilizer and to predict information useful for process optimization and facility design

  18. Monte Carlo N Particle code - Dose distribution of clinical electron beams in inhomogeneous phantoms

    Directory of Open Access Journals (Sweden)

    H A Nedaie

    2013-01-01

    Full Text Available Electron dose distributions calculated using the currently available analytical methods can be associated with large uncertainties. The Monte Carlo method is the most accurate method for dose calculation in electron beams. Most of the clinical electron beam simulation studies have been performed using non- MCNP [Monte Carlo N Particle] codes. Given the differences between Monte Carlo codes, this work aims to evaluate the accuracy of MCNP4C-simulated electron dose distributions in a homogenous phantom and around inhomogeneities. Different types of phantoms ranging in complexity were used; namely, a homogeneous water phantom and phantoms made of polymethyl methacrylate slabs containing different-sized, low- and high-density inserts of heterogeneous materials. Electron beams with 8 and 15 MeV nominal energy generated by an Elekta Synergy linear accelerator were investigated. Measurements were performed for a 10 cm × 10 cm applicator at a source-to-surface distance of 100 cm. Individual parts of the beam-defining system were introduced into the simulation one at a time in order to show their effect on depth doses. In contrast to the first scattering foil, the secondary scattering foil, X and Y jaws and applicator provide up to 5% of the dose. A 2%/2 mm agreement between MCNP and measurements was found in the homogenous phantom, and in the presence of heterogeneities in the range of 1-3%, being generally within 2% of the measurements for both energies in a "complex" phantom. A full-component simulation is necessary in order to obtain a realistic model of the beam. The MCNP4C results agree well with the measured electron dose distributions.

  19. Dose perturbation in the presence of metallic implants: treatment planning system versus Monte Carlo simulations

    Science.gov (United States)

    Wieslander, Elinore; Knöös, Tommy

    2003-10-01

    An increasing number of patients receiving radiation therapy have metallic implants such as hip prostheses. Therefore, beams are normally set up to avoid irradiation through the implant; however, this cannot always be accomplished. In such situations, knowledge of the accuracy of the used treatment planning system (TPS) is required. Two algorithms, the pencil beam (PB) and the collapsed cone (CC), are implemented in the studied TPS. Comparisons are made with Monte Carlo simulations for 6 and 18 MV. The studied materials are steel, CoCrMo, Orthinox® (a stainless steel alloy and registered trademark of Stryker Corporation), TiAlV and Ti. Monte Carlo simulated depth dose curves and dose profiles are compared to CC and PB calculated data. The CC algorithm shows overall a better agreement with Monte Carlo than the PB algorithm. Thus, it is recommended to use the CC algorithm to get the most accurate dose calculation both for the planning target volume and for tissues adjacent to the implants when beams are set up to pass through implants.

  20. Determination of dose distributions for clinical linear accelerators using Monte Carlo method in water phantom

    International Nuclear Information System (INIS)

    Different codes were used for Monte Carlo calculations in radiation therapy. In this study, a new Monte Carlo Simulation Program (MCSP) was developed for the effects of the physical parameters of photons emitted from a Siemens Primus clinical linear accelerator (LINAC) on the dose distribution in water. For MCSP, it was written considering interactions of photons with matter. Here, it was taken into account mainly two interactions: The Compton (or incoherent) scattering and photoelectric effect. Photons which come to water phantom surface emitting from a point source were Bremsstrahlung photons. It should be known the energy distributions of these photons for following photons. Bremsstrahlung photons which have 6 MeV (6 MV photon mode) maximum energies were taken into account. In the 6 MV photon mode, the energies of photons were sampled from using Mohan's experimental energy spectrum (Mohan at al 1985). In order to investigate the performance and accuracy of the simulation, measured and calculated (MCSP) percentage depth dose curves and dose profiles were compared. The Monte Carlo results were shown good agreement with experimental measurements.

  1. For Clinical Linear Accelerators, Obtaining of Dose Distributions in Water Phantoms by Using Monte Carlo Methods

    International Nuclear Information System (INIS)

    Different codes were used for Monte Carlo calculations in radiation therapy. In this study, a new Monte Carlo Simulation Program (MCSP) was developed for the effects of the physical parameters of photons emitted from a Siemens Primus clinical linear accelerator (LINAC) on the dose distribution in water. For MCSP, it was written considering interactions of photons with matter. Here, it was taken into account mainly two interactions: The Compton (or incoherent) scattering and photoelectric effect. Photons which come to water phantom surface emitting from a point source were Bremsstrahlung photons. It should be known the energy distributions of these photons for following photons. Bremsstrahlung photons which have 6 MeV (6 MV photon mode) maximum energies were taken into account. In the 6 MV photon mode, the energies of photons were sampled from using Mohan's experimental energy spectrum (Mohan at al 1985). In order to investigate the performance and accuracy of the simulation, measured and calculated (MCSP) percentage depth dose curves and dose profiles were compared. The Monte Carlo results were shown good agreement with experimental measurements.

  2. Applying graphics processor units to Monte Carlo dose calculation in radiation therapy

    Directory of Open Access Journals (Sweden)

    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.

  3. Assessment of the dose distribution inside a cardiac cath lab using TLD measurements and Monte Carlo simulations

    International Nuclear Information System (INIS)

    Over the last decade, there was a substantial increase in the number of interventional cardiology procedures worldwide, and the corresponding ionizing radiation doses for both the medical staff and patients became a subject of concern. Interventional procedures in cardiology are normally very complex, resulting in long exposure times. Also, these interventions require the operator to work near the patient and, consequently, close to the primary X-ray beam. Moreover, due to the scattered radiation from the patient and the equipment, the medical staff is also exposed to a non-uniform radiation field that can lead to a significant exposure of sensitive body organs and tissues, such as the eye lens, the thyroid and the extremities. In order to better understand the spatial variation of the dose and dose rate distributions during an interventional cardiology procedure, the dose distribution around a C-arm fluoroscopic system, in operation in a cardiac cath lab at Portuguese Hospital, was estimated using both Monte Carlo (MC) simulations and dosimetric measurements. To model and simulate the cardiac cath lab, including the fluoroscopic equipment used to execute interventional procedures, the state-of-the-art MC radiation transport code MCNPX 2.7.0 was used. Subsequently, Thermo-Luminescent Detector (TLD) measurements were performed, in order to validate and support the simulation results obtained for the cath lab model. The preliminary results presented in this study reveal that the cardiac cath lab model was successfully validated, taking into account the good agreement between MC calculations and TLD measurements. The simulated results for the isodose curves related to the C-arm fluoroscopic system are also consistent with the dosimetric information provided by the equipment manufacturer (Siemens). The adequacy of the implemented computational model used to simulate complex procedures and map dose distributions around the operator and the medical staff is discussed, in

  4. 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.)

  5. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  7. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Da; Li, Xinhua; Liu, Bob [Division of Diagnostic Imaging Physics and Webster Center for Advanced Research and Education in Radiation, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States); Gao, Yiming; Xu, X. George [Nuclear Engineering Program, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2013-08-15

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

  9. 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

  10. Uncertainties in Monte Carlo-based absorbed dose calculations for an experimental benchmark.

    Science.gov (United States)

    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

  11. Organ doses for reference pediatric and adolescent patients undergoing computed tomography estimated by Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Choonsik; Kim, Kwang Pyo; Long, Daniel J.; Bolch, Wesley E. [Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institute of Health, Bethesda, Maryland 20852 (United States); Department of Nuclear Engineering, Kyung Hee University, Gyeonggi-do, 446906 (Korea, Republic of); J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida 32611 (United States)

    2012-04-15

    Purpose: To establish an organ dose database for pediatric and adolescent reference individuals undergoing computed tomography (CT) examinations by using Monte Carlo simulation. The data will permit rapid estimates of organ and effective doses for patients of different age, gender, examination type, and CT scanner model. Methods: The Monte Carlo simulation model of a Siemens Sensation 16 CT scanner previously published was employed as a base CT scanner model. A set of absorbed doses for 33 organs/tissues normalized to the product of 100 mAs and CTDI{sub vol} (mGy/100 mAs mGy) was established by coupling the CT scanner model with age-dependent reference pediatric hybrid phantoms. A series of single axial scans from the top of head to the feet of the phantoms was performed at a slice thickness of 10 mm, and at tube potentials of 80, 100, and 120 kVp. Using the established CTDI{sub vol}- and 100 mAs-normalized dose matrix, organ doses for different pediatric phantoms undergoing head, chest, abdomen-pelvis, and chest-abdomen-pelvis (CAP) scans with the Siemens Sensation 16 scanner were estimated and analyzed. The results were then compared with the values obtained from three independent published methods: CT-Expo software, organ dose for abdominal CT scan derived empirically from patient abdominal circumference, and effective dose per dose-length product (DLP). Results: Organ and effective doses were calculated and normalized to 100 mAs and CTDI{sub vol} for different CT examinations. At the same technical setting, dose to the organs, which were entirely included in the CT beam coverage, were higher by from 40 to 80% for newborn phantoms compared to those of 15-year phantoms. An increase of tube potential from 80 to 120 kVp resulted in 2.5-2.9-fold greater brain dose for head scans. The results from this study were compared with three different published studies and/or techniques. First, organ doses were compared to those given by CT-Expo which revealed dose

  12. GPUMCD: a new GPU-oriented Monte Carlo dose calculation platform

    CERN Document Server

    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...

  13. Patient-dependent beam-modifier physics in Monte Carlo photon dose calculations.

    Science.gov (United States)

    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.

  14. Fast Monte Carlo Simulation for Patient-specific CT/CBCT Imaging Dose Calculation

    CERN Document Server

    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 ...

  15. SU-E-T-35: An Investigation of the Accuracy of Cervical IMRT Dose Distribution Using 2D/3D Ionization Chamber Arrays System and Monte Carlo Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y; Yang, J; Liu, H [Cangzhou People' s Hospital, Cangzhou, Hebei (China); Liu, D [The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei (China)

    2014-06-01

    Purpose: The purpose of this work is to compare the verification results of three solutions (2D/3D ionization chamber arrays measurement and Monte Carlo simulation), the results will help make a clinical decision as how to do our cervical IMRT verification. Methods: Seven cervical cases were planned with Pinnacle 8.0m to meet the clinical acceptance criteria. The plans were recalculated in the Matrixx and Delta4 phantom with the accurate plans parameters. The plans were also recalculated by Monte Carlo using leaf sequences and MUs for individual plans of every patient, Matrixx and Delta4 phantom. All plans of Matrixx and Delta4 phantom were delivered and measured. The dose distribution of iso slice, dose profiles, gamma maps of every beam were used to evaluate the agreement. Dose-volume histograms were also compared. Results: The dose distribution of iso slice and dose profiles from Pinnacle calculation were in agreement with the Monte Carlo simulation, Matrixx and Delta4 measurement. A 95.2%/91.3% gamma pass ratio was obtained between the Matrixx/Delta4 measurement and Pinnacle distributions within 3mm/3% gamma criteria. A 96.4%/95.6% gamma pass ratio was obtained between the Matrixx/Delta4 measurement and Monte Carlo simulation within 2mm/2% gamma criteria, almost 100% gamma pass ratio within 3mm/3% gamma criteria. The DVH plot have slightly differences between Pinnacle and Delta4 measurement as well as Pinnacle and Monte Carlo simulation, but have excellent agreement between Delta4 measurement and Monte Carlo simulation. Conclusion: It was shown that Matrixx/Delta4 and Monte Carlo simulation can be used very efficiently to verify cervical IMRT delivery. In terms of Gamma value the pass ratio of Matrixx was little higher, however, Delta4 showed more problem fields. The primary advantage of Delta4 is the fact it can measure true 3D dosimetry while Monte Carlo can simulate in patients CT images but not in phantom.

  16. A comparison of Monte Carlo and analytic first scatter dose spread arrays.

    Science.gov (United States)

    McGary, J E; Boyer, A L; Mackie, T R

    1999-05-01

    We compare first scattered point dose spread arrays generated by Monte Carlo and an analytic method. The analytic method models energy deposition using Klein-Nishina cross sections for Compton scatter and approximations for electron transport. Assumptions in the analytic method are shown to be valid within a region of the point dose spread kernel in which meaningful comparisons can be made. Differences between the models are less than 10% for the forward scatter directions for radii greater than the electron range associated with the first scattered Compton photon. Differences in the backscatter region are discussed and indicate that the analytic model is useful for identifying large errors that might be present in numerically generated first scatter point dose spread arrays. The analytic method is simple and useful for validating first scatter kernels. PMID:10360537

  17. Development of a Monte Carlo model for treatment planning dose verification of the Leksell Gamma Knife Perfexion radiosurgery system.

    Science.gov (United States)

    Yuan, Jiankui; Lo, Simon S; Zheng, Yiran; Sohn, Jason W; Sloan, Andrew E; Ellis, Rodney; Machtay, Mitchell; Wessels, Barry

    2016-01-01

    Detailed Monte Carlo (MC) modeling of the Leksell Gamma Knife (GK) Perfexion (PFX) collimator system is the only accurate ab initio approach appearing in the literature. As a different approach, in this work, we present a MC model based on film measurement. By adjusting the model parameters and fine-tuning the derived fluence map for each individual source to match the manufacturer's ring output factors, we created a reasonable virtual source model for MC simulations to verify treatment planning dose for the GK PFX radiosurgery system. The MC simulation model was commissioned by simple single shots. Dose profiles and both ring and collimator output factors were compared with the treatment planning system (TPS). Good agreement was achieved for dose profiles especially for the region of plateau (< 2%), while larger difference (< 5%) came from the penumbra region. The maximum difference of the calculated output factor was within 0.7%. The model was further validated by a clinical test case. Good agreement was obtained. The DVHs for brainstem and the skull were almost identical and, for the target, the volume covered by the prescription (12.5 Gy to 50% isodose line) was 95.6% from MC calculation versus 100% from the TPS. PMID:27455497

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

    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

  19. SU-E-T-238: Monte Carlo Estimation of Cerenkov Dose for Photo-Dynamic Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Chibani, O; Price, R; Ma, C [Fox Chase Cancer Center, Philadelphia, PA (United States); Eldib, A [Fox Chase Cancer Center, Philadelphia, PA (United States); University Cairo (Egypt); Mora, G [de Lisboa, Codex, Lisboa (Portugal)

    2014-06-01

    Purpose: Estimation of Cerenkov dose from high-energy megavoltage photon and electron beams in tissue and its impact on the radiosensitization using Protoporphyrine IX (PpIX) for tumor targeting enhancement in radiotherapy. Methods: The GEPTS Monte Carlo code is used to generate dose distributions from 18MV Varian photon beam and generic high-energy (45-MV) photon and (45-MeV) electron beams in a voxel-based tissueequivalent phantom. In addition to calculating the ionization dose, the code scores Cerenkov energy released in the wavelength range 375–425 nm corresponding to the pick of the PpIX absorption spectrum (Fig. 1) using the Frank-Tamm formula. Results: The simulations shows that the produced Cerenkov dose suitable for activating PpIX is 4000 to 5500 times lower than the overall radiation dose for all considered beams (18MV, 45 MV and 45 MeV). These results were contradictory to the recent experimental studies by Axelsson et al. (Med. Phys. 38 (2011) p 4127), where Cerenkov dose was reported to be only two orders of magnitude lower than the radiation dose. Note that our simulation results can be corroborated by a simple model where the Frank and Tamm formula is applied for electrons with 2 MeV/cm stopping power generating Cerenkov photons in the 375–425 nm range and assuming these photons have less than 1mm penetration in tissue. Conclusion: The Cerenkov dose generated by high-energy photon and electron beams may produce minimal clinical effect in comparison with the photon fluence (or dose) commonly used for photo-dynamic therapy. At the present time, it is unclear whether Cerenkov radiation is a significant contributor to the recently observed tumor regression for patients receiving radiotherapy and PpIX versus patients receiving radiotherapy only. The ongoing study will include animal experimentation and investigation of dose rate effects on PpIX response.

  20. Monte Carlo simulation of photon migration in a cloud computing environment with MapReduce.

    Science.gov (United States)

    Pratx, Guillem; Xing, Lei

    2011-12-01

    Monte Carlo simulation is considered the most reliable method for modeling photon migration in heterogeneous media. However, its widespread use is hindered by the high computational cost. The purpose of this work is to report on our implementation of a simple MapReduce method for performing fault-tolerant Monte Carlo computations in a massively-parallel cloud computing environment. We ported the MC321 Monte Carlo package to Hadoop, an open-source MapReduce framework. In this implementation, Map tasks compute photon histories in parallel while a Reduce task scores photon absorption. The distributed implementation was evaluated on a commercial compute cloud. The simulation time was found to be linearly dependent on the number of photons and inversely proportional to the number of nodes. For a cluster size of 240 nodes, the simulation of 100 billion photon histories took 22 min, a 1258 × speed-up compared to the single-threaded Monte Carlo program. The overall computational throughput was 85,178 photon histories per node per second, with a latency of 100 s. The distributed simulation produced the same output as the original implementation and was resilient to hardware failure: the correctness of the simulation was unaffected by the shutdown of 50% of the nodes. PMID:22191916

  1. Monte Carlo simulation of red bone marrow dose from CT examination

    International Nuclear Information System (INIS)

    To evaluate the methods of calculating red bone marrow dose from CT scan, simulating red bone marrow do ses from different CT scan protocols using different energy can provide the basic dose data for patient radiation protection. Method: Monte Carlo software MCNPX and RPI voxel phantom were used for the simulation, by mass absorption coefficient (MEAC) method, energy including 80 kV, 100 kV, 120 kV and 140 kV of the CT device were simulated, and different CT protocols such as chest scan, abdomen scan and body scan were taken into consideration when simulating the red bone marrow dose (mGy/100 mAs). Results: Under the same other conditions, the larger beam energy caused larger red bone marrow dose, the results of 140 kV was two times larger than that of 80 kV for the same protocol; while under the same beam energy, the difference among different protocol was less than 10%. Conclusion: Under the same conditions, the red bone marrow dose from CT scan depends on beam energy (tube voltage) and total effective mAs; if the total effective mAs was constant, the influence of scan protocol to red bone marrow dose was not much. (authors)

  2. 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

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

    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

  4. Environmental dose rate assessment of ITER using the Monte Carlo method

    Directory of Open Access Journals (Sweden)

    Karimian Alireza

    2014-01-01

    Full Text Available Exposure to radiation is one of the main sources of risk to staff employed in reactor facilities. The staff of a tokamak is exposed to a wide range of neutrons and photons around the tokamak hall. The International Thermonuclear Experimental Reactor (ITER is a nuclear fusion engineering project and the most advanced experimental tokamak in the world. From the radiobiological point of view, ITER dose rates assessment is particularly important. The aim of this study is the assessment of the amount of radiation in ITER during its normal operation in a radial direction from the plasma chamber to the tokamak hall. To achieve this goal, the ITER system and its components were simulated by the Monte Carlo method using the MCNPX 2.6.0 code. Furthermore, the equivalent dose rates of some radiosensitive organs of the human body were calculated by using the medical internal radiation dose phantom. Our study is based on the deuterium-tritium plasma burning by 14.1 MeV neutron production and also photon radiation due to neutron activation. As our results show, the total equivalent dose rate on the outside of the bioshield wall of the tokamak hall is about 1 mSv per year, which is less than the annual occupational dose rate limit during the normal operation of ITER. Also, equivalent dose rates of radiosensitive organs have shown that the maximum dose rate belongs to the kidney. The data may help calculate how long the staff can stay in such an environment, before the equivalent dose rates reach the whole-body dose limits.

  5. A Monte Carlo tool for raster-scanning particle therapy dose computation

    Science.gov (United States)

    Jelen, U.; Radon, M.; Santiago, A.; Wittig, A.; Ammazzalorso, F.

    2014-03-01

    Purpose of this work was to implement Monte Carlo (MC) dose computation in realistic patient geometries with raster-scanning, the most advanced ion beam delivery technique, combining magnetic beam deflection with energy variation. FLUKA, a Monte Carlo package well-established in particle therapy applications, was extended to simulate raster-scanning delivery with clinical data, unavailable as built-in feature. A new complex beam source, compatible with FLUKA public programming interface, was implemented in Fortran to model the specific properties of raster-scanning, i.e. delivery by means of multiple spot sources with variable spatial distributions, energies and numbers of particles. The source was plugged into the MC engine through the user hook system provided by FLUKA. Additionally, routines were provided to populate the beam source with treatment plan data, stored as DICOM RTPlan or TRiP98's RST format, enabling MC recomputation of clinical plans. Finally, facilities were integrated to read computerised tomography (CT) data into FLUKA. The tool was used to recompute two representative carbon ion treatment plans, a skull base and a prostate case, prepared with analytical dose calculation (TRiP98). Selected, clinically relevant issues influencing the dose distributions were investigated: (1) presence of positioning errors, (2) influence of fiducial markers and (3) variations in pencil beam width. Notable differences in modelling of these challenging situations were observed between the analytical and Monte Carlo results. In conclusion, a tool was developed, to support particle therapy research and treatment, when high precision MC calculations are required, e.g. in presence of severe density heterogeneities or in quality assurance procedures.

  6. Assessment of the dose distribution inside a cardiac cath lab using TLD measurements and Monte Carlo simulations

    Science.gov (United States)

    Baptista, M.; Teles, P.; Cardoso, G.; Vaz, P.

    2014-11-01

    Over the last decade, there was a substantial increase in the number of interventional cardiology procedures worldwide, and the corresponding ionizing radiation doses for both the medical staff and patients became a subject of concern. Interventional procedures in cardiology are normally very complex, resulting in long exposure times. Also, these interventions require the operator to work near the patient and, consequently, close to the primary X-ray beam. Moreover, due to the scattered radiation from the patient and the equipment, the medical staff is also exposed to a non-uniform radiation field that can lead to a significant exposure of sensitive body organs and tissues, such as the eye lens, the thyroid and the extremities. In order to better understand the spatial variation of the dose and dose rate distributions during an interventional cardiology procedure, the dose distribution around a C-arm fluoroscopic system, in operation in a cardiac cath lab at Portuguese Hospital, was estimated using both Monte Carlo (MC) simulations and dosimetric measurements. To model and simulate the cardiac cath lab, including the fluoroscopic equipment used to execute interventional procedures, the state-of-the-art MC radiation transport code MCNPX 2.7.0 was used. Subsequently, Thermo-Luminescent Detector (TLD) measurements were performed, in order to validate and support the simulation results obtained for the cath lab model. The preliminary results presented in this study reveal that the cardiac cath lab model was successfully validated, taking into account the good agreement between MC calculations and TLD measurements. The simulated results for the isodose curves related to the C-arm fluoroscopic system are also consistent with the dosimetric information provided by the equipment manufacturer (Siemens). The adequacy of the implemented computational model used to simulate complex procedures and map dose distributions around the operator and the medical staff is discussed, in

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  8. 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)

  9. 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

  10. Monte Carlo Dosimetry of the 60Co BEBIG High Dose Rate for Brachytherapy.

    Directory of Open Access Journals (Sweden)

    Luciana Tourinho Campos

    Full Text Available The use of high-dose-rate brachytherapy is currently a widespread practice worldwide. The most common isotope source is 192Ir, but 60Co is also becoming available for HDR. One of main advantages of 60Co compared to 192Ir is the economic and practical benefit because of its longer half-live, which is 5.27 years. Recently, Eckert & Ziegler BEBIG, Germany, introduced a new afterloading brachytherapy machine (MultiSource®; it has the option to use either the 60Co or 192Ir HDR source. The source for the Monte Carlo calculations is the new 60Co source (model Co0.A86, which is referred to as the new BEBIG 60Co HDR source and is a modified version of the 60Co source (model GK60M21, which is also from BEBIG.The purpose of this work is to obtain the dosimetry parameters in accordance with the AAPM TG-43U1 formalism with Monte Carlo calculations regarding the BEBIG 60Co high-dose-rate brachytherapy to investigate the required treatment-planning parameters. The geometric design and material details of the source was provided by the manufacturer and was used to define the Monte Carlo geometry. To validate the source geometry, a few dosimetry parameters had to be calculated according to the AAPM TG-43U1 formalism. The dosimetry studies included the calculation of the air kerma strength Sk, collision kerma in water along the transverse axis with an unbounded phantom, dose rate constant and radial dose function. The Monte Carlo code system that was used was EGSnrc with a new cavity code, which is a part of EGS++ that allows calculating the radial dose function around the source. The spectrum to simulate 60Co was composed of two photon energies, 1.17 and 1.33 MeV. Only the gamma part of the spectrum was used; the contribution of the electrons to the dose is negligible because of the full absorption by the stainless-steel wall around the metallic 60Co. The XCOM photon cross-section library was used in subsequent simulations, and the photoelectric effect, pair

  11. An improved Monte Carlo (MC) dose simulation for charged particle cancer therapy

    Energy Technology Data Exchange (ETDEWEB)

    Ying, C. K. [Advanced Medical and Dental Institute, AMDI, Universiti Sains Malaysia, Penang, Malaysia and School of Medical Sciences, Universiti Sains Malaysia, Kota Bharu (Malaysia); Kamil, W. A. [Advanced Medical and Dental Institute, AMDI, Universiti Sains Malaysia, Penang, Malaysia and Radiology Department, Hospital USM, Kota Bharu (Malaysia); Shuaib, I. L. [Advanced Medical and Dental Institute, AMDI, Universiti Sains Malaysia, Penang (Malaysia); Matsufuji, Naruhiro [Research Centre of Charged Particle Therapy, National Institute of Radiological Sciences, NIRS, Chiba (Japan)

    2014-02-12

    Heavy-particle therapy such as carbon ion therapy are more popular nowadays because of the nature characteristics of charged particle and almost no side effect to patients. An effective treatment is achieved with high precision of dose calculation, in this research work, Geant4 based Monte Carlo simulation method has been used to calculate the radiation transport and dose distribution. The simulation have the same setting with the treatment room in Heavy Ion Medical Accelerator, HIMAC. The carbon ion beam at the isocentric gantry nozzle for the therapeutic energy of 290 MeV/u was simulated, experimental work was carried out in National Institute of Radiological Sciences, NIRS, Chiba, Japan by using the HIMAC to confirm the accuracy and qualities dose distribution by MC methods. The Geant4 based simulated dose distribution were verified with measurements for Bragg peak and spread out Bragg peak (SOBP) respectively. The verification of results shows that the Bragg peak depth-dose and SOBP distributions in simulation has good agreement with measurements. In overall, the study showed that Geant4 based can be fully applied in the heavy-ion therapy field for simulation, further works need to be carry on to refine and improve the Geant4 MC simulations.

  12. An improved Monte Carlo (MC) dose simulation for charged particle cancer therapy

    Science.gov (United States)

    Ying, C. K.; Kamil, W. A.; Shuaib, I. L.; Matsufuji, Naruhiro

    2014-02-01

    Heavy-particle therapy such as carbon ion therapy are more popular nowadays because of the nature characteristics of charged particle and almost no side effect to patients. An effective treatment is achieved with high precision of dose calculation, in this research work, Geant4 based Monte Carlo simulation method has been used to calculate the radiation transport and dose distribution. The simulation have the same setting with the treatment room in Heavy Ion Medical Accelerator, HIMAC. The carbon ion beam at the isocentric gantry nozzle for the therapeutic energy of 290 MeV/u was simulated, experimental work was carried out in National Institute of Radiological Sciences, NIRS, Chiba, Japan by using the HIMAC to confirm the accuracy and qualities dose distribution by MC methods. The Geant4 based simulated dose distribution were verified with measurements for Bragg peak and spread out Bragg peak (SOBP) respectively. The verification of results shows that the Bragg peak depth-dose and SOBP distributions in simulation has good agreement with measurements. In overall, the study showed that Geant4 based can be fully applied in the heavy-ion therapy field for simulation, further works need to be carry on to refine and improve the Geant4 MC simulations.

  13. Characterization of 60Co dose distribution using BEAMnrc Monte Carlo code

    International Nuclear Information System (INIS)

    In this study BEAMnrc based on EGSnrc as Monte Carlo code has been used for modeling and simulating 60Co machine in radioisotope centre of Khartoum (RICK), Two fields size ( 5 cm x 5 cm and 35 cm x 35 cm), were been studied, to define the characterization of 60Co machine and to investigate the effect of increasing the surface to skin distance (SSD) on the 60Co machine properties, e.g.; beam profile and percentage depth dose (Pdd). For the narrow field size there is a small change observed in the curves representing beam profile and the percentage depth dose when increasing the distance by 5 cm, for the wide fi ld size there relatively clear different in curves. The study results been compared with other previous studies and clear consistence observed. (Author)

  14. The use of Monte Carlo technique to optimize the dose distribution in total skin irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Poli, M.E.R. E-mail: esmeraldapoli@hotmail.com; Pereira, S.A.; Yoriyaz, H

    2001-06-01

    Cutaneous T-cell lymphoma (mycosis fungoides) is an indolent disease with a low percentage of cure. Total skin irradiation using an electron beam has become an efficient treatment of mycosis fungoides with curative intention, with success in almost 40% of the patients. In this work, we propose the use of a Monte Carlo technique to simulate the dose distribution in the patients during total skin irradiation treatments. Use was made of MCNP-4B, a well known and established code used to simulate transport of electrons, photons and neutrons through matter, especially in the area of reactor physics, and also finding increasing utility in medical physics. The goal of our work is to simulate different angles between each beam with a fixed treatment distance in order to obtain a uniform dose distribution in the patient.

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

    CERN Document Server

    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...

  16. Monte Carlo analysis of pion contribution to absorbed dose from Galactic cosmic rays

    Energy Technology Data Exchange (ETDEWEB)

    Aghara, S.K. [Prairie View A and M University, Chemical Engineering (Nuclear Program), P.O. Box 519, MS 2505, Prairie View, TX 77446 (United States)], E-mail: Sukesh.K.Aghara@nasa.gov; Blattnig, S.R.; Norbury, J.W.; Singleterry, R.C. [NASA Langley Research Center, Hampton, VA 23681 (United States)

    2009-04-15

    Accurate knowledge of the physics of interaction, particle production and transport is necessary to estimate the radiation damage to equipment used on spacecraft and the biological effects of space radiation. For long duration astronaut missions, both on the International Space Station and the planned manned missions to Moon and Mars, the shielding strategy must include a comprehensive knowledge of the secondary radiation environment. The distribution of absorbed dose and dose equivalent is a function of the type, energy and population of these secondary products. Galactic cosmic rays (GCR) comprised of protons and heavier nuclei have energies from a few MeV per nucleon to the ZeV region, with the spectra reaching flux maxima in the hundreds of MeV range. Therefore, the MeV-GeV region is most important for space radiation. Coincidentally, the pion production energy threshold is about 280 MeV. The question naturally arises as to how important these particles are with respect to space radiation problems. The space radiation transport code, HZETRN (High charge (Z) and Energy TRaNsport), currently used by NASA, performs neutron, proton and heavy ion transport explicitly, but it does not take into account the production and transport of mesons, photons and leptons. In this paper, we present results from the Monte Carlo code MCNPX (Monte Carlo N-Particle eXtended), showing the effect of leptons and mesons when they are produced and transported in a GCR environment.

  17. Monte Carlo Analysis of Pion Contribution to Absorbed Dose from Galactic Cosmic Rays

    Science.gov (United States)

    Aghara, S.K.; Battnig, S.R.; Norbury, J.W.; Singleterry, R.C.

    2009-01-01

    Accurate knowledge of the physics of interaction, particle production and transport is necessary to estimate the radiation damage to equipment used on spacecraft and the biological effects of space radiation. For long duration astronaut missions, both on the International Space Station and the planned manned missions to Moon and Mars, the shielding strategy must include a comprehensive knowledge of the secondary radiation environment. The distribution of absorbed dose and dose equivalent is a function of the type, energy and population of these secondary products. Galactic cosmic rays (GCR) comprised of protons and heavier nuclei have energies from a few MeV per nucleon to the ZeV region, with the spectra reaching flux maxima in the hundreds of MeV range. Therefore, the MeV - GeV region is most important for space radiation. Coincidentally, the pion production energy threshold is about 280 MeV. The question naturally arises as to how important these particles are with respect to space radiation problems. The space radiation transport code, HZETRN (High charge (Z) and Energy TRaNsport), currently used by NASA, performs neutron, proton and heavy ion transport explicitly, but it does not take into account the production and transport of mesons, photons and leptons. In this paper, we present results from the Monte Carlo code MCNPX (Monte Carlo N-Particle eXtended), showing the effect of leptons and mesons when they are produced and transported in a GCR environment.

  18. Monte Carlo analysis of pion contribution to absorbed dose from Galactic cosmic rays

    Science.gov (United States)

    Aghara, S. K.; Blattnig, S. R.; Norbury, J. W.; Singleterry, R. C.

    2009-04-01

    Accurate knowledge of the physics of interaction, particle production and transport is necessary to estimate the radiation damage to equipment used on spacecraft and the biological effects of space radiation. For long duration astronaut missions, both on the International Space Station and the planned manned missions to Moon and Mars, the shielding strategy must include a comprehensive knowledge of the secondary radiation environment. The distribution of absorbed dose and dose equivalent is a function of the type, energy and population of these secondary products. Galactic cosmic rays (GCR) comprised of protons and heavier nuclei have energies from a few MeV per nucleon to the ZeV region, with the spectra reaching flux maxima in the hundreds of MeV range. Therefore, the MeV-GeV region is most important for space radiation. Coincidentally, the pion production energy threshold is about 280 MeV. The question naturally arises as to how important these particles are with respect to space radiation problems. The space radiation transport code, HZETRN (High charge (Z) and Energy TRaNsport), currently used by NASA, performs neutron, proton and heavy ion transport explicitly, but it does not take into account the production and transport of mesons, photons and leptons. In this paper, we present results from the Monte Carlo code MCNPX (Monte Carlo N-Particle eXtended), showing the effect of leptons and mesons when they are produced and transported in a GCR environment.

  19. Development of a GPU-based Monte Carlo dose calculation code for coupled electron-photon transport

    CERN Document Server

    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 .

  20. Accuracy and Radiation Dose of CT-Based Attenuation Correction for Small Animal PET: A Monte Carlo Simulation Study

    International Nuclear Information System (INIS)

    -Small animal PET allows qualitative assessment and quantitative measurement of biochemical processes in vivo, but the accuracy and reproducibility of imaging results can be affected by several parameters. The first aim of this study was to investigate the performance of different CT-based attenuation correction strategies and assess the resulting impact on PET images. The absorbed dose in different tissues caused by scanning procedures was also discussed to minimize biologic damage generated by radiation exposure due to PET/CT scanning. A small animal PET/CT system was modeled based on Monte Carlo simulation to generate imaging results and dose distribution. Three energy mapping methods, including the bilinear scaling method, the dual-energy method and the hybrid method which combines the kVp conversion and the dual-energy method, were investigated comparatively through assessing the accuracy of estimating linear attenuation coefficient at 511 keV and the bias introduced into PET quantification results due to CT-based attenuation correction. Our results showed that the hybrid method outperformed the bilinear scaling method, while the dual-energy method achieved the highest accuracy among the three energy mapping methods. Overall, the accuracy of PET quantification results have similar trend as that for the estimation of linear attenuation coefficients, whereas the differences between the three methods are more obvious in the estimation of linear attenuation coefficients than in the PET quantification results. With regards to radiation exposure from CT, the absorbed dose ranged between 7.29-45.58 mGy for 50-kVp scan and between 6.61-39.28 mGy for 80-kVp scan. For 18F radioactivity concentration of 1.86x105 Bq/ml, the PET absorbed dose was around 24 cGy for tumor with a target-to-background ratio of 8. The radiation levels for CT scans are not lethal to the animal, but concurrent use of PET in longitudinal study can increase the risk of biological effects. The

  1. Dosimetry and dose planning in boron neutron capture therapy : Monte Carlo studies

    Energy Technology Data Exchange (ETDEWEB)

    Koivunoro, H.

    2012-07-01

    Boron neutron capture therapy (BNCT) is a biologically targeted radiotherapy modality. So far, 249 cancer patients have received BNCT at the Finnish Research Reactor 1 (FiR 1) in Finland. The effectiveness and safety of radiotherapy are dependent on the radiation dose delivered to the tumor and healthy tissues, and on the accuracy of the doses. At FiR 1, patient dose calculations are performed with the Monte Carlo (MC) -based treatmentplanning system (TPS), Simulation Environment for Radiotherapy Applications (SERA). Initially, BNCT was applied to head and neck cancer, brain tumors, and malignant melanoma. To evaluate the applicability of the new target tumors for BNCT, calculation dosimetry studies are needed. So far, clinical BNCT has been performed with the neutrons from a nuclear reactor, while an accelerator based neutron sources applicable for hospital operation would be preferable. In this thesis, BNCT patient dose calculation practice in Finland was evaluated against reference calculations and experimental data in several cases. Calculations with two TPSs applied in clinical BNCT were compared. The suitability of the deuterium-deuterium (DD) and deuterium-tritium (D-T) fusion reaction-based compact neutron sources for BNCT were evaluated. In addition, feasibility of BNCT for noninvasive liver tumor treatments was examined. The deviation between SERA and the reference calculations was within 4% in the phantoms studied and in a brain cancer patient model elsewhere, except on the phantom or skin surface, for the boron, nitrogen, and photon dose components. These dose components produce 99% of the tumor dose and > 90% of the healthy tissue dose at points of relevance for treatment at the FiR 1 facility. The reduced voxel cell size ({<=} 0.5 cm) in the SERA edit mesh improved calculation accuracy on the surface. The erratic biased fastneutron run option in SERA led to significant underestimation (up to 30-60%) of the fastneutron dose, while more accurate fast

  2. Feasibility Study of Neutron Dose for Real Time Image Guided Proton Therapy: A Monte Carlo Study

    CERN Document Server

    Kim, Jin Sung; Kim, Daehyun; Shin, EunHyuk; Chung, Kwangzoo; Cho, Sungkoo; Ahn, Sung Hwan; Ju, Sanggyu; Chung, Yoonsun; Jung, Sang Hoon; Han, Youngyih

    2015-01-01

    Two full rotating gantry with different nozzles (Multipurpose nozzle with MLC, Scanning Dedicated nozzle) with conventional cyclotron system is installed and under commissioning for various proton treatment options at Samsung Medical Center in Korea. The purpose of this study is to investigate neutron dose equivalent per therapeutic dose, H/D, to x-ray imaging equipment under various treatment conditions with monte carlo simulation. At first, we investigated H/D with the various modifications of the beam line devices (Scattering, Scanning, Multi-leaf collimator, Aperture, Compensator) at isocenter, 20, 40, 60 cm distance from isocenter and compared with other research groups. Next, we investigated the neutron dose at x-ray equipments used for real time imaging with various treatment conditions. Our investigation showed the 0.07 ~ 0.19 mSv/Gy at x-ray imaging equipments according to various treatment options and intestingly 50% neutron dose reduction effect of flat panel detector was observed due to multi- lea...

  3. Monte Carlo simulation methods of determining red bone marrow dose from external radiation

    International Nuclear Information System (INIS)

    Objective: To provide evidence for a more reasonable method of determining red bone marrow dose by analyzing and comparing existing simulation methods. Methods: By utilizing Monte Carlo simulation software MCNPX, the absorbed doses of red hone marrow of Rensselaer Polytechnic Institute (RPI) adult female voxel phantom were calculated through 4 different methods: direct energy deposition.dose response function (DRF), King-Spiers factor method and mass-energy absorption coefficient (MEAC). The radiation sources were defined as infinite plate.sources with the energy ranging from 20 keV to 10 MeV, and 23 sources with different energies were simulated in total. The source was placed right next to the front of the RPI model to achieve a homogeneous anteroposterior radiation scenario. The results of different simulated photon energy sources through different methods were compared. Results: When the photon energy was lower than 100 key, the direct energy deposition method gave the highest result while the MEAC and King-Spiers factor methods showed more reasonable results. When the photon energy was higher than 150 keV taking into account of the higher absorption ability of red bone marrow at higher photon energy, the result of the King-Spiers factor method was larger than those of other methods. Conclusions: The King-Spiers factor method might be the most reasonable method to estimate the red bone marrow dose from external radiation. (authors)

  4. SU-E-T-29: A Web Application for GPU-Based Monte Carlo IMRT/VMAT QA with Delivered Dose Verification

    Energy Technology Data Exchange (ETDEWEB)

    Folkerts, M [The University of Texas Southwestern Medical Ctr, Dallas, TX (United States); University of California, San Diego, La Jolla, CA (United States); Graves, Y [University of California, San Diego, La Jolla, CA (United States); Tian, Z; Gu, X; Jia, X; Jiang, S [The University of Texas Southwestern Medical Ctr, Dallas, TX (United States)

    2014-06-01

    Purpose: To enable an existing web application for GPU-based Monte Carlo (MC) 3D dosimetry quality assurance (QA) to compute “delivered dose” from linac logfile data. Methods: We added significant features to an IMRT/VMAT QA web application which is based on existing technologies (HTML5, Python, and Django). This tool interfaces with python, c-code libraries, and command line-based GPU applications to perform a MC-based IMRT/VMAT QA. The web app automates many complicated aspects of interfacing clinical DICOM and logfile data with cutting-edge GPU software to run a MC dose calculation. The resultant web app is powerful, easy to use, and is able to re-compute both plan dose (from DICOM data) and delivered dose (from logfile data). Both dynalog and trajectorylog file formats are supported. Users upload zipped DICOM RP, CT, and RD data and set the expected statistic uncertainty for the MC dose calculation. A 3D gamma index map, 3D dose distribution, gamma histogram, dosimetric statistics, and DVH curves are displayed to the user. Additional the user may upload the delivery logfile data from the linac to compute a 'delivered dose' calculation and corresponding gamma tests. A comprehensive PDF QA report summarizing the results can also be downloaded. Results: We successfully improved a web app for a GPU-based QA tool that consists of logfile parcing, fluence map generation, CT image processing, GPU based MC dose calculation, gamma index calculation, and DVH calculation. The result is an IMRT and VMAT QA tool that conducts an independent dose calculation for a given treatment plan and delivery log file. The system takes both DICOM data and logfile data to compute plan dose and delivered dose respectively. Conclusion: We sucessfully improved a GPU-based MC QA tool to allow for logfile dose calculation. The high efficiency and accessibility will greatly facilitate IMRT and VMAT QA.

  5. SU-E-T-29: A Web Application for GPU-Based Monte Carlo IMRT/VMAT QA with Delivered Dose Verification

    International Nuclear Information System (INIS)

    Purpose: To enable an existing web application for GPU-based Monte Carlo (MC) 3D dosimetry quality assurance (QA) to compute “delivered dose” from linac logfile data. Methods: We added significant features to an IMRT/VMAT QA web application which is based on existing technologies (HTML5, Python, and Django). This tool interfaces with python, c-code libraries, and command line-based GPU applications to perform a MC-based IMRT/VMAT QA. The web app automates many complicated aspects of interfacing clinical DICOM and logfile data with cutting-edge GPU software to run a MC dose calculation. The resultant web app is powerful, easy to use, and is able to re-compute both plan dose (from DICOM data) and delivered dose (from logfile data). Both dynalog and trajectorylog file formats are supported. Users upload zipped DICOM RP, CT, and RD data and set the expected statistic uncertainty for the MC dose calculation. A 3D gamma index map, 3D dose distribution, gamma histogram, dosimetric statistics, and DVH curves are displayed to the user. Additional the user may upload the delivery logfile data from the linac to compute a 'delivered dose' calculation and corresponding gamma tests. A comprehensive PDF QA report summarizing the results can also be downloaded. Results: We successfully improved a web app for a GPU-based QA tool that consists of logfile parcing, fluence map generation, CT image processing, GPU based MC dose calculation, gamma index calculation, and DVH calculation. The result is an IMRT and VMAT QA tool that conducts an independent dose calculation for a given treatment plan and delivery log file. The system takes both DICOM data and logfile data to compute plan dose and delivered dose respectively. Conclusion: We sucessfully improved a GPU-based MC QA tool to allow for logfile dose calculation. The high efficiency and accessibility will greatly facilitate IMRT and VMAT QA

  6. Monte Carlo estimation of radiation doses during paediatric barium meal and cystourethrography examinations

    Energy Technology Data Exchange (ETDEWEB)

    Dimitriadis, A; Gialousis, G; Karlatira, M; Karaiskos, P; Georgiou, E; Yakoumakis, E [Medical Physics Department, Medical School, University of Athens, 75 Mikras Asias Str., Goudi 11527, Athens (Greece); Makri, T; Papaodysseas, S, E-mail: anestisdim@yahoo.com [Radiological Imaging Department, Ag. Sofia Hospital, Lebadias and Thibon, Goudi 11527, Athens (Greece)

    2011-01-21

    Organ doses are important quantities in assessing the radiation risk. In the case of children, estimation of this risk is of particular concern due to their significant radiosensitivity and the greater health detriment. The purpose of this study is to estimate the organ doses to paediatric patients undergoing barium meal and micturating cystourethrography examinations by clinical measurements and Monte Carlo simulation. In clinical measurements, dose-area products (DAPs) were assessed during examination of 50 patients undergoing barium meal and 90 patients undergoing cystourethrography examinations, separated equally within three age categories: namely newborn, 1 year and 5 years old. Monte Carlo simulation of photon transport in male and female mathematical phantoms was applied using the MCNP5 code in order to estimate the equivalent organ doses. Regarding the micturating cystourethrography examinations, the organs receiving considerable amounts of radiation doses were the urinary bladder (1.87, 2.43 and 4.7 mSv, the first, second and third value in the parentheses corresponds to neonatal, 1 year old and 5 year old patients, respectively), the large intestines (1.54, 1.8, 3.1 mSv), the small intestines (1.34, 1.56, 2.78 mSv), the stomach (1.46, 1.02, 2.01 mSv) and the gall bladder (1.46, 1.66, 2.18 mSv), depending upon the age of the child. Organs receiving considerable amounts of radiation during barium meal examinations were the stomach (9.81, 9.92, 11.5 mSv), the gall bladder (3.05, 5.74, 7.15 mSv), the rib bones (9.82, 10.1, 11.1 mSv) and the pancreas (5.8, 5.93, 6.65 mSv), depending upon the age of the child. DAPs to organ/effective doses conversion factors were derived for each age and examination in order to be compared with other studies.

  7. First macro Monte Carlo based commercial dose calculation module for electron beam treatment planning—new issues for clinical consideration

    Science.gov (United States)

    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.

  8. Development of Monte Carlo simulations to provide scanner-specific organ dose coefficients for contemporary CT

    Science.gov (United States)

    Jansen, Jan T. M.; Shrimpton, Paul C.

    2016-07-01

    The ImPACT (imaging performance assessment of CT scanners) CT patient dosimetry calculator is still used world-wide to estimate organ and effective doses (E) for computed tomography (CT) examinations, although the tool is based on Monte Carlo calculations reflecting practice in the early 1990’s. Subsequent developments in CT scanners, definitions of E, anthropomorphic phantoms, computers and radiation transport codes, have all fuelled an urgent need for updated organ dose conversion factors for contemporary CT. A new system for such simulations has been developed and satisfactorily tested. Benchmark comparisons of normalised organ doses presently derived for three old scanners (General Electric 9800, Philips Tomoscan LX and Siemens Somatom DRH) are within 5% of published values. Moreover, calculated normalised values of CT Dose Index for these scanners are in reasonable agreement (within measurement and computational uncertainties of  ±6% and  ±1%, respectively) with reported standard measurements. Organ dose coefficients calculated for a contemporary CT scanner (Siemens Somatom Sensation 16) demonstrate potential deviations by up to around 30% from the surrogate values presently assumed (through a scanner matching process) when using the ImPACT CT Dosimetry tool for newer scanners. Also, illustrative estimates of E for some typical examinations and a range of anthropomorphic phantoms demonstrate the significant differences (by some 10’s of percent) that can arise when changing from the previously adopted stylised mathematical phantom to the voxel phantoms presently recommended by the International Commission on Radiological Protection (ICRP), and when following the 2007 ICRP recommendations (updated from 1990) concerning tissue weighting factors. Further simulations with the validated dosimetry system will provide updated series of dose coefficients for a wide range of contemporary scanners.

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

    Science.gov (United States)

    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.

  10. Comparison between Acuros XB and Brainlab Monte Carlo algorithms for photon dose calculation

    Energy Technology Data Exchange (ETDEWEB)

    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.)

  11. The use of Monte Carlo technique to optimize the dose distribution in total skin irradiation

    International Nuclear Information System (INIS)

    Cutaneous T-cell lymphoma (Mycosis Fungoides) is an indolent disease with a low percentage of cure. The total skin irradiation with electron beam became an efficient treatment of mycosis fungoides with curative intention, with success in almost 40% of the patients. The classical technique was developed in Stanford, where patients are irradiated in all longitudinal extension. Two angled fields of about 20 degrees are used, above and below the horizontal line, passing through from the waistline of the patient on foot, distant 3 meters from the focus. During the treatment, 4 or 6 pairs of these beams irradiate the patient; being rotated 90 or 60 degrees on his longitudinal axis, respectively. The energy normally used is about 3-7 MeV. The determination of the dose distribution in the patient can be made in many different ways: using three parallel-plate ionization chambers (Victoreen-Holt plus CNMC 206 electrometer) in the air, using dosimetric films and others. In the first case, at least three ionization chambers are necessary, which is unusual in Brazilian hospitals. In the second case, a lot of dosimetric films are necessary, which is too expensive. In this work, we propose the use of the Monte Carlo technique to simulate the dose distribution in the patients during Total Skin Irradiation treatments. The Monte Carlo code used is the MCNP4B, a well known and established code used to perform the transport of electrons, photons and neutrons through matter, especially in reactor physics, but with increasing utilization in medical physics in recent years. The goals of our work is to simulate different angles between each beam with a fixed treatment distance, which is characteristic of each treatment room, in order to obtain a uniform dose distribution in the patient. (author)

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

    Science.gov (United States)

    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

  13. Evaluation of organ doses in adult and paediatric CT examinations based on Monte Carlo simulations and in-phantom dosimetry.

    Science.gov (United States)

    Fujii, K; Nomura, K; Muramatsu, Y; Takahashi, K; Obara, S; Akahane, K; Satake, M

    2015-07-01

    The aim of this study was to validate the computed tomography dose index (CTDI) and organ doses evaluated by Monte Carlo simulations through comparisons with doses evaluated by in-phantom dosimetry. Organ doses were measured with radio-photoluminescence glass dosemeter (RGD) set at various organ positions within adult and 1-y-old anthropomorphic phantoms. For the dose simulations, the X-ray spectrum and bow-tie filter shape of a CT scanner were estimated and 3D voxelised data of the CTDI and anthropomorphic phantoms from the acquired CT images were derived. Organ dose simulations and measurements were performed with chest and abdomen-pelvis CT examination scan parameters. Relative differences between the simulated and measured doses were within 5 % for the volume CTDI and 13 % for organ doses for organs within the scan range in adult and paediatric CT examinations. The simulation results were considered to be in good agreement with the measured doses. PMID:25848103

  14. An approach to using conventional brachytherapy software for clinical treatment planning of complex, Monte Carlo-based brachytherapy dose distributions

    Energy Technology Data Exchange (ETDEWEB)

    Rivard, Mark J.; Melhus, Christopher S.; Granero, Domingo; Perez-Calatayud, Jose; Ballester, Facundo [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Radiation Oncology Department, Physics Section, ' ' La Fe' ' University Hospital, Avenida Campanar 21, E-46009 Valencia (Spain); Department of Atomic, Molecular, and Nuclear Physics, University of Valencia, C/Dr. Moliner 50, E-46100 Burjassot, Spain and IFIC (University of Valencia-CSIC), C/Dr. Moliner 50, E-46100 Burjassot (Spain)

    2009-06-15

    Certain brachytherapy dose distributions, such as those for LDR prostate implants, are readily modeled by treatment planning systems (TPS) that use the superposition principle of individual seed dose distributions to calculate the total dose distribution. However, dose distributions for brachytherapy treatments using high-Z shields or having significant material heterogeneities are not currently well modeled using conventional TPS. The purpose of this study is to establish a new treatment planning technique (Tufts technique) that could be applied in some clinical situations where the conventional approach is not acceptable and dose distributions present cylindrical symmetry. Dose distributions from complex brachytherapy source configurations determined with Monte Carlo methods were used as input data. These source distributions included the 2 and 3 cm diameter Valencia skin applicators from Nucletron, 4-8 cm diameter AccuBoost peripheral breast brachytherapy applicators from Advanced Radiation Therapy, and a 16 mm COMS-based eye plaque using {sup 103}Pd, {sup 125}I, and {sup 131}Cs seeds. Radial dose functions and 2D anisotropy functions were obtained by positioning the coordinate system origin along the dose distribution cylindrical axis of symmetry. Origin:tissue distance and active length were chosen to minimize TPS interpolation errors. Dosimetry parameters were entered into the PINNACLE TPS, and dose distributions were subsequently calculated and compared to the original Monte Carlo-derived dose distributions. The new planning technique was able to reproduce brachytherapy dose distributions for all three applicator types, producing dosimetric agreement typically within 2% when compared with Monte Carlo-derived dose distributions. Agreement between Monte Carlo-derived and planned dose distributions improved as the spatial resolution of the fitted dosimetry parameters improved. For agreement within 5% throughout the clinical volume, spatial resolution of

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

    Science.gov (United States)

    Koger, B; Kirkby, C

    2016-03-01

    Gold nanoparticles (GNPs) have shown potential in recent years as a means of therapeutic dose enhancement in radiation therapy. However, a major challenge in moving towards clinical implementation is the exact characterisation of the dose enhancement they provide. Monte Carlo studies attempt to explore this property, but they often face computational limitations when examining macroscopic scenarios. In this study, a method of converting dose from macroscopic simulations, where the medium is defined as a mixture containing both gold and tissue components, to a mean dose-to-tissue on a microscopic scale was established. Monte Carlo simulations were run for both explicitly-modeled GNPs in tissue and a homogeneous mixture of tissue and gold. A dose ratio was obtained for the conversion of dose scored in a mixture medium to dose-to-tissue in each case. Dose ratios varied from 0.69 to 1.04 for photon sources and 0.97 to 1.03 for electron sources. The dose ratio is highly dependent on the source energy as well as GNP diameter and concentration, though this effect is less pronounced for electron sources. By appropriately weighting the monoenergetic dose ratios obtained, the dose ratio for any arbitrary spectrum can be determined. This allows complex scenarios to be modeled accurately without explicitly simulating each individual GNP. PMID:26895030

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

    Science.gov (United States)

    Koger, B.; Kirkby, C.

    2016-03-01

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

  17. Monte Carlo dosimetric study of the medium dose rate CSM40 source

    International Nuclear Information System (INIS)

    The 137Cs medium dose rate (MDR) CSM40 source model (Eckert and Ziegler BEBIG, Germany) is in clinical use but no dosimetric dataset has been published. This study aims to obtain dosimetric data for the CSM40 source for its use in clinical practice as required by the American Association of Physicists in Medicine (AAPM) and the European Society for Radiotherapy and Oncology (ESTRO). Penelope2008 and Geant4 Monte Carlo codes were used to characterize this source dosimetrically. It was located in an unbounded water phantom with composition and mass density as recommended by AAPM and ESTRO. Due to the low photon energies of 137Cs, absorbed dose was approximated by collisional kerma. Additional simulations were performed to obtain the air-kerma strength, sK. Mass–energy absorption coefficients in water and air were consistently derived and used to calculate collisional kerma. Results performed with both radiation transport codes showed agreement typically within 0.05%. Dose rate constant, radial dose function and anisotropy function are provided for the CSM40 and compared with published data for other commercially available 137Cs sources. An uncertainty analysis has been performed. The data provided by this study can be used as input data and verification in the treatment planning systems. - Highlights: • A dosimetric dataset is obtained for the 137Cs medium dose rate CSM40 source model. • Along-away table and TG-43 formalism parameters and functions are derived as recommended by AAPM-ESTRO. • This can be used as input data and verification in the treatment planning systems used in clinical practice

  18. An Analytic Linear Accelerator Source Model for Monte Carlo Dose Calculations. I. Model Representation and Construction

    CERN Document Server

    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...

  19. Dose and shielding calculation of galactic cosmic ray using FLUKA Mont Carlo code

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

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

    2013-01-01

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

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

    Science.gov (United States)

    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

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

    International Nuclear Information System (INIS)

    Isotope production and Application Division of Bhabha Atomic Research Center developed 32P patch sources for treatment of superficial tumors. Surface dose rate of a newly developed 32P patch source of nominal diameter 25 mm was measured experimentally using standard extrapolation ionization chamber and Gafchromic EBT film. Monte Carlo model of the 32P patch source along with the extrapolation chamber was also developed to estimate the surface dose rates from these sources. The surface dose rates to tissue (cGy/min) measured using extrapolation chamber and radiochromic films are 82.03±4.18 (k=2) and 79.13±2.53 (k=2) respectively. The two values of the surface dose rates measured using the two independent experimental methods are in good agreement to each other within a variation of 3.5%. The surface dose rate to tissue (cGy/min) estimated using the MCNP Monte Carlo code works out to be 77.78±1.16 (k=2). The maximum deviation between the surface dose rates to tissue obtained by Monte Carlo and the extrapolation chamber method is 5.2% whereas the difference between the surface dose rates obtained by radiochromic film measurement and the Monte Carlo simulation is 1.7%. The three values of the surface dose rates of the 32P patch source obtained by three independent methods are in good agreement to one another within the uncertainties associated with their measurements and calculation. This work has demonstrated that MCNP based electron transport simulations are accurate enough for determining the dosimetry parameters of the indigenously developed 32P patch sources for contact brachytherapy applications. - Highlights: • Surface dose rates of 25 mm nominal diameter newly developed 32P patch sources were measured experimentally using extrapolation chamber and Gafchromic EBT2 film. Monte Carlo model of the 32P patch source along with the extrapolation chamber was also developed. • The surface dose rates to tissue (cGy/min) measured using extrapolation chamber and

  3. Pion and electromagnetic contribution to dose: Comparisons of HZETRN to Monte Carlo results and ISS data

    Science.gov (United States)

    Slaba, Tony C.; Blattnig, Steve R.; Reddell, Brandon; Bahadori, Amir; Norman, Ryan B.; Badavi, Francis F.

    2013-07-01

    Recent work has indicated that pion production and the associated electromagnetic (EM) cascade may be an important contribution to the total astronaut exposure in space. Recent extensions to the deterministic space radiation transport code, HZETRN, allow the production and transport of pions, muons, electrons, positrons, and photons. In this paper, the extended code is compared to the Monte Carlo codes, Geant4, PHITS, and FLUKA, in slab geometries exposed to galactic cosmic ray (GCR) boundary conditions. While improvements in the HZETRN transport formalism for the new particles are needed, it is shown that reasonable agreement on dose is found at larger shielding thicknesses commonly found on the International Space Station (ISS). Finally, the extended code is compared to ISS data on a minute-by-minute basis over a seven day period in 2001. The impact of pion/EM production on exposure estimates and validation results is clearly shown. The Badhwar-O'Neill (BO) 2004 and 2010 models are used to generate the GCR boundary condition at each time-step allowing the impact of environmental model improvements on validation results to be quantified as well. It is found that the updated BO2010 model noticeably reduces overall exposure estimates from the BO2004 model, and the additional production mechanisms in HZETRN provide some compensation. It is shown that the overestimates provided by the BO2004 GCR model in previous validation studies led to deflated uncertainty estimates for environmental, physics, and transport models, and allowed an important physical interaction (π/EM) to be overlooked in model development. Despite the additional π/EM production mechanisms in HZETRN, a systematic under-prediction of total dose is observed in comparison to Monte Carlo results and measured data.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    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

  6. Radioactivity determination of sealed pure beta-sources by surface dose measurements and Monte Carlo simulations

    Science.gov (United States)

    Choi, Chang Heon; Jung, Seongmoon; Choi, Kanghyuk; Son, Kwang-Jae; Lee, Jun Sig; Ye, Sung-Joon

    2016-04-01

    This study aims to determine the activity of a sealed pure beta-source by measuring the surface dose rate using an extrapolation chamber. A conversion factor (cGy s-1 Bq-1), which was defined as the ratio of surface dose rate to activity, can be calculated by Monte Carlo simulations of the extrapolation chamber measurement. To validate this hypothesis the certified activities of two standard pure beta-sources of Sr/Y-90 and Si/P-32 were compared with those determined by this method. In addition, a sealed test source of Sr/Y-90 was manufactured by the HANARO reactor group of KAERI (Korea Atomic Energy Research Institute) and used to further validate this method. The measured surface dose rates of the Sr/Y-90 and Si/P-32 standard sources were 4.615×10-5 cGy s-1 and 2.259×10-5 cGy s-1, respectively. The calculated conversion factors of the two sources were 1.213×10-8 cGy s-1 Bq-1 and 1.071×10-8 cGy s-1 Bq-1, respectively. Therefore, the activity of the standard Sr/Y-90 source was determined to be 3.995 kBq, which was 2.0% less than the certified value (4.077 kBq). For Si/P-32 the determined activity was 2.102 kBq, which was 6.6% larger than the certified activity (1.971 kBq). The activity of the Sr/Y-90 test source was determined to be 4.166 kBq, while the apparent activity reported by KAERI was 5.803 kBq. This large difference might be due to evaporation and diffusion of the source liquid during preparation and uncertainty in the amount of weighed aliquot of source liquid. The overall uncertainty involved in this method was determined to be 7.3%. We demonstrated that the activity of a sealed pure beta-source could be conveniently determined by complementary combination of measuring the surface dose rate and Monte Carlo simulations.

  7. Development and verification of an analytical algorithm to predict absorbed dose distributions in ocular proton therapy using Monte Carlo simulations.

    Science.gov (United States)

    Koch, Nicholas C; Newhauser, Wayne D

    2010-02-01

    Proton beam radiotherapy is an effective and non-invasive treatment for uveal melanoma. Recent research efforts have focused on improving the dosimetric accuracy of treatment planning and overcoming the present limitation of relative analytical dose calculations. Monte Carlo algorithms have been shown to accurately predict dose per monitor unit (D/MU) values, but this has yet to be shown for analytical algorithms dedicated to ocular proton therapy, which are typically less computationally expensive than Monte Carlo algorithms. The objective of this study was to determine if an analytical method could predict absolute dose distributions and D/MU values for a variety of treatment fields like those used in ocular proton therapy. To accomplish this objective, we used a previously validated Monte Carlo model of an ocular nozzle to develop an analytical algorithm to predict three-dimensional distributions of D/MU values from pristine Bragg peaks and therapeutically useful spread-out Bragg peaks (SOBPs). Results demonstrated generally good agreement between the analytical and Monte Carlo absolute dose calculations. While agreement in the proximal region decreased for beams with less penetrating Bragg peaks compared with the open-beam condition, the difference was shown to be largely attributable to edge-scattered protons. A method for including this effect in any future analytical algorithm was proposed. Comparisons of D/MU values showed typical agreement to within 0.5%. We conclude that analytical algorithms can be employed to accurately predict absolute proton dose distributions delivered by an ocular nozzle.

  8. Development and verification of an analytical algorithm to predict absorbed dose distributions in ocular proton therapy using Monte Carlo simulations

    International Nuclear Information System (INIS)

    Proton beam radiotherapy is an effective and non-invasive treatment for uveal melanoma. Recent research efforts have focused on improving the dosimetric accuracy of treatment planning and overcoming the present limitation of relative analytical dose calculations. Monte Carlo algorithms have been shown to accurately predict dose per monitor unit (D/MU) values, but this has yet to be shown for analytical algorithms dedicated to ocular proton therapy, which are typically less computationally expensive than Monte Carlo algorithms. The objective of this study was to determine if an analytical method could predict absolute dose distributions and D/MU values for a variety of treatment fields like those used in ocular proton therapy. To accomplish this objective, we used a previously validated Monte Carlo model of an ocular nozzle to develop an analytical algorithm to predict three-dimensional distributions of D/MU values from pristine Bragg peaks and therapeutically useful spread-out Bragg peaks (SOBPs). Results demonstrated generally good agreement between the analytical and Monte Carlo absolute dose calculations. While agreement in the proximal region decreased for beams with less penetrating Bragg peaks compared with the open-beam condition, the difference was shown to be largely attributable to edge-scattered protons. A method for including this effect in any future analytical algorithm was proposed. Comparisons of D/MU values showed typical agreement to within 0.5%. We conclude that analytical algorithms can be employed to accurately predict absolute proton dose distributions delivered by an ocular nozzle.

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

    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

  10. Spatial fractionation of the dose using neon and heavier ions: A Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Peucelle, C.; Martínez-Rovira, I.; Prezado, Y., E-mail: prezado@imnc.in2p3.fr [IMNC-UMR 8165, CNRS Paris 7 and Paris 11 Universities, 15 rue Georges Clemenceau, Orsay Cedex 91406 (France)

    2015-10-15

    Purpose: This work explores a new radiation therapy approach which might trigger a renewed use of neon and heavier ions to treat cancers. These ions were shown to be extremely efficient in radioresistant tumor killing. Unfortunately, the efficient region also extends into the normal tissue in front of the tumor. The strategy the authors propose is to profit from the well-established sparing effect of thin spatially fractionated beams, so that the impact on normal tissues might be minimized while a high tumor control is achieved. The main goal of this work is to provide a proof of concept of this new approach. With that aim, a dosimetric study was carried out as a first step to evaluate the interest of further explorations of this avenue. Methods: The GATE/GEANT4 v.6.1 Monte Carlo simulation platform was employed to simulate arrays of rectangular minibeams (700 μm × 2 cm) of four ions (Ne, Si, Ar, and Fe). The irradiations were performed with a 2 cm-long spread-out Bragg peak centered at 7 cm-depth. Dose distributions in a water phantom were scored considering two minibeams center-to-center distances: 1400 and 3500 μm. Peak and valley doses, peak-to-valley dose ratios (PVDRs), beam penumbras, and relative contribution of nuclear fragments and electromagnetic processes were assessed as figures of merit. In addition, the type and proportion of the secondary nuclear fragments were evaluated in both peak and valley regions. Results: Extremely high PVDR values (>100) and low valley doses were obtained. The higher the atomic number (Z) of the primary ion is, the lower the valleys and the narrower the penumbras. Although the yield of secondary nuclear products increases with Z, the actual dose being deposited by the secondary nuclear fragments in the valleys starts to be the dominant contribution at deeper points, helping in the sparing of proximal normal tissues. Additionally, a wider center-to-center distance leads to a minimized contribution of heavier secondary

  11. Monte Carlo investigation of backscatter factors for skin dose determination in interventional neuroradiology procedures

    Science.gov (United States)

    Omar, Artur; Benmakhlouf, Hamza; Marteinsdottir, Maria; Bujila, Robert; Nowik, Patrik; Andreo, Pedro

    2014-03-01

    Complex interventional and diagnostic x-ray angiographic (XA) procedures may yield patient skin doses exceeding the threshold for radiation induced skin injuries. Skin dose is conventionally determined by converting the incident air kerma free-in-air into entrance surface air kerma, a process that requires the use of backscatter factors. Subsequently, the entrance surface air kerma is converted into skin kerma using mass energy-absorption coefficient ratios tissue-to-air, which for the photon energies used in XA is identical to the skin dose. The purpose of this work was to investigate how the cranial bone affects backscatter factors for the dosimetry of interventional neuroradiology procedures. The PENELOPE Monte Carlo system was used to calculate backscatter factors at the entrance surface of a spherical and a cubic water phantom that includes a cranial bone layer. The simulations were performed for different clinical x-ray spectra, field sizes, and thicknesses of the bone layer. The results show a reduction of up to 15% when a cranial bone layer is included in the simulations, compared with conventional backscatter factors calculated for a homogeneous water phantom. The reduction increases for thicker bone layers, softer incident beam qualities, and larger field sizes, indicating that, due to the increased photoelectric crosssection of cranial bone compared to water, the bone layer acts primarily as an absorber of low-energy photons. For neurointerventional radiology procedures, backscatter factors calculated at the entrance surface of a water phantom containing a cranial bone layer increase the accuracy of the skin dose determination.

  12. Variations of dose to the lung during computed tomography (CT) thorax examinations: A Monte Carlo study

    International Nuclear Information System (INIS)

    This study determined the influence of patient individuality on lung organ doses for chest CT examinations. The aim was a statistical statement on the variability as well as the uncertainty caused by the patient individuality. Furthermore, the reproducibility of the mean organ dose value of the lung using the new ICRP 110 voxelized adult female phantom was determined. Calculation of lung doses for 61 female chest CT studies with identical scan parameters (120 kV, 135 mAs, 100 mm collimation, 1.5 pitch) were done. For all patients, the lung was contoured and the geometry was simulated using the Monte Carlo method without patient table and with its original voxel size. The lungs were completely included in the scan area. A so-called user code CTDOSPP was developed which extends the Monte Carlo package EGSnrc and enables rotational simulation of CT X-ray sources. A developed graphical user interface GMctdospp allows easy handling of simulation parameters and CT studies, which are loaded in the DicomRT struct format. The transformation of CT values to material and density values is carried out with a standard relationship. The ICRP adult female material composition of all organs were directly taken from the publication. The patient table and bed and pillow were assumed to be air in order to be similar to patient pool. All simulations were calibrated for better handling and visualisation to a CTDIair value of 22.9 mGy. Simulation values were grouped into 1 mSv classes. The organ dose classes fit well to a Gaussian distribution (correlation coefficient R2 = 0.97). The fit's mean value is 10 mSv with a standard deviation of 2 mSv. The variability is about ± 30 % with minimum at 8 mSv and maximum at 13 mSv. The calculated organ dose to the lungs of the ICRP adult female phantom is about 11 mSv and thus within the calculated standard deviation of the patient pool. For all simulations the statistical uncertainty was between 2 and 3.5 %. This present study shows good

  13. PCXMC. A PC-based Monte Carlo program for calculating patient doses in medical x-ray examinations

    International Nuclear Information System (INIS)

    The report describes PCXMC, a Monte Carlo program for calculating patients' organ doses and the effective dose in medical x-ray examinations. The organs considered are: the active bone marrow, adrenals, brain, breasts, colon (upper and lower large intestine), gall bladder, heats, kidneys, liver, lungs, muscle, oesophagus, ovaries, pancreas, skeleton, skin, small intestine, spleen, stomach, testes, thymes, thyroid, urinary bladder, and uterus. (42 refs.)

  14. Using MCNP and Monte Carlo method for Investigation of dose field of Irradiation facility at Hanoi Irradiation Center

    International Nuclear Information System (INIS)

    MCNP and Monte Carlo method was used to calculate dose rate in the air-space of irradiation room at Hanoi Irradiation Center. Experiment measurements were also carried out to investigate the real distribution of dose field in air of the irradiator as well as the distribution of absorbed dose in sample product containers. The results show that there is a deviation between calculated data given by MCNP and measurements. The data of MCNP give a symmetric distribution of dose field against the axes going through the center of the source rack meanwhile the experiment data show that dose rate get higher values in the lower part of the space. Going to lower position to the floor dose rate getting higher value. This phenomenon was also occurred for the measurements of absorbed dose in sample product container. (author)

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

    Science.gov (United States)

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

    2015-10-01

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

  16. 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)

  17. 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)

  18. Dose point kernel simulation for monoenergetic electrons and radionuclides using monte Carlo techniques

    International Nuclear Information System (INIS)

    Monte Carlo (MC) simulation has been commonly used in the dose evaluation of radiation accidents and for medical purposes. The accuracy of simulated results is affected by the particle-tracking algorithm, cross-sectional database, random number generator and statistical error. The differences among MC simulation software packages must be validated. This study simulated the dose point kernel (DPK) and the cellular S-values of monoenergetic electrons ranging from 0.01 to 2 MeV and the radionuclides of 90Y, 177Lu and 103mmRh, using Fluktuierende Kaskade (FLUKA) and MC N-Particle Transport Code Version 5 (MCNP5). A 6-μm-radius cell model consisting of the cell surface, cytoplasm and cell nucleus was constructed for cellular S-value calculation. The mean absolute percentage errors (MAPEs) of the scaled DPKs, simulated using FLUKA and MCNP5, were 7.92, 9.64, 4.62, 3.71 and 3.84 % for 0.01, 0.1, 0.5, 1 and 2 MeV, respectively. For the three radionuclides, the MAPEs of the scaled DPKs were within 5 %. The maximum deviations of S(N<-N), S(N<-Cy) and S(N<-CS) for the electron energy larger than 10 keV were 6.63, 6.77 and 5.24 %, respectively. The deviations for the self-absorbed S-values and cross-dose S-values of the three radionuclides were within 4 %. On the basis of the results of this study, it was concluded that the simulation results are consistent between FLUKA and MCNP5. However, there is a minor inconsistency for low energy range. The DPK and the cellular S-value should be used as the quality assurance tools before the MC simulation results are adopted as the gold standard. (authors)

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

    Science.gov (United States)

    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

  20. Estimation of the delivered patient dose in lung IMRT treatment based on deformable registration of 4D-CT data and Monte Carlo simulations

    Science.gov (United States)

    Flampouri, Stella; Jiang, Steve B.; Sharp, Greg C.; Wolfgang, John; Patel, Abhijit A.; Choi, Noah C.

    2006-06-01

    The purpose of this study is to accurately estimate the difference between the planned and the delivered dose due to respiratory motion and free breathing helical CT artefacts for lung IMRT treatments, and to estimate the impact of this difference on clinical outcome. Six patients with representative tumour motion, size and position were selected for this retrospective study. For each patient, we had acquired both a free breathing helical CT and a ten-phase 4D-CT scan. A commercial treatment planning system was used to create four IMRT plans for each patient. The first two plans were based on the GTV as contoured on the free breathing helical CT set, with a GTV to PTV expansion of 1.5 cm and 2.0 cm, respectively. The third plan was based on the ITV, a composite volume formed by the union of the CTV volumes contoured on free breathing helical CT, end-of-inhale (EOI) and end-of-exhale (EOE) 4D-CT. The fourth plan was based on GTV contoured on the EOE 4D-CT. The prescribed dose was 60 Gy for all four plans. Fluence maps and beam setup parameters of the IMRT plans were used by the Monte Carlo dose calculation engine MCSIM for absolute dose calculation on both the free breathing CT and 4D-CT data. CT deformable registration between the breathing phases was performed to estimate the motion trajectory for both the tumour and healthy tissue. Then, a composite dose distribution over the whole breathing cycle was calculated as a final estimate of the delivered dose. EUD values were computed on the basis of the composite dose for all four plans. For the patient with the largest motion effect, the difference in the EUD of CTV between the planed and the delivered doses was 33, 11, 1 and 0 Gy for the first, second, third and fourth plan, respectively. The number of breathing phases required for accurate dose prediction was also investigated. With the advent of 4D-CT, deformable registration and Monte Carlo simulations, it is feasible to perform an accurate calculation of the

  1. Estimation of the delivered patient dose in lung IMRT treatment based on deformable registration of 4D-CT data and Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Flampouri, Stella; Jiang, Steve B; Sharp, Greg C; Wolfgang, John; Patel, Abhijit A; Choi, Noah C [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114 (United States)

    2006-06-07

    The purpose of this study is to accurately estimate the difference between the planned and the delivered dose due to respiratory motion and free breathing helical CT artefacts for lung IMRT treatments, and to estimate the impact of this difference on clinical outcome. Six patients with representative tumour motion, size and position were selected for this retrospective study. For each patient, we had acquired both a free breathing helical CT and a ten-phase 4D-CT scan. A commercial treatment planning system was used to create four IMRT plans for each patient. The first two plans were based on the GTV as contoured on the free breathing helical CT set, with a GTV to PTV expansion of 1.5 cm and 2.0 cm, respectively. The third plan was based on the ITV, a composite volume formed by the union of the CTV volumes contoured on free breathing helical CT, end-of-inhale (EOI) and end-of-exhale (EOE) 4D-CT. The fourth plan was based on GTV contoured on the EOE 4D-CT. The prescribed dose was 60 Gy for all four plans. Fluence maps and beam setup parameters of the IMRT plans were used by the Monte Carlo dose calculation engine MCSIM for absolute dose calculation on both the free breathing CT and 4D-CT data. CT deformable registration between the breathing phases was performed to estimate the motion trajectory for both the tumour and healthy tissue. Then, a composite dose distribution over the whole breathing cycle was calculated as a final estimate of the delivered dose. EUD values were computed on the basis of the composite dose for all four plans. For the patient with the largest motion effect, the difference in the EUD of CTV between the planed and the delivered doses was 33, 11, 1 and 0 Gy for the first, second, third and fourth plan, respectively. The number of breathing phases required for accurate dose prediction was also investigated. With the advent of 4D-CT, deformable registration and Monte Carlo simulations, it is feasible to perform an accurate calculation of the

  2. Estimation of the delivered patient dose in lung IMRT treatment based on deformable registration of 4D-CT data and Monte Carlo simulations

    International Nuclear Information System (INIS)

    The purpose of this study is to accurately estimate the difference between the planned and the delivered dose due to respiratory motion and free breathing helical CT artefacts for lung IMRT treatments, and to estimate the impact of this difference on clinical outcome. Six patients with representative tumour motion, size and position were selected for this retrospective study. For each patient, we had acquired both a free breathing helical CT and a ten-phase 4D-CT scan. A commercial treatment planning system was used to create four IMRT plans for each patient. The first two plans were based on the GTV as contoured on the free breathing helical CT set, with a GTV to PTV expansion of 1.5 cm and 2.0 cm, respectively. The third plan was based on the ITV, a composite volume formed by the union of the CTV volumes contoured on free breathing helical CT, end-of-inhale (EOI) and end-of-exhale (EOE) 4D-CT. The fourth plan was based on GTV contoured on the EOE 4D-CT. The prescribed dose was 60 Gy for all four plans. Fluence maps and beam setup parameters of the IMRT plans were used by the Monte Carlo dose calculation engine MCSIM for absolute dose calculation on both the free breathing CT and 4D-CT data. CT deformable registration between the breathing phases was performed to estimate the motion trajectory for both the tumour and healthy tissue. Then, a composite dose distribution over the whole breathing cycle was calculated as a final estimate of the delivered dose. EUD values were computed on the basis of the composite dose for all four plans. For the patient with the largest motion effect, the difference in the EUD of CTV between the planed and the delivered doses was 33, 11, 1 and 0 Gy for the first, second, third and fourth plan, respectively. The number of breathing phases required for accurate dose prediction was also investigated. With the advent of 4D-CT, deformable registration and Monte Carlo simulations, it is feasible to perform an accurate calculation of the

  3. Dual-energy CT-based material extraction for tissue segmentation in Monte Carlo dose calculations

    Science.gov (United States)

    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.

  4. Effect of elemental compositions on Monte Carlo dose calculations in proton therapy of eye tumors

    Science.gov (United States)

    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

  5. Radiological Dose Rate Mapping of D-D/D-T Neutron Generator Facilities

    International Nuclear Information System (INIS)

    Full text: DD/DT reaction neutron generators are used as sources of 2.5 MeV/14 MeV neutrons in laboratories for various purposes. 14 MeV neutron generators are proposed to be located at several positions in the ITER vessel for calibrating neutron/gamma diagnostic systems. Detailed knowledge of the radiation dose rates around the neutron generators is essential to obtain data on personnel exposures, calibration time, optimizing the number of calibration points with accuracy and radiological protection of the personnel involved with operation of 2.5 MeV and 14 MeV neutron sources. This work describes the studies carried out towards verifying the neutron and gamma dose rates near DD/DT neutron sources and the adequacy of bulk shielding to meet the stipulated dose limits in personnel occupancy areas of a neutron generator lab. Shielding adequacy was verified by experimental measurements at various locations inside and outside the neutron generator hall during different conditions. The experimental measurements were validated by Monte Carlo simulation code FLUKA, taking into account the geometry and structural details of source and the surrounding materials. Ambient neutron and gamma dose rate profiles and dose rate spectra at various locations are presented in this work. Measurements show a good agreement (up to 20% deviation) with FLUKA simulations. This study has served in generating detailed radiological dose rate maps around 2.5 MeV and 14 MeV neutron generators for various source neutron yields and also in benchmarking the Monte Carlo simulation methods adopted for dose rate evaluations and shield design of such facilities. This study has also yielded valuable information on the response of the various radiological monitoring instruments and the recently procured personnel neutron/gamma dosimeters (MGP-make) for use in mixed neutron and gamma fields in the vicinity of D-D (2.5 MeV) and D-T (14 MeV) generator based neutron sources. Work supported by the Health

  6. 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

  7. Radiological mapping of Kelantan, Malaysia, using terrestrial radiation dose rate.

    Science.gov (United States)

    Garba, Nuraddeen Nasiru; Ramli, Ahmad Termizi; Saleh, Muneer Aziz; Sanusi, Syazwan Mohd; Gabdo, Hamman Tukur

    2016-06-01

    Measurements of the environmental terrestrial gamma radiation dose rate (TGRD) in each district of Kelantan state, Malaysia, were carried out using a portable hand-held radiation survey meter and global positioning system. The measurements were done based on geology and soil types of the area. The mean TGRD was found to be 209 nGy h(-1). Few areas of relatively enhanced activity were observed in Pasir Mas, Tanah Merah and Jeli districts, which have a mean TGRD between 300 and 500 nGy h(-1). An isodose map of the area was produced using ArcGIS software version 9.3. PMID:26540360

  8. Radiological mapping of Kelantan, Malaysia, using terrestrial radiation dose rate.

    Science.gov (United States)

    Garba, Nuraddeen Nasiru; Ramli, Ahmad Termizi; Saleh, Muneer Aziz; Sanusi, Syazwan Mohd; Gabdo, Hamman Tukur

    2016-06-01

    Measurements of the environmental terrestrial gamma radiation dose rate (TGRD) in each district of Kelantan state, Malaysia, were carried out using a portable hand-held radiation survey meter and global positioning system. The measurements were done based on geology and soil types of the area. The mean TGRD was found to be 209 nGy h(-1). Few areas of relatively enhanced activity were observed in Pasir Mas, Tanah Merah and Jeli districts, which have a mean TGRD between 300 and 500 nGy h(-1). An isodose map of the area was produced using ArcGIS software version 9.3.

  9. Size Effects of Gold and Iron Nanoparticles on Radiation Dose Enhancement in Brachytherapy and Teletherapy: A Monte Carlo Study

    Directory of Open Access Journals (Sweden)

    Ahad Ollah Ezzati

    2014-08-01

    Full Text Available Introduction In this study, we aimed to calculate dose enhancement factor (DEF for gold (Au and iron (Fe nanoparticles (NPs in brachytherapy and teletherapy, using Monte Carlo (MC method. Materials and Methods In this study, a new algorithm was introduced to calculate dose enhancement by AuNPs and FeNPs for Iridium-192 (Ir-192 brachytherapy and Cobalt-60 (Co-60 teletherapy sources, using the MC method. In this algorithm, the semi-random distribution of NPs was used instead of the regular distribution. Diameters were assumed to be 15, 30, and 100 nm in brachytherapy and 15 and 30 nm in teletherapy. Monte Carlo MCNP4C code was used for simulations, and NP density values were 0.107 mg/ml and 0.112 mg/ml in brachytherapy and teletherapy, respectively. Results AuNPs significantly enhanced the radiation dose in brachytherapy (approximately 60%, and 100 nm diameter NPs showed the most uniform dose distribution. AuNPs had an insignificant effect on teletherapy radiation field, with a dose enhancement ratio of 3% (about the calculation uncertainty or less. In addition, FeNPs had an insignificant effect on both brachytherapy and teletherapy radiation fields. FeNPs dose enhancement was 3% in brachytherapy and 6% (about the calculation uncertainty or less in teletherapy. Conclusion It can be concluded that AuNPs can significantly increase the absorbed dose in brachytherapy; however, FeNPs do not have a noticeable effect on the absorbed dose

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  11. Real time Monte Carlo simulation for evaluation of patient doses involved in radiological examinations

    Energy Technology Data Exchange (ETDEWEB)

    Fulea, D. [Institute of Public Health ' Prof.Dr.Iuliu Moldovan' , Cluj-Napoca (Romania); Cosma, C. [Babes-Bolyai Univ., Faculty of Physics, Cluj-Napoca (Romania)

    2006-07-01

    In order to apply the Monte Carlo simulation technique for usual radiological examinations we developed a Pc program, 'IradMed', written entirely in Java. The main purpose of this program is to compute the organ doses and the effective dose of patients, which are exposed at a X-ray beam having photon energies in 10 to 150 keV radiodiagnostic range. Three major radiological procedures are considered, namely mammography, radiography and CT. The fluoroscopy implies an irregular geometry and therefore it is neglected. Nevertheless, a gross estimation of patient doses can be made taking into account the fluoroscopy as being composed of several radiographic examinations applied in different anatomical regions. The interactions between radiation and matter are well-known, and the accuracy of the calculation is limited by the accuracy of the anatomical model used to describe actual patients and by characterisation of the radiation field applied. In this version of IradMed, it is assumed that the absorbed dose is equal with kerma for all tissues. No procedure has been used to take account of the finite range of the secondary electrons that are produced by photoelectric or Compton interactions. These ranges are small compared with the dimensions of the organs, and the absorbed dose will not change abruptly with distance except at boundary where composition and density change. However these boundary effects would have little effect in the determination of the average doses to almost all organs, except the active bone marrow which is treated separately. Another justification for this kerma approximation is the fact that the sum of all electron energies that exit the organ is statistically equal with the sum of all electron energies that enter in that particular organ. In this version of program, it is considered the following interactions: the Rayleigh scattering, the Compton scattering and the photoelectric effect. The Compton scattering is modeled by several

  12. Experimental and Monte Carlo evaluation of Eclipse treatment planning system for effects on dose distribution of the hip prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Çatlı, Serap, E-mail: serapcatli@hotmail.com [Gazi University, Faculty of Sciences, 06500 Teknikokullar, Ankara (Turkey); Tanır, Güneş [Gazi University, Faculty of Sciences, 06500 Teknikokullar, Ankara (Turkey)

    2013-10-01

    The present study aimed to investigate the effects of titanium, titanium alloy, and stainless steel hip prostheses on dose distribution based on the Monte Carlo simulation method, as well as the accuracy of the Eclipse treatment planning system (TPS) at 6 and 18 MV photon energies. In the present study the pencil beam convolution (PBC) method implemented in the Eclipse TPS was compared to the Monte Carlo method and ionization chamber measurements. The present findings show that if high-Z material is used in prosthesis, large dose changes can occur due to scattering. The variance in dose observed in the present study was dependent on material type, density, and atomic number, as well as photon energy; as photon energy increased back scattering decreased. The dose perturbation effect of hip prostheses was significant and could not be predicted accurately by the PBC method for hip prostheses. The findings show that for accurate dose calculation the Monte Carlo-based TPS should be used in patients with hip prostheses.

  13. Estimation of absorbed doses from paediatric cone-beam CT scans: MOSFET measurements and Monte Carlo simulations.

    Science.gov (United States)

    Kim, Sangroh; Yoshizumi, Terry T; Toncheva, Greta; Frush, Donald P; Yin, Fang-Fang

    2010-03-01

    The purpose of this study was to establish a dose estimation tool with Monte Carlo (MC) simulations. A 5-y-old paediatric anthropomorphic phantom was computed tomography (CT) scanned to create a voxelised phantom and used as an input for the abdominal cone-beam CT in a BEAMnrc/EGSnrc MC system. An X-ray tube model of the Varian On-Board Imager((R)) was built in the MC system. To validate the model, the absorbed doses at each organ location for standard-dose and low-dose modes were measured in the physical phantom with MOSFET detectors; effective doses were also calculated. In the results, the MC simulations were comparable to the MOSFET measurements. This voxelised phantom approach could produce a more accurate dose estimation than the stylised phantom method. This model can be easily applied to multi-detector CT dosimetry. PMID:19889800

  14. DEEP code to calculate dose equivalents in human phantom for external photon exposure by Monte Carlo method

    International Nuclear Information System (INIS)

    The present report describes a computer code DEEP which calculates the organ dose equivalents and the effective dose equivalent for external photon exposure by the Monte Carlo method. MORSE-CG, Monte Carlo radiation transport code, is incorporated into the DEEP code to simulate photon transport phenomena in and around a human body. The code treats an anthropomorphic phantom represented by mathematical formulae and user has a choice for the phantom sex: male, female and unisex. The phantom can wear personal dosimeters on it and user can specify their location and dimension. This document includes instruction and sample problem for the code as well as the general description of dose calculation, human phantom and computer code. (author)

  15. Effective dose in individuals from exposure the patients treated with {sup 131}I using Monte Carlo method

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho Junior, Alberico B. de; Silva, Ademir X. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Nuclear]. E-mail: ajunior@con.ufrj.br; Hunt, John G. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN), Rio de Janeiro, RJ (Brazil)]. E-mail: john@ird.gov.br

    2007-07-01

    In this work, using the Visual Monte Carlo code and the voxel phantom FAX, elaborated similar scenes of irradiation to the treatments used in the nuclear medicine, with the intention of estimate the effective dose in individuals from exposure the patients treated with {sup 131}I. We considered often specific situations, such as doses to others while sleeping, using public or private transportation, or being in a cinema for a few hours. In the possible situations that has been considered, the value of the effective dose did not overcome 0.05 mSv, demonstrating that, for the considered parameters the patient could be release without receiving instructions from radioprotection. (author)

  16. The role of nuclear reactions in Monte Carlo calculations of absorbed and biological effective dose distributions in hadron therapy

    CERN Document Server

    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.

  17. Primary and scattering contributions to beta scaled dose point kernels by means of Monte Carlo simulations; Contribuicoes primaria e espalhada para dosimetria beta calculadas pelo dose point kernels empregando simulacoes pelo Metodo Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Valente, Mauro [CONICET - Consejo Nacional de Investigaciones Cientificas y Tecnicas de La Republica Argentina (Conicet), Buenos Aires, AR (Brazil); Botta, Francesca; Pedroli, Guido [European Institute of Oncology, Milan (Italy). Medical Physics Department; Perez, Pedro, E-mail: valente@famaf.unc.edu.ar [Universidad Nacional de Cordoba, Cordoba (Argentina). Fac. de Matematica, Astronomia y Fisica (FaMAF)

    2012-07-01

    Beta-emitters have proved to be appropriate for radioimmunotherapy. The dosimetric characterization of each radionuclide has to be carefully investigated. One usual and practical dosimetric approach is the calculation of dose distribution from a unit point source emitting particles according to any radionuclide of interest, which is known as dose point kernel. Absorbed dose distributions are due to primary and radiation scattering contributions. This work presented a method capable of performing dose distributions for nuclear medicine dosimetry by means of Monte Carlo methods. Dedicated subroutines have been developed in order to separately compute primary and scattering contributions to the total absorbed dose, performing particle transport up to 1 keV or least. Preliminarily, the suitability of the calculation method has been satisfactory, being tested for monoenergetic sources, and it was further applied to the characterization of different beta-minus radionuclides of nuclear medicine interests for radioimmunotherapy. (author)

  18. Map Building and Monte Carlo Localization Using Global Appearance of Omnidirectional Images

    Directory of Open Access Journals (Sweden)

    Oscar Reinoso

    2010-12-01

    Full Text Available In this paper we deal with the problem of map building and localization of a mobile robot in an environment using the information provided by an omnidirectional vision sensor that is mounted on the robot. Our main objective consists of studying the feasibility of the techniques based in the global appearance of a set of omnidirectional images captured by this vision sensor to solve this problem. First, we study how to describe globally the visual information so that it represents correctly locations and the geometrical relationships between these locations. Then, we integrate this information using an approach based on a spring-mass-damper model, to create a topological map of the environment. Once the map is built, we propose the use of a Monte Carlo localization approach to estimate the most probable pose of the vision system and its trajectory within the map. We perform a comparison in terms of computational cost and error in localization. The experimental results we present have been obtained with real indoor omnidirectional images.

  19. A dual resolution measurement based Monte Carlo simulation technique for detailed dose analysis of small volume organs in the skull base region

    International Nuclear Information System (INIS)

    The purpose of this study was to examine dose distribution of a skull base tumor and surrounding critical structures in response to high dose intensity-modulated radiosurgery (IMRS) with Monte Carlo (MC) simulation using a dual resolution sandwich phantom. The measurement-based Monte Carlo (MBMC) method (Lin et al., 2009) was adopted for the study. The major components of the MBMC technique involve (1) the BEAMnrc code for beam transport through the treatment head of a Varian 21EX linear accelerator, (2) the DOSXYZnrc code for patient dose simulation and (3) an EPID-measured efficiency map which describes non-uniform fluence distribution of the IMRS treatment beam. For the simulated case, five isocentric 6 MV photon beams were designed to deliver a total dose of 1200 cGy in two fractions to the skull base tumor. A sandwich phantom for the MBMC simulation was created based on the patient's CT scan of a skull base tumor [gross tumor volume (GTV)=8.4 cm3] near the right 8th cranial nerve. The phantom, consisted of a 1.2-cm thick skull base region, had a voxel resolution of 0.05×0.05×0.1 cm3 and was sandwiched in between 0.05×0.05×0.3 cm3 slices of a head phantom. A coarser 0.2×0.2×0.3 cm3 single resolution (SR) phantom was also created for comparison with the sandwich phantom. A particle history of 3×108 for each beam was used for simulations of both the SR and the sandwich phantoms to achieve a statistical uncertainty of <2%. Our study showed that the planning target volume (PTV) receiving at least 95% of the prescribed dose (VPTV95) was 96.9%, 96.7% and 99.9% for the TPS, SR, and sandwich phantom, respectively. The maximum and mean doses to large organs such as the PTV, brain stem, and parotid gland for the TPS, SR and sandwich MC simulations did not show any significant difference; however, significant dose differences were observed for very small structures like the right 8th cranial nerve, right cochlea, right malleus and right semicircular canal

  20. IMRT dose delivery effects in radiotherapy treatment planning using Monte Carlo methods

    Science.gov (United States)

    Tyagi, Neelam

    Inter- and intra-leaf transmission and head scatter can play significant roles in Intensity Modulated Radiation Therapy (IMRT)-based treatment deliveries. In order to accurately calculate the dose in the IMRT planning process, it is therefore important that the detailed geometry of the multi-leaf collimator (MLC), in addition to other components in the accelerator treatment head be accurately modeled. In this thesis Monte Carlo (MC) methods have been used to model the treatment head of a Varian linear accelerator. A comprehensive model of the Varian 120-leaf MLC has been developed within the DPM MC code and has been verified against measurements in homogeneous and heterogeneous phantom geometries under different IMRT delivery circumstances. Accuracy of the MLC model in simulating details in the leaf geometry has been established over a range of arbitrarily shaped fields and IMRT fields. A sensitivity analysis of the effect of the electron-on-target parameters and the structure of the flattening filter on the accuracy of calculated dose distributions has been conducted. Adjustment of the electron-on-target parameters resulting in optimal agreement with measurements was an iterative process, with the final parameters representing a tradeoff between small (3x3 cm2) and large (40x40 cm2) field sizes. A novel method based on adaptive kernel density estimation, in the phase space simulation process is also presented as an alternative to particle recycling. Using this model dosimetric differences between MLC-based static (SMLC) and dynamic (DMLC) deliveries have been investigated. Differences between SMLC and DMLC, possibly related to fluence and/or spectral changes, appear to vary systematically with the density of the medium. The effect of fluence modulation due to leaf sequencing shows differences, up to 10% between plans developed with 1% and 10% fluence intervals for both SMLC and DMLC-delivered sequences. Dose differences between planned and delivered leaf sequences

  1. Monte Carlo derivation of filtered tungsten anode X-ray spectra for dose computation in digital mammography*

    Science.gov (United States)

    Paixão, Lucas; Oliveira, Bruno Beraldo; Viloria, Carolina; de Oliveira, Marcio Alves; Teixeira, Maria Helena Araújo; Nogueira, Maria do Socorro

    2015-01-01

    Objective Derive filtered tungsten X-ray spectra used in digital mammography systems by means of Monte Carlo simulations. Materials and Methods Filtered spectra for rhodium filter were obtained for tube potentials between 26 and 32 kV. The half-value layer (HVL) of simulated filtered spectra were compared with those obtained experimentally with a solid state detector Unfors model 8202031-H Xi R/F & MAM Detector Platinum and 8201023-C Xi Base unit Platinum Plus w mAs in a Hologic Selenia Dimensions system using a direct radiography mode. Results Calculated HVL values showed good agreement as compared with those obtained experimentally. The greatest relative difference between the Monte Carlo calculated HVL values and experimental HVL values was 4%. Conclusion The results show that the filtered tungsten anode X-ray spectra and the EGSnrc Monte Carlo code can be used for mean glandular dose determination in mammography. PMID:26811553

  2. Monte Carlo derivation of filtered tungsten anode X-ray spectra for dose computation in digital mammography

    Directory of Open Access Journals (Sweden)

    Lucas Paixão

    2015-12-01

    Full Text Available Abstract Objective: Derive filtered tungsten X-ray spectra used in digital mammography systems by means of Monte Carlo simulations. Materials and Methods: Filtered spectra for rhodium filter were obtained for tube potentials between 26 and 32 kV. The half-value layer (HVL of simulated filtered spectra were compared with those obtained experimentally with a solid state detector Unfors model 8202031-H Xi R/F & MAM Detector Platinum and 8201023-C Xi Base unit Platinum Plus w mAs in a Hologic Selenia Dimensions system using a direct radiography mode. Results: Calculated HVL values showed good agreement as compared with those obtained experimentally. The greatest relative difference between the Monte Carlo calculated HVL values and experimental HVL values was 4%. Conclusion: The results show that the filtered tungsten anode X-ray spectra and the EGSnrc Monte Carlo code can be used for mean glandular dose determination in mammography.

  3. Calculation of organ doses from environmental gamma rays using human phantoms and Monte Carlo methods. Pt. 1

    International Nuclear Information System (INIS)

    Organ doses from environmental γ-rays (U-238, Th-232, K-40) were calculated using Monte Carlo methods for three typical sources of a semi-infinite volume source in the air, an infinite plane source in the ground and a volume source in the ground. γ-ray fields in the natural environment were simulated rigourously without approximations or simplifications in the intermediate steps except for the disturbance of the radiation field by the human body which was neglected. Organ doses were calculated for four anthropomorphic phantoms representing a baby, a child, a female and a male adult. The dose of a fetus is given by the dose to the uterus of the adult female. Air kerma and dose conversion factors normalised to air kerma and to source intensity are given for monoenergetic sources and for the natural radionuclides. (orig./HP)

  4. Dosimetric measurements and Monte Carlo simulation for achieving uniform surface dose in pulsed electron beam irradiation facility

    Indian Academy of Sciences (India)

    V C Petwal; J N Rao; Jishnu Dwivedi; V K Senecha; K V Subbaiah

    2010-03-01

    A prototype pulsed electron beam irradiation facility for radiation processing of food and medical products is being commissioned at our centre in Indore, India. Analysis of surface dose and uniformity for a pulsed beam facility is of crucial importance because it is influenced by various operating parameters such as beam current, pulse repetition rate (PRR), scanning current profile and frequency, scanning width and product conveying speed. A large number of experiments are required to determine the harmonized setting of these operating parameters for achieving uniform dose. Since there is no readily available tool to set these parameters, use of Monte Carlo methods and computational tools can prove to be the most viable and time saving technique to support the assessment of the dose distribution. In the present study, Monte Carlo code, MCNP, is used to simulate the transport of 10 MeV electron beam through various mediums coming into the beam path and generate an equivalent dose profile in a polystyrene phantom for stationary state. These results have been verified with experimentally measured dose profile, showing that results are in good agreement within 4%. The Monte Carlo simulation further has been used to optimize the overlapping between the successive pulses of a scan to achieve ± 5% dose uniformity along the scanning direction. A mathematical model, which uses the stationary state data, is developed to include the effect of conveyor speed. The algorithm of the model is discussed and the results are compared with the experimentally measured values, which show that the agreement is better than 15%. Finally, harmonized setting for operating parameters of the accelerator are derived to deliver uniform surface dose in the range of 1–13 kGy/pass.

  5. Development of 1-year-old computational phantom and calculation of organ doses during CT scans using Monte Carlo simulation

    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)

  6. Development of 1-year-old computational phantom and calculation of organ doses during CT scans using Monte Carlo simulation.

    Science.gov (United States)

    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.

  7. ARCHERRT – A GPU-based and photon-electron coupled Monte Carlo dose computing engine for radiation therapy: Software development and application to helical tomotherapy

    International Nuclear Information System (INIS)

    Purpose: Using the graphical processing units (GPU) hardware technology, an extremely fast Monte Carlo (MC) code ARCHERRT is developed for radiation dose calculations in radiation therapy. This paper describes the detailed software development and testing for three clinical TomoTherapy® cases: the prostate, lung, and head and neck. Methods: To obtain clinically relevant dose distributions, phase space files (PSFs) created from optimized radiation therapy treatment plan fluence maps were used as the input to ARCHERRT. Patient-specific phantoms were constructed from patient CT images. Batch simulations were employed to facilitate the time-consuming task of loading large PSFs, and to improve the estimation of statistical uncertainty. Furthermore, two different Woodcock tracking algorithms were implemented and their relative performance was compared. The dose curves of an Elekta accelerator PSF incident on a homogeneous water phantom were benchmarked against DOSXYZnrc. For each of the treatment cases, dose volume histograms and isodose maps were produced from ARCHERRT and the general-purpose code, GEANT4. The gamma index analysis was performed to evaluate the similarity of voxel doses obtained from these two codes. The hardware accelerators used in this study are one NVIDIA K20 GPU, one NVIDIA K40 GPU, and six NVIDIA M2090 GPUs. In addition, to make a fairer comparison of the CPU and GPU performance, a multithreaded CPU code was developed using OpenMP and tested on an Intel E5-2620 CPU. Results: For the water phantom, the depth dose curve and dose profiles from ARCHERRT agree well with DOSXYZnrc. For clinical cases, results from ARCHERRT are compared with those from GEANT4 and good agreement is observed. Gamma index test is performed for voxels whose dose is greater than 10% of maximum dose. For 2%/2mm criteria, the passing rates for the prostate, lung case, and head and neck cases are 99.7%, 98.5%, and 97.2%, respectively. Due to specific architecture of GPU

  8. A dual resolution measurement based Monte Carlo simulation technique for detailed dose analysis of small volume organs in the skull base region

    Science.gov (United States)

    Yeh, Chi-Yuan; Tung, Chuan-Jung; Chao, Tsi-Chain; Lin, Mu-Han; Lee, Chung-Chi

    2014-11-01

    The purpose of this study was to examine dose distribution of a skull base tumor and surrounding critical structures in response to high dose intensity-modulated radiosurgery (IMRS) with Monte Carlo (MC) simulation using a dual resolution sandwich phantom. The measurement-based Monte Carlo (MBMC) method (Lin et al., 2009) was adopted for the study. The major components of the MBMC technique involve (1) the BEAMnrc code for beam transport through the treatment head of a Varian 21EX linear accelerator, (2) the DOSXYZnrc code for patient dose simulation and (3) an EPID-measured efficiency map which describes non-uniform fluence distribution of the IMRS treatment beam. For the simulated case, five isocentric 6 MV photon beams were designed to deliver a total dose of 1200 cGy in two fractions to the skull base tumor. A sandwich phantom for the MBMC simulation was created based on the patient's CT scan of a skull base tumor [gross tumor volume (GTV)=8.4 cm3] near the right 8th cranial nerve. The phantom, consisted of a 1.2-cm thick skull base region, had a voxel resolution of 0.05×0.05×0.1 cm3 and was sandwiched in between 0.05×0.05×0.3 cm3 slices of a head phantom. A coarser 0.2×0.2×0.3 cm3 single resolution (SR) phantom was also created for comparison with the sandwich phantom. A particle history of 3×108 for each beam was used for simulations of both the SR and the sandwich phantoms to achieve a statistical uncertainty of <2%. Our study showed that the planning target volume (PTV) receiving at least 95% of the prescribed dose (VPTV95) was 96.9%, 96.7% and 99.9% for the TPS, SR, and sandwich phantom, respectively. The maximum and mean doses to large organs such as the PTV, brain stem, and parotid gland for the TPS, SR and sandwich MC simulations did not show any significant difference; however, significant dose differences were observed for very small structures like the right 8th cranial nerve, right cochlea, right malleus and right semicircular canal. Dose

  9. Measurement-based Monte Carlo simulation of high definition dose evaluation for nasopharyngeal cancer patients treated by using intensity modulated radiation therapy

    International Nuclear Information System (INIS)

    Measurement-based Monte Carlo (MBMC) simulation using a high definition (HD) phantom was used to evaluate the dose distribution in nasopharyngeal cancer (NPC) patients treated with intensity modulated radiation therapy (IMRT). Around nasopharyngeal cavity, there exists many small volume organs-at-risk (OARs) such as the optic nerves, auditory nerves, cochlea, and semicircular canal which necessitate the use of a high definition phantom for accurate and correct dose evaluation. The aim of this research was to study the advantages of using an HD phantom for MBMC simulation in NPC patients treated with IMRT. The MBMC simulation in this study was based on the IMRT treatment plan of three NPC patients generated by the anisotropic analytical algorithm (AAA) of the Eclipse treatment planning system (Varian Medical Systems, Palo Alto, CA, USA) using a calculation grid of 2 mm2. The NPC tumor was treated to a cumulative dose of 7000 cGy in 35 fractions using the shrinking-field sequential IMRT (SIMRT) method. The BEAMnrc MC Code was used to simulate a Varian EX21 linear accelerator treatment head. The HD phantom contained 0.5 × 0.5 × 1 mm3 voxels for the nasopharyngeal area and 0.5 × 0.5 × 3 mm3 for the rest of the head area. An efficiency map was obtained for the amorphous silicon aS1000 electronic portal imaging device (EPID) to adjust the weighting of each particle in the phase-space file for each IMRT beam. Our analysis revealed that small volume organs such as the eighth cranial nerve, semicircular canal, cochlea and external auditory canal showed an absolute dose difference of ≥200 cGy, while the dose difference for larger organs such as the parotid glands and tumor was negligible for the MBMC simulation using the HD phantom. The HD phantom was found to be suitable for Monte Carlo dose volume analysis of small volume organs. - Highlights: • HD dose evaluation for IMRT of NPC patients have been verified by the MC method. • MC results shows higher

  10. Monte Carlo method studies and a comparative between GEANT4 tool kit and MCNPX to depth dose in medical physics

    International Nuclear Information System (INIS)

    Knowing the depth dose at the central axis is fundamental for the accurate planning of medical treatment systems involving ionizing radiation. With the evolution of the informatics it is possible the utilization of various computational tools such as GEANT4 and the MCNPX, which use the Monte Carlo Method for simulation of such situations, This paper makes a comparative between the two tools for the this type of application

  11. Monte Carlo simulations of adult and pediatric computed tomography exams: Validation studies of organ doses with physical phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Long, Daniel J.; Lee, Choonsik; Tien, Christopher; Fisher, Ryan; Hoerner, Matthew R.; Hintenlang, David; Bolch, Wesley E. [J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida 32611-6131 (United States); National Cancer Institute, National Institute of Health, Bethesda, Maryland 20892-1502 (United States); J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida 32611-6131 (United States); Department of Radiology, University of Florida, Gainesville, Florida 32610-0374 (United States); J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida 32611-6131 (United States)

    2013-01-15

    Purpose: To validate the accuracy of a Monte Carlo source model of the Siemens SOMATOM Sensation 16 CT scanner using organ doses measured in physical anthropomorphic phantoms. Methods: The x-ray output of the Siemens SOMATOM Sensation 16 multidetector CT scanner was simulated within the Monte Carlo radiation transport code, MCNPX version 2.6. The resulting source model was able to perform various simulated axial and helical computed tomographic (CT) scans of varying scan parameters, including beam energy, filtration, pitch, and beam collimation. Two custom-built anthropomorphic phantoms were used to take dose measurements on the CT scanner: an adult male and a 9-month-old. The adult male is a physical replica of University of Florida reference adult male hybrid computational phantom, while the 9-month-old is a replica of University of Florida Series B 9-month-old voxel computational phantom. Each phantom underwent a series of axial and helical CT scans, during which organ doses were measured using fiber-optic coupled plastic scintillator dosimeters developed at University of Florida. The physical setup was reproduced and simulated in MCNPX using the CT source model and the computational phantoms upon which the anthropomorphic phantoms were constructed. Average organ doses were then calculated based upon these MCNPX results. Results: For all CT scans, good agreement was seen between measured and simulated organ doses. For the adult male, the percent differences were within 16% for axial scans, and within 18% for helical scans. For the 9-month-old, the percent differences were all within 15% for both the axial and helical scans. These results are comparable to previously published validation studies using GE scanners and commercially available anthropomorphic phantoms. Conclusions: Overall results of this study show that the Monte Carlo source model can be used to accurately and reliably calculate organ doses for patients undergoing a variety of axial or helical CT

  12. Monte Carlo simulation for the estimation of the glandular breast dose for a digital breast tomosynthesis system

    International Nuclear Information System (INIS)

    Digital breast tomosynthesis (DBT) is a screening and diagnostic modality that acquires images of the breast at multiple angles during a short scan. The Selenia Dimensions (Hologic, Bedford, Mass) DBT system can perform both full-field digital mammography and DBT. The system acquires 15 projections over a 15 deg. angular range (from -7.5 deg. to +7.5 deg.). An important factor in determining the optimal imaging technique for breast tomosynthesis is the radiation dose. In breast imaging, the radiation dose of concern is that deposited in the glandular tissue of the breast because this is the tissue that has a risk of developing cancer. The concept of the normalised mean glandular dose (DgN) has been introduced as the metric for the dose in breast imaging. The DgN is difficult to measure. The Monte Carlo techniques offer an alternative method for a realistic estimation of the radiation dose. The purpose of this work was to use the Monte Carlo code MCNPX technique to generate monoenergetic glandular dose data for estimating the breast tissue dose in tomosynthesis for arbitrary spectra as well as to observe the deposited radiation dose by projection on the glandular portion of the breast in a Selenia Dimensions DBT system. A Monte Carlo simulation of the system was developed to compute the DgN in a craniocaudal view. Monoenergetic X-ray beams from 10 to 49 keV in 1-keV increments were used. The simulation utilised the assumption of a homogeneous breast composition and three compositions (0 % glandular, 50 % glandular and 100 % glandular). The glandular and adipose tissue compositions were specified according ICRU Report 44. A skin layer of 4 mm was assumed to encapsulate the breast on all surfaces. The breast size was varied using the chest wall-to-nipple distance (CND) and compressed breast thickness (t). In this work, the authors assumed a CND of 5 cm and the thicknesses ranged from 2 to 8 cm, in steps of 2 cm. The fractional energy absorption increases (up to 44

  13. Study of percent depth doses in the water phantom with Co-60 photon irradiation by Monte-Carlo simulation

    International Nuclear Information System (INIS)

    Monte-Carlo simulation is one of the most essential computational tools to study the particle transport and interaction of radiation with matter as well as radiation protection and dosimetry. In this paper it was used to calculate percent depth doses in the water phantom for two Co-60 beam irradiation cases with using the MCNP-4C2 code. The simulation results was validated by comparison with those of measurements. Application of the MCNP-4C2 code for dose calculations in Co-60 beam treatment planning was recommended. (author)

  14. A Monte Carlo study on tissue dose enhancement in brachytherapy: a comparison between gadolinium and gold nanoparticles

    International Nuclear Information System (INIS)

    The aim of this study was to quantify the dose enhancement by gadolinium and gold nanoparticles in brachytherapy. MCNPX Monte Carlo code was used to simulate four brachytherapy sources: 60Co, 198Au, 192Ir, 169Yb. To verify the accuracy of our simulations, the obtained values of dose rate constants and radial dose functions were compared with corresponding published values for these sources. To study dose enhancements, a spherical soft tissue phantom with 15 cm in radius was simulated. Gadolinium and gold nanoparticles at 10, 20 and 30 mg/ml concentrations were separately assumed in a 1 × 1 × 1 cm3 volume simulating tumour. The simulated dose to the tumour with the impurity was compared to the dose without impurity, as a function of radial distance and concentration of the impurity, to determine the enhancement of dose due to the presence of the impurity. Dose enhancements in the tumour obtained in the presence of gadolinium and gold nanoparticles with concentration of 30 mg/ml, were found to be in the range of −0.5–106.1 and 0.4–153.1 % respectively. In addition, at higher radial distances from the source center, higher dose enhancements were observed. GdNPs can be used as a high atomic number material to enhance dose in tumour volume with dose enhancements up to 106.1 % when used in brachytherapy. Regardless considering the clinical limitations of the here-in presented model, for a similar source and concentration of nanoparticles, gold nanoparticles show higher dose enhancement than gadolinium nanoparticles and can have more clinical usefulness as dose enhancer material.

  15. The calculation of dose from external photon exposures using reference human phantoms and Monte Carlo methods. Pt. 4

    International Nuclear Information System (INIS)

    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.)

  16. A set of patient and staff dose data for validation of Monte Carlo calculations in interventional cardiology

    International Nuclear Information System (INIS)

    The purpose of this paper is to report a set of experimental values of patient and staff doses in a cardiac catheterisation laboratory using the range of radiographic and geometric parameters from routine clinical practice. The data obtained will be available for validation of Monte Carlo calculations and for training purposes. They will also help optimise radiation protection for patients and staff. Experimental measurements were made with an anthropomorphic phantom, and a monoplane flat detector-based X-ray system was used for interventional cardiology procedures. Standard operational protocols used in clinical practice were applied. Around 1000 patient dose and 5000 staff dose values were measured for different operational conditions (angulations, distances, collimation and wedge filter, magnification, phantom thicknesses, using Copper absorber, etc.). Uncertainties were also estimated. Increase factors of 3-10 for patients and staff doses were measured for the different C-arm angulations. (authors)

  17. Local dose enhancement in radiation therapy: Monte Carlo simulation study; Reforco local de dose em radioterapia utilizando nanoparticulas: estudo por simulacao Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Laura E. da; Nicolucci, Patricia, E-mail: laura.emilia.fm@gmail.com [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras

    2014-04-15

    The development of nanotechnology has boosted the use of nanoparticles in radiation therapy in order to achieve greater therapeutic ratio between tumor and healthy tissues. Gold has been shown to be most suitable to this task due to the high biocompatibility and high atomic number, which contributes to a better in vivo distribution and for the local energy deposition. As a result, this study proposes to study, nanoparticle in the tumor cell. At a range of 11 nm from the nanoparticle surface, results have shown an absorbed dose 141 times higher for the medium with the gold nanoparticle compared to the water for an incident energy spectrum with maximum photon energy of 50 keV. It was also noted that when only scattered radiation is interacting with the gold nanoparticles, the dose was 134 times higher compared to enhanced local dose that remained significant even for scattered radiation. (author)

  18. Neutron and photon doses in high energy radiotherapy facilities and evaluation of shielding performance by Monte Carlo method

    International Nuclear Information System (INIS)

    Highlights: → The MCNP5 code has been used to model a radiotherapy room of a 18 MV linear accelerator. → The neutron and the secondary gamma ray dose equivalents were evaluated at various points inside the treatment room and along the the maze. → To reduce the neutron and gamma ray doses, we have also investigated the radiotherapy room shielding performance. → The use of paraffin wax containing boron carbide indicates much better shielding effects. - Abstract: Medical accelerators operating above 10 MV are a source of undesirable neutron radiations which contaminate the therapeutic photon beam. These photoneutrons can also generate secondary gamma rays which increases undesirable dose to the patient body and to personnel and general public. In this study, the Monte Carlo N-Particle MCNP5 code has been used to model the radiotherapy room of a medical linear accelerator operating at 18 MV and to calculate the neutron and the secondary gamma ray energy spectra and the dose equivalents at various points inside the treatment room and along the maze. To validate our Monte Carlo simulation we compared our results with those evaluated by the recommended analytical methods of IAEA Report No. 47, and with experimental and simulated values published in the literature. After validation, the Monte Carlo simulation has been used to evaluate the shielding performance of the radiotherapy room. The obtained results showed that the use of paraffin wax containing boron carbide, in the lining of the radiotherapy room walls, presents enough effectiveness to reduce both neutron and gamma ray doses inside the treatment room and at the maze entrance. Such evaluation cannot be performed by the analytical methods since room material and wall surface lining are not taken into consideration.

  19. Estimation of computed tomography dose index in cone beam computed tomography: MOSFET measurements and Monte Carlo simulations.

    Science.gov (United States)

    Kim, Sangroh; Yoshizumi, Terry; Toncheva, Greta; Yoo, Sua; Yin, Fang-Fang; Frush, Donald

    2010-05-01

    To address the lack of accurate dose estimation method in cone beam computed tomography (CBCT), we performed point dose metal oxide semiconductor field-effect transistor (MOSFET) measurements and Monte Carlo (MC) simulations. A Varian On-Board Imager (OBI) was employed to measure point doses in the polymethyl methacrylate (PMMA) CT phantoms with MOSFETs for standard and low dose modes. A MC model of the OBI x-ray tube was developed using BEAMnrc/EGSnrc MC system and validated by the half value layer, x-ray spectrum and lateral and depth dose profiles. We compared the weighted computed tomography dose index (CTDIw) between MOSFET measurements and MC simulations. The CTDIw was found to be 8.39 cGy for the head scan and 4.58 cGy for the body scan from the MOSFET measurements in standard dose mode, and 1.89 cGy for the head and 1.11 cGy for the body in low dose mode, respectively. The CTDIw from MC compared well to the MOSFET measurements within 5% differences. In conclusion, a MC model for Varian CBCT has been established and this approach may be easily extended from the CBCT geometry to multi-detector CT geometry. PMID:20386198

  20. Accuracy of patient dose calculation for lung IMRT: A comparison of Monte Carlo, convolution/superposition, and pencil beam computations.

    Science.gov (United States)

    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

  1. Accuracy of patient dose calculation for lung IMRT: A comparison of Monte Carlo, convolution/superposition, and pencil beam computations

    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

  2. TU-F-18A-03: Improving Tissue Segmentation for Monte Carlo Dose Calculation Using DECT Data

    Energy Technology Data Exchange (ETDEWEB)

    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.

  3. NOTE: Monte Carlo dose calculation of segmental IMRT delivery to a moving phantom using dynamic MLC and gating log files

    Science.gov (United States)

    Oliver, Mike; Staruch, Robert; Gladwish, Adam; Craig, Jeff; Chen, Jeff; Wong, Eugene

    2008-05-01

    Respiratory gating is emerging as a tool to limit the effect of motion for liver and lung tumors. In order to study the impact of target motion and gated intensity modulated radiation therapy (IMRT) delivery, a computer program was developed to simulate segmental IMRT delivery to a moving phantom. Two distinct plans were delivered to a rigid-motion phantom with a film insert in place under four conditions: static, sinusoidal motion, gated sinusoidal motion with a duty cycle of 25% and gated sinusoidal motion with duty cycle of 50% under motion conditions of a typical patient (A = 1 cm, T = 4 s). The MLC controller log files and gating log files were retained to perform a retrospective Monte Carlo dose calculation of the plans. Comparison of the 2D planar dose distributions between simulation and measurement demonstrated that our technique had at least 94% of the points passing gamma criteria of 3% for dose difference and 3 mm as the distance to agreement. This note demonstrates that the use of dynamic multi-leaf collimator and respiratory monitoring system log files together with a fast Monte Carlo dose calculation algorithm is an accurate and efficient way to study the dosimetric effect of motion for gated or non-gated IMRT delivery on a rigidly-moving body.

  4. Investigation of geometrical and scoring grid resolution for Monte Carlo dose calculations for IMRT

    Science.gov (United States)

    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

  5. Experimental verification of a commercial Monte Carlo-based dose calculation module for high-energy photon beams

    Science.gov (United States)

    Künzler, Thomas; Fotina, Irina; Stock, Markus; Georg, Dietmar

    2009-12-01

    The dosimetric performance of a Monte Carlo algorithm as implemented in a commercial treatment planning system (iPlan, BrainLAB) was investigated. After commissioning and basic beam data tests in homogenous phantoms, a variety of single regular beams and clinical field arrangements were tested in heterogeneous conditions (conformal therapy, arc therapy and intensity-modulated radiotherapy including simultaneous integrated boosts). More specifically, a cork phantom containing a concave-shaped target was designed to challenge the Monte Carlo algorithm in more complex treatment cases. All test irradiations were performed on an Elekta linac providing 6, 10 and 18 MV photon beams. Absolute and relative dose measurements were performed with ion chambers and near tissue equivalent radiochromic films which were placed within a transverse plane of the cork phantom. For simple fields, a 1D gamma (γ) procedure with a 2% dose difference and a 2 mm distance to agreement (DTA) was applied to depth dose curves, as well as to inplane and crossplane profiles. The average gamma value was 0.21 for all energies of simple test cases. For depth dose curves in asymmetric beams similar gamma results as for symmetric beams were obtained. Simple regular fields showed excellent absolute dosimetric agreement to measurement values with a dose difference of 0.1% ± 0.9% (1 standard deviation) at the dose prescription point. A more detailed analysis at tissue interfaces revealed dose discrepancies of 2.9% for an 18 MV energy 10 × 10 cm2 field at the first density interface from tissue to lung equivalent material. Small fields (2 × 2 cm2) have their largest discrepancy in the re-build-up at the second interface (from lung to tissue equivalent material), with a local dose difference of about 9% and a DTA of 1.1 mm for 18 MV. Conformal field arrangements, arc therapy, as well as IMRT beams and simultaneous integrated boosts were in good agreement with absolute dose measurements in the

  6. Secondary Neutron Doses to Pediatric Patients During Intracranial Proton Therapy: Monte Carlo Simulation of the Neutron Energy Spectrum and its Organ Doses.

    Science.gov (United States)

    Matsumoto, Shinnosuke; Koba, Yusuke; Kohno, Ryosuke; Lee, Choonsik; Bolch, Wesley E; Kai, Michiaki

    2016-04-01

    Proton therapy has the physical advantage of a Bragg peak that can provide a better dose distribution than conventional x-ray therapy. However, radiation exposure of normal tissues cannot be ignored because it is likely to increase the risk of secondary cancer. Evaluating secondary neutrons generated by the interaction of the proton beam with the treatment beam-line structure is necessary; thus, performing the optimization of radiation protection in proton therapy is required. In this research, the organ dose and energy spectrum were calculated from secondary neutrons using Monte Carlo simulations. The Monte Carlo code known as the Particle and Heavy Ion Transport code System (PHITS) was used to simulate the transport proton and its interaction with the treatment beam-line structure that modeled the double scattering body of the treatment nozzle at the National Cancer Center Hospital East. The doses of the organs in a hybrid computational phantom simulating a 5-y-old boy were calculated. In general, secondary neutron doses were found to decrease with increasing distance to the treatment field. Secondary neutron energy spectra were characterized by incident neutrons with three energy peaks: 1×10, 1, and 100 MeV. A block collimator and a patient collimator contributed significantly to organ doses. In particular, the secondary neutrons from the patient collimator were 30 times higher than those from the first scatter. These results suggested that proactive protection will be required in the design of the treatment beam-line structures and that organ doses from secondary neutrons may be able to be reduced. PMID:26910030

  7. Influence of difference in cross-sectional dose profile in a CTDI phantom on X-ray CT dose estimation: a Monte Carlo study.

    Science.gov (United States)

    Haba, Tomonobu; Koyama, Shuji; Ida, Yoshihiro

    2014-01-01

    The longitudinal dose profile in a computed tomography dose index (CTDI) phantom had been studied by many researchers. The cross-sectional dose profile in the CTDI phantom, however, has not been studied. It is also important to understand the cross-sectional dose profile in the CTDI phantom for dose estimation in X-ray CT. In this study, the cross-sectional dose profile in the CTDI phantom was calculated by use of a Monte Carlo (MC) simulation method. A helical or a 320-detector-row cone-beam X-ray CT scanner was simulated. The cross-sectional dose profile in the CTDI phantom from surface to surface through the center point was calculated by MC simulation. The shape of the calculation region was a cylinder of 1-mm-diameter. The length of the cylinder was 23, 100, or 300 mm to represent various CT ionization chamber lengths. Detailed analyses of the energy depositions demonstrated that the cross-sectional dose profile was different in measurement methods and phantom sizes. In this study, we also focused on the validation of the weighting factor used in weighted CTDI (CTDI w ). As it stands now, the weighting factor used in CTDI w is (1/3, 2/3) for the (central, peripheral) axes. Our results showed that an equal weighting factor, which is (1/2, 1/2) for the (central, peripheral) axes, is more suitable to estimate the average cross-sectional dose when X-ray CT dose estimation is performed.

  8. Calculation of electron and isotopes dose point kernels with FLUKA Monte Carlo code for dosimetry in nuclear medicine therapy

    CERN Document Server

    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...

  9. Evaluation of PENFAST - A fast Monte Carlo code for dose calculations in photon and electron radiotherapy treatment planning

    Energy Technology Data Exchange (ETDEWEB)

    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)

  10. On-board Dose Measurement and its Monte Carlo Analysis in a Low Level Waste Shipping Vessel

    International Nuclear Information System (INIS)

    On-board dose measurements were made in a shipping vessel for low level radioactive wastes, the Seiei Maru. The measured values are much smaller than the regulation values both on the hatch covers and in the accommodation area. The dose equivalent rates on the hatch cover are analysed by using a continuous energy Monte Carlo code, MCNP 4B, with two kinds of calculational models. One is the detailed model with the geometry of containers and LLW drums, and an asymmetrical source distribution. The results of the detailed calculation approached the shape of the measured dose rate distribution graphs. The other is the simplified model that mixes source volume uniformly. The calculated values obtained with the simplified model are twice as large as those calculated with the detailed model. (author)

  11. Influencing factors of dose equivalence for X and γ rays with different energy based on Monte Carlo

    International Nuclear Information System (INIS)

    Background: The accuracy of dosimeter measurement of X and γ rays needs to be resolved. Purpose: The aim is to study the correction term of the equivalent process of low energy X-ray and the natural radioactive source. Methods: Instead of the standard sources, X-ray machine was adopted on the dose instrument calibration. The influence factors of the equivalence between low-energy X-ray and high-energy X or γ rays were simulated using Monte Carlo (MCNP) software. Results: The influences of distance, space scattering, response of detector on dose equivalence were obtained. The simulation results were also analyzed. Conclusion: The method can be used in dose equivalent correction for low-energy X-ray, high-energy X or γ rays, which is significant for the widespread use of X rays. (authors)

  12. Changes in dose with segmentation of breast tissues in Monte Carlo calculations for low-energy brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    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

  13. SU-E-T-117: Dose to Organs Outside of CT Scan Range- Monte Carlo and Hybrid Phantom Approach

    International Nuclear Information System (INIS)

    Purpose: Epidemiological study of second cancer risk for cancer survivors often requires the dose to normal tissues located outside the anatomy covered by radiological imaging, which is usually limited to tumor and organs at risk. We have investigated the feasibility of using whole body computational human phantoms for estimating out-of-field organ doses for patients treated by Intensity Modulated Radiation Therapy (IMRT). Methods: Identical 7-field IMRT prostate plans were performed using X-ray Voxel Monte Carlo (XVMC), a radiotherapy-specific Monte Carlo transport code, on the computed tomography (CT) images of the torso of an adult male patient (175 cm height, 66 kg weight) and an adult male hybrid computational phantom with the equivalent body size. Dose to the liver, right lung, and left lung were calculated and compared. Results: Considerable differences are seen between the doses calculated by XVMC for the patient CT and the hybrid phantom. One major contributing factor is the treatment method, deep inspiration breath hold (DIBH), used for this patient. This leads to significant differences in the organ position relative to the treatment isocenter. The transverse distances from the treatment isocenter to the inferior border of the liver, left lung, and right lung are 19.5cm, 29.5cm, and 30.0cm, respectively for the patient CT, compared with 24.3cm, 36.6cm, and 39.1cm, respectively, for the hybrid phantom. When corrected for the distance, the mean doses calculated using the hybrid phantom are within 28% of those calculated using the patient CT. Conclusion: This study showed that mean dose to the organs located in the missing CT coverage can be reconstructed by using whole body computational human phantoms within reasonable dosimetric uncertainty, however appropriate corrections may be necessary if the patient is treated with a technique that will significantly deform the size or location of the organs relative to the hybrid phantom

  14. Electron Irradiation of Conjunctival Lymphoma—Monte Carlo Simulation of the Minute Dose Distribution and Technique Optimization

    International Nuclear Information System (INIS)

    Purpose: External beam radiotherapy is the only conservative curative approach for Stage I non-Hodgkin lymphomas of the conjunctiva. The target volume is geometrically complex because it includes the eyeball and lid conjunctiva. Furthermore, the target volume is adjacent to radiosensitive structures, including the lens, lacrimal glands, cornea, retina, and papilla. The radiotherapy planning and optimization requires accurate calculation of the dose in these anatomical structures that are much smaller than the structures traditionally considered in radiotherapy. Neither conventional treatment planning systems nor dosimetric measurements can reliably determine the dose distribution in these small irradiated volumes. Methods and Materials: The Monte Carlo simulations of a Varian Clinac 2100 C/D and human eye were performed using the PENELOPE and PENEASYLINAC codes. Dose distributions and dose volume histograms were calculated for the bulbar conjunctiva, cornea, lens, retina, papilla, lacrimal gland, and anterior and posterior hemispheres. Results: The simulated results allow choosing the most adequate treatment setup configuration, which is an electron beam energy of 6 MeV with additional bolus and collimation by a cerrobend block with a central cylindrical hole of 3.0 cm diameter and central cylindrical rod of 1.0 cm diameter. Conclusions: Monte Carlo simulation is a useful method to calculate the minute dose distribution in ocular tissue and to optimize the electron irradiation technique in highly critical structures. Using a voxelized eye phantom based on patient computed tomography images, the dose distribution can be estimated with a standard statistical uncertainty of less than 2.4% in 3 min using a computing cluster with 30 cores, which makes this planning technique clinically relevant.

  15. Electron Irradiation of Conjunctival Lymphoma-Monte Carlo Simulation of the Minute Dose Distribution and Technique Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Brualla, Lorenzo, E-mail: lorenzo.brualla@uni-due.de [NCTeam, Strahlenklinik, Universitaetsklinikum Essen, Essen (Germany); Zaragoza, Francisco J.; Sempau, Josep [Institut de Tecniques Energetiques, Universitat Politecnica de Catalunya, Barcelona (Spain); Wittig, Andrea [Department of Radiation Oncology, University Hospital Giessen and Marburg, Philipps-University Marburg, Marburg (Germany); Sauerwein, Wolfgang [NCTeam, Strahlenklinik, Universitaetsklinikum Essen, Essen (Germany)

    2012-07-15

    Purpose: External beam radiotherapy is the only conservative curative approach for Stage I non-Hodgkin lymphomas of the conjunctiva. The target volume is geometrically complex because it includes the eyeball and lid conjunctiva. Furthermore, the target volume is adjacent to radiosensitive structures, including the lens, lacrimal glands, cornea, retina, and papilla. The radiotherapy planning and optimization requires accurate calculation of the dose in these anatomical structures that are much smaller than the structures traditionally considered in radiotherapy. Neither conventional treatment planning systems nor dosimetric measurements can reliably determine the dose distribution in these small irradiated volumes. Methods and Materials: The Monte Carlo simulations of a Varian Clinac 2100 C/D and human eye were performed using the PENELOPE and PENEASYLINAC codes. Dose distributions and dose volume histograms were calculated for the bulbar conjunctiva, cornea, lens, retina, papilla, lacrimal gland, and anterior and posterior hemispheres. Results: The simulated results allow choosing the most adequate treatment setup configuration, which is an electron beam energy of 6 MeV with additional bolus and collimation by a cerrobend block with a central cylindrical hole of 3.0 cm diameter and central cylindrical rod of 1.0 cm diameter. Conclusions: Monte Carlo simulation is a useful method to calculate the minute dose distribution in ocular tissue and to optimize the electron irradiation technique in highly critical structures. Using a voxelized eye phantom based on patient computed tomography images, the dose distribution can be estimated with a standard statistical uncertainty of less than 2.4% in 3 min using a computing cluster with 30 cores, which makes this planning technique clinically relevant.

  16. SU-E-T-117: Dose to Organs Outside of CT Scan Range- Monte Carlo and Hybrid Phantom Approach

    Energy Technology Data Exchange (ETDEWEB)

    Pelletier, C; Jung, J [East Carolina University, Greenville, NC (United States); Lee, C [University of Michigan, Ann Arbor, MI (United States); Kim, J [University of Pittsburgh Medical Center, Pittsburgh, PA (United States); Lee, C [National Cancer Institute, Rockville, MD (United States)

    2014-06-01

    Purpose: Epidemiological study of second cancer risk for cancer survivors often requires the dose to normal tissues located outside the anatomy covered by radiological imaging, which is usually limited to tumor and organs at risk. We have investigated the feasibility of using whole body computational human phantoms for estimating out-of-field organ doses for patients treated by Intensity Modulated Radiation Therapy (IMRT). Methods: Identical 7-field IMRT prostate plans were performed using X-ray Voxel Monte Carlo (XVMC), a radiotherapy-specific Monte Carlo transport code, on the computed tomography (CT) images of the torso of an adult male patient (175 cm height, 66 kg weight) and an adult male hybrid computational phantom with the equivalent body size. Dose to the liver, right lung, and left lung were calculated and compared. Results: Considerable differences are seen between the doses calculated by XVMC for the patient CT and the hybrid phantom. One major contributing factor is the treatment method, deep inspiration breath hold (DIBH), used for this patient. This leads to significant differences in the organ position relative to the treatment isocenter. The transverse distances from the treatment isocenter to the inferior border of the liver, left lung, and right lung are 19.5cm, 29.5cm, and 30.0cm, respectively for the patient CT, compared with 24.3cm, 36.6cm, and 39.1cm, respectively, for the hybrid phantom. When corrected for the distance, the mean doses calculated using the hybrid phantom are within 28% of those calculated using the patient CT. Conclusion: This study showed that mean dose to the organs located in the missing CT coverage can be reconstructed by using whole body computational human phantoms within reasonable dosimetric uncertainty, however appropriate corrections may be necessary if the patient is treated with a technique that will significantly deform the size or location of the organs relative to the hybrid phantom.

  17. Comparison of absorbed dose in the cervix carcinoma therapy by brachytherapy of high dose rate using the conventional planning and Monte Carlo simulation

    International Nuclear Information System (INIS)

    This study aims to compare the doses received for patients submitted to brachytherapy High Dose Rate (HDR) brachytherapy, a method of treatment of the cervix carcinoma, performed in the planning system PLATO BPS with the doses obtained by Monte Carlo simulation using the radiation transport code MCNP 5 and one female anthropomorphic phantom based on voxel, the FAX. The implementation of HDR brachytherapy treatment for the cervix carcinoma consists of the insertion of an intrauterine probe and an intravaginal probe (ring or ovoid) and then two radiographs are obtained, anteroposterior (AP) and lateral (LAT) to confirm the position of the applicators in the patient and to allow the treatment planning and the determination of the absorbed dose at points of interest: rectum, bladder, sigmoid and point A, which corresponds anatomically to the crossings of the uterine arteries with ureters The absorbed doses obtained with the code MCNP 5, with the exception of the absorbed dose in the rectum and sigmoid for the simulation considering a point source of 192Ir, are lower than the absorbed doses from PLATO BPS calculations because the MCNP 5 considers the chemical compositions and densities of FAX body, not considering the medium as water. When considering the Monte Carlo simulation for a source with dimensions equal to that used in the brachytherapy irradiator used in this study, the values of calculated absorbed dose to the bladder, to the rectum, to the right point A and to the left point A were respectively lower than those determined by the treatment planning system in 33.29, 5.01, 22.93 and 19.04%. These values are almost all larger than the maximum acceptable deviation between patient planned and administered doses (5 %). With regard to the rectum and bladder, which are organs that must be protected, the present results are in favor of the radiological protection of patients. The point A, that is on the isodose of 100%, used to tumor treatment, the results indicate an

  18. Assessment of ocular beta radiation dose distribution due to 106Ru/106Rh brachytherapy applicators using MCNPX Monte Carlo code

    Directory of Open Access Journals (Sweden)

    Nilseia Aparecida Barbosa

    2014-08-01

    Full Text Available Purpose: Melanoma at the choroid region is the most common primary cancer that affects the eye in adult patients. Concave ophthalmic applicators with 106Ru/106Rh beta sources are the more used for treatment of these eye lesions, mainly lesions with small and medium dimensions. The available treatment planning system for 106Ru applicators is based on dose distributions on a homogeneous water sphere eye model, resulting in a lack of data in the literature of dose distributions in the eye radiosensitive structures, information that may be crucial to improve the treatment planning process, aiming the maintenance of visual acuity. Methods: The Monte Carlo code MCNPX was used to calculate the dose distribution in a complete mathematical model of the human eye containing a choroid melanoma; considering the eye actual dimensions and its various component structures, due to an ophthalmic brachytherapy treatment, using 106Ru/106Rh beta-ray sources. Two possibilities were analyzed; a simple water eye and a heterogeneous eye considering all its structures. Two concave applicators, CCA and CCB manufactured by BEBIG and a complete mathematical model of the human eye were modeled using the MCNPX code. Results and Conclusion: For both eye models, namely water model and heterogeneous model, mean dose values simulated for the same eye regions are, in general, very similar, excepting for regions very distant from the applicator, where mean dose values are very low, uncertainties are higher and relative differences may reach 20.4%. For the tumor base and the eye structures closest to the applicator, such as sclera, choroid and retina, the maximum difference observed was 4%, presenting the heterogeneous model higher mean dose values. For the other eye regions, the higher doses were obtained when the homogeneous water eye model is taken into consideration. Mean dose distributions determined for the homogeneous water eye model are similar to those obtained for the

  19. An OpenCL-based Monte Carlo dose calculation engine (oclMC) for coupled photon-electron transport

    CERN Document Server

    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 ...

  20. On the use of Gafchromic EBT3 films for validating a commercial electron Monte Carlo dose calculation algorithm

    International Nuclear Information System (INIS)

    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)

  1. A Monte Carlo study on the effect of the orbital bone to the radiation dose delivered to the eye lens

    Science.gov (United States)

    Stratis, Andreas; Zhang, Guozhi; Jacobs, Reinhilde; Bogaerts, Ria; Bosmans, Hilde

    2015-03-01

    The aim of this work was to investigate the influence of backscatter radiation from the orbital bone and the intraorbital fat on the eye lens dose in the dental CBCT energy range. To this end we conducted three different yet interrelated studies; A preliminary simulation study was conducted to examine the impact of a bony layer situated underneath a soft tissue layer on the amount of backscatter radiation. We compared the Percentage Depth Dose (PDD) curves in soft tissue with and without the bone layer and we estimated the depth in tissue where the decrease in backscatter caused by the presence of the bone is noticeable. In a supplementary study, an eye voxel phantom was designed with the DOSxyznrc code. Simulations were performed exposing the phantom at different x-ray energies sequentially in air, in fat tissue and in realistic anatomy with the incident beam perpendicular to the phantom. Finally, a virtual head phantom was implemented into a validated hybrid Monte Carlo (MC) framework to simulate a large Field of View protocol of a real CBCT scanner and examine the influence of scattered dose to the eye lens during the whole rotation of the paired tube-detector system. The results indicated an increase in the dose to the lens due to the fatty tissue in the surrounding anatomy. There is a noticeable dose reduction close to the bone-tissue interface which weakens with increasing distance from the interface, such that the impact of the orbital bone in the eye lens dose becomes small.

  2. The Monte Carlo SRNA code as the engine in ISTAR proton dose planning software for the tesla accelerator installation

    International Nuclear Information System (INIS)

    This paper describes the application of SRNA Monte Carlo package for proton transport simulations in complex geometry and different material composition. SRNA package was developed for 3D dose distribution calculation in proton therapy and dosimetry and it was based on the theory of multiple scattering. The compound nuclei decay was simulated by our own and the Russian MSDM models using ICRU 63 data. The developed package consists of two codes: SRNA-2KG, which simulates proton transport in the combinatorial geometry and SRNA-VOX, which uses the voxelized geometry using the CT data and conversion of the Hounsfield's data to tissue elemental composition. Transition probabilities for both codes are prepared by the SRNADAT code. The simulation of proton beam characterization by Multi-Layer Faraday Cup, spatial distribution of positron emitters obtained by SRNA-2KG code, and intercomparison of computational codes in radiation dosimetry, indicate the immediate application of the Monte Carlo techniques in clinical practice. In this paper, we briefly present the physical model implemented in SRNA package, the ISTAR proton dose planning software, as well as the results of the numerical experiments with proton beams to obtain 3D dose distribution in the eye and breast tumor. (author)

  3. The Monte Carlo SRNA-VOX code for 3D proton dose distribution in voxelized geometry using CT data

    Energy Technology Data Exchange (ETDEWEB)

    Ilic, Radovan D [Laboratory of Physics (010), Vinca Institute of Nuclear Sciences, PO Box 522, 11001 Belgrade (Serbia and Montenegro); Spasic-Jokic, Vesna [Laboratory of Physics (010), Vinca Institute of Nuclear Sciences, PO Box 522, 11001 Belgrade (Serbia and Montenegro); Belicev, Petar [Laboratory of Physics (010), Vinca Institute of Nuclear Sciences, PO Box 522, 11001 Belgrade (Serbia and Montenegro); Dragovic, Milos [Center for Nuclear Medicine MEDICA NUCLEARE, Bulevar Despota Stefana 69, 11000 Belgrade (Serbia and Montenegro)

    2005-03-07

    This paper describes the application of the SRNA Monte Carlo package for proton transport simulations in complex geometry and different material compositions. The SRNA package was developed for 3D dose distribution calculation in proton therapy and dosimetry and it was based on the theory of multiple scattering. The decay of proton induced compound nuclei was simulated by the Russian MSDM model and our own using ICRU 63 data. The developed package consists of two codes: the SRNA-2KG, which simulates proton transport in combinatorial geometry and the SRNA-VOX, which uses the voxelized geometry using the CT data and conversion of the Hounsfield's data to tissue elemental composition. Transition probabilities for both codes are prepared by the SRNADAT code. The simulation of the proton beam characterization by multi-layer Faraday cup, spatial distribution of positron emitters obtained by the SRNA-2KG code and intercomparison of computational codes in radiation dosimetry, indicate immediate application of the Monte Carlo techniques in clinical practice. In this paper, we briefly present the physical model implemented in the SRNA package, the ISTAR proton dose planning software, as well as the results of the numerical experiments with proton beams to obtain 3D dose distribution in the eye and breast tumour.

  4. The Monte Carlo SRNA-VOX code for 3D proton dose distribution in voxelized geometry using CT data

    Science.gov (United States)

    Ilic, Radovan D.; Spasic-Jokic, Vesna; Belicev, Petar; Dragovic, Milos

    2005-03-01

    This paper describes the application of the SRNA Monte Carlo package for proton transport simulations in complex geometry and different material compositions. The SRNA package was developed for 3D dose distribution calculation in proton therapy and dosimetry and it was based on the theory of multiple scattering. The decay of proton induced compound nuclei was simulated by the Russian MSDM model and our own using ICRU 63 data. The developed package consists of two codes: the SRNA-2KG, which simulates proton transport in combinatorial geometry and the SRNA-VOX, which uses the voxelized geometry using the CT data and conversion of the Hounsfield's data to tissue elemental composition. Transition probabilities for both codes are prepared by the SRNADAT code. The simulation of the proton beam characterization by multi-layer Faraday cup, spatial distribution of positron emitters obtained by the SRNA-2KG code and intercomparison of computational codes in radiation dosimetry, indicate immediate application of the Monte Carlo techniques in clinical practice. In this paper, we briefly present the physical model implemented in the SRNA package, the ISTAR proton dose planning software, as well as the results of the numerical experiments with proton beams to obtain 3D dose distribution in the eye and breast tumour.

  5. The Monte Carlo SRNA-VOX code for 3D proton dose distribution in voxelized geometry using CT data

    International Nuclear Information System (INIS)

    This paper describes the application of the SRNA Monte Carlo package for proton transport simulations in complex geometry and different material compositions. The SRNA package was developed for 3D dose distribution calculation in proton therapy and dosimetry and it was based on the theory of multiple scattering. The decay of proton induced compound nuclei was simulated by the Russian MSDM model and our own using ICRU 63 data. The developed package consists of two codes: the SRNA-2KG, which simulates proton transport in combinatorial geometry and the SRNA-VOX, which uses the voxelized geometry using the CT data and conversion of the Hounsfield's data to tissue elemental composition. Transition probabilities for both codes are prepared by the SRNADAT code. The simulation of the proton beam characterization by multi-layer Faraday cup, spatial distribution of positron emitters obtained by the SRNA-2KG code and intercomparison of computational codes in radiation dosimetry, indicate immediate application of the Monte Carlo techniques in clinical practice. In this paper, we briefly present the physical model implemented in the SRNA package, the ISTAR proton dose planning software, as well as the results of the numerical experiments with proton beams to obtain 3D dose distribution in the eye and breast tumour

  6. The Monte Carlo srna code as the engine in istar proton dose planning software for the tesla accelerator installation

    Directory of Open Access Journals (Sweden)

    Ilić Radovan D.

    2004-01-01

    Full Text Available This paper describes the application of SRNA Monte Carlo package for proton transport simulations in complex geometry and different material composition. SRNA package was developed for 3D dose distribution calculation in proton therapy and dosimetry and it was based on the theory of multiple scattering. The compound nuclei decay was simulated by our own and the Russian MSDM models using ICRU 63 data. The developed package consists of two codes SRNA-2KG, which simulates proton transport in the combinatorial geometry and SRNA-VOX, which uses the voxelized geometry using the CT data and conversion of the Hounsfield’s data to tissue elemental composition. Transition probabilities for both codes are prepared by the SRNADAT code. The simulation of proton beam characterization by Multi-Layer Faraday Cup, spatial distribution of positron emitters obtained by SRNA-2KG code, and intercomparison of computational codes in radiation dosimetry, indicate the immediate application of the Monte Carlo techniques in clinical practice. In this paper, we briefly present the physical model implemented in SRNA pack age, the ISTAR proton dose planning software, as well as the results of the numerical experiments with proton beams to obtain 3D dose distribution in the eye and breast tumor.

  7. Monte Carlo evaluation of hand and finger doses due to exposure to {sup 18}F in PET procedures

    Energy Technology Data Exchange (ETDEWEB)

    Pessanha, Paula R.; Queiroz Filho, Pedro P.; Santos, Denison S.; Mauricio, Claudia L.P., E-mail: paula@ird.gov.br, E-mail: queiroz@ird.gov.br, E-mail: santosd@ird.gov.br, E-mail: claudia@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    The increasing number of PET procedures performed in nuclear medicine, and, consequently, of workers handling radiopharmaceuticals, is a potential hazard in radiation protection. It is then necessary to evaluate the doses of workers employed in the practice of PET. In this work, the Geant4 Monte Carlo code was used to evaluate doses to fingers and hands of those workers. A geometric phantom, representing the hand of the professional inserted in the clinical procedure, was implemented in the simulation code, with dimensions of a standard man's forearm, which in this case will assess the exposure of the extremities. The geometric phantom is designed so that a simple definition of joint angles configures the fingers, allowing investigations into alternative configurations. Thus, it was possible the placement of the phantom fingers, to simulate all forms of manipulation of a syringe, and subsequently obtain exposure data, relating to the administration procedure of the PET radiopharmaceutical to the patient. The simulation was validated by the irradiation of a REMAB{sup R} hand phantom, consisting of a human skeleton hand covered by a tenite II shell, which can be filled with water. Air Kerma values were obtained from the beam dosimetry, which was done with a calibrated ionization chamber. The reading of TLD's, placed on certain points of the surface of the phantom, were compared with the values obtained in the Monte Carlo simulation. After validation of the program, we obtained dose values for the PET procedure, simulating syringes with and without shielding. (author)

  8. Monte Carlo evaluation of hand and finger doses due to exposure to 18F in PET procedures

    International Nuclear Information System (INIS)

    The increasing number of PET procedures performed in nuclear medicine, and, consequently, of workers handling radiopharmaceuticals, is a potential hazard in radiation protection. It is then necessary to evaluate the doses of workers employed in the practice of PET. In this work, the Geant4 Monte Carlo code was used to evaluate doses to fingers and hands of those workers. A geometric phantom, representing the hand of the professional inserted in the clinical procedure, was implemented in the simulation code, with dimensions of a standard man's forearm, which in this case will assess the exposure of the extremities. The geometric phantom is designed so that a simple definition of joint angles configures the fingers, allowing investigations into alternative configurations. Thus, it was possible the placement of the phantom fingers, to simulate all forms of manipulation of a syringe, and subsequently obtain exposure data, relating to the administration procedure of the PET radiopharmaceutical to the patient. The simulation was validated by the irradiation of a REMABR hand phantom, consisting of a human skeleton hand covered by a tenite II shell, which can be filled with water. Air Kerma values were obtained from the beam dosimetry, which was done with a calibrated ionization chamber. The reading of TLD's, placed on certain points of the surface of the phantom, were compared with the values obtained in the Monte Carlo simulation. After validation of the program, we obtained dose values for the PET procedure, simulating syringes with and without shielding. (author)

  9. Development of virtual CT DICOM images of patients with tumors: application for TPS and Monte Carlo dose evaluation

    International Nuclear Information System (INIS)

    A novel procedure for the generation of a realistic virtual Computed Tomography (CT) image of a patient, using the advanced Boundary RE Presentation (BREP)-based model MASH, has been implemented. This method can be used in radiotherapy assessment. It is shown that it is possible to introduce an artificial cancer, which can be modeled using mesh surfaces. The use of virtual CT images based on BREP models presents several advantages with respect to CT images of actual patients, such as automation, control and flexibility. As an example, two artificial cases, namely a brain and a prostate cancer, were created through the generation of images and tumor/organ contours. As a secondary objective, the described methodology has been used to generate input files for treatment planning system (TPS) and Monte Carlo code dose evaluation. In this paper, we consider treatment plans generated assuming a dose delivery via an active proton beam scanning performed with the INFN-IBA TPS kernel. Additionally, Monte Carlo simulations of the two treatment plans were carried out with GATE/GEANT4. The work demonstrates the feasibility of the approach based on the BREP modeling to produce virtual CT images. In conclusion, this study highlights the benefits in using digital phantom model capable of representing different anatomical structures and varying tumors across different patients. These models could be useful for assessing radiotherapy treatment planning systems (TPS) and computer simulations for the evaluation of the adsorbed dose. (author)

  10. Electron dose distributions caused by the contact-type metallic eye shield: Studies using Monte Carlo and pencil beam algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sei-Kwon; Yoon, Jai-Woong; Hwang, Taejin; Park, Soah; Cheong, Kwang-Ho; Jin Han, Tae; Kim, Haeyoung; Lee, Me-Yeon; Ju Kim, Kyoung, E-mail: kjkim@hallym.or.kr; Bae, Hoonsik

    2015-10-01

    A metallic contact eye shield has sometimes been used for eyelid treatment, but dose distribution has never been reported for a patient case. This study aimed to show the shield-incorporated CT-based dose distribution using the Pinnacle system and Monte Carlo (MC) calculation for 3 patient cases. For the artifact-free CT scan, an acrylic shield machined as the same size as that of the tungsten shield was used. For the MC calculation, BEAMnrc and DOSXYZnrc were used for the 6-MeV electron beam of the Varian 21EX, in which information for the tungsten, stainless steel, and aluminum material for the eye shield was used. The same plan was generated on the Pinnacle system and both were compared. The use of the acrylic shield produced clear CT images, enabling delineation of the regions of interest, and yielded CT-based dose calculation for the metallic shield. Both the MC and the Pinnacle systems showed a similar dose distribution downstream of the eye shield, reflecting the blocking effect of the metallic eye shield. The major difference between the MC and the Pinnacle results was the target eyelid dose upstream of the shield such that the Pinnacle system underestimated the dose by 19 to 28% and 11 to 18% for the maximum and the mean doses, respectively. The pattern of dose difference between the MC and the Pinnacle systems was similar to that in the previous phantom study. In conclusion, the metallic eye shield was successfully incorporated into the CT-based planning, and the accurate dose calculation requires MC simulation.

  11. Electron dose distributions caused by the contact-type metallic eye shield: Studies using Monte Carlo and pencil beam algorithms

    International Nuclear Information System (INIS)

    A metallic contact eye shield has sometimes been used for eyelid treatment, but dose distribution has never been reported for a patient case. This study aimed to show the shield-incorporated CT-based dose distribution using the Pinnacle system and Monte Carlo (MC) calculation for 3 patient cases. For the artifact-free CT scan, an acrylic shield machined as the same size as that of the tungsten shield was used. For the MC calculation, BEAMnrc and DOSXYZnrc were used for the 6-MeV electron beam of the Varian 21EX, in which information for the tungsten, stainless steel, and aluminum material for the eye shield was used. The same plan was generated on the Pinnacle system and both were compared. The use of the acrylic shield produced clear CT images, enabling delineation of the regions of interest, and yielded CT-based dose calculation for the metallic shield. Both the MC and the Pinnacle systems showed a similar dose distribution downstream of the eye shield, reflecting the blocking effect of the metallic eye shield. The major difference between the MC and the Pinnacle results was the target eyelid dose upstream of the shield such that the Pinnacle system underestimated the dose by 19 to 28% and 11 to 18% for the maximum and the mean doses, respectively. The pattern of dose difference between the MC and the Pinnacle systems was similar to that in the previous phantom study. In conclusion, the metallic eye shield was successfully incorporated into the CT-based planning, and the accurate dose calculation requires MC simulation

  12. A global reaction route mapping-based kinetic Monte Carlo algorithm.

    Science.gov (United States)

    Mitchell, Izaac; Irle, Stephan; Page, Alister J

    2016-07-14

    We propose a new on-the-fly kinetic Monte Carlo (KMC) method that is based on exhaustive potential energy surface searching carried out with the global reaction route mapping (GRRM) algorithm. Starting from any given equilibrium state, this GRRM-KMC algorithm performs a one-step GRRM search to identify all surrounding transition states. Intrinsic reaction coordinate pathways are then calculated to identify potential subsequent equilibrium states. Harmonic transition state theory is used to calculate rate constants for all potential pathways, before a standard KMC accept/reject selection is performed. The selected pathway is then used to propagate the system forward in time, which is calculated on the basis of 1st order kinetics. The GRRM-KMC algorithm is validated here in two challenging contexts: intramolecular proton transfer in malonaldehyde and surface carbon diffusion on an iron nanoparticle. We demonstrate that in both cases the GRRM-KMC method is capable of reproducing the 1st order kinetics observed during independent quantum chemical molecular dynamics simulations using the density-functional tight-binding potential. PMID:27421395

  13. A global reaction route mapping-based kinetic Monte Carlo algorithm

    Science.gov (United States)

    Mitchell, Izaac; Irle, Stephan; Page, Alister J.

    2016-07-01

    We propose a new on-the-fly kinetic Monte Carlo (KMC) method that is based on exhaustive potential energy surface searching carried out with the global reaction route mapping (GRRM) algorithm. Starting from any given equilibrium state, this GRRM-KMC algorithm performs a one-step GRRM search to identify all surrounding transition states. Intrinsic reaction coordinate pathways are then calculated to identify potential subsequent equilibrium states. Harmonic transition state theory is used to calculate rate constants for all potential pathways, before a standard KMC accept/reject selection is performed. The selected pathway is then used to propagate the system forward in time, which is calculated on the basis of 1st order kinetics. The GRRM-KMC algorithm is validated here in two challenging contexts: intramolecular proton transfer in malonaldehyde and surface carbon diffusion on an iron nanoparticle. We demonstrate that in both cases the GRRM-KMC method is capable of reproducing the 1st order kinetics observed during independent quantum chemical molecular dynamics simulations using the density-functional tight-binding potential.

  14. A Monte Carlo simulation framework for electron beam dose calculations using Varian phase space files for TrueBeam Linacs

    International Nuclear Information System (INIS)

    Purpose: To develop a framework for accurate electron Monte Carlo dose calculation. In this study, comprehensive validations of vendor provided electron beam phase space files for Varian TrueBeam Linacs against measurement data are presented. Methods: In this framework, the Monte Carlo generated phase space files were provided by the vendor and used as input to the downstream plan-specific simulations including jaws, electron applicators, and water phantom computed in the EGSnrc environment. The phase space files were generated based on open field commissioning data. A subset of electron energies of 6, 9, 12, 16, and 20 MeV and open and collimated field sizes 3 × 3, 4 × 4, 5 × 5, 6 × 6, 10 × 10, 15 × 15, 20 × 20, and 25 × 25 cm2 were evaluated. Measurements acquired with a CC13 cylindrical ionization chamber and electron diode detector and simulations from this framework were compared for a water phantom geometry. The evaluation metrics include percent depth dose, orthogonal and diagonal profiles at depths R100, R50, Rp, and Rp+ for standard and extended source-to-surface distances (SSD), as well as cone and cut-out output factors. Results: Agreement for the percent depth dose and orthogonal profiles between measurement and Monte Carlo was generally within 2% or 1 mm. The largest discrepancies were observed within depths of 5 mm from phantom surface. Differences in field size, penumbra, and flatness for the orthogonal profiles at depths R100, R50, and Rp were within 1 mm, 1 mm, and 2%, respectively. Orthogonal profiles at SSDs of 100 and 120 cm showed the same level of agreement. Cone and cut-out output factors agreed well with maximum differences within 2.5% for 6 MeV and 1% for all other energies. Cone output factors at extended SSDs of 105, 110, 115, and 120 cm exhibited similar levels of agreement. Conclusions: We have presented a Monte Carlo simulation framework for electron beam dose calculations for Varian TrueBeam Linacs. Electron beam energies of 6

  15. A Monte Carlo simulation framework for electron beam dose calculations using Varian phase space files for TrueBeam Linacs

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Anna; Yin, Fang-Fang; Wu, Qiuwen, E-mail: Qiuwen.Wu@Duke.edu [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710 and Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705 (United States); Sawkey, Daren [Varian Medical Systems, Palo Alto, California 94304 (United States)

    2015-05-15

    Purpose: To develop a framework for accurate electron Monte Carlo dose calculation. In this study, comprehensive validations of vendor provided electron beam phase space files for Varian TrueBeam Linacs against measurement data are presented. Methods: In this framework, the Monte Carlo generated phase space files were provided by the vendor and used as input to the downstream plan-specific simulations including jaws, electron applicators, and water phantom computed in the EGSnrc environment. The phase space files were generated based on open field commissioning data. A subset of electron energies of 6, 9, 12, 16, and 20 MeV and open and collimated field sizes 3 × 3, 4 × 4, 5 × 5, 6 × 6, 10 × 10, 15 × 15, 20 × 20, and 25 × 25 cm{sup 2} were evaluated. Measurements acquired with a CC13 cylindrical ionization chamber and electron diode detector and simulations from this framework were compared for a water phantom geometry. The evaluation metrics include percent depth dose, orthogonal and diagonal profiles at depths R{sub 100}, R{sub 50}, R{sub p}, and R{sub p+} for standard and extended source-to-surface distances (SSD), as well as cone and cut-out output factors. Results: Agreement for the percent depth dose and orthogonal profiles between measurement and Monte Carlo was generally within 2% or 1 mm. The largest discrepancies were observed within depths of 5 mm from phantom surface. Differences in field size, penumbra, and flatness for the orthogonal profiles at depths R{sub 100}, R{sub 50}, and R{sub p} were within 1 mm, 1 mm, and 2%, respectively. Orthogonal profiles at SSDs of 100 and 120 cm showed the same level of agreement. Cone and cut-out output factors agreed well with maximum differences within 2.5% for 6 MeV and 1% for all other energies. Cone output factors at extended SSDs of 105, 110, 115, and 120 cm exhibited similar levels of agreement. Conclusions: We have presented a Monte Carlo simulation framework for electron beam dose calculations for

  16. Monte Carlo simulations of the dose from imaging with GE eXplore 120 micro-CT using GATE

    International Nuclear Information System (INIS)

    Purpose: Small animals are increasingly used as translational models in preclinical imaging studies involving microCT, during which the subjects can be exposed to large amounts of radiation. While the radiation levels are generally sublethal, studies have shown that low-level radiation can change physiological parameters in mice. In order to rule out any influence of radiation on the outcome of such experiments, or resulting deterministic effects in the subjects, the levels of radiation involved need to be addressed. The aim of this study was to investigate the radiation dose delivered by the GE eXplore 120 microCT non-invasively using Monte Carlo simulations in GATE and to compare results to previously obtained experimental values. Methods: Tungsten X-ray spectra were simulated at 70, 80, and 97 kVp using an analytical tool and their half-value layers were simulated for spectra validation against experimentally measured values of the physical X-ray tube. A Monte Carlo model of the microCT system was set up and four protocols that are regularly applied to live animal scanning were implemented. The computed tomography dose index (CTDI) inside a PMMA phantom was derived and multiple field of view acquisitions were simulated using the PMMA phantom, a representative mouse and rat. Results: Simulated half-value layers agreed with experimentally obtained results within a 7% error window. The CTDI ranged from 20 to 56 mGy and closely matched experimental values. Derived organ doses in mice reached 459 mGy in bones and up to 200 mGy in soft tissue organs using the highest energy protocol. Dose levels in rats were lower due to the increased mass of the animal compared to mice. The uncertainty of all dose simulations was below 14%. Conclusions: Monte Carlo simulations proved a valuable tool to investigate the 3D dose distribution in animals from microCT. Small animals, especially mice (due to their small volume), receive large amounts of radiation from the GE eXplore 120

  17. Monte Carlo simulations of the dose from imaging with GE eXplore 120 micro-CT using GATE

    Energy Technology Data Exchange (ETDEWEB)

    Bretin, Florian; Bahri, Mohamed Ali; Luxen, André; Phillips, Christophe; Plenevaux, Alain; Seret, Alain, E-mail: aseret@ulg.ac.be [Cyclotron Research Centre, University of Liège, Sart Tilman B30, Liège 4000 (Belgium)

    2015-10-15

    Purpose: Small animals are increasingly used as translational models in preclinical imaging studies involving microCT, during which the subjects can be exposed to large amounts of radiation. While the radiation levels are generally sublethal, studies have shown that low-level radiation can change physiological parameters in mice. In order to rule out any influence of radiation on the outcome of such experiments, or resulting deterministic effects in the subjects, the levels of radiation involved need to be addressed. The aim of this study was to investigate the radiation dose delivered by the GE eXplore 120 microCT non-invasively using Monte Carlo simulations in GATE and to compare results to previously obtained experimental values. Methods: Tungsten X-ray spectra were simulated at 70, 80, and 97 kVp using an analytical tool and their half-value layers were simulated for spectra validation against experimentally measured values of the physical X-ray tube. A Monte Carlo model of the microCT system was set up and four protocols that are regularly applied to live animal scanning were implemented. The computed tomography dose index (CTDI) inside a PMMA phantom was derived and multiple field of view acquisitions were simulated using the PMMA phantom, a representative mouse and rat. Results: Simulated half-value layers agreed with experimentally obtained results within a 7% error window. The CTDI ranged from 20 to 56 mGy and closely matched experimental values. Derived organ doses in mice reached 459 mGy in bones and up to 200 mGy in soft tissue organs using the highest energy protocol. Dose levels in rats were lower due to the increased mass of the animal compared to mice. The uncertainty of all dose simulations was below 14%. Conclusions: Monte Carlo simulations proved a valuable tool to investigate the 3D dose distribution in animals from microCT. Small animals, especially mice (due to their small volume), receive large amounts of radiation from the GE eXplore 120

  18. Criticality prompt gamma and neutron dose equations validated by Monte Carlo analyses and compared to known criticality accident doses

    Science.gov (United States)

    Hochhalter, Eugene

    The United States (US) Department of Energy [DOE] and the Nuclear Regulatory Commission [NRC] have provided the nuclear industry with requirements, goals, and objectives for the preparation of safety analysis and the finalization of that safety analysis in the form of a documented safety analysis (DSA) and technical safety requirements (TSRs). The deterministic guidance provided by the NRC in Regulatory Guide (RG) 3.33 for calculating the prompt gamma and neutron doses from a criticality has a number of potential issues associated with the semi-empirical equations, which make these equations potentially out dated. The NRC guidance for estimating the prompt gamma and neutron doses to a facility worker due to an accidental criticality was withdrawn without newer deterministic guidance being issued. This research project determined the original basis for the RG prompt gamma and neutron equations, evaluated the potential issues associated with the RG 3.33 prompt gamma and neutron equations, and modified the RG 3.33 point source prompt gamma and neutron equations to calculate the doses for the selected set of criticality accidents. The criticality accidents addressed by this dissertation include: 1. U-235, Pu-239, and Pu-241 point source criticality, 2. U-235, Pu-239, and Pu-241 sphere source criticality, 3. Uranyl nitrate and plutonium nitrate solutions in a cylindrical process vessel and 4. Low level waste in 55-gallon and 30-gallon drums. The prompt gamma and neutron equation doses (RG 3.33/3.34/3.35) are compared to actual nuclear industry criticality accident worker doses to assess the conservatism of the RG equations. Finally, the RG 3.33 prompt gamma and neutron dose equations are compared to MCNP5 results to investigate consistency with respect to the modified prompt gamma and neutron dose equations and the representative dose estimates for each of the criticality configurations (point source, spherical source, and cylindrical source). Knowledge and accurate

  19. Quality control of the treatment planning systems dose calculations in external radiation therapy using the Penelope Monte Carlo code; Controle qualite des systemes de planification dosimetrique des traitements en radiotherapie externe au moyen du code Monte-Carlo Penelope

    Energy Technology Data Exchange (ETDEWEB)

    Blazy-Aubignac, L

    2007-09-15

    The treatment planning systems (T.P.S.) occupy a key position in the radiotherapy service: they realize the projected calculation of the dose distribution and the treatment duration. Traditionally, the quality control of the calculated distribution doses relies on their comparisons with dose distributions measured under the device of treatment. This thesis proposes to substitute these dosimetry measures to the profile of reference dosimetry calculations got by the Penelope Monte-Carlo code. The Monte-Carlo simulations give a broad choice of test configurations and allow to envisage a quality control of dosimetry aspects of T.P.S. without monopolizing the treatment devices. This quality control, based on the Monte-Carlo simulations has been tested on a clinical T.P.S. and has allowed to simplify the quality procedures of the T.P.S.. This quality control, in depth, more precise and simpler to implement could be generalized to every center of radiotherapy. (N.C.)

  20. TestDose: A nuclear medicine software based on Monte Carlo modeling for generating gamma camera acquisitions and dosimetry

    International Nuclear Information System (INIS)

    Purpose: The TestDose platform was developed to generate scintigraphic imaging protocols and associated dosimetry by Monte Carlo modeling. TestDose is part of a broader project (www.dositest.com) whose aim is to identify the biases induced by different clinical dosimetry protocols. Methods: The TestDose software allows handling the whole pipeline from virtual patient generation to resulting planar and SPECT images and dosimetry calculations. The originality of their approach relies on the implementation of functional segmentation for the anthropomorphic model representing a virtual patient. Two anthropomorphic models are currently available: 4D XCAT and ICRP 110. A pharmacokinetic model describes the biodistribution of a given radiopharmaceutical in each defined compartment at various time-points. The Monte Carlo simulation toolkit GATE offers the possibility to accurately simulate scintigraphic images and absorbed doses in volumes of interest. The TestDose platform relies on GATE to reproduce precisely any imaging protocol and to provide reference dosimetry. For image generation, TestDose stores user’s imaging requirements and generates automatically command files used as input for GATE. Each compartment is simulated only once and the resulting output is weighted using pharmacokinetic data. Resulting compartment projections are aggregated to obtain the final image. For dosimetry computation, emission data are stored in the platform database and relevant GATE input files are generated for the virtual patient model and associated pharmacokinetics. Results: Two samples of software runs are given to demonstrate the potential of TestDose. A clinical imaging protocol for the Octreoscan™ therapeutical treatment was implemented using the 4D XCAT model. Whole-body “step and shoot” acquisitions at different times postinjection and one SPECT acquisition were generated within reasonable computation times. Based on the same Octreoscan™ kinetics, a dosimetry

  1. TestDose: A nuclear medicine software based on Monte Carlo modeling for generating gamma camera acquisitions and dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Marie-Paule, E-mail: marie-paule.garcia@univ-brest.fr; Villoing, Daphnée [UMR 1037 INSERM/UPS, CRCT, 133 Route de Narbonne, 31062 Toulouse (France); McKay, Erin [St George Hospital, Gray Street, Kogarah, New South Wales 2217 (Australia); Ferrer, Ludovic [ICO René Gauducheau, Boulevard Jacques Monod, St Herblain 44805 (France); Cremonesi, Marta; Botta, Francesca; Ferrari, Mahila [European Institute of Oncology, Via Ripamonti 435, Milano 20141 (Italy); Bardiès, Manuel [UMR 1037 INSERM/UPS, CRCT, 133 Route de Narbonne, Toulouse 31062 (France)

    2015-12-15

    Purpose: The TestDose platform was developed to generate scintigraphic imaging protocols and associated dosimetry by Monte Carlo modeling. TestDose is part of a broader project (www.dositest.com) whose aim is to identify the biases induced by different clinical dosimetry protocols. Methods: The TestDose software allows handling the whole pipeline from virtual patient generation to resulting planar and SPECT images and dosimetry calculations. The originality of their approach relies on the implementation of functional segmentation for the anthropomorphic model representing a virtual patient. Two anthropomorphic models are currently available: 4D XCAT and ICRP 110. A pharmacokinetic model describes the biodistribution of a given radiopharmaceutical in each defined compartment at various time-points. The Monte Carlo simulation toolkit GATE offers the possibility to accurately simulate scintigraphic images and absorbed doses in volumes of interest. The TestDose platform relies on GATE to reproduce precisely any imaging protocol and to provide reference dosimetry. For image generation, TestDose stores user’s imaging requirements and generates automatically command files used as input for GATE. Each compartment is simulated only once and the resulting output is weighted using pharmacokinetic data. Resulting compartment projections are aggregated to obtain the final image. For dosimetry computation, emission data are stored in the platform database and relevant GATE input files are generated for the virtual patient model and associated pharmacokinetics. Results: Two samples of software runs are given to demonstrate the potential of TestDose. A clinical imaging protocol for the Octreoscan™ therapeutical treatment was implemented using the 4D XCAT model. Whole-body “step and shoot” acquisitions at different times postinjection and one SPECT acquisition were generated within reasonable computation times. Based on the same Octreoscan™ kinetics, a dosimetry

  2. Absorbed dose measurements in mammography using Monte Carlo method and ZrO{sub 2}+PTFE dosemeters

    Energy Technology Data Exchange (ETDEWEB)

    Duran M, H. A.; Hernandez O, M. [Departamento de Investigacion en Polimeros y Materiales, Universidad de Sonora, Blvd. Luis Encinas y Rosales s/n, Col. Centro, 83190 Hermosillo, Sonora (Mexico); Salas L, M. A.; Hernandez D, V. M.; Vega C, H. R. [Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, Cipres 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Pinedo S, A.; Ventura M, J.; Chacon, F. [Hospital General de Zona No. 1, IMSS, Interior Alameda 45, 98000 Zacatecas (Mexico); Rivera M, T. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, IPN, Av. Legaria 694, Col. Irrigacion, 11500 Mexico D. F.(Mexico)], e-mail: hduran20_1@hotmail.com

    2009-10-15

    Mammography test is a central tool for breast cancer diagnostic. In addition, programs are conducted periodically to detect the asymptomatic women in certain age groups; these programs have shown a reduction on breast cancer mortality. Early detection of breast cancer is achieved through a mammography, which contrasts the glandular and adipose tissue with a probable calcification. The parameters used for mammography are based on the thickness and density of the breast, their values depend on the voltage, current, focal spot and anode-filter combination. To achieve an image clear and a minimum dose must be chosen appropriate irradiation conditions. Risk associated with mammography should not be ignored. This study was performed in the General Hospital No. 1 IMSS in Zacatecas. Was used a glucose phantom and measured air Kerma at the entrance of the breast that was calculated using Monte Carlo methods and ZrO{sub 2}+PTFE thermoluminescent dosemeters, this calculation was completed with calculating the absorbed dose. (author)

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

    Science.gov (United States)

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

    2015-10-01

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

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

    Science.gov (United States)

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

    2015-09-01

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

  5. Typical exposure parameters, organ doses and effective doses for endovascular aortic aneurysm repair: Comparison of Monte Carlo simulations and direct measurements with an anthropomorphic phantom

    Energy Technology Data Exchange (ETDEWEB)

    Foerth, Monika; Treitl, Karla Maria; Treitl, Marcus [Ludwig Maximilians University of Munich, Institute for Clinical Radiology, Munich (Germany); Seidenbusch, Michael C. [Ludwig Maximilians University of Munich, Institute for Clinical Radiology, Munich (Germany); Clinical Centre of the Ludwig Maximilian University of Munich, Institute for Clinical Radiology, Munich (Germany); Sadeghi-Azandaryani, Mojtaba [Clinical Centre of the County of Erding, Department of Vascular Surgery, Erding (Germany); Lechel, Ursula [Federal Office for Radiation Protection, Department of Medical and Occupational Radiation Protection, Oberschleissheim (Germany)

    2015-09-15

    Radiation exposure of patients during endovascular aneurysm repair (EVAR) procedures ranks in the upper sector of medical exposure. Thus, estimation of radiation doses achieved during EVAR is of great importance. Organ doses (OD) and effective doses (ED) administered to 17 patients receiving EVAR were determined (1) from the exposure parameters by performing Monte Carlo simulations in mathematical phantoms and (2) by measurements with thermoluminescent dosimeters in a physical anthropomorphic phantom. The mean fluoroscopy time was 26 min, the mean dose area product was 24995 cGy cm2. The mean ED was 34.8 mSv, ODs up to 626 mSv were found. Whereas digital subtraction angiographies (DSA) and fluoroscopies each contributed about 50 % to the cumulative ED, the ED rates of DSAs were found to be ten times higher than those of fluoroscopies. Doubling of the field size caused an ED rate enhancement up to a factor of 3. EVAR procedures cause high radiation exposure levels that exceed the values published thus far. As a consequence, (1) DSAs should be only performed when necessary and with a low image rate, (2) fluoroscopies should be kept as short as possible, and (3) field sizes should be minimized. (orig.)

  6. Calculating of Dose Distribution in Tongue Brachytherapy by Different Radioisotopes using Monte Carlo Simulation and Comparing by Experimental Data

    Directory of Open Access Journals (Sweden)

    Banafsheh Zeinali Rafsanjani

    2011-06-01

    Full Text Available Introduction: Among different kinds of oral cavity cancers, the frequency of tongue cancer occurrence is more significant. Brachytherapy is the most common method to cure tongue cancers. Long sources are used in different techniques of tongue brachytherapy. The objective of this study is to asses the dose distribution around long sources, comparing different radioisotopes as brachytherapy sources, measuring the homogeneity of delivered dose to treatment volume and also comparing mandible dose and dose of tongue in the regions near the mandible with and without using shield. Material and Method: The Monte Carlo code MCNP4C was used for simulation. The accuracy of simulation was verified by comparing the results with experimental data. The sources like Ir-192, Cs-137, Ra-226, Au-198, In-111 and Ba-131 were simulated and the position of sources was determined by Paris system. Results: The percentage of mandible dose reduction with use of 2 mm Pb shield for the sources mentioned above were: 35.4%, 20.1%, 86.6%, 32.24%, 75.6%, and 36.8%. The tongue dose near the mandible with use of shied did not change significantly. The dose homogeneity from the most to least was obtained from these sources: Cs-137, Au-198, Ir-192, Ba-131, In-111 and Ra-226. Discussion and Conclusion: Ir-192 and Cs-137 were the best sources for tongue brachytherapy treatment but In-111 and Ra-226 were not suitable choices for tongue brachytherapy. The sources like Au-198 and Ba-131 had rather the same performance as Ir-192

  7. Dose enhancement in gold nanoparticle-aided radiotherapy for the therapeutic photon beams using Monte Carlo technique

    Directory of Open Access Journals (Sweden)

    Nitin Ramesh Kakade

    2015-01-01

    Full Text Available Background: Gold nanoparticle (GNP-aided radiation therapy (RT is useful to make the tumor more sensitive to radiation damage because of the enhancement in the dose inside the tumor region. Polymer gel dosimeter (PGD can be a good choice for the physical measurement of dose enhancement produced by GNP inside the gel. Materials and Methods: The present study uses EGSnrc Monte Carlo code to estimate dose enhancement factor (DEF due to the introduction of GNPs inside the PGD at different concentrations (7 and 18 mg Au/g of gel when irradiated by therapeutic X-rays of energy 100 kVp, 150 kVp, 6 MV, and 15 MV. The simulation was also carried out to quantify the dose enhancement in PAGAT gel and tumor for 100 kVp X-rays. Results: For 100 kVp X-rays, average DEF of 1.86 and 2.91 is observed in the PAGAT gel dosimeter with 7 and 18 mg Au/g of gel, respectively. Average DEF of 1.69 and 2.61 is recorded for 150 kVp X-rays with 7 and 18 mg Au/g of gel, respectively. No clinically meaningful DEF was observed for 6 and 15 MV photon beams. Furthermore, the dose enhancement within the PAGAT gel dosimeter and tumor closely matches with each other. Conclusion: The polymer gel dosimetry can be a suitable method of dose estimation and verification for clinical implementation of GNP-aided RT. GNP-aided RT has the potential of delivering high localized tumoricidal dose with significant sparing of normal structures when the treatment is delivered with low energy X-rays.

  8. High-density dental implants and radiotherapy planning: evaluation of effects on dose distribution using pencil beam convolution algorithm and Monte Carlo method.

    Science.gov (United States)

    Çatli, Serap

    2015-01-01

    High atomic number and density of dental implants leads to major problems at providing an accurate dose distribution in radiotherapy and contouring tumors and organs caused by the artifact in head and neck tumors. The limits and deficiencies of the algorithms using in the treatment planning systems can lead to large errors in dose calculation, and this may adversely affect the patient's treatment. In the present study, four commercial dental implants were used: pure titanium, titanium alloy (Ti-6Al-4V), amalgam, and crown. The effects of dental implants on dose distribution are determined with two methods: pencil beam convolution (PBC) algorithm and Monte Carlo code for 6 MV photon beam. The central axis depth doses were calculated on the phantom for a source-skin distance (SSD) of 100 cm and a 10 × 10 cm2 field using both of algorithms. The results of Monte Carlo method and Eclipse TPS were compared to each other and to those previously reported. In the present study, dose increases in tissue at a distance of 2 mm in front of the dental implants were seen due to the backscatter of electrons for dental implants at 6 MV using the Monte Carlo method. The Eclipse treatment planning system (TPS) couldn't precisely account for the backscatter radiation caused by the dental prostheses. TPS underestimated the back scatter dose and overestimated the dose after the dental implants. The large errors found for TPS in this study are due to the limits and deficiencies of the algorithms. The accuracy of the PBC algorithm of Eclipse TPS was evaluated in comparison to Monte Carlo calculations in consideration of the recommendations of the American Association of Physicists in Medicine Radiation Therapy Committee Task Group 65. From the comparisons of the TPS and Monte Carlo calculations, it is verified that the Monte Carlo simulation is a good approach to derive the dose distribution in heterogeneous media. PMID:26699323

  9. Estimation of staff doses in complex radiological examinations using a Monte Carlo computer code

    International Nuclear Information System (INIS)

    The protection of medical personnel in interventional radiology is an important issue of radiological protection. The irradiation of the worker is largely non-uniform, and a large part of his body is shielded by a lead apron. The estimation of effective dose (E) under these conditions is difficult and several approaches are used to estimate effective dose involving such a protective apron. This study presents a summary from an extensive series of simulations to determine scatter-dose distribution around the patient and staff effective dose from personal dosimeter readings. The influence of different parameters (like beam energy and size, patient size, irradiated region, worker position and orientation) on the staff doses has been determined. Published algorithms that combine readings of an unshielded and a shielded dosimeter to estimate effective dose have been applied and a new algorithm, that gives more accurate dose estimates for a wide range of situations was proposed. A computational approach was used to determine the dose distribution in the worker's body. The radiation transport and energy deposition was simulated using the MCNP4B code. The human bodies of the patient and radiologist were generated with the Body Builder anthropomorphic model-generating tool. The radiologist is protected with a lead apron (0.5 mm lead equivalent in the front and 0.25 mm lead equivalent in the back and sides) and a thyroid collar (0.35 mm lead equivalent). The lower-arms of the worker were folded to simulate the arms position during clinical examinations. This realistic situation of the folded arms affects the effective dose to the worker. Depending on the worker position and orientation (and of course the beam energy), the difference can go up to 25 percent. A total of 12 Hp(10) dosimeters were positioned above and under the lead apron at the neck, chest and waist levels. Extra dosimeters for the skin dose were positioned at the forehead, the forearms and the front surface of

  10. Calculation of dose distribution in compressible breast tissues using finite element modeling, Monte Carlo simulation and thermoluminescence dosimeters

    Science.gov (United States)

    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%.

  11. Use of Monte Carlo simulation software for the calculation of the effective dose in cone beam Tomography

    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)

  12. Calculation of dose distribution in compressible breast tissues using finite element modeling, Monte Carlo simulation and thermoluminescence dosimeters

    International Nuclear Information System (INIS)

    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)

  13. Monte Carlo modeling of the Yttrium-90 nanospheres application in the liver radionuclide therapy and organs doses calculation

    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.

  14. Study the sensitivity of dose calculation in prism treatment planning system using Monte Carlo simulation of 6 MeV electron beam

    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.

  15. Study the sensitivity of dose calculation in prism treatment planning system using Monte Carlo simulation of 6 MeV electron beam

    Science.gov (United States)

    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.

  16. Study the sensitivity of dose calculation in prism treatment planning system using Monte Carlo simulation of 6 MeV electron beam

    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

  17. Dose estimation in the crystalline lens of industrial radiography personnel using Monte Carlo Method; Estimativa de dose nos cristalinos de operadores de gamagrafia industrial usando o metodo de Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Alexandre Roza de

    2014-07-01

    The International Commission on Radiological Protection, ICRP, in its publication 103, reviewed recent epidemiological evidence and indicated that, for the eye lens, the absorbed dose threshold for induction of late detriment is around 0.5 Gy. On this basis, on April 21, 2011, the ICRP recommended changes to the occupational dose limit in planned exposure situations, reducing the eye lens equivalent dose limit from 150 mSv to 20 mSv per year, on average, during the period of 5 years, with exposure not to exceed 50 mSv in a single year. This paper presents the dose estimation to eye lens, H{sub p}(10), effective dose and doses to important organs in the body, received by industrial gamma radiography workers, during planned or accidental exposure situations. The computer program Visual Monte Carlo was used and two relevant scenarios were postulated. The first is a planned exposure situation scenario where the operator is directly exposed to radiation during the operation. 12 radiographic exposures per day for 250 days per year, which leads to an exposure of 36,000 seconds or 10 hours per year were considered. The simulation was carried out using the following parameters: a {sup 192}Ir source with 1.0 TBq of activity, the source/operator distance varying from 5 m to 10 m at three different heights of 0.2 m, 1.0 m and 2.0 m. The eyes lens doses were estimated as being between 16.9 mSv/year and 66.9 mSv/year and for H{sub p}(10) the doses were between 17.7 mSv/year and 74.2 mSv/year. For the accidental exposure situation scenario, the same radionuclide and activity were used, but in this case the doses were calculated with and without a collimator. The heights above ground considered were 1.0 m, 1.5 m e 2.0 m, the source/operator distance was 40 cm and, the exposure time 74 seconds. The eyes lens doses, for 1.5 m, were 12.3 mGy and 0.28 mGy without and with a collimator, respectively. Three conclusions resulted from this work. The first was that the estimated doses show

  18. Calculated organ doses using Monte Carlo simulations in a reference male phantom undergoing HDR brachytherapy applied to localized prostate carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Candela-Juan, Cristian [Radioprotection Department, La Fe University and Polytechnic Hospital, Valencia 46026 (Spain); Perez-Calatayud, Jose [Radiotherapy Department, La Fe University and Polytechnic Hospital, Valencia 46026 (Spain); Ballester, Facundo [Department of Atomic, Molecular and Nuclear Physics, University of Valencia, Burjassot 46100 (Spain); Rivard, Mark J. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States)

    2013-03-15

    Purpose: The aim of this study was to obtain equivalent doses in radiosensitive organs (aside from the bladder and rectum) when applying high-dose-rate (HDR) brachytherapy to a localized prostate carcinoma using {sup 60}Co or {sup 192}Ir sources. These data are compared with results in a water phantom and with expected values in an infinite water medium. A comparison with reported values from proton therapy and intensity-modulated radiation therapy (IMRT) is also provided. Methods: Monte Carlo simulations in Geant4 were performed using a voxelized phantom described in International Commission on Radiological Protection (ICRP) Publication 110, which reproduces masses and shapes from an adult reference man defined in ICRP Publication 89. Point sources of {sup 60}Co or {sup 192}Ir with photon energy spectra corresponding to those exiting their capsules were placed in the center of the prostate, and equivalent doses per clinical absorbed dose in this target organ were obtained in several radiosensitive organs. Values were corrected to account for clinical circumstances with the source located at various positions with differing dwell times throughout the prostate. This was repeated for a homogeneous water phantom. Results: For the nearest organs considered (bladder, rectum, testes, small intestine, and colon), equivalent doses given by {sup 60}Co source were smaller (8%-19%) than from {sup 192}Ir. However, as the distance increases, the more penetrating gamma rays produced by {sup 60}Co deliver higher organ equivalent doses. The overall result is that effective dose per clinical absorbed dose from a {sup 60}Co source (11.1 mSv/Gy) is lower than from a {sup 192}Ir source (13.2 mSv/Gy). On the other hand, equivalent doses were the same in the tissue and the homogeneous water phantom for those soft tissues closer to the prostate than about 30 cm. As the distance increased, the differences of photoelectric effect in water and soft tissue, and appearance of other materials

  19. Efficiency of radiation protection equipment in interventional radiology: a systematic Monte Carlo study of eye lens and whole body doses

    International Nuclear Information System (INIS)

    Monte Carlo calculations were used to investigate the efficiency of radiation protection equipment in reducing eye and whole body doses during fluoroscopically guided interventional procedures. Eye lens doses were determined considering different models of eyewear with various shapes, sizes and lead thickness. The origin of scattered radiation reaching the eyes was also assessed to explain the variation in the protection efficiency of the different eyewear models with exposure conditions. The work also investigates the variation of eye and whole body doses with ceiling-suspended shields of various shapes and positioning. For all simulations, a broad spectrum of configurations typical for most interventional procedures was considered. Calculations showed that ‘wrap around’ glasses are the most efficient eyewear models reducing, on average, the dose by 74% and 21% for the left and right eyes respectively. The air gap between the glasses and the eyes was found to be the primary source of scattered radiation reaching the eyes. The ceiling-suspended screens were more efficient when positioned close to the patient’s skin and to the x-ray field. With the use of such shields, the Hp(10) values recorded at the collar, chest and waist level and the Hp(3) values for both eyes were reduced on average by 47%, 37%, 20% and 56% respectively. Finally, simulations proved that beam quality and lead thickness have little influence on eye dose while beam projection, the position and head orientation of the operator as well as the distance between the image detector and the patient are key parameters affecting eye and whole body doses. (paper)

  20. TH-A-19A-10: Fast Four Dimensional Monte Carlo Dose Computations for Proton Therapy of Lung Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Mirkovic, D; Titt, U; Mohan, R [U.T M.D. Anderson Cancer Center, Houston, TX (United States); Yepes, P [Rice University, Houston, TX (United States)

    2014-06-15

    Purpose: To develop and validate a fast and accurate four dimensional (4D) Monte Carlo (MC) dose computation system for proton therapy of lung cancer and other thoracic and abdominal malignancies in which the delivered dose distributions can be affected by respiratory motion of the patient. Methods: A 4D computer tomography (CT) scan for a lung cancer patient treated with protons in our clinic was used to create a time dependent patient model using our in-house, MCNPX-based Monte Carlo system (“MC{sup 2}”). The beam line configurations for two passively scattered proton beams used in the actual treatment were extracted from the clinical treatment plan and a set of input files was created automatically using MC{sup 2}. A full MC simulation of the beam line was computed using MCNPX and a set of phase space files for each beam was collected at the distal surface of the range compensator. The particles from these phase space files were transported through the 10 voxelized patient models corresponding to the 10 phases of the breathing cycle in the 4DCT, using MCNPX and an accelerated (fast) MC code called “FDC”, developed by us and which is based on the track repeating algorithm. The accuracy of the fast algorithm was assessed by comparing the two time dependent dose distributions. Results: The error of less than 1% in 100% of the voxels in all phases of the breathing cycle was achieved using this method with a speedup of more than 1000 times. Conclusion: The proposed method, which uses full MC to simulate the beam line and the accelerated MC code FDC for the time consuming particle transport inside the complex, time dependent, geometry of the patient shows excellent accuracy together with an extraordinary speed.

  1. Simulation of dose deposition in stereotactic synchrotron radiation therapy: a fast approach combining Monte Carlo and deterministic algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Smekens, F; Freud, N; Letang, J M; Babot, D [CNDRI (Nondestructive Testing using Ionizing Radiations) Laboratory, INSA-Lyon, 69621 Villeurbanne Cedex (France); Adam, J-F; Elleaume, H; Esteve, F [INSERM U-836, Equipe 6 ' Rayonnement Synchrotron et Recherche Medicale' , Institut des Neurosciences de Grenoble (France); Ferrero, C; Bravin, A [European Synchrotron Radiation Facility, Grenoble (France)], E-mail: francois.smekens@insa-lyon.fr

    2009-08-07

    A hybrid approach, combining deterministic and Monte Carlo (MC) calculations, is proposed to compute the distribution of dose deposited during stereotactic synchrotron radiation therapy treatment. The proposed approach divides the computation into two parts: (i) the dose deposited by primary radiation (coming directly from the incident x-ray beam) is calculated in a deterministic way using ray casting techniques and energy-absorption coefficient tables and (ii) the dose deposited by secondary radiation (Rayleigh and Compton scattering, fluorescence) is computed using a hybrid algorithm combining MC and deterministic calculations. In the MC part, a small number of particle histories are simulated. Every time a scattering or fluorescence event takes place, a splitting mechanism is applied, so that multiple secondary photons are generated with a reduced weight. The secondary events are further processed in a deterministic way, using ray casting techniques. The whole simulation, carried out within the framework of the Monte Carlo code Geant4, is shown to converge towards the same results as the full MC simulation. The speed of convergence is found to depend notably on the splitting multiplicity, which can easily be optimized. To assess the performance of the proposed algorithm, we compare it to state-of-the-art MC simulations, accelerated by the track length estimator technique (TLE), considering a clinically realistic test case. It is found that the hybrid approach is significantly faster than the MC/TLE method. The gain in speed in a test case was about 25 for a constant precision. Therefore, this method appears to be suitable for treatment planning applications.

  2. A clinical study of lung cancer dose calculation accuracy with Monte Carlo simulation

    OpenAIRE

    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...

  3. Applicability of dose conversion coefficients of ICRP 74 to Asian adult males: Monte Carlo simulation study

    International Nuclear Information System (INIS)

    International Commission on Radiological Protection (ICRP) reported comprehensive dose conversion coefficients for adult population, which is exposed to external photon sources in the Publication 74. However, those quantities were calculated from so-called stylized (or mathematical) phantoms composed of simplified mathematical surface equations so that the discrepancy between the phantoms and real human anatomy has been investigated by several authors using Caucasian-based voxel phantoms. To address anatomical and racial limitations of the stylized phantoms, several Asian-based voxel phantoms have been developed by Korean and Japanese investigators, independently. In the current study, photon dose conversion coefficients of ICRP 74 were compared with those from a total of five Asian-based male voxel phantoms, whose body dimensions were almost identical. Those of representative radio-sensitive organs (testes, red bone marrow, colon, lungs, and stomach), and effective dose conversion coefficients were obtained for comparison. Even though organ doses for testes, colon and lungs, and effective doses from ICRP 74 agreed well with those from Asian voxel phantoms within 10%, absorbed doses for red bone marrow and stomach showed significant discrepancies up to 30% which was mainly attributed to difference of phantom description between stylized and voxel phantoms. This study showed that the ICRP 74 dosimetry data, which have been reported to be unrealistic compared to those from Caucasian-based voxel phantoms, are also not appropriate for Asian population

  4. Using the Monte Carlo technique to calculate dose conversion coefficients for medical professionals in interventional radiology

    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

  5. Spectra and depth-dose deposition in a polymethylmethacrylate breast phantom obtained by experimental and Monte Carlo method; Espectros e deposicao de dose em profundidade em phantom de mama de polimetilmetacrilato: obtencao experimental e por metodo de Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    David, Mariano G.; Pires, Evandro J.; Magalhaes, Luis A.; Almeida, Carlos E. de; Alves, Carlos F.E., E-mail: marianogd08@gmail.com [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil). Lab. Ciencias Radiologicas; Albuquerque, Marcos A. [Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE/UFRJ), RJ (Brazil). Instituto Alberto Luiz Coimbra; Bernal, Mario A. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Instituto de Fisica Gleb Wataghin; Peixoto, Jose G. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2012-08-15

    This paper focuses on the obtainment, using experimental and Monte Carlo-simulated (MMC) methods, of the photon spectra at various depths and depth-dose deposition curves for x-rays beams used in mammography, obtained on a polymethylmethacrylate (PMMA) breast phantom. Spectra were obtained for 28 and 30 kV quality-beams and the corresponding average energy values (Emed) were calculated. For the experimental acquisition was used a Si-PIN photodiode spectrometer and for the MMC simulations the PENELOPE code was employed. The simulated and the experimental spectra show a very good agreement, which was corroborated by the low differences found between the Emed values. An increase in the Emed values and a strong attenuation of the beam through the depth of the PMMA phantom was also observed. (author)

  6. Monte Carlo dose calculations and radiobiological modelling: analysis of the effect of the statistical noise of the dose distribution on the probability of tumour control

    International Nuclear Information System (INIS)

    The aim of this work is to investigate the influence of the statistical fluctuations of Monte Carlo (MC) dose distributions on the dose volume histograms (DVHs) and radiobiological models, in particular the Poisson model for tumour control probability (tcp). The MC matrix is characterized by a mean dose in each scoring voxel, d, and a statistical error on the mean dose, σd; whilst the quantities d and σd depend on many statistical and physical parameters, here we consider only their dependence on the phantom voxel size and the number of histories from the radiation source. Dose distributions from high-energy photon beams have been analysed. It has been found that the DVH broadens when increasing the statistical noise of the dose distribution, and the tcp calculation systematically underestimates the real tumour control value, defined here as the value of tumour control when the statistical error of the dose distribution tends to zero. When increasing the number of energy deposition events, either by increasing the voxel dimensions or increasing the number of histories from the source, the DVH broadening decreases and tcp converges to the 'correct' value. It is shown that the underestimation of the tcp due to the noise in the dose distribution depends on the degree of heterogeneity of the radiobiological parameters over the population; in particular this error decreases with increasing the biological heterogeneity, whereas it becomes significant in the hypothesis of a radiosensitivity assay for single patients, or for subgroups of patients. It has been found, for example, that when the voxel dimension is changed from a cube with sides of 0.5 cm to a cube with sides of 0.25 cm (with a fixed number of histories of 108 from the source), the systematic error in the tcp calculation is about 75% in the homogeneous hypothesis, and it decreases to a minimum value of about 15% in a case of high radiobiological heterogeneity. The possibility of using the error on the tcp to

  7. Tissue classifications in Monte Carlo simulations of patient dose for photon beam tumor treatments

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Mu-Han [Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, 101 Sec. 2, Kung Fu Road, Hsinchu 30013, Taiwan (China); Chao, Tsi-Chian [Department of Medical Imaging and Radiological Sciences, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan 333, Taiwan (China); Lee, Chung-Chi [Department of Medical Imaging and Radiological Sciences, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan 333, Taiwan (China); Department of Radiation Oncology, Chang Gung Memorial Hospital, 5 Fu-Hsin Street, Kwei-Shan, Tao-Yuan 333, Taiwan (China); Tung-Chieh Chang, Joseph [Department of Radiation Oncology, Chang Gung Memorial Hospital, 5 Fu-Hsin Street, Kwei-Shan, Tao-Yuan 333, Taiwan (China); Tung, Chuan-Jong, E-mail: cjtung@mail.cgu.edu.t [Department of Medical Imaging and Radiological Sciences, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan 333, Taiwan (China)

    2010-07-21

    The purpose of this work was to study the calculated dose uncertainties induced by the material classification that determined the interaction cross-sections and the water-to-material stopping-power ratios. Calculations were made for a head- and neck-cancer patient treated with five intensity-modulated radiotherapy fields using 6 MV photon beams. The patient's CT images were reconstructed into two voxelized patient phantoms based on different CT-to-material classification schemes. Comparisons of the depth-dose curve of the anterior-to-posterior field and the dose-volume-histogram of the treatment plan were used to evaluate the dose uncertainties from such schemes. The results indicated that any misassignment of tissue materials could lead to a substantial dose difference, which would affect the treatment outcome. To assure an appropriate material assignment, it is desirable to have different conversion tables for various parts of the body. The assignment of stopping-power ratio should be based on the chemical composition and the density of the material.

  8. Dosimetric characterization and organ dose assessment in digital breast tomosynthesis: Measurements and Monte Carlo simulations using voxel phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Baptista, Mariana, E-mail: marianabaptista@ctn.ist.utl.pt; Di Maria, Salvatore; Barros, Sílvia; Vaz, Pedro [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, km 139,7, Bobadela LRS 2695-066 (Portugal); Figueira, Catarina [Centre for Plasma Physics, School of Mathematics and Physics, Queen’s University, Belfast BT7 1NN (United Kingdom); Sarmento, Marta; Orvalho, Lurdes [Serviço de Imagiologia, Hospital da Luz, Avenida Lusíada, 100, Lisboa 1500-650 (Portugal)

    2015-07-15

    Purpose: Due to its capability to more accurately detect deep lesions inside the breast by removing the effect of overlying anatomy, digital breast tomosynthesis (DBT) has the potential to replace the standard mammography technique in clinical screening exams. However, the European Guidelines for DBT dosimetry are still a work in progress and there are little data available on organ doses other than to the breast. It is, therefore, of great importance to assess the dosimetric performance of DBT with respect to the one obtained with standard digital mammography (DM) systems. The aim of this work is twofold: (i) to study the dosimetric properties of a combined DBT/DM system (MAMMOMAT Inspiration Siemens{sup ®}) for a tungsten/rhodium (W/Rh) anode/filter combination and (ii) to evaluate organs doses during a DBT examination. Methods: For the first task, measurements were performed in manual and automatic exposure control (AEC) modes, using two homogeneous breast phantoms: a PMMA slab phantom and a 4 cm thick breast-shaped rigid phantom, with 50% of glandular tissue in its composition. Monte Carlo (MC) simulations were performed using Monte Carlo N-Particle eXtended v.2.7.0. A MC model was implemented to mimic DM and DBT acquisitions for a wide range of x-ray spectra (24 –34 kV). This was used to calculate mean glandular dose (MGD) and to compute series of backscatter factors (BSFs) that could be inserted into the DBT dosimetric formalism proposed by Dance et al. Regarding the second aim of the study, the implemented MC model of the clinical equipment, together with a female voxel phantom (“Laura”), was used to calculate organ doses considering a typical DBT acquisition. Results were compared with a standard two-view mammography craniocaudal (CC) acquisition. Results: Considering the AEC mode, the acquisition of a single CC view results in a MGD ranging from 0.53 ± 0.07 mGy to 2.41 ± 0.31 mGy in DM mode and from 0.77 ± 0.11 mGy to 2.28 ± 0.32 mGy in DBT mode

  9. MAGIK: a Monte Carlo system for computing induced residual activation dose rates

    International Nuclear Information System (INIS)

    The photon dose rate from the induced activity produced by sustained bombardment of materials by neutrons and charged particles may present a significant radiation hazard. To minimize this hazard, the material configuration must be so designed that the photon dose rate decays to an acceptable level soon after the source beam is turned off. MAGIK calculates the time-independent photon dose rates that result from activities produced by nucleon-nucleus and meson-nucleus collisions over a wide range of energies. The system has been used both for high-energy accelerator studies and for fusion reactor studies. In the MAGIK system the lengthy photon transport calculations are carried out independent of time, and the time dependence is introduced in the final program, thereby permitting study of various operating scenarios with a minimum computing cost

  10. Monte Carlo simulation of the CTA/IEAV electron linear accelerator environmental doses using albedo coefficients

    International Nuclear Information System (INIS)

    With the purpose of determining the radiation field in the accelerator environment in an efficient way, it was developed an approximate methodology which uses multigroup albedo coefficients to describe the particle reflection by the walls. This method avoids the particle transport calculation inside the walls, which spends much of the processing time. The Monte Carlo code MCNP was suitably modified to allow the simulation of such calculations. To assess the accuracy achieved with this methodology, very realistic calculations considering the transport of particles inside all the walls are performed. The results showed that the use of albedo coefficients for some walls while allowing the transport of particles inside the other walls in the same calculation gives accurate results, saving significant computational time. The results obtained for the accelerator showed an excellent agreement with the realistic calculation, and that the technique is applicable to large environments. (author)

  11. Dual-energy contrast-enhanced digital mammography: patient radiation dose estimation using a Monte Carlo code

    International Nuclear Information System (INIS)

    Mammography is a standard procedure that facilitates breast cancer detection. Initial results of contrast-enhanced digital mammography (CEDM) are promising. The purpose of this study is to assess the CEDM radiation dose using a Monte Carlo code. EGSnrc MC code was used to simulate the interaction of photons with matter and estimate the glandular dose (Dg). A voxel female human phantom with a 2-8-cm breast thickness range and a breast glandular composition of 50 % was applied. Dg values ranged between 0.96 and 1.45 mGy (low and high energy). Dg values for a breast thickness of 5.0 cm and a glandular fraction of 50 % for craniocaudal and mediolateral oblique view were 1.12 (low energy image contribution is 0.98 mGy) and 1.07 (low energy image contribution is 0.95 mGy), respectively. The low kV part of CEDM is the main contributor to total glandular breast dose. (authors)

  12. 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

  13. Using the Monte Carlo technique to calculate dose conversion coefficients for medical professionals in interventional radiology

    Science.gov (United States)

    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.

  14. Monte Carlo derivation of filtered tungsten anode X-ray spectra for dose computation in digital mammography

    Energy Technology Data Exchange (ETDEWEB)

    Paixao, L.; Oliveira, B. B.; Nogueira, M. do S. [Centro de Desenvolvimento da Tecnologia Nuclear, Post-graduation in Science and Technology of Radiations, Minerals and Materials, Pte. Antonio Carlos 6.627, Pampulha, 31270-901 Belo Horizonte (Brazil); Viloria, C. [UFMG, Departamento de Engenharia Nuclear, Post-graduation in Nuclear Sciences and Techniques, Pte. Antonio Carlos 6.627, Pampulha, 31270-901 Belo Horizonte (Brazil); Alves de O, M. [UFMG, Department of Anatomy and Imaging, Prof. Alfredo Balena 190, 30130-100 Belo Horizonte (Brazil); Araujo T, M. H., E-mail: lpr@cdtn.br [Dr Maria Helena Araujo Teixeira Clinic, Guajajaras 40, 30180-100 Belo Horizonte (Brazil)

    2014-08-15

    It is widely accepted that the mean glandular dose (D{sub G}) for the glandular tissue is the more useful magnitude for characterizing the breast cancer risk. The procedure to estimate the D{sub G}, for being difficult to measure it directly in the breast, it is to make the use of conversion factors that relate incident air kerma (K{sub i}) at this dose. Generally, the conversion factors vary with the x-ray spectrum half-value layer and the breast composition and thickness. Several authors through computer simulations have calculated such factors by the Monte Carlo (Mc) method. Many spectral models for D{sub G} computer simulations purposes are available in the diagnostic range. One of the models available generates unfiltered spectra. In this work, the Monte Carlo EGSnrc code package with the C++ class library (eg spp) was employed to derive filtered tungsten x-ray spectra used in digital mammography systems. Filtered spectra for rhodium and aluminium filters were obtained for tube potentials between 26 and 32 kV. The half-value layer of simulated filtered spectra were compared with those obtained experimentally with a solid state detector Unfors model 8202031-H Xi R/F and Mam Detector Platinum and 8201023-C Xi Base unit Platinum Plus w m As in a Hologic Selenia Dimensions system using a Direct Radiography mode. Calculated half-value layer values showed good agreement compared to those obtained experimentally. These results show that the filtered tungsten anode x-ray spectra and the EGSnrc Mc code can be used for D{sub G} determination in mammography. (Author)

  15. An estimation of the percentage of dose in intraoral radiology exams using Monte Carlo simulation

    International Nuclear Information System (INIS)

    In this work we used the EGS4 code in a simulated study of dose percentage in intraoral examination to 10 energy range to 140 keV. The simulation was carried out on a model consisting of different geometry (cheek, tooth and mouth cavity) under normal incidence X-ray beam over the surface of the various simulated materials. It was observed that for energy smaller than 30 keV most of the energy is deposited on the cheek. In 30 keV there is a point of maximum radiation absorption in the tooth (approximately 60% of the energy of the incident radiation is deposited on the tooth) in relation to other simulated materials. It means that in this energy there is a better contrast in the radiographic image of the tooth and a smaller dose on the cheek. In 40 keV the deposited energy in the tooth is roughly equal to the energy that is transmitted (to the radiographic film or buccal cavity) causing a degradation in the radiographic image and/or a higher dose in the oral cavity. For energies above 40 keV, the amount of energy transmitted (to the oral cavity and/or radiographic film) is higher than the energy deposited in other materials, i.e, it only contributes to increasing of dose in the regions close to the oral cavity and the radiographic image degradation. These results can provide important information for radiological procedures applied in dentistry where the image quality is a relevant factor to a dental evaluation needs as well as reducing dose in the oral cavity.

  16. Is wax equivalent to tissue in electron conformal therapy planning? A Monte Carlo study of material approximation introduced dose difference.

    Science.gov (United States)

    Zhang, Ray R; Feygelman, Vladimir; Harris, Eleanor R; Rao, Nikhil; Moros, Eduardo G; Zhang, Geoffrey G

    2013-01-07

    With CT-based Monte Carlo (MC) dose calculations, material composition is often assigned based on the standard Hounsfield unit ranges. This is known as the density threshold method. In bolus electron conformal therapy (BolusECT), the bolus material, machineable wax, would be assigned as soft tissue and the electron density is assumed equivalent to soft tissue based on its Hounsfield unit. This study investigates the dose errors introduced by this material assignment. BEAMnrc was used to simulate electron beams from a Trilogy accelerator. SPRRZnrc was used to calculate stopping power ratios (SPR) of tissue to wax, SPR (tissue) (wax), and tissue to water, SPR(tissue) (water), for 6, 9, 12, 15, and 18 MeV electron beams, of which 12 and 15MeV beams are the most commonly used energies in BolusECT. DOSXYZnrc was applied in dose distribution calculations in a tissue phantom with either flat wax slabs of various thicknesses or a wedge-shaped bolus on top. Dose distribution for two clinical cases, a chest wall and a head and neck, were compared with the bolus material treated as wax or tissue. The SPR(tissue) (wax) values for 12 and 15MeV beams are between 0.935 and 0.945, while the SPR(tissue) (water) values are between 0.990 and 0.991. For a 12 MeV beam, the dose in tissue immediately under the bolus is overestimated by 2.5% for a 3 cm bolus thickness if the wax bolus is treated as tissue. For 15 MeV beams, the error is 1.4%. However, in both clinical cases the differences in the PTV DVH is negligible. Due to stopping power differences, dose differences of up to 2.5% are observed in MC simulations if the bolus material is misassigned as tissue in BolusECT dose calculations. However, for boluses thinner than 2 cm that are more likely encountered in practice, the error is within clinical tolerance.

  17. Monte Carlo calculations of the depth-dose distribution in skin contaminated by hot particles

    Energy Technology Data Exchange (ETDEWEB)

    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).

  18. Absorbed dose estimations of 131I for critical organs using the GEANT4 Monte Carlo simulation code

    Institute of Scientific and Technical Information of China (English)

    Ziaur Rahman; Shakeel ur Rehman; Waheed Arshed; Nasir M Mirza; Abdul Rashid; Jahan Zeb

    2012-01-01

    The aim of this study is to compare the absorbed doses of critical organs of 131I using the MIRD (Medical Internal Radiation Dose) with the corresponding predictions made by GEANT4 simulations.S-values (mean absorbed dose rate per unit activity) and energy deposition per decay for critical organs of 131I for various ages,using standard cylindrical phantom comprising water and ICRP soft-tissue material,have also been estimated.In this study the effect of volume reduction of thyroid,during radiation therapy,on the calculation of absorbed dose is also being estimated using GEANT4.Photon specific energy deposition in the other organs of the neck,due to 131I decay in the thyroid organ,has also been estimated.The maximum relative difference of MIRD with the GEANT4 simulated results is 5.64% for an adult's critical organs of 131I.Excellent agreement was found between the results of water and ICRP soft tissue using the cylindrical model.S-values are tabulated for critical organs of 131I,using 1,5,10,15 and 18 years (adults) individuals.S-values for a cylindrical thyroid of different sizes,having 3.07% relative differences of GEANT4 with Siegel & Stabin results.Comparison of the experimentally measured values at 0.5 and 1 m away from neck of the ionization chamber with GEANT4 based Monte Carlo simulations results show good agreement.This study shows that GEANT4 code is an important tool for the internal dosimetry calculations.

  19. Comparison of absorbed dose in the cervix carcinoma therapy by brachytherapy of high dose rate using the conventional planning and Monte Carlo simulation; Comparacao da dose absorvida no tratamento do cancer ginecologico por braquiterapia de alta taxa de dose utilizando o planejamento convencional do tratamento e simulacao de Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Aneli Oliveira da

    2010-07-01

    This study aims to compare the doses received for patients submitted to brachytherapy High Dose Rate (HDR) brachytherapy, a method of treatment of the cervix carcinoma, performed in the planning system PLATO BPS with the doses obtained by Monte Carlo simulation using the radiation transport code MCNP 5 and one female anthropomorphic phantom based on voxel, the FAX. The implementation of HDR brachytherapy treatment for the cervix carcinoma consists of the insertion of an intrauterine probe and an intravaginal probe (ring or ovoid) and then two radiographs are obtained, anteroposterior (AP) and lateral (LAT) to confirm the position of the applicators in the patient and to allow the treatment planning and the determination of the absorbed dose at points of interest: rectum, bladder, sigmoid and point A, which corresponds anatomically to the crossings of the uterine arteries with ureters The absorbed doses obtained with the code MCNP 5, with the exception of the absorbed dose in the rectum and sigmoid for the simulation considering a point source of {sup 192}Ir, are lower than the absorbed doses from PLATO BPS calculations because the MCNP 5 considers the chemical compositions and densities of FAX body, not considering the medium as water. When considering the Monte Carlo simulation for a source with dimensions equal to that used in the brachytherapy irradiator used in this study, the values of calculated absorbed dose to the bladder, to the rectum, to the right point A and to the left point A were respectively lower than those determined by the treatment planning system in 33.29, 5.01, 22.93 and 19.04%. These values are almost all larger than the maximum acceptable deviation between patient planned and administered doses (5 %). With regard to the rectum and bladder, which are organs that must be protected, the present results are in favor of the radiological protection of patients. The point A, that is on the isodose of 100%, used to tumor treatment, the results

  20. Standard Guide for Absorbed-Dose Mapping in Radiation Processing Facilities

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2003-01-01

    1.1 This document provides guidance in determining absorbed-dose distributions in products, materials or substances irradiated in gamma, X-ray (bremsstrahlung) and electron beam facilities. Note 1—For irradiation of food and the radiation sterilization of health care products, other specific ISO and ISO/ASTM standards containing dose mapping requirements exist. For food irradiation, see ISO/ASTM 51204, Practice for Dosimetry in Gamma Irradiation Facilities for Food Processing and ISO/ASTM 51431, Practice for Dosimetry in Electron and Bremsstrahlung Irradiation Facilities for Food Processing. For the radiation sterilization of health care products, see ISO 11137: 1995, Sterilization of Health Care Products Requirements for Validation and Routine Control Radiation Sterilization. In those areas covered by ISO 11137, that standard takes precedence. ISO/ASTM Practice 51608, ISO/ASTM Practice 51649, and ISO/ASTM Practice 51702 also contain dose mapping requirements. 1.2 Methods of analyzing the dose map data ar...

  1. Deuterons at energies of 10 MeV to 1 TeV: Conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C

    International Nuclear Information System (INIS)

    Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult female and an adult male to deuterons (2H+) in the energy range 10 MeV-1 TeV (0.01-1000 GeV). Coefficients were calculated using the Monte Carlo transport code MCNPX 2.7.C and BodyBuilderTM 1.3 anthropomorphic phantoms. Phantoms were modified to allow calculation of the effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. Coefficients for the equivalent and effective dose incorporated a radiation weighting factor of 2. At 15 of 19 energies for which coefficients for the effective dose were calculated, coefficients based on ICRP 1990 and 2007 recommendations differed by < 3 %. The greatest difference, 47 %, occurred at 30 MeV. (authors)

  2. Verification measurements and clinical evaluation of the iPlan RT Monte Carlo dose algorithm for 6 MV photon energy

    Science.gov (United States)

    Petoukhova, A. L.; van Wingerden, K.; Wiggenraad, R. G. J.; van de Vaart, P. J. M.; van Egmond, J.; Franken, E. M.; van Santvoort, J. P. C.

    2010-08-01

    This study presents data for verification of the iPlan RT Monte Carlo (MC) dose algorithm (BrainLAB, Feldkirchen, Germany). MC calculations were compared with pencil beam (PB) calculations and verification measurements in phantoms with lung-equivalent material, air cavities or bone-equivalent material to mimic head and neck and thorax and in an Alderson anthropomorphic phantom. Dosimetric accuracy of MC for the micro-multileaf collimator (MLC) simulation was tested in a homogeneous phantom. All measurements were performed using an ionization chamber and Kodak EDR2 films with Novalis 6 MV photon beams. Dose distributions measured with film and calculated with MC in the homogeneous phantom are in excellent agreement for oval, C and squiggle-shaped fields and for a clinical IMRT plan. For a field with completely closed MLC, MC is much closer to the experimental result than the PB calculations. For fields larger than the dimensions of the inhomogeneities the MC calculations show excellent agreement (within 3%/1 mm) with the experimental data. MC calculations in the anthropomorphic phantom show good agreement with measurements for conformal beam plans and reasonable agreement for dynamic conformal arc and IMRT plans. For 6 head and neck and 15 lung patients a comparison of the MC plan with the PB plan was performed. Our results demonstrate that MC is able to accurately predict the dose in the presence of inhomogeneities typical for head and neck and thorax regions with reasonable calculation times (5-20 min). Lateral electron transport was well reproduced in MC calculations. We are planning to implement MC calculations for head and neck and lung cancer patients.

  3. Monte-Carlo determination of dose rates in spherical PWR shield

    International Nuclear Information System (INIS)

    An operating nuclear reactor is a source of potentially dangerous nuclear radiation. It emits many different types of nuclear radiations. However, the neutrons and gamma rays are the main sources of radiation to give the contributions to the radiation situation in the reactor during operation, and the principal concern of reactor shielding. In current study the neutron and gamma radiation dose rates at different depths in concrete bio-shield of a PWR are calculated in spherical model by M-C simulation with using MCNP4C2. The simulation results are compared with the results obtained from similar calculations based on S8P3 spherical approximation with using the ANISN code. (author)

  4. Two computational approaches for Monte Carlo based shutdown dose rate calculation with applications to the JET fusion machine

    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

  5. Helions at energies of 10 MeV to 1 TeV: Conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C

    International Nuclear Information System (INIS)

    Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent, for isotropic exposure of an adult male and an adult female to helions (3He2+) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). Calculations were performed using Monte Carlo transport code MCNPX 2.7.C and BodyBuilderTM 1.3 anthropomorphic phantoms modified to allow calculation of effective dose using tissues and tissue weighting factors from either the 1990 or 2007 recommendations of the International Commission on Radiological Protection (ICRP), and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. At 15 of the 19 energies for which coefficients for effective dose were calculated, coefficients based on ICRP 2007 and 1990 recommendations differed by less than 2%. The greatest difference, 62%, occurred at 100 MeV. Published by Oxford Univ. Press on behalf of the U.S. Government 2010. (authors)

  6. Tritons at energies of 10 MeV to 1 TeV: Conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose, and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C

    International Nuclear Information System (INIS)

    Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult female and an adult male to tritons (3H+) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). Coefficients were calculated using Monte Carlo transport code MCNPX 2.7.C and BodyBuilderTM 1.3 anthropomorphic phantoms. Phantoms were modified to allow calculation of effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and calculation of gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. At 15 of the 19 energies for which coefficients for effective dose were calculated, coefficients based on ICRP 2007 and 1990 recommendations differed by less than 3%. The greatest difference, 43%, occurred at 30 MeV. Published by Oxford Univ. Press on behalf of the US Government 2010. (authors)

  7. Calculation of equivalent dose index for electrons from 5,0 to 22,0 MeV by the Monte Carlo method

    International Nuclear Information System (INIS)

    The index of equivalent dose in depth and in a sphere surface of a soft tissue equivalent material were determined by Monte Carlo method for electron irradiations from 5,0 to 22.00 MeV. The effect of different irradiation geometries which simulate the incidence of onedirectional opposite rotational and isotropic beams was studied. It is also shown that the detector of wall thickness with 0.5g/cm2 and isotropic response com be used to measure index of equivalent dose for fast electrons. The alternative concept of average equivalent dose for radiation protection is discussed. (M.C.K.)

  8. Dose calculations for a simplified Mammosite system with the Monte Carlo Penelope and MCNPX simulation codes; Calculos de dosis para un sistema Mammosite simplificado con los codigos de simulacion Monte Carlo PENELOPE y MCNPX

    Energy Technology Data Exchange (ETDEWEB)

    Rojas C, E.L.; Varon T, C.F.; Pedraza N, R. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)]. e-mail: elrc@nuclear.inin.mx

    2007-07-01

    The treatment of the breast cancer at early stages is of vital importance. For that, most of the investigations are dedicated to the early detection of the suffering and their treatment. As investigation consequence and clinical practice, in 2002 it was developed in U.S.A. an irradiation system of high dose rate known as Mammosite. In this work we carry out dose calculations for a simplified Mammosite system with the Monte Carlo Penelope simulation code and MCNPX, varying the concentration of the contrast material that it is used in the one. (Author)

  9. Studies on the radial dose distribution for clinical electron beams of 9 and 16 MeV using Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Yoriyaz, Helio; Siqueira, Paulo T.D.; Zevallos-Chavez, Juan Y. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Centro de Engenharia Nuclear]. E-mail: hyoriyaz@ipen.br; Furnari, Laura; Poli, Maria Esmeralda R. [Sao Paulo Univ., SP (Brazil). Faculdade de Medicina. Hospital das Clinicas

    2005-07-01

    Radial dose distributions have been obtained for several electron beam field sizes through the Monte Carlo simulation. Measurements were performed by an ionization chamber in a 50x50x50 cm{sup 3} water phantom which is routinely used for calibration. Calculated and measured values were compared to adjust the input energy spectra used for the Monte Carlo simulation. The methodology presented here is part of the 'tuning procedure' for the construction of electron beam sources typically used for radiotherapy. (author)

  10. Monte Carlo design of a system for the detection of explosive materials and analysis of the dose

    International Nuclear Information System (INIS)

    The problems associated with insecurity and terrorism have forced to designing systems for detecting nuclear materials, drugs and explosives that are installed on roads, ports and airports. Organic materials are composed of C, H, O and N; similarly the explosive materials are manufactured which can be distinguished by the concentration of these elements. Its elemental composition, particularly the concentration of hydrogen and oxygen, allow distinguish them from other organic substances. When these materials are irradiated with neutrons nuclear reactions (n, γ) are produced, where the emitted photons are ready gamma rays whose energy is characteristic of each element and its abundance allows estimating their concentration. The aim of this study was designed using Monte Carlo methods a system with neutron source, gamma rays detector and moderator able to distinguish the presence of Rdx and urea. In design were used as moderators: paraffin, light water, polyethylene and graphite; as detectors were used HPGe and the NaI(Tl). The design that showed the best performance was the moderator of light water and HPGe, with a source of 241AmBe. For this design, the values of ambient dose equivalent around the system were calculated. (Author)

  11. Comparison between Monte Carlo simulation and measurement with a 3D polymer gel dosimeter for dose distributions in biological samples

    International Nuclear Information System (INIS)

    In this research, we used a 135 MeV/nucleon carbon-ion beam to irradiate a biological sample composed of fresh chicken meat and bones, which was placed in front of a PAGAT gel dosimeter, and compared the measured and simulated transverse-relaxation-rate (R2) distributions in the gel dosimeter. We experimentally measured the three-dimensional R2 distribution, which records the dose induced by particles penetrating the sample, by using magnetic resonance imaging. The obtained R2 distribution reflected the heterogeneity of the biological sample. We also conducted Monte Carlo simulations using the PHITS code by reconstructing the elemental composition of the biological sample from its computed tomography images while taking into account the dependence of the gel response on the linear energy transfer. The simulation reproduced the experimental distal edge structure of the R2 distribution with an accuracy under about 2 mm, which is approximately the same as the voxel size currently used in treatment planning. (paper)

  12. Comparison between Monte Carlo simulation and measurement with a 3D polymer gel dosimeter for dose distributions in biological samples

    Science.gov (United States)

    Furuta, T.; Maeyama, T.; Ishikawa, K. L.; Fukunishi, N.; Fukasaku, K.; Takagi, S.; Noda, S.; Himeno, R.; Hayashi, S.

    2015-08-01

    In this research, we used a 135 MeV/nucleon carbon-ion beam to irradiate a biological sample composed of fresh chicken meat and bones, which was placed in front of a PAGAT gel dosimeter, and compared the measured and simulated transverse-relaxation-rate (R2) distributions in the gel dosimeter. We experimentally measured the three-dimensional R2 distribution, which records the dose induced by particles penetrating the sample, by using magnetic resonance imaging. The obtained R2 distribution reflected the heterogeneity of the biological sample. We also conducted Monte Carlo simulations using the PHITS code by reconstructing the elemental composition of the biological sample from its computed tomography images while taking into account the dependence of the gel response on the linear energy transfer. The simulation reproduced the experimental distal edge structure of the R2 distribution with an accuracy under about 2 mm, which is approximately the same as the voxel size currently used in treatment planning.

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

    Science.gov (United States)

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

    2014-03-01

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

  14. Isodose mapping of terrestrial gamma radiation dose rate of Selangor state, Kuala Lumpur and Putrajaya, Malaysia

    International Nuclear Information System (INIS)

    A terrestrial gamma radiation survey for the state of Selangor, Kuala Lumpur and Putrajaya was conducted to obtain baseline data for environmental radiological health practices. Based on soil type, geological background and information from airborne survey maps, 95 survey points statistically representing the study area were determined. The measured doses varied according to geological background and soil types. They ranged from 17 nGy h−1 to 500 nGy h−1. The mean terrestrial gamma dose rate in air above the ground was 182 ± 81 nGy h−1. This is two times higher than the average dose rate of terrestrial gamma radiation in Malaysia which is 92 nGy h−1 (UNSCEAR 2000). An isodose map was produced to represent exposure rate from natural sources of terrestrial gamma radiation. - Highlights: • A methodology is presented to reduce terrestrial gamma dose rate field survey. • Geological background of acid intrusive of granitic type has the highest dose rates. • The mean dose rate is 2 times higher than the world average. • Isodose map of terrestrial gamma radiation for Selangor, Kuala Lumpur and Putrajaya was produced

  15. Comprehensive Evaluations of Cone-beam CT dose in Image-guided Radiation Therapy via GPU-based Monte Carlo simulations

    CERN Document Server

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

    2013-01-01

    Cone beam CT (CBCT) has been widely used for patient setup in image guided radiation therapy (IGRT). Radiation dose from CBCT scans has become a clinical concern. The purposes of this study are 1) to commission a GPU-based Monte Carlo (MC) dose calculation package gCTD for Varian On-Board Imaging (OBI) system and test the calculation accuracy, and 2) to quantitatively evaluate CBCT dose from the OBI system in typical IGRT scan protocols. We first conducted dose measurements in a water phantom. X-ray source model parameters used in gCTD are obtained through a commissioning process. gCTD accuracy is demonstrated by comparing calculations with measurements in water and in CTDI phantoms. 25 brain cancer patients are used to study dose in a standard-dose head protocol, and 25 prostate cancer patients are used to study dose in pelvis protocol and pelvis spotlight protocol. Mean dose to each organ is calculated. Mean dose to 2% voxels that have the highest dose is also computed to quantify the maximum dose. It is fo...

  16. {sup 32}P Brachytherapy Conformal Source Model RIC-100 for High-Dose-Rate Treatment of Superficial Disease: Monte Carlo Calculations, Diode Measurements, and Clinical Implementation

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Gil' ad N., E-mail: coheng@mskcc.org [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Munro, John J. [Montrose Technology, Inc, North Andover, Massachusetts (United States); Kirov, Assen; Losasso, Thomas [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Yamada, Yoshiya [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Williamson, Matthew; Dauer, Lawrence T.; Zaider, Marco [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)

    2014-03-01

    Purpose: A novel {sup 32}P brachytherapy source has been in use at our institution intraoperatively for temporary radiation therapy of the spinal dura and other localized tumors. We describe the dosimetry and clinical implementation of the source. Methods and Materials: Dosimetric evaluation for the source was done with a complete set of MCNP5 Monte Carlo calculations preceding clinical implementation. In addition, the depth dose curve and dose rate were measured by use of an electron field diode to verify the Monte Carlo calculations. Calibration procedures using the diode in a custom-designed phantom to provide an absolute dose calibration and to check dose uniformity across the source area for each source before treatment were established. Results: Good agreement was established between the Monte Carlo calculations and diode measurements. Quality assurance measurements results are provided for about 100 sources used to date. Clinical source calibrations were usually within 10% of manufacturer specifications. Procedures for safe handling of the source are described. Discussion: Clinical considerations for using the source are discussed.

  17. Study on mapping Quantitative Trait Loci for animal complex binary traits using Bayesian-Markov chain Monte Carlo approach

    Institute of Scientific and Technical Information of China (English)

    LIU; Jianfeng; ZHANG; Yuan; ZHANG; Qin; WANG; Lixian; ZHANG; Jigang

    2006-01-01

    It is a challenging issue to map Quantitative Trait Loci (QTL) underlying complex discrete traits, which usually show discontinuous distribution and less information, using conventional statistical methods. Bayesian-Markov chain Monte Carlo (Bayesian-MCMC) approach is the key procedure in mapping QTL for complex binary traits, which provides a complete posterior distribution for QTL parameters using all prior information. As a consequence, Bayesian estimates of all interested variables can be obtained straightforwardly basing on their posterior samples simulated by the MCMC algorithm. In our study, utilities of Bayesian-MCMC are demonstrated using simulated several animal outbred full-sib families with different family structures for a complex binary trait underlied by both a QTL and polygene. Under the Identity-by-Descent-Based variance component random model, three samplers basing on MCMC, including Gibbs sampling, Metropolis algorithm and reversible jump MCMC, were implemented to generate the joint posterior distribution of all unknowns so that the QTL parameters were obtained by Bayesian statistical inferring. The results showed that Bayesian-MCMC approach could work well and robust under different family structures and QTL effects. As family size increases and the number of family decreases, the accuracy of the parameter estimates will be improved. When the true QTL has a small effect, using outbred population experiment design with large family size is the optimal mapping strategy.

  18. The effect of voxel size on dose distribution in Varian Clinac iX 6 MV photon beam using Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Yani, Sitti, E-mail: sitti.yani@s.itb.ac.id [Nuclear Physics and Biophysics Division, Physics Department, Institut Teknologi Bandung (Indonesia); Akademi Kebidanan Pelita Ibu, Kendari (Indonesia); Dirgayussa, I Gde E.; Haryanto, Freddy; Arif, Idam [Nuclear Physics and Biophysics Division, Physics Department, Institut Teknologi Bandung (Indonesia); Rhani, Moh. Fadhillah [Tan Tock Seng Hospital (Singapore)

    2015-09-30

    Recently, Monte Carlo (MC) calculation method has reported as the most accurate method of predicting dose distributions in radiotherapy. The MC code system (especially DOSXYZnrc) has been used to investigate the different voxel (volume elements) sizes effect on the accuracy of dose distributions. To investigate this effect on dosimetry parameters, calculations were made with three different voxel sizes. The effects were investigated with dose distribution calculations for seven voxel sizes: 1 × 1 × 0.1 cm{sup 3}, 1 × 1 × 0.5 cm{sup 3}, and 1 × 1 × 0.8 cm{sup 3}. The 1 × 10{sup 9} histories were simulated in order to get statistical uncertainties of 2%. This simulation takes about 9-10 hours to complete. Measurements are made with field sizes 10 × 10 cm2 for the 6 MV photon beams with Gaussian intensity distribution FWHM 0.1 cm and SSD 100.1 cm. MC simulated and measured dose distributions in a water phantom. The output of this simulation i.e. the percent depth dose and dose profile in d{sub max} from the three sets of calculations are presented and comparisons are made with the experiment data from TTSH (Tan Tock Seng Hospital, Singapore) in 0-5 cm depth. Dose that scored in voxels is a volume averaged estimate of the dose at the center of a voxel. The results in this study show that the difference between Monte Carlo simulation and experiment data depend on the voxel size both for percent depth dose (PDD) and profile dose. PDD scan on Z axis (depth) of water phantom, the big difference obtain in the voxel size 1 × 1 × 0.8 cm{sup 3} about 17%. In this study, the profile dose focused on high gradient dose area. Profile dose scan on Y axis and the big difference get in the voxel size 1 × 1 × 0.1 cm{sup 3} about 12%. This study demonstrated that the arrange voxel in Monte Carlo simulation becomes important.

  19. The effect of voxel size on dose distribution in Varian Clinac iX 6 MV photon beam using Monte Carlo simulation

    International Nuclear Information System (INIS)

    Recently, Monte Carlo (MC) calculation method has reported as the most accurate method of predicting dose distributions in radiotherapy. The MC code system (especially DOSXYZnrc) has been used to investigate the different voxel (volume elements) sizes effect on the accuracy of dose distributions. To investigate this effect on dosimetry parameters, calculations were made with three different voxel sizes. The effects were investigated with dose distribution calculations for seven voxel sizes: 1 × 1 × 0.1 cm3, 1 × 1 × 0.5 cm3, and 1 × 1 × 0.8 cm3. The 1 × 109 histories were simulated in order to get statistical uncertainties of 2%. This simulation takes about 9-10 hours to complete. Measurements are made with field sizes 10 × 10 cm2 for the 6 MV photon beams with Gaussian intensity distribution FWHM 0.1 cm and SSD 100.1 cm. MC simulated and measured dose distributions in a water phantom. The output of this simulation i.e. the percent depth dose and dose profile in dmax from the three sets of calculations are presented and comparisons are made with the experiment data from TTSH (Tan Tock Seng Hospital, Singapore) in 0-5 cm depth. Dose that scored in voxels is a volume averaged estimate of the dose at the center of a voxel. The results in this study show that the difference between Monte Carlo simulation and experiment data depend on the voxel size both for percent depth dose (PDD) and profile dose. PDD scan on Z axis (depth) of water phantom, the big difference obtain in the voxel size 1 × 1 × 0.8 cm3 about 17%. In this study, the profile dose focused on high gradient dose area. Profile dose scan on Y axis and the big difference get in the voxel size 1 × 1 × 0.1 cm3 about 12%. This study demonstrated that the arrange voxel in Monte Carlo simulation becomes important

  20. The effect of voxel size on dose distribution in Varian Clinac iX 6 MV photon beam using Monte Carlo simulation

    Science.gov (United States)

    Yani, Sitti; Dirgayussa, I. Gde E.; Rhani, Moh. Fadhillah; Haryanto, Freddy; Arif, Idam

    2015-09-01

    Recently, Monte Carlo (MC) calculation method has reported as the most accurate method of predicting dose distributions in radiotherapy. The MC code system (especially DOSXYZnrc) has been used to investigate the different voxel (volume elements) sizes effect on the accuracy of dose distributions. To investigate this effect on dosimetry parameters, calculations were made with three different voxel sizes. The effects were investigated with dose distribution calculations for seven voxel sizes: 1 × 1 × 0.1 cm3, 1 × 1 × 0.5 cm3, and 1 × 1 × 0.8 cm3. The 1 × 109 histories were simulated in order to get statistical uncertainties of 2%. This simulation takes about 9-10 hours to complete. Measurements are made with field sizes 10 × 10 cm2 for the 6 MV photon beams with Gaussian intensity distribution FWHM 0.1 cm and SSD 100.1 cm. MC simulated and measured dose distributions in a water phantom. The output of this simulation i.e. the percent depth dose and dose profile in dmax from the three sets of calculations are presented and comparisons are made with the experiment data from TTSH (Tan Tock Seng Hospital, Singapore) in 0-5 cm depth. Dose that scored in voxels is a volume averaged estimate of the dose at the center of a voxel. The results in this study show that the difference between Monte Carlo simulation and experiment data depend on the voxel size both for percent depth dose (PDD) and profile dose. PDD scan on Z axis (depth) of water phantom, the big difference obtain in the voxel size 1 × 1 × 0.8 cm3 about 17%. In this study, the profile dose focused on high gradient dose area. Profile dose scan on Y axis and the big difference get in the voxel size 1 × 1 × 0.1 cm3 about 12%. This study demonstrated that the arrange voxel in Monte Carlo simulation becomes important.

  1. Isodose mapping of terrestrial gamma radiation dose rate of Selangor state, Kuala Lumpur and Putrajaya, Malaysia.

    Science.gov (United States)

    Sanusi, M S M; Ramli, A T; Gabdo, H T; Garba, N N; Heryanshah, A; Wagiran, H; Said, M N

    2014-09-01

    A terrestrial gamma radiation survey for the state of Selangor, Kuala Lumpur and Putrajaya was conducted to obtain baseline data for environmental radiological health practices. Based on soil type, geological background and information from airborne survey maps, 95 survey points statistically representing the study area were determined. The measured doses varied according to geological background and soil types. They ranged from 17 nGy h(-1) to 500 nGy h(-1). The mean terrestrial gamma dose rate in air above the ground was 182 ± 81 nGy h(-1). This is two times higher than the average dose rate of terrestrial gamma radiation in Malaysia which is 92 nGy h(-1) (UNSCEAR 2000). An isodose map was produced to represent exposure rate from natural sources of terrestrial gamma radiation.

  2. A General Monte Carlo Method for Mapping Multiple Quantitative Trait Loci

    NARCIS (Netherlands)

    Jansen, Ritsert C.

    1996-01-01

    In this paper we address the mapping of multiple quantitative trait loci (QTLs) in line crosses for which the genetic data are highly incomplete. Such complicated situations occur, for instance, when dominant markers are used or when unequally informative markers are used in experiments with outbred

  3. Study of the heterogeneities effect in the dose distributions of Leksell Gamma Knife (R), through Monte Carlo simulation; Estudio del efecto de las heterogeneidades en las distribuciones de dosis del Leksell GammaKnife (R), mediante simulacion Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Rojas C, E.L. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Al-Dweri, F.M.O.; Lallena R, A.M. [Universidad de Granada, Granada (Spain)]. e-mail: elrc@nuclear.inin.mx

    2005-07-01

    In this work they are studied, by means of Monte Carlo simulation, the effects that take place in the dose profiles that are obtained with the Leksell Gamma Knife (R), when they are kept in account heterogeneities. The considered heterogeneities simulate the skull and the spaces of air that are in the head, like they can be the nasal breasts or the auditory conduits. The calculations were made using the Monte Carlo Penelope simulation code (v. 2003). The geometry of each one of the 201 sources that this instrument is composed, as well as of the corresponding channels of collimation of the Gamma Knife (R), it was described by means of a simplified model of geometry that has been recently studied. The obtained results when they are kept in mind the heterogeneities they present non worthless differences regarding those obtained when those are not considered. These differences are maximum in the proximities of the interfaces among different materials. (Author)

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

    International Nuclear Information System (INIS)

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

  5. Calculation of size specific dose estimates (SSDE) value at cylindrical phantom from CBCT Varian OBI v1.4 X-ray tube EGSnrc Monte Carlo simulation based

    Science.gov (United States)

    Nasir, M.; Pratama, D.; Anam, C.; Haryanto, F.

    2016-03-01

    The aim of this research was to calculate Size Specific Dose Estimates (SSDE) generated by the varian OBI CBCT v1.4 X-ray tube working at 100 kV using EGSnrc Monte Carlo simulations. The EGSnrc Monte Carlo code used in this simulation was divided into two parts. Phase space file data resulted by the first part simulation became an input to the second part. This research was performed with varying phantom diameters of 5 to 35 cm and varying phantom lengths of 10 to 25 cm. Dose distribution data were used to calculate SSDE values using trapezoidal rule (trapz) function in a Matlab program. SSDE obtained from this calculation was compared to that in AAPM report and experimental data. It was obtained that the normalization of SSDE value for each phantom diameter was between 1.00 and 3.19. The normalization of SSDE value for each phantom length was between 0.96 and 1.07. The statistical error in this simulation was 4.98% for varying phantom diameters and 5.20% for varying phantom lengths. This study demonstrated the accuracy of the Monte Carlo technique in simulating the dose calculation. In the future, the influence of cylindrical phantom material to SSDE would be studied.

  6. Clinical evaluation of fast electron Monte Carlo dose calculation algorithms for treatment planning systems validation with experimental measurements and EGSnrc Monte Carlo simulation

    OpenAIRE

    Edimo, Paul

    2012-01-01

    The present study is focused on the clinical validation of two electron Monte Carlo (eMC) based treatment planning systems (TPS), Oncentra MasterPlan TPS (OMTPS) and XiO eMC. We present a new approach on the commissioning process based on, (a) homogeneous water phantom validation, (b) heterogeneous phantom validation with film measurements and, (c) Full MC validation. As a first step, MC models of electron beams (4, 8, 12 and 18 MeV) from an Elekta SL25 medical linear accelerator were buil...

  7. A Monte Carlo study on dose enhancement and photon contamination production by various nanoparticles in electron mode of a medical linac

    OpenAIRE

    Toossi Mohammad Taghi Bahreyni; Ghorbani Mahdi; Sabet Leila Sobhkhiz; Akbari Fateme; Mehrpouyan Mohammad

    2015-01-01

    The aim of this study is the evaluation of electron dose enhancement and photon contamination production by various nanoparticles in the electron mode of a medical linac. MCNPX Monte Carlo code was used for simulation of Siemens Primus linac as well as a phantom and a tumor loaded with nanoparticles. Electron dose enhancement by Au, Ag, I and Fe2O3 nanoparticles of 7, 18 and 30 mg/ml concentrations for 8, 12 and 14 MeV electrons was calculated. The increase in photon contamination due to the ...

  8. Dose distribution and mapping with 3D imaging presentation in intraoral and panoramic examinations

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hsiu-Ling [Department of Dental Medicine, Mackay Memorial Hospital, Taipei, Taiwan (China); Huang, Yung-Hui [Department of Medical Imaging and Radiological Science, I-Shou University, Kaohsiung, Taiwan (China); Wu, Tung-Hsin, E-mail: tung@ym.edu.tw [Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Taipei 112 Taiwan (China); Wang, Shih-Yuan [Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Taipei 112 Taiwan (China); Lee, Jason J.S., E-mail: jslee@ym.edu.tw [Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Taipei 112 Taiwan (China)

    2011-10-01

    In current medical imaging applications, high quality images not only provide more diagnostic value for anatomic delineation but also offer functional information for treatment direction. However, this approach would potentially subscribe higher radiation dose in dental radiographies, which has been putatively associated with low-birth-weight during pregnancy, which affects the hypothalamus-pituitary-thyroid axis or thereby directly affects the reproductive organs. The aim of this study was to apply the high resolution 3-D image mapping technique to evaluate radiation doses from the following aspects: (1) verifying operating parameters of dental X-ray units, (2) measuring the leakage radiations and (3) mapping dose with 3-D radiographic imaging to evaluate dose distribution in head and neck regions. From the study results, we found that (1) leakage radiation from X-ray units was about 21.31{+-}15.24 mR/h (<100 mR/h), (2) error of actual tube voltage for 60 kVp setting was from 0.2% to 6.5%, with an average of 2.5% (<7%) and (3) the error of exposure time for a 0.5-1.5 s setting was within 0.7-8.5%, with an average of 7.3% (<10%) error as well. Our 3-D dose mapping demonstrated that dose values were relatively lower in soft tissues and higher in bone surfaces compared with other investigations. Multiple causes could contribute to these variations, including irradiation geometry, image equipment and type of technique applied, etc. From the results, we also observed that larger accumulated doses were presented in certain critical organs, such as salivary gland, thyroid gland and bone marrow. Potential biological affects associated with these findings warrant further investigation.

  9. Monte Carlo study of the impact of a magnetic field on the dose distribution in MRI-guided HDR brachytherapy using Ir-192

    Science.gov (United States)

    Beld, E.; Seevinck, P. R.; Lagendijk, J. J. W.; Viergever, M. A.; Moerland, M. A.

    2016-09-01

    In the process of developing a robotic MRI-guided high-dose-rate (HDR) prostate brachytherapy treatment, the influence of the MRI scanner’s magnetic field on the dose distribution needs to be investigated. A magnetic field causes a deflection of electrons in the plane perpendicular to the magnetic field, and it leads to less lateral scattering along the direction parallel with the magnetic field. Monte Carlo simulations were carried out to determine the influence of the magnetic field on the electron behavior and on the total dose distribution around an Ir-192 source. Furthermore, the influence of air pockets being present near the source was studied. The Monte Carlo package Geant4 was utilized for the simulations. The simulated geometries consisted of a simplified point source inside a water phantom. Magnetic field strengths of 0 T, 1.5 T, 3 T, and 7 T were considered. The simulation results demonstrated that the dose distribution was nearly unaffected by the magnetic field for all investigated magnetic field strengths. Evidence was found that, from a dose perspective, the HDR prostate brachytherapy treatment using Ir-192 can be performed safely inside the MRI scanner. No need was found to account for the magnetic field during treatment planning. Nevertheless, the presence of air pockets in close vicinity to the source, particularly along the direction parallel with the magnetic field, appeared to be an important point for consideration.

  10. Determination of the optimal statistical uncertainty to perform electron-beam Monte Carlo absorbed dose estimation in the target volume; Determination de l'incertitude statistique optimale pour realiser un calcul de dose dans le volume cible en utilisant la methode de Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Isambert, A.; Lefkopoulos, D. [Institut Gustave-Roussy, Medical Physics Dept., 94 - Villejuif (France); Brualla, L. [NCTeam, Strahlenklinik, Universitatsklinikum Essen (Germany); Benkebil, M. [DOSIsoft, 94 - Cachan (France)

    2010-04-15

    Purpose of study Monte Carlo based treatment planning system are known to be more accurate than analytical methods for performing absorbed dose estimation, particularly in and near heterogeneities. However, the required computation time can still be an issue. The present study focused on the determination of the optimum statistical uncertainty in order to minimise computation time while keeping the reliability of the absorbed dose estimation in treatments planned with electron-beams. Materials and methods Three radiotherapy plans (medulloblastoma, breast and gynaecological) were used to investigate the influence of the statistical uncertainty of the absorbed dose on the target volume dose-volume histograms (spinal cord, intra-mammary nodes and pelvic lymph nodes, respectively). Results The study of the dose-volume histograms showed that for statistical uncertainty levels (1 S.D.) above 2 to 3%, the standard deviation of the mean dose in the target volume calculated from the dose-volume histograms increases by at least 6%, reflecting the gradual flattening of the dose-volume histograms. Conclusions This work suggests that, in clinical context, Monte Carlo based absorbed dose estimations should be performed with a maximum statistical uncertainty of 2 to 3%. (authors)

  11. Energy spectra, angular spread, fluence profiles and dose distributions of 6 and 18 MV photon beams: results of Monte Carlo simulations for a Varian 2100EX accelerator

    International Nuclear Information System (INIS)

    The purpose of this study is to provide detailed characteristics of incident photon beams for different field sizes and beam energies. This information is critical to the future development of accurate treatment planning systems. It also enhances our knowledge of radiotherapy photon beams. The EGS4 Monte Carlo code, BEAM, has been used to simulate 6 and 18 MV photon beams from a Varian Clinac-2100EX accelerator. A simulated realistic beam is stored in a phase space data file, which contains details of each particle's complete history including where it has been and where it has interacted. The phase space files are analysed to obtain energy spectra, angular distribution, fluence profile and mean energy profiles at the phantom surface for particles separated according to their charge and history. The accuracy of a simulated beam is validated by the excellent agreement between the Monte Carlo calculated and measured dose distributions. Measured depth-dose curves are obtained from depth-ionization curves by accounting for newly introduced chamber fluence corrections and the stopping-power ratios for realistic beams. The study presents calculated depth-dose components from different particles as well as calculated surface dose and contribution from different particles to surface dose across the field. It is shown that the increase of surface dose with the increase of the field size is mainly due to the increase of incident contaminant charged particles. At 6 MV, the incident charged particles contribute 7% to 21% of maximum dose at the surface when the field size increases from 10x10 to 40x40 cm2. At 18 MV, their contributions are up to 11% and 29% of maximum dose at the surface for 10x10 cm2 and 40x40 cm2 fields respectively. However, the fluence of these incident charged particles is less than 1% of incident photon fluence in all cases. (author)

  12. A 3D Monte Carlo Method for Estimation of Patient-specific Internal Organs Absorbed Dose for (99m)Tc-hynic-Tyr(3)-octreotide Imaging.

    Science.gov (United States)

    Momennezhad, Mehdi; Nasseri, Shahrokh; Zakavi, Seyed Rasoul; Parach, Ali Asghar; Ghorbani, Mahdi; Asl, Ruhollah Ghahraman

    2016-01-01

    Single-photon emission computed tomography (SPECT)-based tracers are easily available and more widely used than positron emission tomography (PET)-based tracers, and SPECT imaging still remains the most prevalent nuclear medicine imaging modality worldwide. The aim of this study is to implement an image-based Monte Carlo method for patient-specific three-dimensional (3D) absorbed dose calculation in patients after injection of (99m)Tc-hydrazinonicotinamide (hynic)-Tyr(3)-octreotide as a SPECT radiotracer. (99m)Tc patient-specific S values and the absorbed doses were calculated with GATE code for each source-target organ pair in four patients who were imaged for suspected neuroendocrine tumors. Each patient underwent multiple whole-body planar scans as well as SPECT imaging over a period of 1-24 h after intravenous injection of (99m)hynic-Tyr(3)-octreotide. The patient-specific S values calculated by GATE Monte Carlo code and the corresponding S values obtained by MIRDOSE program differed within 4.3% on an average for self-irradiation, and differed within 69.6% on an average for cross-irradiation. However, the agreement between total organ doses calculated by GATE code and MIRDOSE program for all patients was reasonably well (percentage difference was about 4.6% on an average). Normal and tumor absorbed doses calculated with GATE were slightly higher than those calculated with MIRDOSE program. The average ratio of GATE absorbed doses to MIRDOSE was 1.07 ± 0.11 (ranging from 0.94 to 1.36). According to the results, it is proposed that when cross-organ irradiation is dominant, a comprehensive approach such as GATE Monte Carlo dosimetry be used since it provides more reliable dosimetric results. PMID:27134562

  13. GATE based Monte Carlo simulation of planar scintigraphy to estimate the nodular dose in radioiodine therapy for autonomous thyroid adenoma

    International Nuclear Information System (INIS)

    The recommended target dose in radioiodine therapy of solitary hyperfunctioning thyroid nodules is 300-400 Gy and therefore higher than in other radiotherapies. This is due to the fact that an unknown, yet significant portion of the activity is stored in extranodular areas but is neglected in the calculatory dosimetry. We investigate the feasibility of determining the ratio of nodular and extranodular activity concentrations (uptakes) from post-therapeutically acquired planar scintigrams with Monte Carlo simulations in GATE. The geometry of a gamma camera with a high energy collimator was emulated in GATE (Version 5). A geometrical thyroid-neck phantom (GP) and the ICRP reference voxel phantoms 'Adult Female' (AF, 16 ml thyroid) and 'Adult Male' (AM, 19 ml thyroid) were used as source regions. Nodules of 1 ml and 3 ml volume were placed in the phantoms. For each phantom and each nodule 200 scintigraphic acquisitions were simulated. Uptake ratios of nodule and rest of thyroid ranging from 1 to 20 could be created by summation. Quantitative image analysis was performed by investigating the number of simulated counts in regions of interest (ROIs). ROIs were created by perpendicular projection of the phantom onto the camera plane to avoid a user dependant bias. The ratio of count densities in ROIs over the nodule and over the contralateral lobe, which should be least affected by nodular activity, was taken to be the best available measure for the uptake ratios. However, the predefined uptake ratios are underestimated by these count density ratios: For an uptake ratio of 20 the count ratios range from 4.5 (AF, 1 ml nodule) to 15.3 (AM, 3 ml nodule). Furthermore, the contralateral ROI is more strongly affected by nodular activity than expected: For an uptake ratio of 20 between nodule and rest of thyroid up to 29% of total counts in the ROI over the contralateral lobe are caused by decays in the nodule (AF 3 ml). In the case of the 1 ml nodules this effect is smaller: 9

  14. GATE based Monte Carlo simulation of planar scintigraphy to estimate the nodular dose in radioiodine therapy for autonomous thyroid adenoma

    Energy Technology Data Exchange (ETDEWEB)

    Hammes, Jochen; Schmidt, Matthias; Schicha, Harald; Eschner, Wolfgang [Universitaetsklinikum Koeln (Germany). Klinik und Poliklinik fuer Nuklearmedizin; Pietrzyk, Uwe [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Neurowissenschaften und Medizin (INM-4); Wuppertal Univ. (Germany). Fachbereich C - Physik

    2011-07-01

    The recommended target dose in radioiodine therapy of solitary hyperfunctioning thyroid nodules is 300-400 Gy and therefore higher than in other radiotherapies. This is due to the fact that an unknown, yet significant portion of the activity is stored in extranodular areas but is neglected in the calculatory dosimetry. We investigate the feasibility of determining the ratio of nodular and extranodular activity concentrations (uptakes) from post-therapeutically acquired planar scintigrams with Monte Carlo simulations in GATE. The geometry of a gamma camera with a high energy collimator was emulated in GATE (Version 5). A geometrical thyroid-neck phantom (GP) and the ICRP reference voxel phantoms 'Adult Female' (AF, 16 ml thyroid) and 'Adult Male' (AM, 19 ml thyroid) were used as source regions. Nodules of 1 ml and 3 ml volume were placed in the phantoms. For each phantom and each nodule 200 scintigraphic acquisitions were simulated. Uptake ratios of nodule and rest of thyroid ranging from 1 to 20 could be created by summation. Quantitative image analysis was performed by investigating the number of simulated counts in regions of interest (ROIs). ROIs were created by perpendicular projection of the phantom onto the camera plane to avoid a user dependant bias. The ratio of count densities in ROIs over the nodule and over the contralateral lobe, which should be least affected by nodular activity, was taken to be the best available measure for the uptake ratios. However, the predefined uptake ratios are underestimated by these count density ratios: For an uptake ratio of 20 the count ratios range from 4.5 (AF, 1 ml nodule) to 15.3 (AM, 3 ml nodule). Furthermore, the contralateral ROI is more strongly affected by nodular activity than expected: For an uptake ratio of 20 between nodule and rest of thyroid up to 29% of total counts in the ROI over the contralateral lobe are caused by decays in the nodule (AF 3 ml). In the case of the 1 ml nodules this

  15. SU-E-T-356: Accuracy of Eclipse Electron Macro Monte Carlo Dose Algorithm for Use in Bolus Electron Conformal Therapy

    International Nuclear Information System (INIS)

    Purpose: To evaluate the accuracy of electron dose distribution calculated by the Varian Eclipse electron Monte Carlo (eMC) algorithm for use with recent commercially available bolus electron conformal therapy (ECT). Methods: eMC-calculated electron dose distributions for bolus ECT have been compared to those previously measured for cylindrical phantoms (retromolar trigone and nose), whose axial cross sections were based on the mid-PTV CT anatomy for each site. The phantoms consisted of SR4 muscle substitute, SR4 bone substitute, and air. The bolus ECT treatment plans were imported into the Eclipse treatment planning system and calculated using the maximum allowable histories (2×109), resulting in a statistical error of <0.2%. Smoothing was not used for these calculations. Differences between eMC-calculated and measured dose distributions were evaluated in terms of absolute dose difference as well as distance to agreement (DTA). Results: Results from the eMC for the retromolar trigone phantom showed 89% (41/46) of dose points within 3% dose difference or 3 mm DTA. There was an average dose difference of −0.12% with a standard deviation of 2.56%. Results for the nose phantom showed 95% (54/57) of dose points within 3% dose difference or 3 mm DTA. There was an average dose difference of 1.12% with a standard deviation of 3.03%. Dose calculation times for the retromolar trigone and nose treatment plans were 15 min and 22 min, respectively, using 16 processors (Intel Xeon E5-2690, 2.9 GHz) on a Varian Eclipse framework agent server (FAS). Results of this study were consistent with those previously reported for accuracy of the eMC electron dose algorithm and for the .decimal, Inc. pencil beam redefinition algorithm used to plan the bolus. Conclusion: These results show that the accuracy of the Eclipse eMC algorithm is suitable for clinical implementation of bolus ECT

  16. Dose-rate mapping and search of radioactive sources in Estonia

    Energy Technology Data Exchange (ETDEWEB)

    Ylaetalo, S.; Karvonen, J.; Ilander, T.; Honkamaa, T.; Toivonen, H.

    1996-12-01

    The Estonian Ministry of Environment and the Finnish Centre for Radiation and Nuclear Safety (STUK) agreed in 1995 on a radiation mapping project in Estonia. The country was searched to find potential man-made radioactive sources. Another goal of the project was to produce a background dose-rate map over the whole country. The measurements provided an excellent opportunity to test new in-field measuring systems that are useful in a nuclear disaster. The basic idea was to monitor road sides, cities, domestic waste storage places and former military or rocket bases from a moving vehicle by measuring gamma spectrum and dose rate. The measurements were carried out using vehicle installed systems consisting of a pressurised ionisation chamber (PIC) in 1995 and a combination of a scintillation spectrometer (NaI(TI)) and Geiger-Mueller-counter (GM) in 1996. All systems utilised GPS-satellite navigation signals to relate the measured dose rates and gamma-spectra to current geographical location. The data were recorded for further computer analysis. The dose rate varied usually between 0.03-0.17 {mu}Sv/h in the whole country, excluding a few nuclear material storage places (in Saku and in Sillamae). Enhanced dose rates of natural origin (0.17-0.5 {mu}Sv/h) were measured near granite statues, buildings and bridges. No radioactive sources were found on road sides or in towns or villages. (orig.) (14 refs.).

  17. Dose-rate mapping and search of radioactive sources in Estonia

    International Nuclear Information System (INIS)

    The Estonian Ministry of Environment and the Finnish Centre for Radiation and Nuclear Safety (STUK) agreed in 1995 on a radiation mapping project in Estonia. The country was searched to find potential man-made radioactive sources. Another goal of the project was to produce a background dose-rate map over the whole country. The measurements provided an excellent opportunity to test new in-field measuring systems that are useful in a nuclear disaster. The basic idea was to monitor road sides, cities, domestic waste storage places and former military or rocket bases from a moving vehicle by measuring gamma spectrum and dose rate. The measurements were carried out using vehicle installed systems consisting of a pressurised ionisation chamber (PIC) in 1995 and a combination of a scintillation spectrometer (NaI(TI)) and Geiger-Mueller-counter (GM) in 1996. All systems utilised GPS-satellite navigation signals to relate the measured dose rates and gamma-spectra to current geographical location. The data were recorded for further computer analysis. The dose rate varied usually between 0.03-0.17 μSv/h in the whole country, excluding a few nuclear material storage places (in Saku and in Sillamae). Enhanced dose rates of natural origin (0.17-0.5 μSv/h) were measured near granite statues, buildings and bridges. No radioactive sources were found on road sides or in towns or villages. (orig.) (14 refs.)

  18. SU-E-T-58: Calculation of Dose Distribution of Accuboost Brachytherapy in Deformable Polyvinil Alcohol Breast Phantom Using Biomechanical Modeling and Monte Carlo Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadyari, P [Nuclear Engineering Department, School of Mechanical Engineering, Shiraz Un, Ilam (Iran, Islamic Republic of); Faghihi, R [Nuclear Engineering Department, Shiraz University, Shiraz (Iran, Islamic Republic of); Shirazi, M Mosleh [Radiotherapy and Oncology Department, Namazi Hospital, Shiraz University of M, Shiraz (Iran, Islamic Republic of); Lotfi, M [Shiraz University of Medical Sciences, Medical Imaging Research Center, Shiraz (Iran, Islamic Republic of); Meigooni, A [Comprehensive cancer center of Nevada - University of Nevada Las Vegas UNL, Las Vegas, NV (United States)

    2014-06-01

    Purpose: the accuboost is the most modern method of breast brachytherapy that is a boost method in compressed tissue by a mammography unit. the dose distribution in uncompressed tissue, as compressed tissue is important that should be characterized. Methods: In this study, the mechanical behavior of breast in mammography loading, the displacement of breast tissue and the dose distribution in compressed and uncompressed tissue, are investigated. Dosimetry was performed by two dosimeter methods of Monte Carlo simulations using MCNP5 code and thermoluminescence dosimeters. For Monte Carlo simulations, the dose values in cubical lattice were calculated using tally F6. The displacement of the breast elements was simulated by Finite element model and calculated using ABAQUS software, from which the 3D dose distribution in uncompressed tissue was determined. The geometry of the model is constructed from MR images of 6 volunteers. Experimental dosimetery was performed by placing the thermoluminescence dosimeters into the polyvinyl alcohol breast equivalent phantom and on the proximal edge of compression plates to the chest. Results: The results indicate that using the cone applicators would deliver more than 95% of dose to the depth of 5 to 17mm, while round applicator will increase the skin dose. Nodal displacement, in presence of gravity and 60N forces, i.e. in mammography compression, was determined with 43% contraction in the loading direction and 37% expansion in orthogonal orientation. Finally, in comparison of the acquired from thermoluminescence dosimeters with MCNP5, they are consistent with each other in breast phantom and in chest's skin with average different percentage of 13.7±5.7 and 7.7±2.3, respectively. Conclusion: The major advantage of this kind of dosimetry is the ability of 3D dose calculation by FE Modeling. Finally, polyvinyl alcohol is a reliable material as a breast tissue equivalent dosimetric phantom that provides the ability of TLD

  19. Predicting standard-dose PET image from low-dose PET and multimodal MR images using mapping-based sparse representation

    Science.gov (United States)

    Wang, Yan; Zhang, Pei; An, Le; Ma, Guangkai; Kang, Jiayin; Shi, Feng; Wu, Xi; Zhou, Jiliu; Lalush, David S.; Lin, Weili; Shen, Dinggang

    2016-01-01

    Positron emission tomography (PET) has been widely used in clinical diagnosis for diseases and disorders. To obtain high-quality PET images requires a standard-dose radionuclide (tracer) injection into the human body, which inevitably increases risk of radiation exposure. One possible solution to this problem is to predict the standard-dose PET image from its low-dose counterpart and its corresponding multimodal magnetic resonance (MR) images. Inspired by the success of patch-based sparse representation (SR) in super-resolution image reconstruction, we propose a mapping-based SR (m-SR) framework for standard-dose PET image prediction. Compared with the conventional patch-based SR, our method uses a mapping strategy to ensure that the sparse coefficients, estimated from the multimodal MR images and low-dose PET image, can be applied directly to the prediction of standard-dose PET image. As the mapping between multimodal MR images (or low-dose PET image) and standard-dose PET images can be particularly complex, one step of mapping is often insufficient. To this end, an incremental refinement framework is therefore proposed. Specifically, the predicted standard-dose PET image is further mapped to the target standard-dose PET image, and then the SR is performed again to predict a new standard-dose PET image. This procedure can be repeated for prediction refinement of the iterations. Also, a patch selection based dictionary construction method is further used to speed up the prediction process. The proposed method is validated on a human brain dataset. The experimental results show that our method can outperform benchmark methods in both qualitative and quantitative measures.

  20. An Analytic Linear Accelerator Source Model for Monte Carlo dose calculations. II. Model Utilization in a GPU-based Monte Carlo Package and Automatic Source Commissioning

    CERN Document Server

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

    2015-01-01

    We recently built an analytical source model for GPU-based MC dose engine. In this paper, we present a sampling strategy to efficiently utilize this source model in GPU-based dose calculation. Our source model was based on a concept of phase-space-ring (PSR). This ring structure makes it effective to account for beam rotational symmetry, but not suitable for dose calculations due to rectangular jaw settings. Hence, we first convert PSR source model to its phase-space let (PSL) representation. Then in dose calculation, different types of sub-sources were separately sampled. Source sampling and particle transport were iterated. So that the particles being sampled and transported simultaneously are of same type and close in energy to alleviate GPU thread divergence. We also present an automatic commissioning approach to adjust the model for a good representation of a clinical linear accelerator . Weighting factors were introduced to adjust relative weights of PSRs, determined by solving a quadratic minimization ...

  1. Organ doses from hepatic radioembolization with 90Y, 153Sm, 166Ho and 177Lu: A Monte Carlo simulation study using Geant4

    Science.gov (United States)

    Hashikin, N. A. A.; Yeong, C. H.; Guatelli, S.; Abdullah, B. J. J.; Ng, K. H.; Malaroda, A.; Rosenfeld, A. B.; Perkins, A. C.

    2016-03-01

    90Y-radioembolization is a palliative treatment for liver cancer. 90Y decays via beta emission, making imaging difficult due to absence of gamma radiation. Since post-procedure imaging is crucial, several theranostic radionuclides have been explored as alternatives. However, exposures to gamma radiation throughout the treatment caused concern for the organs near the liver. Geant4 Monte Carlo simulation using MIRD Pamphlet 5 reference phantom was carried out. A spherical tumour with 4.3cm radius was modelled within the liver. 1.82GBq of 90Y sources were isotropically distributed within the tumour, with no extrahepatic shunting. The simulation was repeated with 153Sm, 166Ho and 177Lu. The estimated tumour doses for all radionuclides were 262.9Gy. Tumour dose equivalent to 1.82GBq 90Y can be achieved with 8.32, 5.83, and 4.44GBq for 153Sm, 166Ho and 177Lu, respectively. Normal liver doses by the other radionuclides were lower than 90Y, hence beneficial for normal tissue sparing. The organ doses from 153Sm and 177Lu were relatively higher due to higher gamma energy, but were still well below 1Gy. 166Ho, 177Lu and 153Sm offer useful gamma emission for post-procedure imaging. They show potential as 90Y substitutes, delivering comparable tumour doses, lower normal liver doses and other organs doses far below the tolerance limit.

  2. Using rainfall radar data to improve interpolated maps of dose rate in the Netherlands

    Energy Technology Data Exchange (ETDEWEB)

    Hiemstra, Paul H., E-mail: p.hiemstra@geo.uu.nl [University of Utrecht, Department of Physical Geography, P.O. Box 80.115, 3508 TC Utrecht (Netherlands); Pebesma, Edzer J., E-mail: edzer.pebesma@uni-muenster.de [University of Muenster, Institute for Geoinformatics, Weseler Strasse 253, 48151 Muenster (Germany); Heuvelink, Gerard B.M. [Environmental Sciences Group, Wageningen University, P.O. Box 47, 6700 AA Wageningen (Netherlands); Twenhoefel, Chris J.W. [National Institute for Public Health and the Environment (RIVM), Antonie van Leeuwenhoeklaan 9, 3721 MA Bilthoven (Netherlands)

    2010-12-01

    The radiation monitoring network in the Netherlands is designed to detect and track increased radiation levels, dose rate more specifically, in 10-minute intervals. The network consists of 153 monitoring stations. Washout of radon progeny by rainfall is the most important cause of natural variations in dose rate. The increase in dose rate at a given time is a function of the amount of progeny decaying, which in turn is a balance between deposition of progeny by rainfall and radioactive decay. The increase in progeny is closely related to average rainfall intensity over the last 2.5 h. We included decay of progeny by using weighted averaged rainfall intensity, where the weight decreases back in time. The decrease in weight is related to the half-life of radon progeny. In this paper we show for a rainstorm on the 20th of July 2007 that weighted averaged rainfall intensity estimated from rainfall radar images, collected every 5 min, performs much better as a predictor of increases in dose rate than using the non-averaged rainfall intensity. In addition, we show through cross-validation that including weighted averaged rainfall intensity in an interpolated map using universal kriging (UK) does not necessarily lead to a more accurate map. This might be attributed to the high density of monitoring stations in comparison to the spatial extent of a typical rain event. Reducing the network density improved the accuracy of the map when universal kriging was used instead of ordinary kriging (no trend). Consequently, in a less dense network the positive influence of including a trend is likely to increase. Furthermore, we suspect that UK better reproduces the sharp boundaries present in rainfall maps, but that the lack of short-distance monitoring station pairs prevents cross-validation from revealing this effect.

  3. Preliminary study of the distribution of dose in patients with Graves' disease undergoing examination of uptake of iodine-131 using Monte Carlo simulation; Estudo preliminar da distribuicao de dose em pacientes com doenca de Graves submetidos a exame de captacao de iodo-131 utilizando simulacao Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Schwarcke, Marcelo; Marques, Tatiana; Nicolucci, Patricia; Baffa, Oswaldo, E-mail: mschwarcke@usp.b [Universidade de Sao Paulo (FFCLRP/USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Dept. de Fisica e Matematica; Bornemann, Clarissa [Hospital de Caridade Astrogildo de Azevedo, Santa Maria, RS (Brazil). Servico de Medicina Nuclear de Santa Maria

    2010-06-15

    Patients with Graves disease have a high hormonal disorder, which causes behavioral changes. One way to treat this disease is the use of high doses of {sup 131} Iodine, requiring that the patient carries out the examination of {sup 131}I uptake to estimate the activity to be administered. Using these data capture and compared with the simulated data using the Monte Carlo code PENELOPE is possible to determine a distribution of dose to the region surrounding the thyroid. As noted the difference between the simulated values and the experimentally obtained were 10.36%, thus showing the code of simulation for accurate determination of absorbed dose in tissue near the thyroid. (author)

  4. SU-E-I-42: Normalized Embryo/fetus Doses for Fluoroscopically Guided Pacemaker Implantation Procedures Calculated Using a Monte Carlo Technique

    Energy Technology Data Exchange (ETDEWEB)

    Damilakis, J; Stratakis, J; Solomou, G [University of Crete, Heraklion (Greece)

    2014-06-01

    Purpose: It is well known that pacemaker implantation is sometimes needed in pregnant patients with symptomatic bradycardia. To our knowledge, there is no reported experience regarding radiation doses to the unborn child resulting from fluoroscopy during pacemaker implantation. The purpose of the current study was to develop a method for estimating embryo/fetus dose from fluoroscopically guided pacemaker implantation procedures performed on pregnant patients during all trimesters of gestation. Methods: The Monte Carlo N-Particle (MCNP) radiation transport code was employed in this study. Three mathematical anthropomorphic phantoms representing the average pregnant patient at the first, second and third trimesters of gestation were generated using Bodybuilder software (White Rock science, White Rock, NM). The normalized embryo/fetus dose from the posteroanterior (PA), the 30° left-anterior oblique (LAO) and the 30° right-anterior oblique (RAO) projections were calculated for a wide range of kVp (50–120 kVp) and total filtration values (2.5–9.0 mm Al). Results: The results consist of radiation doses normalized to a) entrance skin dose (ESD) and b) dose area product (DAP) so that the dose to the unborn child from any fluoroscopic technique and x-ray device used can be calculated. ESD normalized doses ranged from 0.008 (PA, first trimester) to 2.519 μGy/mGy (RAO, third trimester). DAP normalized doses ranged from 0.051 (PA, first trimester) to 12.852 μGy/Gycm2 (RAO, third trimester). Conclusion: Embryo/fetus doses from fluoroscopically guided pacemaker implantation procedures performed on pregnant patients during all stages of gestation can be estimated using the method developed in this study. This study was supported by the Greek Ministry of Education and Religious Affairs, General Secretariat for Research and Technology, Operational Program ‘Education and Lifelong Learning’, ARISTIA (Research project: CONCERT)

  5. SU-E-I-42: Normalized Embryo/fetus Doses for Fluoroscopically Guided Pacemaker Implantation Procedures Calculated Using a Monte Carlo Technique

    International Nuclear Information System (INIS)

    Purpose: It is well known that pacemaker implantation is sometimes needed in pregnant patients with symptomatic bradycardia. To our knowledge, there is no reported experience regarding radiation doses to the unborn child resulting from fluoroscopy during pacemaker implantation. The purpose of the current study was to develop a method for estimating embryo/fetus dose from fluoroscopically guided pacemaker implantation procedures performed on pregnant patients during all trimesters of gestation. Methods: The Monte Carlo N-Particle (MCNP) radiation transport code was employed in this study. Three mathematical anthropomorphic phantoms representing the average pregnant patient at the first, second and third trimesters of gestation were generated using Bodybuilder software (White Rock science, White Rock, NM). The normalized embryo/fetus dose from the posteroanterior (PA), the 30° left-anterior oblique (LAO) and the 30° right-anterior oblique (RAO) projections were calculated for a wide range of kVp (50–120 kVp) and total filtration values (2.5–9.0 mm Al). Results: The results consist of radiation doses normalized to a) entrance skin dose (ESD) and b) dose area product (DAP) so that the dose to the unborn child from any fluoroscopic technique and x-ray device used can be calculated. ESD normalized doses ranged from 0.008 (PA, first trimester) to 2.519 μGy/mGy (RAO, third trimester). DAP normalized doses ranged from 0.051 (PA, first trimester) to 12.852 μGy/Gycm2 (RAO, third trimester). Conclusion: Embryo/fetus doses from fluoroscopically guided pacemaker implantation procedures performed on pregnant patients during all stages of gestation can be estimated using the method developed in this study. This study was supported by the Greek Ministry of Education and Religious Affairs, General Secretariat for Research and Technology, Operational Program ‘Education and Lifelong Learning’, ARISTIA (Research project: CONCERT)

  6. BIA interpretation techniques for vegetation mapping using thematic mapper false color composites (interim report for San Carlos Reservation)

    Science.gov (United States)

    Bonner, W.J.; English, T.C.; Haas, R.H.; Feagan, T.R.; McKinley, R.A.

    1987-01-01

    The Bureau of Indian Affairs (BIA) is responsible for the natural resource management of approximately 52 million acres of Trust lands in the contiguous United States. The lands are distributed in a "patchwork" fashion throughout the country. Management responsibilities on these areas include: minerals, range, timber, fish and wildlife, agricultural, cultural, and archaeological resources. In an age of decreasing natural resources and increasing natural resource values, effective multiple resource management is critical. BIA has adopted a "systems approach" to natural resource management which utilizes Geographic Information System (GIS) technology. The GIS encompasses a continuum of spatial and relational data elements, and included functional capabilities such as: data collection, data entry, data base development, data analysis, data base management, display, and report generalization. In support of database development activities, BIA and BLM/TGS conducted a cooperative effort to investigate the potential of 1:100,000 scale Thematic Mapper (TM) False Color Composites (FCCs) for providing vegetation information suitable for input to the GIS and to later be incorporated as a generalized Bureau wide land cover map. Land cover information is critical as the majority of reservations currently have no land cover information in either map or digital form. This poster outlines an approach which includes the manual interpretation of land cover using TM FCCs, the digitizing of interpreted polygons, and the editing of digital data, used upon ground truthing exercises. An efficient and cost-effective methodology for generating large area land cover information is illustrated for the Mineral Strip area on the San Carlos Indian Reservation in Arizona. Techniques which capitalize on the knowledge of the local natural resources professionals, while minimizing machine processing requirements, are suggested.

  7. SU-E-T-561: Monte Carlo-Based Organ Dose Reconstruction Using Pre-Contoured Human Model for Hodgkins Lymphoma Patients Treated by Cobalt-60 External Beam Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Jung, J; Pelletier, C [East Carolina University, Greenville, NC (United States); Lee, C [University of Michigan, Ann Arbor, MI (United States); Kim, J [University of Pittsburgh Medical Center, Pittsburgh, PA (United States); Pyakuryal, A; Lee, C [National Cancer Institute, Rockville, MD (United States)

    2015-06-15

    Purpose: Organ doses for the Hodgkin’s lymphoma patients treated with cobalt-60 radiation were estimated using an anthropomorphic model and Monte Carlo modeling. Methods: A cobalt-60 treatment unit modeled in the BEAMnrc Monte Carlo code was used to produce phase space data. The Monte Carlo simulation was verified with percent depth dose measurement in water at various field sizes. Radiation transport through the lung blocks were modeled by adjusting the weights of phase space data. We imported a precontoured adult female hybrid model and generated a treatment plan. The adjusted phase space data and the human model were imported to the XVMC Monte Carlo code for dose calculation. The organ mean doses were estimated and dose volume histograms were plotted. Results: The percent depth dose agreement between measurement and calculation in water phantom was within 2% for all field sizes. The mean organ doses of heart, left breast, right breast, and spleen for the selected case were 44.3, 24.1, 14.6 and 3.4 Gy, respectively with the midline prescription dose of 40.0 Gy. Conclusion: Organ doses were estimated for the patient group whose threedimensional images are not available. This development may open the door to more accurate dose reconstruction and estimates of uncertainties in secondary cancer risk for Hodgkin’s lymphoma patients. This work was partially supported by the intramural research program of the National Institutes of Health, National Cancer Institute, Division of Cancer Epidemiology and Genetics.

  8. Comparison of film measurements and Monte Carlo simulations of dose delivered with very high-energy electron beams in a polystyrene phantom

    Energy Technology Data Exchange (ETDEWEB)

    Bazalova-Carter, Magdalena; Liu, Michael; Palma, Bianey; Koong, Albert C.; Maxim, Peter G., E-mail: Peter.Maxim@Stanford.edu, E-mail: BWLoo@Stanford.edu; Loo, Billy W., E-mail: Peter.Maxim@Stanford.edu, E-mail: BWLoo@Stanford.edu [Department of Radiation Oncology, Stanford University, Stanford, California 94305-5847 (United States); Dunning, Michael; McCormick, Doug; Hemsing, Erik; Nelson, Janice; Jobe, Keith; Colby, Eric; Tantawi, Sami; Dolgashev, Valery [SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)

    2015-04-15

    Purpose: To measure radiation dose in a water-equivalent medium from very high-energy electron (VHEE) beams and make comparisons to Monte Carlo (MC) simulation results. Methods: Dose in a polystyrene phantom delivered by an experimental VHEE beam line was measured with Gafchromic films for three 50 MeV and two 70 MeV Gaussian beams of 4.0–6.9 mm FWHM and compared to corresponding MC-simulated dose distributions. MC dose in the polystyrene phantom was calculated with the EGSnrc/BEAMnrc and DOSXYZnrc codes based on the experimental setup. Additionally, the effect of 2% beam energy measurement uncertainty and possible non-zero beam angular spread on MC dose distributions was evaluated. Results: MC simulated percentage depth dose (PDD) curves agreed with measurements within 4% for all beam sizes at both 50 and 70 MeV VHEE beams. Central axis PDD at 8 cm depth ranged from 14% to 19% for the 5.4–6.9 mm 50 MeV beams and it ranged from 14% to 18% for the 4.0–4.5 mm 70 MeV beams. MC simulated relative beam profiles of regularly shaped Gaussian beams evaluated at depths of 0.64 to 7.46 cm agreed with measurements to within 5%. A 2% beam energy uncertainty and 0.286° beam angular spread corresponded to a maximum 3.0% and 3.8% difference in depth dose curves of the 50 and 70 MeV electron beams, respectively. Absolute dose differences between MC simulations and film measurements of regularly shaped Gaussian beams were between 10% and 42%. Conclusions: The authors demonstrate that relative dose distributions for VHEE beams of 50–70 MeV can be measured with Gafchromic films and modeled with Monte Carlo simulations to an accuracy of 5%. The reported absolute dose differences likely caused by imperfect beam steering and subsequent charge loss revealed the importance of accurate VHEE beam control and diagnostics.

  9. Effect of the normalized prescription isodose line on the magnitude of Monte Carlo vs. pencil beam target dose differences for lung stereotactic body radiotherapy.

    Science.gov (United States)

    Zheng, Dandan; Zhang, Qinghui; Liang, Xiaoying; Zhu, Xiaofeng; Verma, Vivek; Wang, Shuo; Zhou, Sumin

    2016-07-08

    In lung stereotactic body radiotherapy (SBRT) cases, the pencil beam (PB) dose calculation algorithm is known to overestimate target dose as compared to the more accurate Monte Carlo (MC) algorithm. We investigated whether changing the normalized prescription isodose line affected the magnitude of MC vs. PB target dose differences. Forty-eight patient plans and twenty virtual-tumor phantom plans were studied. For patient plans, four alternative plans prescribed to 60%, 70%, 80%, and 90% isodose lines were each created for 12 patients who previously received lung SBRT treatments. Using 6 MV dynamic conformal arcs, the plans were individually optimized to achieve similar dose coverage and conformity for all plans of the same patient, albeit at the different prescription levels. These plans, having used a PB algorithm, were all recalculated with MC to compare the target dose differences. The relative MC vs. PB target dose variations were investigated by comparing PTV D95, Dmean, and D5 loss at the four prescription levels. The MC-to-PB ratio of the plan heterogeneity index (HI) was also evaluated and compared among different isodose levels. To definitively demonstrate the cause of the isodose line dependence, a simulated phantom study was conducted using simple, spherical virtual tumors planned with uniform block margins. The tumor size and beam energy were also altered in the phantom study to investigate the interplay between these confounding factors and the isodose line effect. The magnitude of the target dose overestimation by PB was greater for higher prescription isodose levels. The MC vs. PB reduction in the target dose coverage indices, D95 and V100 of PTV, were found to monotonically increase with increasing isodose lines from 60% to 90%, resulting in more pronounced target dose coverage deficiency at higher isodose prescription levels. No isodose level-dependent trend was observed for the dose errors in the target mean or high dose indices, Dmean or D5. The

  10. Use of Monte Carlo simulation software for the calculation of the effective dose in cone beam Tomography; Uso del software de simulacion Monte Carlo para el calculo de la dosis efectiva en Tomografia de haz conico

    Energy Technology Data Exchange (ETDEWEB)

    Gomes B, W. O., E-mail: wilsonottobatista@gmail.com [Instituto Federal da Bahia, Rua Emidio dos Santos s/n, Bardalho, 40301-015 Salvador, Bahia (Brazil)

    2015-10-15

    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, P{sub KA}. 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)

  11. Graded-threshold parametric response maps: towards a strategy for adaptive dose painting

    International Nuclear Information System (INIS)

    Purpose: To modify the single-threshold parametric response map (ST-PRM) method for predicting treatment outcomes in order to facilitate its use for guidance of adaptive dose painting in intensity-modulated radiotherapy. Methods: Multiple graded thresholds were used to extend the ST-PRM method (Nat. Med. 2009;15(5):572-576) such that the full functional change distribution within tumours could be represented with respect to multiple confidence interval estimates for functional changes in similar healthy tissue. The ST-PRM and graded-threshold PRM (GT-PRM) methods were applied to functional imaging scans of 5 patients treated for hepatocellular carcinoma. Pre and post-radiotherapy arterial blood flow maps (ABF) were generated from CT-perfusion scans of each patient. ABF maps were rigidly registered based on aligning tumour centres of mass. ST-PRM and GT-PRM analyses were then performed on overlapping tumour regions within the registered ABF maps. Main findings: The ST-PRMs contained many disconnected clusters of voxels classified as having a significant change in function. While this may be useful to predict treatment response, it may pose challenges for identifying boost volumes or for informing dose-painting by numbers strategies. The GT-PRMs included all of the same information as ST-PRMs but also visualized the full tumour functional change distribution. Heterogeneous clusters in the ST-PRMs often became more connected in the GT-PRMs by voxels with similar functional changes. Conclusions: GT-PRMs provided additional information which helped to visualize relationships between significant functional changes identified by ST-PRMs. This may enhance ST-PRM utility for guiding adaptive dose painting.

  12. Graded-threshold parametric response maps: towards a strategy for adaptive dose painting

    Science.gov (United States)

    Lausch, A.; Jensen, N.; Chen, J.; Lee, T. Y.; Lock, M.; Wong, E.

    2014-03-01

    Purpose: To modify the single-threshold parametric response map (ST-PRM) method for predicting treatment outcomes in order to facilitate its use for guidance of adaptive dose painting in intensity-modulated radiotherapy. Methods: Multiple graded thresholds were used to extend the ST-PRM method (Nat. Med. 2009;15(5):572-576) such that the full functional change distribution within tumours could be represented with respect to multiple confidence interval estimates for functional changes in similar healthy tissue. The ST-PRM and graded-threshold PRM (GT-PRM) methods were applied to functional imaging scans of 5 patients treated for hepatocellular carcinoma. Pre and post-radiotherapy arterial blood flow maps (ABF) were generated from CT-perfusion scans of each patient. ABF maps were rigidly registered based on aligning tumour centres of mass. ST-PRM and GT-PRM analyses were then performed on overlapping tumour regions within the registered ABF maps. Main findings: The ST-PRMs contained many disconnected clusters of voxels classified as having a significant change in function. While this may be useful to predict treatment response, it may pose challenges for identifying boost volumes or for informing dose-painting by numbers strategies. The GT-PRMs included all of the same information as ST-PRMs but also visualized the full tumour functional change distribution. Heterogeneous clusters in the ST-PRMs often became more connected in the GT-PRMs by voxels with similar functional changes. Conclusions: GT-PRMs provided additional information which helped to visualize relationships between significant functional changes identified by ST-PRMs. This may enhance ST-PRM utility for guiding adaptive dose painting.

  13. The MapCHECK Measurement Uncertainty function and its effect on planar dose pass rates.

    Science.gov (United States)

    Bailey, Daniel W; Spaans, Jason D; Kumaraswamy, Lalith K; Podgorsak, Matthew B

    2016-03-08

    Our study aimed to quantify the effect of the Measurement Uncertainty function on planar dosimetry pass rates, as measured and analyzed with the Sun Nuclear Corporation MapCHECK 2 array and its associated software. This optional function is toggled in the program preferences of the software (though turned on by default upon installation), and automatically increases the dose difference tolerance defined by the user for each planar dose comparison. Dose planes from 109 static-gantry IMRT fields and 40 VMAT arcs, of varying modulation complexity, were measured at 5 cm water-equivalent depth in the MapCHECK 2 diode array, and respective calculated dose planes were exported from a commercial treatment planning system. Planar dose comparison pass rates were calculated within the Sun Nuclear Corporation analytic software using a number of calculation parameters, including Measurement Uncertainty on and off. By varying the percent difference (%Diff) criterion for similar analyses performed with Measurement Uncertainty turned off, an effective %Diff criterion was defined for each field/arc corresponding to the pass rate achieved with Measurement Uncertainty turned on. On average, the Measurement Uncertainty function increases the user-defined %Diff criterion by 0.8%-1.1% for 3%/3 mm analysis, depending on plan type and calculation technique (corresponding to an average change in pass rate of 1.0%-3.5%, and a maximum change of 8.7%). At the 2%/2 mm level, the Measurement Uncertainty function increases the user-defined %Diff criterion by 0.7%-1.2% on average, again depending on plan type and calculation technique (corresponding to an average change in pass rate of 3.5%-8.1%, and a maximum change of 14.2%). The largest increases in pass rate due to the Measurement Uncertainty function are generally seen with poorly matched planar dose comparisons, while the function has a notably smaller effect as pass rates approach 100%. The Measurement Uncertainty function, then, may

  14. Monte Carlo simulations of patient dose perturbations in rotational-type radiotherapy due to a transverse magnetic field: A tomotherapy investigation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y. M.; Geurts, M.; Smilowitz, J. B.; Bednarz, B. P., E-mail: bbednarz2@wisc.edu [Department of Medical Physics, Wisconsin Institutes for Medical Research, University of Wisconsin, Madison, Wisconsin 53703 (United States); Sterpin, E. [Molecular Imaging, Radiotherapy and Oncology, Université catholique de Louvain, Brussels, Belgium 1348 (Belgium)

    2015-02-15

    Purpose: Several groups are exploring the integration of magnetic resonance (MR) image guidance with radiotherapy to reduce tumor position uncertainty during photon radiotherapy. The therapeutic gain from reducing tumor position uncertainty using intrafraction MR imaging during radiotherapy could be partially offset if the negative effects of magnetic field-induced dose perturbations are not appreciated or accounted for. The authors hypothesize that a more rotationally symmetric modality such as helical tomotherapy will permit a systematic mediation of these dose perturbations. This investigation offers a unique look at the dose perturbations due to homogeneous transverse magnetic field during the delivery of Tomotherapy{sup ®} Treatment System plans under varying degrees of rotational beamlet symmetry. Methods: The authors accurately reproduced treatment plan beamlet and patient configurations using the Monte Carlo code GEANT4. This code has a thoroughly benchmarked electromagnetic particle transport physics package well-suited for the radiotherapy energy regime. The three approved clinical treatment plans for this study were for a prostate, head and neck, and lung treatment. The dose heterogeneity index metric was used to quantify the effect of the dose perturbations to the target volumes. Results: The authors demonstrate the ability to reproduce the clinical dose–volume histograms (DVH) to within 4% dose agreement at each DVH point for the target volumes and most planning structures, and therefore, are able to confidently examine the effects of transverse magnetic fields on the plans. The authors investigated field strengths of 0.35, 0.7, 1, 1.5, and 3 T. Changes to the dose heterogeneity index of 0.1% were seen in the prostate and head and neck case, reflecting negligible dose perturbations to the target volumes, a change from 5.5% to 20.1% was observed with the lung case. Conclusions: This study demonstrated that the effect of external magnetic fields can

  15. Calculated organ doses from selected prostate treatment plans using Monte Carlo simulations and an anatomically realistic computational phantom

    Science.gov (United States)

    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

  16. Clinically applicable Monte Carlo-based biological dose optimization for the treatment of head and neck cancers with spot-scanning proton therapy

    CERN Document Server

    Tseung, H Wan Chan; Kreofsky, C R; Ma, D; Beltran, C

    2016-01-01

    Purpose: To demonstrate the feasibility of fast Monte Carlo (MC) based inverse biological planning for the treatment of head and neck tumors in spot-scanning proton therapy. Methods: Recently, a fast and accurate Graphics Processor Unit (GPU)-based MC simulation of proton transport was developed and used as the dose calculation engine in a GPU-accelerated IMPT optimizer. Besides dose, the dose-averaged linear energy transfer (LETd) can be simultaneously scored, which makes biological dose (BD) optimization possible. To convert from LETd to BD, a linear relation was assumed. Using this novel optimizer, inverse biological planning was applied to 4 patients: 2 small and 1 large thyroid tumor targets, and 1 glioma case. To create these plans, constraints were placed to maintain the physical dose (PD) within 1.25 times the prescription while maximizing target BD. For comparison, conventional IMRT and IMPT plans were created for each case in Eclipse (Varian, Inc). The same critical structure PD constraints were use...

  17. Corrigendum to "Monte Carlo simulations of the secondary neutron ambient and effective dose equivalent rates from surface to suborbital altitudes and low Earth orbit"

    Science.gov (United States)

    El-Jaby, Samy

    2016-06-01

    A recent paper published in Life Sciences in Space Research (El-Jaby and Richardson, 2015) presented estimates of the secondary neutron ambient and effective dose equivalent rates, in air, from surface altitudes up to suborbital altitudes and low Earth orbit. These estimates were based on MCNPX (LANL, 2011) (Monte Carlo N-Particle eXtended) radiation transport simulations of galactic cosmic radiation passing through Earth's atmosphere. During a recent review of the input decks used for these simulations, a systematic error was discovered that is addressed here. After reassessment, the neutron ambient and effective dose equivalent rates estimated are found to be 10 to 15% different, though, the essence of the conclusions drawn remains unchanged.

  18. Monte Carlo simulations to calculate energy doses in a cow after continuous ingestion of CS 137 and K 40; Monte-Carlo-Simulationen zur Berechnung der Energiedosis in einem Rind nach kontinuierlicher Aufnahme von CS 137 und K 40

    Energy Technology Data Exchange (ETDEWEB)

    Pichl, E. [Technische Univ. Graz (Austria). Inst. fuer Medizintechnik; Rabitsch, H. [Technische Univ. Graz (Austria). Arbeitsgebiet Strahlenphysik

    2009-07-01

    Currently ICRP (International Commission on Radiological Protection) develops a new recommendation to estimate the natural radiation exposure of an agreed set of animals and reference plants. For estimating effective dose in humans and animals, the incorporated activities of natural and artificial radionuclides in body tissues and contents of the digestive system have to be known. It was the aim of this investigation to calculate energy doses caused by Cs 137 and K 40 in the reproductive organs (uterus, ovaries) of a cow. During its whole lifetime from 1986 to 1992, the cow incorporated continuously Cs 137 which was due to the fallout following the Chernobyl accident. K 40 occurs naturally in the cow's fodder. The cow was born in a highly contaminated region of Styria, Austria, and was infertile since 1990. The activities of Cs 137 and K 40 in the cow's fodder and in tissues, organs and contents of the digestive system of the carcass were measured simultaneously with the help of semiconductor detectors. To calculate the specific absorbed fractions by means of the Monte Carlo code MCNP, an appropriate simulation model for the reproductive organs and their surrounding tissues was developed. The contents of rectum and urinary bladder account for the main part of the energy dose in the reproductive organs. Comparison of our results with data from other investigations showed, that lifetime accumulation of Cs 137 and K 40 was too low to cause radiation inferred infertility. (orig.)

  19. Comparison of depth-dose distributions of proton therapeutic beams calculated by means of logical detectors and ionization chamber modeled in Monte Carlo codes

    Science.gov (United States)

    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.

  20. A Monte Carlo study on dose enhancement and photon contamination production by various nanoparticles in electron mode of a medical linac

    Directory of Open Access Journals (Sweden)

    Toossi Mohammad Taghi Bahreyni

    2015-07-01

    Full Text Available The aim of this study is the evaluation of electron dose enhancement and photon contamination production by various nanoparticles in the electron mode of a medical linac. MCNPX Monte Carlo code was used for simulation of Siemens Primus linac as well as a phantom and a tumor loaded with nanoparticles. Electron dose enhancement by Au, Ag, I and Fe2O3 nanoparticles of 7, 18 and 30 mg/ml concentrations for 8, 12 and 14 MeV electrons was calculated. The increase in photon contamination due to the presence of the nanoparticles was evaluated as well. The above effects were evaluated for 500 keV and 10 keV energy cut-offs defined for electrons and photons. For 500 keV energy cut-off, there was no significant electron dose enhancement. However, for 10 keV energy cut-off, a maximum electron dose enhancement factor of 1.08 was observed for 30 mg/ml of gold nanoparticles with 8 MeV electrons. An increase in photon contamination due to nanoparticles was also observed which existed mainly inside the tumor. A maximum photon dose increase factor of 1.07 was observed inside the tumor with Au nanoparticles. Nanoparticles can be used for the enhancement of electron dose in the electron mode of a linac. Lower energy electron beams, and nanoparticles with higher atomic number, can be of greater benefit in this field. Photons originating from nanoparticles will increase the photon dose inside the tumor, and will be an additional advantage of the use of nanoparticles in radiotherapy with electron beams.

  1. Determination of an Absorbed Dose of MOSFET Dosimeter using Monte Carlo N-Particle Simulation with Different Tallies and Response Functions

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, Hae Ri; Hong, Ser Gi [Kyung Hee University, Yongin (Korea, Republic of); Kim, Yong Nam; Kim, Soo Kon [Kangwon National University Hospital, Chuncheon (Korea, Republic of)

    2015-05-15

    In this paper, we performed MOSFET dosimeter simulation using the latest MCNP version code (MCNP 6). In order to determine the absorbed dose, we set the four source positions of 0 .deg. , 90 .deg. , 180 .deg. and 270 .deg. directions as in the previous study2. And, the absorbed dose traversed by electrons in the sensitive volume of extremely thin layer (1..m) was determined by both F4 tally (i.e., track length estimator) and F8 tally (i.e., energy deposition tally). However, the accurate determination of the absorbed dose in the very small volume is quite difficult due to the extremely small sensitive volume, which results a large variance in the tally with the typical number of source particles. To resolve this difficulty, we used MCNP [ESTEP] option and F4 tally. In this paper, we performed Monte Carlo simulation of MOSFET dosimeter using MCNP6. In particular, the F4 track length and*F8 energy deposition estimators coupled with the ESTEP option in MCNP [Material data card] were used to accurately estimate the absorbed doses in the extremely small sensitive volume. In order to calculate the absorbed dose in the sensitive volume, we used MCNP F4 tally which is referred to the track length estimator and F8 tally. The ESTEP option in MCNP accommodates enough number of sub-steps for an accurate simulation of the electron's trajectory. Also, MCNP [DE card] and [DF card] are used in the track length estimator to determine the absorbed dose over the sensitive volume. Also, we considered two different response functions in the F4 track length tally to calculate the absorbed doses. The first one is calculated with the formulations suggested by Schaart et al and the second one is the mass electronic collision stopping power which was extracted from MCNP output.

  2. SU-E-T-71: Commissioning and Acceptance Testing of a Commercial Monte Carlo Electron Dose Calculation Model (eMC) for TrueBeam

    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

  3. Guidelines for planning interventions against external exposure in industrial area after a nuclear accident. Pt. 2. Calculation of doses using Monte Carlo method

    International Nuclear Information System (INIS)

    Countermeasures being different from the usual urban ones and largely applicable in industrial area are collected and evaluated in a separate report. The industrial area is defined here as such an area where productive and/or commercial activity is carried out. A good example is a supermarket or a factory. Based on the history of calculation models it is unambiguous that the Monte Carlo based simulation is the perspective to the dose assessment from external exposures in such a complex environment. A method of the calculation of doses from external exposures in urban-industrial environment is presented. Moreover, this report gives a summary about the time dependence of the source strengths relative to a reference surface and a short overview about the mechanical and chemical intervention techniques which can be applied in this area. Using a hypothetical scenario (a supermarket area contaminated by 137Cs) the details of an exemplary calculation are given directly addressing the dose and averted dose blocks of the templates of industrial countermeasures. In addition, a sensitivity analysis of the results is presented. (orig.)

  4. Monte Carlo simulations to assess the effects of tube current modulation on breast dose for multidetector CT

    OpenAIRE

    Angel, Erin; Yaghmai, Nazanin; Jude, Cecilia Matilda; Demarco, John J.; Cagnon, Christopher H.; Goldin, Jonathan G; Primak, Andrew N.; Stevens, Donna M.; Cody, Dianna D.; McCollough, Cynthia H.; McNitt-Gray, Michael F.

    2009-01-01

    Tube current modulation was designed to reduce radiation dose in CT imaging while maintaining overall image quality. This study aims to develop a method for evaluating the effects of tube current modulation (TCM) on organ dose in CT exams of actual patient anatomy. This method was validated by simulating a TCM and a fixed tube current chest CT exam on 30 voxelized patient models and estimating the radiation dose to each patient’s glandular breast tissue. This new method for estimating organ d...

  5. Organ S values and effective doses for family members exposed to adult patients following I-131 treatment: A Monte Carlo simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Han, Eun Young [Department of Radiation Oncology, University of Arkansas Medical Sciences, Little Rock, Arkansas 72205 (United States); Lee, Choonsik [Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institute of Health, Bethesda, Maryland 20852 (United States); Mcguire, Lynn; Brown, Tracy L. Y. [Department of Radiology, Division of Nuclear Medicine, University of Arkansas Medical Sciences, Little Rock, Arkansas 72205 (United States); Bolch, Wesley E. [J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida 32611 (United States)

    2013-08-15

    Purpose: To calculate organ S values (mGy/Bq-s) and effective doses per time-integrated activity (mSv/Bq-s) for pediatric and adult family members exposed to an adult male or female patient treated with I-131 using a series of hybrid computational phantoms coupled with a Monte Carlo radiation transport technique.Methods: A series of pediatric and adult hybrid computational phantoms were employed in the study. Three different exposure scenarios were considered: (1) standing face-to-face exposures between an adult patient and pediatric or adult family phantoms at five different separation distances; (2) an adult female patient holding her newborn child, and (3) a 1-yr-old child standing on the lap of an adult female patient. For the adult patient model, two different thyroid-related diseases were considered: hyperthyroidism and differentiated thyroid cancer (DTC) with corresponding internal distributions of {sup 131}I. A general purpose Monte Carlo code, MCNPX v2.7, was used to perform the Monte Carlo radiation transport.Results: The S values show a strong dependency on age and organ location within the family phantoms at short distances. The S values and effective dose per time-integrated activity from the adult female patient phantom are relatively high at shorter distances and to younger family phantoms. At a distance of 1 m, effective doses per time-integrated activity are lower than those values based on the NRC (Nuclear Regulatory Commission) by a factor of 2 for both adult male and female patient phantoms. The S values to target organs from the hyperthyroid-patient source distribution strongly depend on the height of the exposed family phantom, so that their values rapidly decrease with decreasing height of the family phantom. Active marrow of the 10-yr-old phantom shows the highest S values among family phantoms for the DTC-patient source distribution. In the exposure scenario of mother and baby, S values and effective doses per time-integrated activity to

  6. ARCHER{sub RT} – A GPU-based and photon-electron coupled Monte Carlo dose computing engine for radiation therapy: Software development and application to helical tomotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Su, Lin; Du, Xining; Liu, Tianyu; Ji, Wei; Xu, X. George, E-mail: xug2@rpi.edu [Nuclear Engineering Program, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Yang, Youming; Bednarz, Bryan [Medical Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States); Sterpin, Edmond [Molecular Imaging, Radiotherapy and Oncology, Université catholique de Louvain, Brussels, Belgium 1348 (Belgium)

    2014-07-15

    Purpose: Using the graphical processing units (GPU) hardware technology, an extremely fast Monte Carlo (MC) code ARCHER{sub RT} is developed for radiation dose calculations in radiation therapy. This paper describes the detailed software development and testing for three clinical TomoTherapy® cases: the prostate, lung, and head and neck. Methods: To obtain clinically relevant dose distributions, phase space files (PSFs) created from optimized radiation therapy treatment plan fluence maps were used as the input to ARCHER{sub RT}. Patient-specific phantoms were constructed from patient CT images. Batch simulations were employed to facilitate the time-consuming task of loading large PSFs, and to improve the estimation of statistical uncertainty. Furthermore, two different Woodcock tracking algorithms were implemented and their relative performance was compared. The dose curves of an Elekta accelerator PSF incident on a homogeneous water phantom were benchmarked against DOSXYZnrc. For each of the treatment cases, dose volume histograms and isodose maps were produced from ARCHER{sub RT} and the general-purpose code, GEANT4. The gamma index analysis was performed to evaluate the similarity of voxel doses obtained from these two codes. The hardware accelerators used in this study are one NVIDIA K20 GPU, one NVIDIA K40 GPU, and six NVIDIA M2090 GPUs. In addition, to make a fairer comparison of the CPU and GPU performance, a multithreaded CPU code was developed using OpenMP and tested on an Intel E5-2620 CPU. Results: For the water phantom, the depth dose curve and dose profiles from ARCHER{sub RT} agree well with DOSXYZnrc. For clinical cases, results from ARCHER{sub RT} are compared with those from GEANT4 and good agreement is observed. Gamma index test is performed for voxels whose dose is greater than 10% of maximum dose. For 2%/2mm criteria, the passing rates for the prostate, lung case, and head and neck cases are 99.7%, 98.5%, and 97.2%, respectively. Due to

  7. Development of virtual patient models for permanent implant brachytherapy Monte Carlo dose calculations: interdependence of CT image artifact mitigation and tissue assignment

    International Nuclear Information System (INIS)

    This work investigates and compares CT image metallic artifact reduction (MAR) methods and tissue assignment schemes (TAS) for the development of virtual patient models for permanent implant brachytherapy Monte Carlo (MC) dose calculations. Four MAR techniques are investigated to mitigate seed artifacts from post-implant CT images of a homogeneous phantom and eight prostate patients: a raw sinogram approach using the original CT scanner data and three methods (simple threshold replacement (STR), 3D median filter, and virtual sinogram) requiring only the reconstructed CT image. Virtual patient models are developed using six TAS ranging from the AAPM-ESTRO-ABG TG-186 basic approach of assigning uniform density tissues (resulting in a model not dependent on MAR) to more complex models assigning prostate, calcification, and mixtures of prostate and calcification using CT-derived densities. The EGSnrc user-code BrachyDose is employed to calculate dose distributions. All four MAR methods eliminate bright seed spot artifacts, and the image-based methods provide comparable mitigation of artifacts compared with the raw sinogram approach. However, each MAR technique has limitations: STR is unable to mitigate low CT number artifacts, the median filter blurs the image which challenges the preservation of tissue heterogeneities, and both sinogram approaches introduce new streaks. Large local dose differences are generally due to differences in voxel tissue-type rather than mass density. The largest differences in target dose metrics (D90, V100, V150), over 50% lower compared to the other models, are when uncorrected CT images are used with TAS that consider calcifications. Metrics found using models which include calcifications are generally a few percent lower than prostate-only models. Generally, metrics from any MAR method and any TAS which considers calcifications agree within 6%. Overall, the studied MAR methods and TAS show promise for further retrospective MC dose

  8. Development of virtual patient models for permanent implant brachytherapy Monte Carlo dose calculations: interdependence of CT image artifact mitigation and tissue assignment

    Science.gov (United States)

    Miksys, N.; Xu, C.; Beaulieu, L.; Thomson, R. M.

    2015-08-01

    This work investigates and compares CT image metallic artifact reduction (MAR) methods and tissue assignment schemes (TAS) for the development of virtual patient models for permanent implant brachytherapy Monte Carlo (MC) dose calculations. Four MAR techniques are investigated to mitigate seed artifacts from post-implant CT images of a homogeneous phantom and eight prostate patients: a raw sinogram approach using the original CT scanner data and three methods (simple threshold replacement (STR), 3D median filter, and virtual sinogram) requiring only the reconstructed CT image. Virtual patient models are developed using six TAS ranging from the AAPM-ESTRO-ABG TG-186 basic approach of assigning uniform density tissues (resulting in a model not dependent on MAR) to more complex models assigning prostate, calcification, and mixtures of prostate and calcification using CT-derived densities. The EGSnrc user-code BrachyDose is employed to calculate dose distributions. All four MAR methods eliminate bright seed spot artifacts, and the image-based methods provide comparable mitigation of artifacts compared with the raw sinogram approach. However, each MAR technique has limitations: STR is unable to mitigate low CT number artifacts, the median filter blurs the image which challenges the preservation of tissue heterogeneities, and both sinogram approaches introduce new streaks. Large local dose differences are generally due to differences in voxel tissue-type rather than mass density. The largest differences in target dose metrics (D90, V100, V150), over 50% lower compared to the other models, are when uncorrected CT images are used with TAS that consider calcifications. Metrics found using models which include calcifications are generally a few percent lower than prostate-only models. Generally, metrics from any MAR method and any TAS which considers calcifications agree within 6%. Overall, the studied MAR methods and TAS show promise for further retrospective MC dose

  9. Behaviors of the percentage depth dose curves along the beam axis of a phantom filled with different clinical PTO objects, a Monte Carlo Geant4 study

    Science.gov (United States)

    EL Bakkali, Jaafar; EL Bardouni, Tarek; Safavi, Seyedmostafa; Mohammed, Maged; Saeed, Mroan

    2016-08-01

    The aim of this work is to assess the capabilities of Monte Carlo Geant4 code to reproduce the real percentage depth dose (PDD) curves generated in phantoms which mimic three important clinical treatment situations that include lung slab, bone slab, bone-lung slab geometries. It is hoped that this work will lead us to a better understanding of dose distributions in an inhomogeneous medium, and to identify any limitations of dose calculation algorithm implemented in the Geant4 code. For this purpose, the PDD dosimetric functions associated to the three clinical situations described above, were compared to one produced in a homogeneous water phantom. Our results show, firstly, that the Geant4 simulation shows potential mistakes on the shape of the calculated PDD curve of the first physical test object (PTO), and it is obviously not able to successfully predict dose values in regions near to the boundaries between two different materials. This is, surely due to the electron transport algorithm and it is well-known as the artifacts at interface phenomenon. To deal with this issue, we have added and optimized the StepMax parameter to the dose calculation program; consequently the artifacts due to the electron transport were quasi disappeared. However, the Geant4 simulation becomes painfully slow when we attempt to completely resolve the electron artifact problems by considering a smaller value of an electron StepMax parameter. After electron transport optimization, our results demonstrate the medium-level capabilities of the Geant4 code to modeling dose distribution in clinical PTO objects.

  10. Determination of absorbed dose distribution in water for COC ophthalmic applicator of {sup 106}Ru/{sup 106}Rh using Monte Carlo code-MCNPX; Determinacao da distribuicao de dose absorvida na agua para o aplicador oftalmico COC de {sup 106}Ru/{sup 106}Rh utilizando o codigo de Monte Carlo - MCNPX

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Nilseia A.; Rosa, Luiz A. Ribeiro da, E-mail: nilseia@ird.gov.br, E-mail: lrosa@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ),Rio de Janeiro, RJ (Brazil); Braz, Delson, E-mail: delson@nuclear.ufrj.br [Coordenacao dos programas de Pos-Graduacao em Engenharia (PEN/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear

    2014-07-01

    The COC ophthalmic applicators using beta radiation source of {sup 106}Ru/{sup 106}Rh are used in the treatment of intraocular tumors near the optic nerve. In this type of treatment is very important to know the dose distribution in order to provide the best possible delivery of prescribed dose to the tumor, preserves the optic nerve region extremely critical, that if damaged, can compromise the patient's visual acuity, and cause brain sequelae. These dose distributions are complex and doctors, who will have the responsibility on the therapy, only have the source calibration certificate provided by the manufacturer Eckert and Ziegler BEBIG GmbH. These certificates provide 10 absorbed dose values at water depth along the central axis applicator with the uncertainties of the order of 20% isodose and in a plane located 1 mm from the applicator surface. Thus, it is important to know with more detail and precision the dose distributions in water generated by such applicators. To this end, the Monte Carlo simulation was used using MCNPX code. Initially, was validated the simulation by comparing the obtained results to the central axis of the applicator with those provided by the certificate. The different percentages were lower than 5%, validating the used method. Lateral dose profile was calculated for 6 different depths in intervals of 1 mm and the dose rates in mGy.min{sup -1} for the same depths.

  11. Practical methods for improving dose distributions in Monte Carlo-based IMRT planning of lung wall-seated tumors treated with SBRT.

    Science.gov (United States)

    Altman, Michael B; Jin, Jian-Yue; Kim, Sangroh; Wen, Ning; Liu, Dezhi; Siddiqui, M Salim; Ajlouni, Munther I; Movsas, Benjamin; Chetty, Indrin J

    2012-01-01

    Current commercially available planning systems with Monte Carlo (MC)-based final dose calculation in IMRT planning employ pencil-beam (PB) algorithms in the optimization process. Consequently, dose coverage for SBRT lung plans can feature cold-spots at the interface between lung and tumor tissue. For lung wall (LW)-seated tumors, there can also be hot spots within nearby normal organs (example: ribs). This study evaluated two different practical approaches to limiting cold spots within the target and reducing high doses to surrounding normal organs in MC-based IMRT planning of LW-seated tumors. First, "iterative reoptimization", where the MC calculation (with PB-based optimization) is initially performed. The resultant cold spot is then contoured and used as a simultaneous boost volume. The MC-based dose is then recomputed. The second technique uses noncoplanar beam angles with limited path through lung tissue. Both techniques were evaluated against a conventional coplanar beam approach with a single MC calculation. In all techniques the prescription dose was normalized to cover 95% of the PTV. Fifteen SBRT lung cases with LW-seated tumors were planned. The results from iterative reoptimization showed that conformity index (CI) and/or PTV dose uniformity (UPTV) improved in 12/15 plans. Average improvement was 13%, and 24%, respectively. Nonimproved plans had PTVs near the skin, trachea, and/or very small lung involvement. The maximum dose to 1cc volume (D1cc) of surrounding OARs decreased in 14/15 plans (average 10%). Using noncoplanar beams showed an average improvement of 7% in 10/15 cases and 11% in 5/15 cases for CI and UPTV, respectively. The D1cc was reduced by an average of 6% in 10/15 cases to surrounding OARs. Choice of treatment planning technique did not statistically significantly change lung V5. The results showed that the proposed practical approaches enhance dose conformity in MC-based IMRT planning of lung tumors treated with SBRT, improving target

  12. Dosimetric verification and clinical evaluation of a new commercially available Monte Carlo-based dose algorithm for application in stereotactic body radiation therapy (SBRT) treatment planning

    Science.gov (United States)

    Fragoso, Margarida; Wen, Ning; Kumar, Sanath; Liu, Dezhi; Ryu, Samuel; Movsas, Benjamin; Munther, Ajlouni; Chetty, Indrin J.

    2010-08-01

    Modern cancer treatment techniques, such as intensity-modulated radiation therapy (IMRT) and stereotactic body radiation therapy (SBRT), have greatly increased the demand for more accurate treatment planning (structure definition, dose calculation, etc) and dose delivery. The ability to use fast and accurate Monte Carlo (MC)-based dose calculations within a commercial treatment planning system (TPS) in the clinical setting is now becoming more of a reality. This study describes the dosimetric verification and initial clinical evaluation of a new commercial MC-based photon beam dose calculation algorithm, within the iPlan v.4.1 TPS (BrainLAB AG, Feldkirchen, Germany). Experimental verification of the MC photon beam model was performed with film and ionization chambers in water phantoms and in heterogeneous solid-water slabs containing bone and lung-equivalent materials for a 6 MV photon beam from a Novalis (BrainLAB) linear accelerator (linac) with a micro-multileaf collimator (m3 MLC). The agreement between calculated and measured dose distributions in the water phantom verification tests was, on average, within 2%/1 mm (high dose/high gradient) and was within ±4%/2 mm in the heterogeneous slab geometries. Example treatment plans in the lung show significant differences between the MC and one-dimensional pencil beam (PB) algorithms within iPlan, especially for small lesions in the lung, where electronic disequilibrium effects are emphasized. Other user-specific features in the iPlan system, such as options to select dose to water or dose to medium, and the mean variance level, have been investigated. Timing results for typical lung treatment plans show the total computation time (including that for processing and I/O) to be less than 10 min for 1-2% mean variance (running on a single PC with 8 Intel Xeon X5355 CPUs, 2.66 GHz). Overall, the iPlan MC algorithm is demonstrated to be an accurate and efficient dose algorithm, incorporating robust tools for MC

  13. Analysis of the track- and dose-averaged LET and LET spectra in proton therapy using the GEANT4 Monte Carlo code

    Energy Technology Data Exchange (ETDEWEB)

    Guan, Fada; Peeler, Christopher; Taleei, Reza; Randeniya, Sharmalee; Ge, Shuaiping; Mirkovic, Dragan; Mohan, Radhe; Titt, Uwe, E-mail: UTitt@mdanderson.org [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); Bronk, Lawrence [Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); Geng, Changran [Department of Nuclear Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China and Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 (United States); Grosshans, David [Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 and Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States)

    2015-11-15

    Purpose: The motivation of this study was to find and eliminate the cause of errors in dose-averaged linear energy transfer (LET) calculations from therapeutic protons in small targets, such as biological cell layers, calculated using the GEANT 4 Monte Carlo code. Furthermore, the purpose was also to provide a recommendation to select an appropriate LET quantity from GEANT 4 simulations to correlate with biological effectiveness of therapeutic protons. Methods: The authors developed a particle tracking step based strategy to calculate the average LET quantities (track-averaged LET, LET{sub t} and dose-averaged LET, LET{sub d}) using GEANT 4 for different tracking step size limits. A step size limit refers to the maximally allowable tracking step length. The authors investigated how the tracking step size limit influenced the calculated LET{sub t} and LET{sub d} of protons with six different step limits ranging from 1 to 500 μm in a water phantom irradiated by a 79.7-MeV clinical proton beam. In addition, the authors analyzed the detailed stochastic energy deposition information including fluence spectra and dose spectra of the energy-deposition-per-step of protons. As a reference, the authors also calculated the averaged LET and analyzed the LET spectra combining the Monte Carlo method and the deterministic method. Relative biological effectiveness (RBE) calculations were performed to illustrate the impact of different LET calculation methods on the RBE-weighted dose. Results: Simulation results showed that the step limit effect was small for LET{sub t} but significant for LET{sub d}. This resulted from differences in the energy-deposition-per-step between the fluence spectra and dose spectra at different depths in the phantom. Using the Monte Carlo particle tracking method in GEANT 4 can result in incorrect LET{sub d} calculation results in the dose plateau region for small step limits. The erroneous LET{sub d} results can be attributed to the algorithm to

  14. Evaluation of the Effects of Inhomogeneities on Dose Profiles Using Polymer Gel Dosimeter and Monte Carlo Simulation in Gamma Knife

    Directory of Open Access Journals (Sweden)

    Tayeb Allahverdi Pourfallah

    2012-03-01

    Full Text Available Introduction Polymer gel dosimeters offer a practical solution to 3D dose verification for conventional radiotherapy as well as intensity-modulated and stereotactic radiotherapy. In this study, EGSnrc calculated and PAGAT polymer gel dosimeter measured dose profiles from single shot irradiation with 18 mm collimator of Gamma Knife in homogeneous and inhomogeneous phantoms were compared with each other. Materials and Methods The head phantom was a custom-built 16 cm diameter plexiglas sphere. Inside the phantom, there were two cubic cutouts for inserting the gel vials and inhomogeneities. Following irradiation with the Gamma Knife unit, the polymer gel dosimeters were scanned with a 1.5 T MRI scanner. For the purpose of simulation the simplified channel of 60Co source of Gamma Knife BEAMnrc and for extracting the 3D dose distribution in the phantom, DOSXYZnrc codes were used. Results Within high isodose levels (>80%, there are dose differences higher than 7%, especially between air inserted and PTFE inserted phantoms, which were obtained using both simulation and experiment. This means that these values exceed the acceptance criterion of conformal radiotherapy and stereotactic radiosurgery (i.e., within some isodose levels, less than 93% of prescription dose are delivered to the target. Conclusion The discrepancies observed between the results obtained from heterogeneous and homogeneous phantoms suggest that Leksell Gamma Knife planning system (LGP predictions which assume the target as a homogeneous material must be corrected in order to take care of the air- and bone-tissue inhomogeneities.

  15. Redução de incertezas em radioterapia utilizando simulação Monte Carlo: análise espectral aplicada à correção de dose absorvida Reduction of uncertainties in radiotherapy assessed by Monte Carlo simulation: spectral analysis applied to absorbed dose correction

    Directory of Open Access Journals (Sweden)

    Tatiana Marques

    2010-04-01

    Full Text Available OBJETIVO: Determinar, por simulação Monte Carlo, os espectros de feixes de cobaltoterapia em profundidade na água e fatores de correção para doses absorvidas em dosímetros termoluminescentes de fluoreto de lítio. MATERIAIS E MÉTODOS: As simulações dos espectros secundários da fonte clínica de cobalto-60 foram realizadas com o código Monte Carlo PENELOPE, em diversas profundidades na água. Medidas experimentais de dose profunda foram obtidas com dosímetros termoluminescentes e câmara de ionização em condições de referência em radioterapia. Os fatores de correção para os dosímetros termoluminescentes foram obtidos através da razão entre as absorções relativas ao espectro de baixa energia e ao espectro total. RESULTADOS: A análise espectral em profundidade revelou a existência de espectros secundários de baixa energia responsáveis por uma parcela significativa da deposição de dose. Foram observadas discrepâncias de 3,2% nas doses medidas experimentalmente com a câmara de ionização e com os dosímetros termoluminescentes. O uso dos fatores de correção nessas medidas permitiu diminuir a discrepância entre as doses absorvidas para, no máximo, 0,3%. CONCLUSÃO: Os espectros simulados permitem o cálculo de fatores de correção para as leituras de dosímetros termoluminescentes utilizados em medidas de dose profunda, contribuindo para a redução das incertezas associadas ao controle de qualidade de feixes clínicos em radioterapia.OBJECTIVE: To calculate spectra of cobalt-60 beam at water depth and correction factors for absorbed dose measurements obtained with lithium fluoride thermoluminescent dosimeters using Monte Carlo simulation. MATERIALS AND METHODS: The simulations of secondary spectra of clinical cobalt-60 sources were performed with the PENELOPE Monte Carlo code at different water depths. Experimental measurements of deep doses were obtained with thermoluminescent dosimeters and ionization chamber

  16. Analytical equations for CT dose profiles derived using a scatter kernel of Monte Carlo parentage with broad applicability to CT dosimetry problems

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, Robert L.; Boone, John M. [Department of Radiology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157 (United States); Departments of Radiology and Biomedical Engineering, University of California Davis, Sacramento, California 95817 (United States)

    2011-07-15

    Purpose: Knowledge of the complete axial dose profile f(z), including its long scatter tails, provides the most complete (and flexible) description of the accumulated dose in CT scanning. The CTDI paradigm (including CTDI{sub vol}) requires shift-invariance along z (identical dose profiles spaced at equal intervals), and is therefore inapplicable to many of the new and complex shift-variant scan protocols, e.g., high dose perfusion studies using variable (or zero) pitch. In this work, a convolution-based beam model developed by Dixon et al.[Med. Phys. 32, 3712-3728, (2005)] updated with a scatter LSF kernel (or DSF) derived from a Monte Carlo simulation by Boone [Med. Phys. 36, 4547-4554 (2009)] is used to create an analytical equation for the axial dose profile f(z) in a cylindrical phantom. Using f(z), equations are derived which provide the analytical description of conventional (axial and helical) dose, demonstrating its physical underpinnings; and likewise for the peak axial dose f(0) appropriate to stationary phantom cone beam CT, (SCBCT). The methodology can also be applied to dose calculations in shift-variant scan protocols. This paper is an extension of our recent work Dixon and Boone [Med. Phys. 37, 2703-2718 (2010)], which dealt only with the properties of the peak dose f(0), its relationship to CTDI, and its appropriateness to SCBCT. Methods: The experimental beam profile data f(z) of Mori et al.[Med. Phys. 32, 1061-1069 (2005)] from a 256 channel prototype cone beam scanner for beam widths (apertures) ranging from a = 28 to 138 mm are used to corroborate the theoretical axial profiles in a 32 cm PMMA body phantom. Results: The theoretical functions f(z) closely-matched the central axis experimental profile data{sup 11} for all apertures (a = 28 -138 mm). Integration of f(z) likewise yields analytical equations for all the (CTDI-based) dosimetric quantities of conventional CT (including CTDI{sub L} itself) in addition to the peak dose f(0) relevant to

  17. TH-C-12A-10: Surface Dose Enhancement Using Novel Hybrid Electron and Photon Low-Z Therapy Beams: Monte Carlo Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, C; Parsons, D [Dept of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia (Canada); Robar, J; Kelly, R [Dept of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia (Canada); Dept of Radiation Oncology, Dalhousie University, Halifax, Nova Scotia (Canada); Nova Scotia Cancer Centre, Halifax, NS (Canada)

    2014-06-15

    Purpose: The introduction of the TrueBeam linac platform provides access to an in-air target assembly making it possible to apply novel treatments using multiple target designs. One such novel treatment uses multiple low-Z targets to enhance surface dose replacing the use of synthetic tissue equivalent material (bolus). This treatment technique will decrease the common dosimetric and set up errors prevalent in using physical treatment accessories like bolus. The groundwork for a novel treatment beam used to enhance surface dose to within 80-100% of the dose at dmax by utilizing low-Z (Carbon) targets of various percent CSDA range thickness operated at 2.5–4 MeV used in conjunction with a clinical 6 MV beam is presented herein. Methods: A standard Monte Carlo model of a Varian Clinac accelerator was developed to manufacturers specifications. Simulations were performed using Be, C, AL, and C, as potential low-Z targets, placed in the secondary target position. The results determined C to be the target material of choice. Simulations of 15, 30 and 60% CSDA range C beams were propagated through slab phantoms. The resulting PDDs were weighted and combined with a standard 6 MV treatment beam. Versions of the experimental targets were installed into a 2100C Clinac and the models were validated. Results: Carbon was shown to be the low-Z material of choice for this project. Using combinations of 15, 30, 60% CSDA beams operated at 2.5 and 4 MeV in combination with a standard 6 MV treatment beam the surface dose was shown to be enhanced to within 80–100% the dose at dmax. Conclusion: The modeled low-Z beams were successfully validated using machined versions of the targets. Water phantom measurements and slab phantom simulations show excellent correlation. Patient simulations are now underway to compare the use of bolus with the proposed novel beams. NSERC.

  18. Sci—Fri PM: Topics — 07: Monte Carlo Simulation of Primary Dose and PET Isotope Production for the TRIUMF Proton Therapy Facility

    Energy Technology Data Exchange (ETDEWEB)

    Lindsay, C; Jirasek, A [University of Victoria (Australia); Blackmore, E; Hoehr, C; Schaffer, P; Trinczek, M [TRIUMF (Canada); Sossi, V [University of British Columbia (Canada)

    2014-08-15

    Uveal melanoma is a rare and deadly tumour of the eye with primary metastases in the liver resulting in an 8% 2-year survival rate upon detection. Large growths, or those in close proximity to the optic nerve, pose a particular challenge to the commonly employed eye-sparing technique of eye-plaque brachytherapy. In these cases external beam charged particle therapy offers improved odds in avoiding catastrophic side effects such as neuropathy or blindness. Since 1995, the British Columbia Cancer Agency in partnership with the TRIUMF national laboratory have offered proton therapy in the treatment of difficult ocular tumors. Having seen 175 patients, yielding 80% globe preservation and 82% metastasis free survival as of 2010, this modality has proven to be highly effective. Despite this success, there have been few studies into the use of the world's largest cyclotron in patient care. Here we describe first efforts of modeling the TRIUMF dose delivery system using the FLUKA Monte Carlo package. Details on geometry, estimating beam parameters, measurement of primary dose and simulation of PET isotope production are discussed. Proton depth dose in both modulated and pristine beams is successfully simulated to sub-millimeter precision in range (within limits of measurement) and 2% agreement to measurement within in a treatment volume. With the goal of using PET signals for in vivo dosimetry (alignment), a first look at PET isotope depth distribution is presented — comparing favourably to a naive method of approximating simulated PET slice activity in a Lucite phantom.

  19. Monte Carlo correction factors for a Farmer 0.6 cm3 ion chamber dose measurement in the build-up region of the 6 MV clinical beam.

    Science.gov (United States)

    Pena, J; Sánchez-Doblado, F; Capote, R; Terrón, J A; Gómez, F

    2006-03-21

    Reference dosimetry of photon fields is a well-established subject and currently available protocols (such as the IAEA TRS-398 and AAPM TG-51) provide methods for converting the ionization chamber (IC) reading into dose to water, provided reference conditions of charged particle equilibrium (CPE) are fulfilled. But these protocols cannot deal with the build-up region, where the lack of CPE limits the applicability of the cavity theorems and so the chamber correction factors become depth dependent. By explicitly including the IC geometry in the Monte Carlo simulations, depth-dependent dose correction factors are calculated for a PTW 30001 0.6 cm(3) ion chamber in the build-up region of the 6 MV photon beam. The corrected percentage depth dose (PDD) agrees within 2% with that measured using the NACP 02 plane-parallel ion chamber in the build-up region at depths greater than 0.4 cm, where the Farmer chamber wall reaches the phantom surface. PMID:16510960

  20. A Monte Carlo Study of the Relationship between the Time Structures of Prompt Gammas and in vivo Radiation Dose in Proton Therapy

    CERN Document Server

    Shin, Wook-Geun; Shin, Jae-Ik; Jeong, Jong Hwi; Lee, Se Byeong

    2015-01-01

    For the in vivo range verification in proton therapy, it has been tried to measure the spatial distribution of the prompt gammas generated by the proton-induced interactions with the close relationship with the proton dose distribution. However, the high energy of the prompt gammas and background gammas are still problematic in measuring the distribution. In this study, we suggested a new method determining the in vivo range by utilizing the time structure of the prompt gammas formed with the rotation of a range modulation wheel (RMW) in the passive scattering proton therapy. To validate the Monte Carlo code simulating the proton beam nozzle, axial percent depth doses (PDDs) were compared with the measured PDDs with the varying beam range of 4.73-24.01 cm. And the relationship between the proton dose rate and the time structure of the prompt gammas was assessed and compared in the water phantom. The results of the PDD showed accurate agreement within the relative errors of 1.1% in the distal range and 2.9% in...

  1. Single doses of piracetam affect 42-channel event-related potential microstate maps in a cognitive paradigm.

    Science.gov (United States)

    Michel, C M; Lehmann, D

    1993-01-01

    We examined whether a single administration of piracetam produces dose-dependent effects on brain functions in healthy young men. In 6 subjects, 42-channel event-related EEG potential maps (ERP) were recorded during a task requiring subjects to watch single digits presented in a pseudorandom order on a screen and to press a button after all triplets of three consecutive odd or even digits. The ERP maps to the three digits of the correctly detected triplets were analyzed in terms of their mapped ERP field configuration (landscape). Different landscapes of the maps indicate different configuration of the activated neural population and therefore reflect different functional microstates of the brain. In order to identify these microstates, adaptive segmentation of the map series based on their landscapes was done. Nineteen time segments were found. These segments were tested for direct effects on brain function of three single doses of piracetam (2.9, 4.8 or 9.6 g) and a placebo given double-blind in balanced order. Piracetam mainly affected the map landscape of the time segments following the triplet's last digit. U-shaped dose-dependent effects were found; they were strongest after 4.8 g piracetam. Since these particular ERP segments are recognized to be strongly correlated to cognitive functions, the present findings suggest that single medium doses of piracetam selectively activate differently located or oriented neurons during cognitive steps of information processing.

  2. Simulation study on potential accuracy gains from dual energy CT tissue segmentation for low-energy brachytherapy Monte Carlo dose calculations

    Science.gov (United States)

    Landry, Guillaume; Granton, Patrick V.; Reniers, Brigitte; Öllers, Michel C.; Beaulieu, Luc; Wildberger, Joachim E.; Verhaegen, Frank

    2011-10-01

    This work compares Monte Carlo (MC) dose calculations for 125I and 103Pd low-dose rate (LDR) brachytherapy sources performed in virtual phantoms containing a series of human soft tissues of interest for brachytherapy. The geometries are segmented (tissue type and density assignment) based on simulated single energy computed tomography (SECT) and dual energy (DECT) images, as well as the all-water TG-43 approach. Accuracy is evaluated by comparison to a reference MC dose calculation performed in the same phantoms, where each voxel's material properties are assigned with exactly known values. The objective is to assess potential dose calculation accuracy gains from DECT. A CT imaging simulation package, ImaSim, is used to generate CT images of calibration and dose calculation phantoms at 80, 120, and 140 kVp. From the high and low energy images electron density ρe and atomic number Z are obtained using a DECT algorithm. Following a correction derived from scans of the calibration phantom, accuracy on Z and ρe of ±1% is obtained for all soft tissues with atomic number Z in [6,8] except lung. GEANT4 MC dose calculations based on DECT segmentation agreed with the reference within ±4% for 103Pd, the most sensitive source to tissue misassignments. SECT segmentation with three tissue bins as well as the TG-43 approach showed inferior accuracy with errors of up to 20%. Using seven tissue bins in our SECT segmentation brought errors within ±10% for 103Pd. In general 125I dose calculations showed higher accuracy than 103Pd. Simulated image noise was found to decrease DECT accuracy by 3-4%. Our findings suggest that DECT-based segmentation yields improved accuracy when compared to SECT segmentation with seven tissue bins in LDR brachytherapy dose calculation for the specific case of our non-anthropomorphic phantom. The validity of our conclusions for clinical geometry as well as the importance of image noise in the tissue segmentation procedure deserves further

  3. Prediction of dose and field mapping around a shielded plutonium fuel fabrication glovebox

    International Nuclear Information System (INIS)

    Westinghouse Hanford Company, as the Department of Energy's (DOE) prime contractor for the operation of the Hanford Engineering Development Laboratory (HEDL), is responsible for the development of the Secure Automated Fabrication (SAF) Line which is to be installed in the recently constructed Fuels and Materials Examination Facility (FMEF). The SAF Line will fabricate mixed-oxide (MOX) fuel pins for the Fast Flux Test Facility (FFTF) at an annual throughput rate of six (6) metric tons (MT) of MOX. The SAF Line will also demonstrate the automated manufacture of fuel pins on a production-scale. This paper describes some of the techniques used to reduce personnel exposure on the SAF Line, as well as the prediction and field mapping of doses from a shielded fuel fabrication glovebox. Tables are also presented from which exposure rate estimates can be made for plutonium recovered from fuels having different isotopic compositions as a result of varied burnup

  4. Non-Uniform Dose Mapping Controlled by Modulated Vertical and Horizontal Scans

    International Nuclear Information System (INIS)

    Since geometries of semi-conductor devices continue to shrink, the requirement for each process becomes severer to keep uniformity of electrical parameters of the semi-conductor devices. A larger wafer also causes larger variations. Thus it has been strongly required for ion implantation process to compensate for the variations from other processes because of its good dose controllability. A newly developed mapping of intentional non-uniform dosage system, which is named 'MIND system', is implemented in SEN's single-wafer-type implanters. The MIND system controls both horizontal and vertical scan speed simultaneously. Intentional two-dimensional non-uniform profiles of sheet resistance, such as concentric and eccentric profiles, are obtained only by single-step ion implantation.

  5. Monte Carlo simulation for dose distribution calculations in a CT-based phantom at the Portuguese gamma irradiation facility

    Science.gov (United States)

    Oliveira, Carlos; Yoriyaz, Hélio; Oliveira, M. Carmo; Ferreira, L. M.

    2004-01-01

    In preview works the Portuguese Gamma Irradiation Facility, UTR, has been simulated using the MCNP code and the product to be irradiated has been drawn using the boolean operators with the MCNP surfaces. However, sometimes the product to be irradiated could have an irregular shape. The paper describes an alternative way for drawing the corresponding volume based on CT image data in a format of a 3D matrix of voxels. This data are read by a specific code called SCMS which transforms it into a MCNP input file. The dimensions of each MCNP voxel depend on the number of elements in the CT-based matrix. Additionally, the new approach allows one to know dose distributions anywhere without extra definitions of surfaces or volumes. Experimental dose measurements were carried out using Amber Perspex dosimeters. This work presents the results of MCNP simulations using both modeling modes - the standard mode and the voxel mode.

  6. Influence of 320-detector-row volume scanning and AAPM report 111 CT dosimetry metrics on size-specific dose estimate: a Monte Carlo study.

    Science.gov (United States)

    Haba, Tomonobu; Koyama, Shuji; Kinomura, Yutaka; Ida, Yoshihiro; Kobayashi, Masanao

    2016-09-01

    The American Association of Physicists in Medicine (AAPM) task group 204 has recommended the use of size-dependent conversion factors to calculate size-specific dose estimate (SSDE) values from volume computed tomography dose index (CTDIvol) values. However, these conversion factors do not consider the effects of 320-detector-row volume computed tomography (CT) examinations or the new CT dosimetry metrics proposed by AAPM task group 111. This study aims to investigate the influence of these examinations and metrics on the conversion factors reported by AAPM task group 204, using Monte Carlo simulations. Simulations were performed modelling a Toshiba Aquilion ONE CT scanner, in order to compute dose values in water for cylindrical phantoms with 8-40-cm diameters at 2-cm intervals for each scanning parameter (tube voltage, bow-tie filter, longitudinal beam width). Then, the conversion factors were obtained by applying exponential regression analysis between the dose values for a given phantom diameter and the phantom diameter combined with various scanning parameters. The conversion factors for each scanning method (helical, axial, or volume scanning) and CT dosimetry method (i.e., the CTDI100 method or the AAPM task group 111 method) were in agreement with those reported by AAPM task group 204, within a percentage error of 14.2 % for phantom diameters ≥11.2 cm. The results obtained in this study indicate that the conversion factors previously presented by AAPM task group 204 can be used to provide appropriate SSDE values for 320-detector-row volume CT examinations and the CT dosimetry metrics proposed by the AAPM task group 111.

  7. Influence of 320-detector-row volume scanning and AAPM report 111 CT dosimetry metrics on size-specific dose estimate: a Monte Carlo study.

    Science.gov (United States)

    Haba, Tomonobu; Koyama, Shuji; Kinomura, Yutaka; Ida, Yoshihiro; Kobayashi, Masanao

    2016-09-01

    The American Association of Physicists in Medicine (AAPM) task group 204 has recommended the use of size-dependent conversion factors to calculate size-specific dose estimate (SSDE) values from volume computed tomography dose index (CTDIvol) values. However, these conversion factors do not consider the effects of 320-detector-row volume computed tomography (CT) examinations or the new CT dosimetry metrics proposed by AAPM task group 111. This study aims to investigate the influence of these examinations and metrics on the conversion factors reported by AAPM task group 204, using Monte Carlo simulations. Simulations were performed modelling a Toshiba Aquilion ONE CT scanner, in order to compute dose values in water for cylindrical phantoms with 8-40-cm diameters at 2-cm intervals for each scanning parameter (tube voltage, bow-tie filter, longitudinal beam width). Then, the conversion factors were obtained by applying exponential regression analysis between the dose values for a given phantom diameter and the phantom diameter combined with various scanning parameters. The conversion factors for each scanning method (helical, axial, or volume scanning) and CT dosimetry method (i.e., the CTDI100 method or the AAPM task group 111 method) were in agreement with those reported by AAPM task group 204, within a percentage error of 14.2 % for phantom diameters ≥11.2 cm. The results obtained in this study indicate that the conversion factors previously presented by AAPM task group 204 can be used to provide appropriate SSDE values for 320-detector-row volume CT examinations and the CT dosimetry metrics proposed by the AAPM task group 111. PMID:27444155

  8. Experimental verification of a Monte Carlo-based MLC simulation model for IMRT dose calculations in heterogeneous media

    Science.gov (United States)

    Tyagi, N.; Curran, B. H.; Roberson, P. L.; Moran, J. M.; Acosta, E.; Fraass, B. A.

    2008-02-01

    IMRT often requires delivering small fields which may suffer from electronic disequilibrium effects. The presence of heterogeneities, particularly low-density tissues in patients, complicates such situations. In this study, we report on verification of the DPM MC code for IMRT treatment planning in heterogeneous media, using a previously developed model of the Varian 120-leaf MLC. The purpose of this study is twofold: (a) design a comprehensive list of experiments in heterogeneous media for verification of any dose calculation algorithm and (b) verify our MLC model in these heterogeneous type geometries that mimic an actual patient geometry for IMRT treatment. The measurements have been done using an IMRT head and neck phantom (CIRS phantom) and slab phantom geometries. Verification of the MLC model has been carried out using point doses measured with an A14 slim line (SL) ion chamber inside a tissue-equivalent and a bone-equivalent material using the CIRS phantom. Planar doses using lung and bone equivalent slabs have been measured and compared using EDR films (Kodak, Rochester, NY).

  9. Dose-rate controlled energy dispersive x-ray spectroscopic mapping of the metallic components in a biohybrid nanosystem

    Science.gov (United States)

    Zhu, Yuanyuan; Munro, Catherine J.; Olszta, Matthew J.; Edwards, Danny J.; Braunschweig, Adam B.; Knecht, Marc R.; Browning, Nigel D.

    2016-08-01

    In this work, we showcase that through precise control of the electron dose rate, state-of-the-art large solid angle energy dispersive x-ray spectroscopy mapping in aberration-corrected scanning transmission electron microscope is capable of faithful and unambiguous chemical characterization of the Pt and Pd distribution in a peptide-mediated nanosystem. This low-dose-rate recording scheme adds another dimension of flexibility to the design of elemental mapping experiments, and holds significant potential for extending its application to a wide variety of beam sensitive hybrid nanostructures.

  10. Dose-rate controlled energy dispersive X-ray spectroscopic mapping of the metallic components in a biohybrid nanosystem

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yuanyuan; Munro, Catherine J.; Olszta, Matthew J.; Edwards, Danny J.; Braunschweig, Adam B.; Knecht, Marc R.; Browning, Nigel D.

    2016-06-30

    In this work, we showcase that through precise control of the electron dose rate, state-of-the-art large solid angle energy dispersive X-ray spectroscopy (EDS) mapping in aberration-corrected scanning transmission electron microscope (STEM) is capable of faithful and unambiguous chemical characterization of the Pt and Pd distribution in a peptide-mediated nanosystem. This low-dose-rate recording scheme adds another dimension of flexibility to the design of elemental mapping experiments, and holds significant potential for extending its application to a wide variety of beam sensitive hybrid nanostructures.

  11. Monte Carlo design of a system for the detection of explosive materials and analysis of the dose; Diseno Monte Carlo de un sistema para la deteccion de materiales explosivos y analisis de la dosis

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez A, P. L.; Medina C, D.; Rodriguez I, J. L.; Salas L, M. A.; Vega C, H. R., E-mail: pabloyae_2@hotmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico)

    2015-10-15

    The problems associated with insecurity and terrorism have forced to designing systems for detecting nuclear materials, drugs and explosives that are installed on roads, ports and airports. Organic materials are composed of C, H, O and N; similarly the explosive materials are manufactured which can be distinguished by the concentration of these elements. Its elemental composition, particularly the concentration of hydrogen and oxygen, allow distinguish them from other organic substances. When these materials are irradiated with neutrons nuclear reactions (n, γ) are produced, where the emitted photons are ready gamma rays whose energy is characteristic of each element and its abundance allows estimating their concentration. The aim of this study was designed using Monte Carlo methods a system with neutron source, gamma rays detector and moderator able to distinguish the presence of Rdx and urea. In design were used as moderators: paraffin, light water, polyethylene and graphite; as detectors were used HPGe and the NaI(Tl). The design that showed the best performance was the moderator of light water and HPGe, with a source of {sup 241}AmBe. For this design, the values of ambient dose equivalent around the system were calculated. (Author)

  12. Re-evaluation of the dose to the cyst wall in P-32 radiocolloid treatments of cystic brain tumors using the Dose-Point-Kernel and Monte Carlo methods

    International Nuclear Information System (INIS)

    Intracavity instillation of β-emitting colloid pharmaceuticals is a common technique used to treat cystic brain tumors. Most of the dosimetric calculations that have been reported in the literature for this problem are based on empirical formulas derived by Loevinger. Concentration of P-32 radiolabeled solution for the delivery of a prescribed dose (200 Gy to the cyst wall) has been published previously using this formalism in what we refer to as a standard nomogram. The calculations using the Loevinger formulas for calculating the P-32 activity necessary to achieve 200 Gy at the cyst wall is re-evaluated and compared to numerically computed results based on full Monte Carlo simulations (EGSnrc) and the dose-point-kernel (DPK) integration method. For cyst diameters greater than 1 cm, the new calculations agree well with previously published results (the standard nomogram) to within a few percents. However, for cyst diameters of less than 1 cm, it is shown that the standard nomogram results underestimate the therapeutic activity by a factor of ∼3 for very small diameters (∼0.2 cm). New tables based on our calculations are presented and the sources of discrepancies are identified. It is concluded that the new set of data based on our calculations should replace the standard nomogram to administer accurately the target dose to the cyst wall for the smaller diameter cysts (<1 cm)

  13. Monte Carlo-derived TLD cross-calibration factors for treatment verification and measurement of skin dose in accelerated partial breast irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Garnica-Garza, H M [Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional Unidad Monterrey, VIa del Conocimiento 201 Parque de Investigacion e Innovacion Tecnologica, Apodaca NL C.P. 66600 (Mexico)], E-mail: hgarnica@cinvestav.mx

    2009-03-21

    Monte Carlo simulation was employed to calculate the response of TLD-100 chips under irradiation conditions such as those found during accelerated partial breast irradiation with the MammoSite radiation therapy system. The absorbed dose versus radius in the last 0.5 cm of the treated volume was also calculated, employing a resolution of 20 {mu}m, and a function that fits the observed data was determined. Several clinically relevant irradiation conditions were simulated for different combinations of balloon size, balloon-to-surface distance and contents of the contrast solution used to fill the balloon. The thermoluminescent dosemeter (TLD) cross-calibration factors were derived assuming that the calibration of the dosemeters was carried out using a Cobalt 60 beam, and in such a way that they provide a set of parameters that reproduce the function that describes the behavior of the absorbed dose versus radius curve. Such factors may also prove to be useful for those standardized laboratories that provide postal dosimetry services.

  14. Introducing a method to derive a multiple virtual point source model of linac for photon beam dose calculation using Monte Carlo method

    International Nuclear Information System (INIS)

    In this study a new simple but a very effective method is introduced for the beam modeling of the invariant part of a medical linear accelerator. In this method, instead of segmentation of scoring plane and analysis of phase space file, the mirror image of a virtual point source, energy and angular distributions and dependencies between them are derived, directly. Then, the method was used for the beam modeling of a 6 MeV photon beam of the Siemens ONCOR Impression accelerator, where the TALLYX capability of MCNP4C was used. Consequently, a multiple point source model with angular dependent photon energy spectra was obtained. Then, the percentage depth dose curves and the lateral dose distributions in water phantom were calculated using the present model for three field sizes including 4 cm x 4 cm, 10 cm x 10 cm and 40 cm x 40 cm, and the results were compared to those of full Monte Carlo simulations. The results showed excellent agreement between them for all the field sizes. The benefits of the present method were verified as compared with the phase space file analysis method, including the ease of application and the errors removal caused by the spatial segmentation of the phase space data.

  15. Dose rate mapping and quantitative analysis of radioactive deposition with simple monitoring instruments in Finland after the Chernobyl accident

    International Nuclear Information System (INIS)

    This article reviews the Finnish dose-rate mapping equipment and the system to process the obtained results, which were used immediately after the 1986 Chernobyl accident. We present the results of the external gamma-radiation monitoring carried out with simple civil-defence gamma monitoring instruments and compare them with the subsequent deposition mapping performed with research-grade instruments. The analysis shows that the quality of radiation mapping is good enough for decision makers to direct protective measures to the right areas. This review also demonstrates that a simple stationary external gamma radiation monitoring network can be effectively used for early warning in radiation emergency situations. (orig.)

  16. Dose rate mapping and quantitative analysis of radioactive deposition with simple monitoring instruments in Finland after the Chernobyl accident.

    Energy Technology Data Exchange (ETDEWEB)

    Koivukoski, J. [Ministry of the Interior, Rescue Dept., Helsinki (Finland); Paatero, J. [Finnish Meteorological Inst., Helsinki (Finland)], E-mail: janne.koivukoski@intermin.fi

    2013-03-01

    This article reviews the Finnish dose-rate mapping equipment and the system to process the obtained results, which were used immediately after the 1986 Chernobyl accident. We present the results of the external gamma-radiation monitoring carried out with simple civil-defence gamma monitoring instruments and compare them with the subsequent deposition mapping performed with research-grade instruments. The analysis shows that the quality of radiation mapping is good enough for decision makers to direct protective measures to the right areas. This review also demonstrates that a simple stationary external gamma radiation monitoring network can be effectively used for early warning in radiation emergency situations. (orig.)

  17. Dose profile measurement using an imaging plate: Evaluation of filters using Monte Carlo simulation of 4 MV x-rays

    International Nuclear Information System (INIS)

    Computed radiography (CR) is gradually replacing film. The application of CR for two-dimensional profiles and off-axis ratio (OAR) measurement using an imaging plate (IP) in a CR system is currently under discussion. However, a well known problem for IPs in dosimetry is that they use high atomic number (Z) materials, such as Ba, which have an energy dependency in a photon interaction. Although there are some reports that it is possible to compensate for the energy dependency with metal filters, the appropriate thicknesses of these filters and where they should be located have not been investigated. The purpose of this study is to find the most suitable filter for use with an IP as a dosimetric tool. Monte Carlo simulation (Geant4 8.1) was used to determine the filter to minimize the measurement error in OAR measurements of 4 MV x-rays. In this simulation, the material and thickness of the filter and distance between the IP and the filter were varied to determine most suitable filter conditions that gave the best fit to the MC calculated OAR in water. With regard to changing the filter material, we found that using higher Z and higher density material increased the effectiveness of the filter. Also, increasing the distance between the filter and the IP reduced the effectiveness, whereas increasing the thickness of the filter increased the effectiveness. The result of this study showed that the most appropriate filter conditions consistent with the calculated OAR in water were the ones with the IP sandwiched between two 2 mm thick lead filters at a distance of 5 mm from the IP or the IP sandwiched directly between two 1 mm lead filters. Using these filters, we measured the OAR at 10 cm depth with 100 cm source-to-surface distance and surface 10x10 cm2 field size. The results of this measurement represented that it is possible to achieve measurements with less than within 2.0% and 2.0% in the field and with less than 1.1% and 0.6% out of the field by using 2 and 1 mm

  18. Adaptation of penelope Monte Carlo code system to the absorbed dose metrology: characterization of high energy photon beams and calculations of reference dosimeter correction factors; Adaptation du code Monte Carlo penelope pour la metrologie de la dose absorbee: caracterisation des faisceaux de photons X de haute energie et calcul de facteurs de correction de dosimetres de reference

    Energy Technology Data Exchange (ETDEWEB)

    Mazurier, J

    1999-05-28

    This thesis has been performed in the framework of national reference setting-up for absorbed dose in water and high energy photon beam provided with the SATURNE-43 medical accelerator of the BNM-LPRI (acronym for National Bureau of Metrology and Primary standard laboratory of ionising radiation). The aim of this work has been to develop and validate different user codes, based on PENELOPE Monte Carlo code system, to determine the photon beam characteristics and calculate the correction factors of reference dosimeters such as Fricke dosimeters and graphite calorimeter. In the first step, the developed user codes have permitted the influence study of different components constituting the irradiation head. Variance reduction techniques have been used to reduce the calculation time. The phase space has been calculated for 6, 12 and 25 MV at the output surface level of the accelerator head, then used for calculating energy spectra and dose distributions in the reference water phantom. Results obtained have been compared with experimental measurements. The second step has been devoted to develop an user code allowing calculation correction factors associated with both BNM-LPRI's graphite and Fricke dosimeters thanks to a correlated sampling method starting with energy spectra obtained in the first step. Then the calculated correction factors have been compared with experimental and calculated results obtained with the Monte Carlo EGS4 code system. The good agreement, between experimental and calculated results, leads to validate simulations performed with the PENELOPE code system. (author)

  19. Estimation of radiation dose and risk to children undergoing cardiac catheterization for the treatment of a congenital heart disease using Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Yakoumakis, Emmanuel; Kostopoulou, Helen; Dimitriadis, Anastastios; Georgiou, Evaggelos [University of Athens, Medical Physics Department, Medical School, Athens (Greece); Makri, Triantafilia [' Agia Sofia' Hospital, Medical Physics Unit, Athens (Greece); Tsalafoutas, Ioannis [Anticancer-Oncology Hospital of Athens ' Agios Savvas' , Medical Physics Department, Athens (Greece)

    2013-03-15

    Children diagnosed with congenital heart disease often undergo cardiac catheterization for their treatment, which involves the use of ionizing radiation and therefore a risk of radiation-induced cancer. The purpose of this study was to calculate the effective and equivalent organ doses (H{sub T}) in those children and estimate the risk of exposure-induced death. Fifty-three children were divided into three groups: atrial septal defect (ASD), ventricular septal defect (VSD) and patent ductus arteriosus (PDA). In all procedures, the exposure conditions and the dose-area product meters readings were recorded for each individual acquisition. Monte Carlo simulations were run using the PCXMC 2.0 code and mathematical phantoms simulating a child's anatomy. The H{sub T} values to all irradiated organs and the resulting E and risk of exposure-induced death values were calculated. The average dose-area product values were, respectively, 40 {+-} 12 Gy.cm{sup 2} for the ASD, 17.5 {+-} 0.7 Gy.cm{sup 2} for the VSD and 9.5 {+-} 1 Gy.cm{sup 2} for the PDA group. The average E values were 40 {+-} 12, 22 {+-} 2.5 and 17 {+-} 3.6 mSv for ASD, VSD and PDA groups, respectively. The respective estimated risk of exposure-induced death values per procedure were 0.109, 0.106 and 0.067%. Cardiac catheterizations in children involve a considerable risk for radiation-induced cancer that has to be further reduced. (orig.)

  20. A virtual photon source model of an Elekta linear accelerator with integrated mini MLC for Monte Carlo based IMRT dose calculation

    Energy Technology Data Exchange (ETDEWEB)

    Sikora, M [Section for Biomedical Physics, University Hospital for Radiation Oncology, Hoppe-Seyler-Str. 3, 72076 Tuebingen (Germany); Dohm, O [Section for Biomedical Physics, University Hospital for Radiation Oncology, Hoppe-Seyler-Str. 3, 72076 Tuebingen (Germany); Alber, M [Section for Biomedical Physics, University Hospital for Radiation Oncology, Hoppe-Seyler-Str. 3, 72076 Tuebingen (Germany)

    2007-08-07

    A dedicated, efficient Monte Carlo (MC) accelerator head model for intensity modulated stereotactic radiosurgery treatment planning is needed to afford a highly accurate simulation of tiny IMRT fields. A virtual source model (VSM) of a mini multi-leaf collimator (MLC) (the Elekta Beam Modulator (EBM)) is presented, allowing efficient generation of particles even for small fields. The VSM of the EBM is based on a previously published virtual photon energy fluence model (VEF) (Fippel et al 2003 Med. Phys. 30 301) commissioned with large field measurements in air and in water. The original commissioning procedure of the VEF, based on large field measurements only, leads to inaccuracies for small fields. In order to improve the VSM, it was necessary to change the VEF model by developing (1) a method to determine the primary photon source diameter, relevant for output factor calculations (2) a model of the influence of the flattening filter on the secondary photon spectrum and (3) a more realistic primary photon spectrum. The VSM model is used to generate the source phase space data above the mini-MLC. Later the particles are transmitted through the mini-MLC by a passive filter function which significantly speeds up the time of generation of the phase space data after the mini-MLC, used for calculation of the dose distribution in the patient. The improved VSM model was commissioned for 6 and 15 MV beams. The results of MC simulation are in very good agreement with measurements. Less than 2% of local difference between the MC simulation and the diamond detector measurement of the output factors in water was achieved. The X, Y and Z profiles measured in water with an ion chamber (V = 0.125 cm{sup 3}) and a diamond detector were used to validate the models. An overall agreement of 2%/2 mm for high dose regions and 3%/2 mm in low dose regions between measurement and MC simulation for field sizes from 0.8 x 0.8 cm{sup 2} to 16 x 21 cm{sup 2} was achieved. An IMRT plan film

  1. MO-E-17A-03: Monte Carlo CT Dose Calculation: A Comparison Between Experiment and Simulation Using ARCHER-CT

    Energy Technology Data Exchange (ETDEWEB)

    Liu, T; Du, X; Su, L; Gao, Y; Ji, W; Xu, X [Rensselaer Polytechnic Institute, Troy, NY (United States); Zhang, D; Shi, J; Liu, B; Kalra, M [Massachusetts General Hospital, Boston, MA (United States)

    2014-06-15

    Purpose: To compare the CT doses derived from the experiments and GPU-based Monte Carlo (MC) simulations, using a human cadaver and ATOM phantom. Methods: The cadaver of an 88-year old male and the ATOM phantom were scanned by a GE LightSpeed Pro 16 MDCT. For the cadaver study, the Thimble chambers (Model 10×5−0.6CT and 10×6−0.6CT) were used to measure the absorbed dose in different deep and superficial organs. Whole-body scans were first performed to construct a complete image database for MC simulations. Abdomen/pelvis helical scans were then conducted using 120/100 kVps, 300 mAs and a pitch factor of 1.375:1. For the ATOM phantom study, the OSL dosimeters were used and helical scans were performed using 120 kVp and x, y, z tube current modulation (TCM). For the MC simulations, sufficient particles were run in both cases such that the statistical errors of the results by ARCHER-CT were limited to 1%. Results: For the human cadaver scan, the doses to the stomach, liver, colon, left kidney, pancreas and urinary bladder were compared. The difference between experiments and simulations was within 19% for the 120 kVp and 25% for the 100 kVp. For the ATOM phantom scan, the doses to the lung, thyroid, esophagus, heart, stomach, liver, spleen, kidneys and thymus were compared. The difference was 39.2% for the esophagus, and within 16% for all other organs. Conclusion: In this study the experimental and simulated CT doses were compared. Their difference is primarily attributed to the systematic errors of the MC simulations, including the accuracy of the bowtie filter modeling, and the algorithm to generate voxelized phantom from DICOM images. The experimental error is considered small and may arise from the dosimeters. R01 grant (R01EB015478) from National Institute of Biomedical Imaging and Bioengineering.

  2. Mapping of isoexposure curves for evaluation of equivalent environmental doses for radiodiagnostic mobile equipment

    International Nuclear Information System (INIS)

    This paper generates iso exposure curves in areas where the mobile radiodiagnostic equipment are used for evaluation of iso kerma map and the environment equivalent dose (H*(d)). It was used a Shimadzu mobile equipment and two Siemens, with non anthropomorphic scatter. The exposure was measured in a mesh of 4.20 x 4.20 square meter in steps of 30 cm, at half height from the scatterer. The calculation of H*(d) were estimated for a worker present in all the procedures in a period of 11 months, being considered 3.55 m As/examination and 44.5 procedures/month (adult UTI) and 3.16 m As/examination and 20.1 procedure/month (pediatric UTI), and 3.16 m As/examination and 20.1 procedure/month (pediatric UTI). It was observed that there exist points where the H*(d) was over the limit established for the free area inside the radius of 30 cm from the central beam of radiation in the case of pediatric UTI and 60 cm for adult UTI. The points localized 2.1 m from the center presented values lower than 25% of those limit

  3. Monte Carlo-Based Dose Calculation in Postprostatectomy Image-Guided Intensity Modulated Radiotherapy: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Ashley Rankine

    2015-01-01

    Full Text Available Step-and-shoot (S&S intensity-modulated radiotherapy (IMRT using the XiO treatment planning system (TPS has been routinely used for patients receiving postprostatectomy radiotherapy (PPRT. After installing the Monaco, a pilot study was undertaken with five patients to compare XiO with Monaco (V2.03 TPS for PPRT with respect to plan quality for S&S as well as volumetric-modulated arc therapy (VMAT. Monaco S&S showed higher mean clinical target volume (CTV coverage (99.85% than both XiO S&S (97.98%, P = 0.04 and Monaco VMAT (99.44, P = 0.02. Rectal V60Gy volumes were lower for Monaco S&S compared to XiO (46.36% versus 58.06%, P = 0.001 and Monaco VMAT (46.36% versus 54.66%, P = 0.02. Rectal V60Gy volume was lowest for Monaco S&S and superior to XiO (mean 19.89% versus 31.25%, P = 0.02. Rectal V60Gy volumes were lower for Monaco VMAT compared to XiO (21.09% versus 31.25%, P = 0.02. Other organ-at-risk (OAR parameters were comparable between TPSs. Compared to XiO S&S, Monaco S&S plans had fewer segments (78.6 versus 116.8 segments, P = 0.02, lower total monitor units (MU (677.6 MU versus 770.7 MU, P = 0.01, and shorter beam-on times (5.7 min versus 7.6 min, P = 0.03. This pilot study suggests that Monaco S&S improves CTV coverage, OAR doses, and planning and treatment times for PPRT.

  4. A portable secondary dose monitoring system using scintillating fibers for proton therapy of prostate cancer: A Geant4 Monte Carlo simulation study

    Directory of Open Access Journals (Sweden)

    Biniam Tesfamicael

    2016-03-01

    Full Text Available Purpose: The main purpose of this study was to monitor the secondary dose distribution originating from a water phantom during proton therapy of prostate cancer using scintillating fibers.Methods: The Geant4 Monte Carlo toolkit version 9.6.p02 was used to simulate a proton therapy of prostate cancer. Two cases were studied. In the first case, 8 × 8 = 64 equally spaced fibers inside three 4 × 4 × 2.54 cm3 Delrin® blocks were used to monitor the emission of secondary particles in the transverse (left and right and distal regions relative to the beam direction. In the second case, a scintillating block with a thickness of 2.54 cm and equal vertical and longitudinal dimensions as the water phantom was used. Geometrical cuts were implemented to extract the energy deposited in each fiber and inside the scintillating block.Results: The transverse dose distributions from the detected secondary particles in both cases are symmetric and agree to within <3.6%. The energy deposited gradually increases as one moves from the peripheral row of fibers towards the center of the block (aligned with the center of the prostate by a factor of approximately 5. The energy deposited was also observed to decrease as one goes from the frontal to distal region of the block. The ratio of the energy deposited in the prostate to the energy deposited in the middle two rows of fibers showed a linear relationship with a slope of (-3.55±2.26 × 10-5 MeV per treatment Gy delivered. The distal detectors recorded a negligible amount of energy deposited due to higher attenuation of the secondary particles by the water in that direction.Conclusion: With a good calibration and with the ability to define a good correlation between the radiation flux recorded by the external fibers and the dose delivered to the prostate, such fibers can be used for real time dose verification to the target. The system was also observed to respond to the series of Bragg Peaks used to generate the

  5. 蒙特卡洛模拟优化磷霉素的给药方案%Optimization the dosing regimens of fosfomycin by Monte Carlo simulation

    Institute of Scientific and Technical Information of China (English)

    周静超; 张睢扬; 周丁华; 童卫杭[; 迟小华; 王丹

    2014-01-01

    Objective To compare the pharmadynamics of fosfomycin in different dosing regimens to obtain the optimal clinical dosing regimen by Monte carlo simulation.Methods Pharmacokinetic datas of fosfomycin in lung tissue of septic patients were determined by in vivo microdialysis , application software ( Crystal Ball 7.2.2 ) performed Monte Carlo simula-tion of 10 000 patients to calculate the probability of target attainment ( PTA) of different doseing regimens.And combined with maximum drug concentration/minimum inhibitory concentration ( cmax/MIC).Results Of all the dosing regimens , PTA(6 g/q6 h) is best, however, when MIC>20, the PTAPIT(4 g/q6 h)>optimized two-step infusion therapy (OTIT) (6 g/q6 h)>OTIT(4 g/q6 h).When MIC≤16 , the antimicrobial PTA is approximately 100%,while the bactericidal PTA reduces to 66.48%.Conclusion When MIC≤20 , the prolonged infusion therapy of 6 g/6 h is best; while MIC>20 , PTA<50%, with poor clinical results , the best choice was drug combination.%目的:通过蒙特卡洛模拟比较磷霉素不同给药方案的药效学。方法用微透析技术测定磷霉素靶组织的药代动力学数据,用蒙特卡洛软件模拟10000例次的治疗试验,得出不同给药方案的达标概率( PTA),并结合峰浓度与最低抑菌浓度的比值(Cmax/MIC)评价临床效果。结果所有给药方案中,PTA(6 g/q6 h)最佳,但当MIC>20时,其PTA<50%;cmax/MIC≥4的达标概率大小依次为:延长输注法(PIT)(6 g/q6 h)>PIT(4 g/q6 h)>两步输注法(OTIT)(6 g/q6 h)>OTIT(4 g/q6 h);当MIC≤16时,抑菌PTA约为100%,而杀菌PTA最低降至66.48%。结论当MIC≤20时,6 g/q6 h延长输注法最优,当MIC>20时,PTA<50%,临床效果不佳,最好联合用药。

  6. Fluence map optimization (FMO) with dose-volume constraints in IMRT using the geometric distance sorting method

    Science.gov (United States)

    Lan, Yihua; Li, Cunhua; Ren, Haozheng; Zhang, Yong; Min, Zhifang

    2012-10-01

    A new heuristic algorithm based on the so-called geometric distance sorting technique is proposed for solving the fluence map optimization with dose-volume constraints which is one of the most essential tasks for inverse planning in IMRT. The framework of the proposed method is basically an iterative process which begins with a simple linear constrained quadratic optimization model without considering any dose-volume constraints, and then the dose constraints for the voxels violating the dose-volume constraints are gradually added into the quadratic optimization model step by step until all the dose-volume constraints are satisfied. In each iteration step, an interior point method is adopted to solve each new linear constrained quadratic programming. For choosing the proper candidate voxels for the current dose constraint adding, a so-called geometric distance defined in the transformed standard quadratic form of the fluence map optimization model was used to guide the selection of the voxels. The new geometric distance sorting technique can mostly reduce the unexpected increase of the objective function value caused inevitably by the constraint adding. It can be regarded as an upgrading to the traditional dose sorting technique. The geometry explanation for the proposed method is also given and a proposition is proved to support our heuristic idea. In addition, a smart constraint adding/deleting strategy is designed to ensure a stable iteration convergence. The new algorithm is tested on four cases including head-neck, a prostate, a lung and an oropharyngeal, and compared with the algorithm based on the traditional dose sorting technique. Experimental results showed that the proposed method is more suitable for guiding the selection of new constraints than the traditional dose sorting method, especially for the cases whose target regions are in non-convex shapes. It is a more efficient optimization technique to some extent for choosing constraints than the dose

  7. The effect of magnification on the image quality and the radiation dose in X-ray digital mammography: a Monte Carlo simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yu-Na; Kim, Hee-Joung; Park, Hye-Suk; Lee, Chang-Lae; Cho, Hyo-Min; Lee, Seung-Wan; Ryu, Hyun-Ju [Yonsei University, Wonju (Korea, Republic of)

    2010-09-15

    There have been many efforts to advance the technology of X-ray digital mammography in order to enhance the early detection of breast pathology. The purpose of this study was to evaluate image quality and the radiation dose after magnifying X-ray digital mammography using the Geant4 Application for Tomographic Emission (GATE). In this study, we simulated a Monte Carlo model of an X-ray digital mammographic system, and we present a technique for magnification and discuss how it affects the image quality. The simulated X-ray digital mammographic system with GATE consists of an X-ray source, a compression paddle, a supporting plate, and an imaging plate (IP) of computed radiography (CR). The degree of magnification ranged from 1.0 to 2.0. We designed a semi-cylindrical phantom with a thickness of 45-mm and a radius of 50-mm in order to evaluate the image quality after magnification. The phantom was made of poly methyl methacrylate (PMMA) and contained four spherical specks with diameters of 750, 500, 250, and 100-{mu}m to simulate microcalcifications. The simulation studies were performed with an X-ray energy spectrum calculated using the spectrum processor SRS-78. A combination of a molybdenum anode and a molybdenum filter (Mo/Mo) was used for the mammographic X-ray tubes. The effects of the degree of magnification were investigated in terms of both the contrast-to-noise ratio (CNR) and the average glandular dose (AGD). The results show that the CNR increased as the degree of magnification increased and decreased as breast glandularity increased. The AGD showed only a minor increase with magnification. Based on the results, magnification of mammographic images can be used to obtain high image quality with an increased CNR. Our X-ray digital mammographic system model with GATE may be used as a basis for future studies on X-ray imaging characteristics.

  8. Monte Carlo simulation of the dose distribution around the {sup 125}I model 6711 seed as function of radius of the silver cylinder using the Penelope code; Simulacion por el Metodo de Monte Carlo de la distribucion de dosis alrededor de la semilla de {sup 125}I modelo 6711 en funcion del radio del cilindro de plata usando el codigo Penelope

    Energy Technology Data Exchange (ETDEWEB)

    Nerio, U. [Universidad de Cordoba, Monteria (Colombia); Instituto Nacional de Cancerologia, Bogota (Colombia); Chica, L. [Universidad Nacional de Colombia, Bogota (Colombia); Paul, A. [Universite de la Mediterranee, Marseille (France)

    2004-07-01

    The Monte Carlo method is applied to find the dose rates distribution in tissue around {sup 125} I seeds model 6711 as a function of the silver cylinder radius, R{sub sc} (0.017, 0.021, 0.025, 0.029 and 0.033) cm are used as radius values. It is found here that the dose rate at any point within the tissue decreases as R{sub sc} increases. The relative difference of dose rate that produced by the standard R{sub sc} seed, is less than 5%, for seeds with Rsc between 0.017 and 0.033 cm. (author)

  9. Dose calculations in diagnostic radiology ICRP 110 voxelizados dummies by the method of Monte Carlo; Calculo de dosis en radiodiagnostico sobre los maniquies voxelizados ICRP 110 mediante el metodo de Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Salvado, M.; Hernandez-Giron, I.; Morant, J. J.; Casanova, R.; Lopez, M.; Calzada, A.

    2011-07-01

    The optimization of the dose given in radiology scans, one of the three fundamental principles of radiation protection implies sufficiently precise knowledge of the dose distribution in organs with weighting factor for the calculation of effective dose in patients.

  10. Investigation of practical approaches to evaluating cumulative dose for cone beam computed tomography (CBCT) from standard CT dosimetry measurements: a Monte Carlo study

    Science.gov (United States)

    Abuhaimed, Abdullah; Martin, Colin J.; Sankaralingam, Marimuthu; Gentle, David J.

    2015-07-01

    A function called Gx(L) was introduced by the International Commission on Radiation Units and Measurements (ICRU) Report-87 to facilitate measurement of cumulative dose for CT scans within long phantoms as recommended by the American Association of Physicists in Medicine (AAPM) TG-111. The Gx(L) function is equal to the ratio of the cumulative dose at the middle of a CT scan to the volume weighted CTDI (CTDIvol), and was investigated for conventional multi-slice CT scanners operating with a moving table. As the stationary table mode, which is the basis for cone beam CT (CBCT) scans, differs from that used for conventional CT scans, the aim of this study was to investigate the extension of the Gx(L) function to CBCT scans. An On-Board Imager (OBI) system integrated with a TrueBeam linac was simulated with Monte Carlo EGSnrc/BEAMnrc, and the absorbed dose was calculated within PMMA, polyethylene (PE), and water head and body phantoms using EGSnrc/DOSXYZnrc, where the body PE body phantom emulated the ICRU/AAPM phantom. Beams of width 40-500 mm and beam qualities at tube potentials of 80-140 kV were studied. Application of a modified function of beam width (W) termed Gx(W), for which the cumulative dose for CBCT scans f (0) is normalized to the weighted CTDI (CTDIw) for a reference beam of width 40 mm, was investigated as a possible option. However, differences were found in Gx(W) with tube potential, especially for body phantoms, and these were considered to be due to differences in geometry between wide beams used for CBCT scans and those for conventional CT. Therefore, a modified function Gx(W)100 has been proposed, taking the form of values of f (0) at each position in a long phantom, normalized with respect to dose indices f 100(150)x measured with a 100 mm pencil ionization chamber within standard 150 mm PMMA phantoms, using the same scanning parameters, beam widths and positions within the phantom. f 100(150)x averages the dose resulting from

  11. SU-E-J-147: Monte Carlo Study of the Precision and Accuracy of Proton CT Reconstructed Relative Stopping Power Maps

    Energy Technology Data Exchange (ETDEWEB)

    Dedes, G; Asano, Y; Parodi, K [Ludwig Maximilians University Munich, Garching, DE (Germany); Arbor, N [Universite de Strasbourg, Strasbourg (France); Dauvergne, D; Testa, E [Universite Lyon 1, Institut de Physique Nucleaire de Lyon, Lyon (France); Letang, J; Rit, S [Universite Lyon 1, INSA Lyon, CREATIS, Lyon (France)

    2015-06-15

    Purpose: The quantification of the intrinsic performances of proton computed tomography (pCT) as a modality for treatment planning in proton therapy. The performance of an ideal pCT scanner is studied as a function of various parameters. Methods: Using GATE/Geant4, we simulated an ideal pCT scanner and scans of several cylindrical phantoms with various tissue equivalent inserts of different sizes. Insert materials were selected in order to be of clinical relevance. Tomographic images were reconstructed using a filtered backprojection algorithm taking into account the scattering of protons into the phantom. To quantify the performance of the ideal pCT scanner, we study the precision and the accuracy with respect to the theoretical relative stopping power ratios (RSP) values for different beam energies, imaging doses, insert sizes and detector positions. The planning range uncertainty resulting from the reconstructed RSP is also assessed by comparison with the range of the protons in the analytically simulated phantoms. Results: The results indicate that pCT can intrinsically achieve RSP resolution below 1%, for most examined tissues at beam energies below 300 MeV and for imaging doses around 1 mGy. RSP maps accuracy of less than 0.5 % is observed for most tissue types within the studied dose range (0.2–1.5 mGy). Finally, the uncertainty in the proton range due to the accuracy of the reconstructed RSP map is well below 1%. Conclusion: This work explores the intrinsic performance of pCT as an imaging modality for proton treatment planning. The obtained results show that under ideal conditions, 3D RSP maps can be reconstructed with an accuracy better than 1%. Hence, pCT is a promising candidate for reducing the range uncertainties introduced by the use of X-ray CT alongside with a semiempirical calibration to RSP.Supported by the DFG Cluster of Excellence Munich-Centre for Advanced Photonics (MAP)

  12. First dose-map measured with a polycrystalline diamond 2D dosimeter under an intensity modulated radiotherapy beam

    Science.gov (United States)

    Scaringella, M.; Zani, M.; Baldi, A.; Bucciolini, M.; Pace, E.; de Sio, A.; Talamonti, C.; Bruzzi, M.

    2015-10-01

    A prototype of bidimensional dosimeter made on a 2.5×2.5 cm2 active area polycrystalline Chemical Vapour Deposited (pCVD) diamond film, equipped with a matrix of 12×12 contacts connected to the read-out electronics, has been used to evaluate a map of dose under Intensity Modulated Radiation Therapy (IMRT) fields for a possible application in pre-treatment verifications of cancer treatments. Tests have been performed under a 6-10 MVRX beams with IMRT fields for prostate and breast cancer. Measurements have been taken by measuring the 144 pixels in different positions, obtained by shifting the device along the x/y axes to span a total map of 14.4×10 cm2. Results show that absorbed doses measured by our pCVD diamond device are consistent with those calculated by the Treatment Planning System (TPS).

  13. First dose-map measured with a polycrystalline diamond 2D dosimeter under an intensity modulated radiotherapy beam

    Energy Technology Data Exchange (ETDEWEB)

    Scaringella, M., E-mail: scaringella@gmail.com [Università di Firenze, Dipartimento di Ingegneria dell’Informazione, Firenze (Italy); Zani, M. [INFN Sezione di Firenze, Sesto Fiorentino, Firenze (Italy); Università di Firenze, Dipartimento di Scienze Biomediche, Sperimentali e Cliniche, Firenze (Italy); Baldi, A. [Università di Firenze, Dipartimento di Ingegneria Industriale, Firenze (Italy); Bucciolini, M. [INFN Sezione di Firenze, Sesto Fiorentino, Firenze (Italy); Università di Firenze, Dipartimento di Scienze Biomediche, Sperimentali e Cliniche, Firenze (Italy); Pace, E.; Sio, A. de [INFN Sezione di Firenze, Sesto Fiorentino, Firenze (Italy); Università di Firenze, Dipartimento di Fisica e Astronomia, Sesto Fiorentino, Firenze (Italy); Talamonti, C. [INFN Sezione di Firenze, Sesto Fiorentino, Firenze (Italy); Università di Firenze, Dipartimento di Scienze Biomediche, Sperimentali e Cliniche, Firenze (Italy); Bruzzi, M. [INFN Sezione di Firenze, Sesto Fiorentino, Firenze (Italy); Università di Firenze, Dipartimento di Fisica e Astronomia, Sesto Fiorentino, Firenze (Italy)

    2015-10-01

    A prototype of bidimensional dosimeter made on a 2.5×2.5 cm{sup 2} active area polycrystalline Chemical Vapour Deposited (pCVD) diamond film, equipped with a matrix of 12×12 contacts connected to the read-out electronics, has been used to evaluate a map of dose under Intensity Modulated Radiation Therapy (IMRT) fields for a possible application in pre-treatment verifications of cancer treatments. Tests have been performed under a 6–10 MVRX beams with IMRT fields for prostate and breast cancer. Measurements have been taken by measuring the 144 pixels in different positions, obtained by shifting the device along the x/y axes to span a total map of 14.4×10 cm{sup 2}. Results show that absorbed doses measured by our pCVD diamond device are consistent with those calculated by the Treatment Planning System (TPS)

  14. Investigation of the effects of cell model and subcellular location of gold nanoparticles on nuclear dose enhancement factors using Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Zhongli; Chattopadhyay, Niladri; Kwon, Yongkyu Luke [Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario M5S 3M2 (Canada); Pignol, Jean-Philippe [Department of Radiation Oncology, University of Toronto, Toronto, Ontario M4N 3M5, Canada and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N 3M5 (Canada); Lechtman, Eli [Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N 3M5 (Canada); Reilly, Raymond M. [Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario M5S 3M2 (Canada); Department of Medical Imaging, University of Toronto, Toronto, Ontario M5S 3E2 (Canada); Toronto General Research Institute, University Health Network, Toronto, Ontario M5G 2C4 (Canada)

    2013-11-15

    Purpose: The authors’ aims were to model how various factors influence radiation dose enhancement by gold nanoparticles (AuNPs) and to propose a new modeling approach to the dose enhancement factor (DEF).Methods: The authors used Monte Carlo N-particle (MCNP 5) computer code to simulate photon and electron transport in cells. The authors modeled human breast cancer cells as a single cell, a monolayer, or a cluster of cells. Different numbers of 5, 30, or 50 nm AuNPs were placed in the extracellular space, on the cell surface, in the cytoplasm, or in the nucleus. Photon sources examined in the simulation included nine monoenergetic x-rays (10–100 keV), an x-ray beam (100 kVp), and {sup 125}I and {sup 103}Pd brachytherapy seeds. Both nuclear and cellular dose enhancement factors (NDEFs, CDEFs) were calculated. The ability of these metrics to predict the experimental DEF based on the clonogenic survival of MDA-MB-361 human breast cancer cells exposed to AuNPs and x-rays were compared.Results: NDEFs show a strong dependence on photon energies with peaks at 15, 30/40, and 90 keV. Cell model and subcellular location of AuNPs influence the peak position and value of NDEF. NDEFs decrease in the order of AuNPs in the nucleus, cytoplasm, cell membrane, and extracellular space. NDEFs also decrease in the order of AuNPs in a cell cluster, monolayer, and single cell if the photon energy is larger than 20 keV. NDEFs depend linearly on the number of AuNPs per cell. Similar trends were observed for CDEFs. NDEFs using the monolayer cell model were more predictive than either single cell or cluster cell models of the DEFs experimentally derived from the clonogenic survival of cells cultured as a monolayer. The amount of AuNPs required to double the prescribed dose in terms of mg Au/g tissue decreases as the size of AuNPs increases, especially when AuNPs are in the nucleus and the cytoplasm. For 40 keV x-rays and a cluster of cells, to double the prescribed x-ray dose (NDEF = 2

  15. Particle induced X-ray emission and ion dose distribution in a biological micro-beam: Geant4 Monte Carlo simulations

    International Nuclear Information System (INIS)

    The goal of a microbeam is to deliver a highly localized and small dose to the biological medium. This can be achieved by using a set of collimators that confine the charged particle beam to a very small spatial area of the order of microns in diameter. By using a system that combines an appropriate beam detection method that signals to a beam shut-down mechanism, a predetermined and counted number of energetic particles can be delivered to targeted biological cells. Since the shutter and the collimators block a significant proportion of the beam, there is a probability of the production of low energy X-rays and secondary electrons through interactions with the beam. There is little information in the biological microbeam literature on potential X-ray production. We therefore used Monte Carlo simulations to investigate the potential production of particle-induced X-rays and secondary electrons in the collimation system (which is predominantly made of tungsten) and the subsequent possible effects on the total absorbed dose delivered to the biological medium. We found, through the simulation, no evidence of the escape of X-rays or secondary electrons from the collimation system for proton energies up to 3 MeV as we found that the thickness of the collimators is sufficient to reabsorb all of the generated low energy X-rays and secondary electrons. However, if the proton energy exceeds 3 MeV our simulations suggest that 10 keV X-rays can escape the collimator and expose the overlying layer of cells and medium. If the proton energy is further increased to 4.5 MeV or beyond, the collimator can become a significant source of 10 keV and 59 keV X-rays. These additional radiation fields could have effects on cells and these results should be verified through experimental measurement. We suggest that researchers using biological microbeams at higher energies need to be aware that cells may be exposed to a mixed LET radiation field and be careful in their interpretation of

  16. TU-A-19A-01: Image Registration I: Deformable Image Registration, Contour Propagation and Dose Mapping: 101 and 201

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, M [The University of Michigan, Ann Arbor, MI (United States)

    2014-06-15

    Deformable image registration, contour propagation and dose mapping have become common, possibly essential tools for modern image-guided radiation therapy. Historically, these tools have been largely developed at academic medical centers and used in a rather limited and well controlled fashion. Today these tools are now available to the radiotherapy community at large, both as stand-alone applications and as integrated components of both treatment planning and treatment delivery systems. Unfortunately, the details of how these tools work and their limitations are not generally documented or described by the vendors that provide them. Although “it looks right”, determining that unphysical deformations may have occurred is crucial. Because of this, understanding how and when to use, and not use these tools to support everyday clinical decisions is far from straight forward. The goal of this session will be to present both the theory (basic and advanced) and practical clinical use of deformable image registration, contour propagation and dose mapping. To the extent possible, the “secret sauce” that different vendor use to produce reasonable/acceptable results will be described. A detailed explanation of the possible sources of errors and actual examples of these will be presented. Knowing the underlying principles of the process and understanding the confounding factors will help the practicing medical physicist be better able to make decisions (about making decisions) using these tools available. Learning Objectives: Understand the basic (101) and advanced (201) principles of deformable image registration, contour propagation and dose mapping data mapping. Understand the sources and impact of errors in registration and data mapping and the methods for evaluating the performance of these tools. Understand the clinical use and value of these tools, especially when used as a “black box”.

  17. A high spatial resolution outdoor dose rate map of the Rio de Janeiro city, Brasil, risk assessment and urbanization effects

    International Nuclear Information System (INIS)

    Geophysical surveys have been widely used for geological mapping, and with appropriate ground calibration the database can be converted to radiometric surveys. Herein we present a case study of a high resolution map of the City of Rio de Janeiro, Brazil, constructed by integrating aerial and in situ (ground) measurements. This allowed assessing the influence of urbanization observed between 1978 and 2009 on radiation external exposure. Radiometric, geological and demographics databases were integrated in a Geographic Information System (GIS) facility. The average absorbed dose rate recorded for the city was 96 ± 0.3 nGy h−1 and ranged from 22 to 152 nGy h−1 among districts. The corresponding annual effective dose was determined as 0.09 ± 0.01 mSv. The number of people at risk per year according to the estimated natural radiation levels was 17 ± 1.4, among the 28,000 new cases estimated by the INCA (Brazilian National Cancer Institute) within a population of approximately 6.3 million people. -- Highlights: • A radiometric high resolution map of the city of Rio de Janeiro was constructed. • Geographic Information System was utilized to integrate diverse databases. • The average absorbed dose rate for the city verified was 96 nGy h−1. • The number of people at risk annually due to radiation was defined in 17

  18. SU-E-T-289: Scintillating Fiber Based In-Vivo Dose Monitoring System to the Rectum in Proton Therapy of Prostate Cancer: A Geant4 Monte Carlo Simulation

    International Nuclear Information System (INIS)

    Purpose: To construct a dose monitoring system based on an endorectal balloon coupled to thin scintillating fibers to study the dose delivered to the rectum during prostate cancer proton therapy Methods: The Geant4 Monte Carlo toolkit version 9.6p02 was used to simulate prostate cancer proton therapy treatments of an endorectal balloon (for immobilization of a 2.9 cm diameter prostate gland) and a set of 34 scintillating fibers symmetrically placed around the balloon and perpendicular to the proton beam direction (for dosimetry measurements) Results: A linear response of the fibers to the dose delivered was observed within <2%, a property that makes them good candidates for real time dosimetry. Results obtained show that the closest fiber recorded about 1/3 of the dose to the target with a 1/r2 decrease in the dose distribution as one goes toward the frontal and distal top fibers. Very low dose was recorded by the bottom fibers (about 45 times comparatively), which is a clear indication that the overall volume of the rectal wall that is exposed to a higher dose is relatively minimized. Further analysis indicated a simple scaling relationship between the dose to the prostate and the dose to the top fibers (a linear fit gave a slope of −0.07±0.07 MeV per treatment Gy) Conclusion: Thin (1 mm × 1 mm × 100 cm) long scintillating fibers were found to be ideal for real time in-vivo dose measurement to the rectum for prostate cancer proton therapy. The linear response of the fibers to the dose delivered makes them good candidates of dosimeters. With thorough calibration and the ability to define a good correlation between the dose to the target and the dose to the fibers, such dosimeters can be used for real time dose verification to the target

  19. Aeolus: A Markov--Chain Monte Carlo code for mapping ultracool atmospheres. An application on Jupiter and brown dwarf HST light curves

    CERN Document Server

    Karalidi, Theodora; Schneider, Glenn; Hanson, Jake R; Pasachoff, Jay M

    2015-01-01

    Deducing the cloud cover and its temporal evolution from the observed planetary spectra and phase curves can give us major insight into the atmospheric dynamics. In this paper, we present Aeolus, a Markov-Chain Monte Carlo code that maps the structure of brown dwarf and other ultracool atmospheres. We validated Aeolus on a set of unique Jupiter Hubble Space Telescope (HST) light curves. Aeolus accurately retrieves the properties of the major features of the jovian atmosphere such as the Great Red Spot and a major 5um hot spot. Aeolus is the first mapping code validated on actual observations of a giant planet over a full rotational period. For this study, we applied Aeolus to J and H-bands HST light curves of 2MASSJ21392676+0220226 and 2MASSJ0136565+093347. Aeolus retrieves three spots at the top-of-the-atmosphere (per observational wavelength) of these two brown dwarfs, with a surface coverage of 21+-3% and 20.3+-1.5% respectively. The Jupiter HST light curves will be publicly available via ADS/VIZIR.

  20. TH-C-12A-08: New Compact 10 MV S-Band Linear Accelerator: 3D Finite-Element Design and Monte Carlo Dose Simulations

    International Nuclear Information System (INIS)

    Purpose: To design a new compact S-band linac waveguide capable of producing a 10 MV x-ray beam, while maintaining the length (27.5 cm) of current 6 MV waveguides. This will allow higher x-ray energies to be used in our linac-MRI systems with the same footprint. Methods: Finite element software COMSOL Multiphysics was used to design an accelerator cavity matching one published in an experiment breakdown study, to ensure that our modeled cavities do not exceed the threshold electric fields published. This cavity was used as the basis for designing an accelerator waveguide, where each cavity of the full waveguide was tuned to resonate at 2.997 GHz by adjusting the cavity diameter. The RF field solution within the waveguide was calculated, and together with an electron-gun phase space generated using Opera3D/SCALA, were input into electron tracking software PARMELA to compute the electron phase space striking the x-ray target. This target phase space was then used in BEAM Monte Carlo simulations to generate percent depth doses curves for this new linac, which were then used to re-optimize the waveguide geometry. Results: The shunt impedance, Q-factor, and peak-to-mean electric field ratio were matched to those published for the breakdown study to within 0.1% error. After tuning the full waveguide, the peak surface fields are calculated to be 207 MV/m, 13% below the breakdown threshold, and a d-max depth of 2.42 cm, a D10/20 value of 1.59, compared to 2.45 cm and 1.59, respectively, for the simulated Varian 10 MV linac and brehmsstrahlung production efficiency 20% lower than a simulated Varian 10 MV linac. Conclusion: This work demonstrates the design of a functional 27.5 cm waveguide producing 10 MV photons with characteristics similar to a Varian 10 MV linac

  1. An atlas of selected beta-ray spectra and depth-dose distributions in lithium fluoride and soft tissue generated by a fast Monte-Carlo-based sampling method

    Science.gov (United States)

    Samei, Ehsan; Kearfott, Kimberlee J.; Gillespie, Timothy J.; Chris Wang, C.-K.

    1996-12-01

    A method to generate depth-dose distributions due to beta radiation in LiF and soft tissue is proposed. In this method, the EGS4 Monte Carlo radiation transport code is initially used to generate a library of monoenergetic electron depth-dose distributions in the material for electron energies in the range of 10 keV to 5 MeV in 10 keV increments. A polynomial least-squares fit is applied to each distribution. In addition, a theoretical model is developed to generate beta-ray energy spectra of selected radionuclides. A standard Monte Carlo random sampling technique is then employed to sample the spectra and generate the depth-dose distributions in LiF and soft tissue. The proposed method has an advantage over more traditional methods in that the actual radiation transport in the media is performed only once for a set of monoenergetic cases and the beta depth-dose distributions are easily generated by sampling this previously-acquired database in a matter of minutes. This method therefore reduces the demand on computer resources and time. The method can be used to calculate depth-dose distribution due to any beta-emitting nuclide or combination of nuclides with up to ten beta components.

  2. Radiation dose rate map interpolation in nuclear plants using neural networks and virtual reality techniques

    International Nuclear Information System (INIS)

    This paper reports the most recent development results of a simulation tool for assessment of radiation dose exposition by nuclear plant's personnel, using artificial intelligence and virtual reality technologies. The main purpose of this tool is to support training of nuclear plants' personnel, to optimize working tasks for minimisation of received dose. A finer grid of measurement points was considered within the nuclear plant's room, for different power operating conditions. Further, an intelligent system was developed, based on neural networks, to interpolate dose rate values among measured points. The intelligent dose prediction system is thus able to improve the simulation of dose received by personnel. This work describes the improvements implemented in this simulation tool.

  3. SU-E-T-566: Neutron Dose Cloud Map for Compact ProteusONE Proton Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Syh, J; Patel, B; Syh, J; Rosen, L; Wu, H [Willis-Knighton Medical Center, Shreveport, LA (United States)

    2015-06-15

    Purpose: To establish the base line of neutron cloud during patient treatment in our new compact Proteus One proton pencil beam scanning (PBS) system with various beam delivery gantry angles, with or without range shifter (RS) at different body sites. Pencil beam scanning is an emerging treatment technique, for the concerns of neutron exposure, this study is to evaluate the neutron dose equivalent per given delivered dose under various treatment conditions at our proton therapy center. Methods: A wide energy neutron dose equivalent detector (SWENDI-II, Thermo Scientific, MA) was used for neutron dose measurements. It was conducted in the proton therapy vault during beam was on. The measurement location was specifically marked in order to obtain the equivalent dose of neutron activities (H). The distances of 100, 150 and 200 cm at various locations are from the patient isocenter. The neutron dose was measured of proton energy layers, # of spots, maximal energy range, modulation width, field radius, gantry angle, snout position and delivered dose in CGE. The neutron dose cloud is reproducible and is useful for the future reference. Results: When distance increased the neutron equivalent dose (H) reading did not decrease rapidly with changes of proton energy range, modulation width or spot layers. For cranial cases, the average mSv/CGE was about 0.02 versus 0.032 for pelvis cases. RS will induce higher H to be 0.10 mSv/CGE in average. Conclusion: From this study, neutron per dose ratio (mSv/CGE) slightly depends upon various treatment parameters for pencil beams. For similar treatment conditions, our measurement demonstrates this value for pencil beam scanning beam has lowest than uniform scanning or passive scattering beam with a factor of 5. This factor will be monitored continuously for other upcoming treatment parameters in our facility.

  4. Calculation of absorbed doses in sphere volumes around the Mammosite using the Monte Carlo simulation code MCNPX; Calculo de dosis absorbida en volumenes esfericos alrededor del Mammosite utilizando el codigo de simulacion Monte Carlo MCNPX

    Energy Technology Data Exchange (ETDEWEB)

    Rojas C, E. L. [ININ, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico)

    2008-07-01

    The objective of this study is to investigate the changes observed in the absorbed doses in mammary gland tissue when irradiated with a equipment of high dose rate known as Mammosite and introducing material resources contrary to the tissue that constitutes the mammary gland. The modeling study is performed with the code MCNPX, 2005 version, the equipment and the mammary gland and calculating the absorbed doses in tissue when introduced small volumes of air or calcium in the system. (Author)

  5. Improved-resolution real-time skin-dose mapping for interventional fluoroscopic procedures

    Science.gov (United States)

    Rana, Vijay K.; Rudin, Stephen; Bednarek, Daniel R.

    2014-03-01

    We have developed a dose-tracking system (DTS) that provides a real-time display of the skin-dose distribution on a 3D patient graphic during fluoroscopic procedures. Radiation dose to individual points on the skin is calculated using exposure and geometry parameters from the digital bus on a Toshiba C-arm unit. To accurately define the distribution of dose, it is necessary to use a high-resolution patient graphic consisting of a large number of elements. In the original DTS version, the patient graphics were obtained from a library of population body scans which consisted of larger-sized triangular elements resulting in poor congruence between the graphic points and the x-ray beam boundary. To improve the resolution without impacting real-time performance, the number of calculations must be reduced and so we created software-designed human models and modified the DTS to read the graphic as a list of vertices of the triangular elements such that common vertices of adjacent triangles are listed once. Dose is calculated for each vertex point once instead of the number of times that a given vertex appears in multiple triangles. By reformatting the graphic file, we were able to subdivide the triangular elements by a factor of 64 times with an increase in the file size of only 1.3 times. This allows a much greater number of smaller triangular elements and improves resolution of the patient graphic without compromising the real-time performance of the DTS and also gives a smoother graphic display for better visualization of the dose distribution.

  6. Spatial map dose of nuclear medicine service of the Clinical Hospital of Botucatu, SP, Brazil

    International Nuclear Information System (INIS)

    This study was conducted to describe levels of occupational and environmental exposure of the Nuclear Medicine Service of the Clinical Hospital of Botucatu. To this end, measurements were made of the radiometric levels of points strategically defined, in all the environments, for a period of six months, sampling different days and times, during operation normal routine of the sector. The results allow to estimate the expected dose for each environment, comparing them to the dose limitation established by the National Commission of Nuclear Energy (CNEN), allowing better targeting of occupationally exposed individuals, indicating the points where the occupation should be the minimum required, enabling the reduction of risks to potential exposures. (author)

  7. Calculation Monte Carlo equivalent dose to organs in a treatment of prostate with Brachytherapy of high rate; Calculo Monte Carlo de dosis equivalente a organos en un tratamiento de prostata con braquiterapia de alta tasa

    Energy Technology Data Exchange (ETDEWEB)

    Candela-Juan, C.; Vijande, J.; Granero, D.; Ballester, F.; Perez-Calatayud, J.; Rivard, M. J.

    2013-07-01

    The objective of this study was to obtain equivalent dose to radiosensitive organs when applies brachytherapy high dose (HDR) with sources of 60 Co or 192 Go to a localized carcinoma of the prostate. The results are compared with those reported in the literature on treatment with protons and intensity modulated (IMRT) radiation therapy. (Author)

  8. Does the fluence map editing in electronic tissue compensator improve dose homogeneity in bilateral field plan of head and neck patients?

    Directory of Open Access Journals (Sweden)

    Kinhikar Rajesh

    2008-01-01

    Full Text Available The purpose of this study was to evaluate the effect of fluence map editing in electronic tissue compensator (ETC on the dose homogeneity for head and neck cancer patients. Treatment planning using 6-MV X-rays and bilateral field arrangement employing ETC was carried out on the computed tomography (CT datasets of 20 patients with head and neck cancer. All the patients were planned in Varian Eclipse three-dimensional treatment planning system (3DTPS with dynamic multileaf collimator (DMLC. The treatment plans, with and without fluence editing, was compared and the effect of pre-editing and post-editing the fluence maps in the treatment field was evaluated. The skin dose was measured with thermoluminescent dosimeters (TLDs and was compared with the skin dose estimated by TPS. The mean percentage volume of the tissue receiving at least 107% of the prescription dose was 5.4 (range 1.5-10; SD 2.4. Post-editing fluence map showed that the mean percentage volume of the tissue receiving at least 107% of the prescription dose was 0.47 (range 0.1-0.9; SD 0.3. The mean skin dose measured with TLD was found to be 74% (range 71-80% of the prescribed dose while the TPS showed the mean skin dose as 85% (range 80-90%. The TPS overestimated the skin dose by 11%. Fluence map editing thus proved to be a potential tool for improving dose homogeneity in head and neck cancer patients planned with ETC, thus reducing the hot spots in the treatment region as well. The treatment with ETC is feasible with DMLC and does not take any additional time for setup or delivery. The method used to edit the fluence maps is simple and time efficient. Manual control over a plan is essential to create the best treatment plan possible.

  9. Application of the measurement-based Monte Carlo method in nasopharyngeal cancer patients for intensity modulated radiation therapy

    International Nuclear Information System (INIS)

    This study aims to utilize a measurement-based Monte Carlo (MBMC) method to evaluate the accuracy of dose distributions calculated using the Eclipse radiotherapy treatment planning system (TPS) based on the anisotropic analytical algorithm. Dose distributions were calculated for the nasopharyngeal carcinoma (NPC) patients treated with the intensity modulated radiotherapy (IMRT). Ten NPC IMRT plans were evaluated by comparing their dose distributions with those obtained from the in-house MBMC programs for the same CT images and beam geometry. To reconstruct the fluence distribution of the IMRT field, an efficiency map was obtained by dividing the energy fluence of the intensity modulated field by that of the open field, both acquired from an aS1000 electronic portal imaging device. The integrated image of the non-gated mode was used to acquire the full dose distribution delivered during the IMRT treatment. This efficiency map redistributed the particle weightings of the open field phase-space file for IMRT applications. Dose differences were observed in the tumor and air cavity boundary. The mean difference between MBMC and TPS in terms of the planning target volume coverage was 0.6% (range: 0.0–2.3%). The mean difference for the conformity index was 0.01 (range: 0.0–0.01). In conclusion, the MBMC method serves as an independent IMRT dose verification tool in a clinical setting. - Highlights: ► The patient-based Monte Carlo method serves as a reference standard to verify IMRT doses. ► 3D Dose distributions for NPC patients have been verified by the Monte Carlo method. ► Doses predicted by the Monte Carlo method matched closely with those by the TPS. ► The Monte Carlo method predicted a higher mean dose to the middle ears than the TPS. ► Critical organ doses should be confirmed to avoid overdose to normal organs

  10. Comparison of two accelerators for Monte Carlo radiation transport calculations, Nvidia Tesla M2090 GPU and Intel Xeon Phi 5110p coprocessor: A case study for X-ray CT imaging dose calculation

    International Nuclear Information System (INIS)

    Highlights: • A new Monte Carlo photon transport code ARCHER-CT for CT dose calculations is developed to execute on the GPU and coprocessor. • ARCHER-CT is verified against MCNP. • The GPU code on an Nvidia M2090 GPU is 5.15–5.81 times faster than the parallel CPU code on an Intel X5650 6-core CPU. • The coprocessor code on an Intel Xeon Phi 5110p coprocessor is 3.30–3.38 times faster than the CPU code. - Abstract: Hardware accelerators are currently becoming increasingly important in boosting high performance computing systems. In this study, we tested the performance of two accelerator models, Nvidia Tesla M2090 GPU and Intel Xeon Phi 5110p coprocessor, using a new Monte Carlo photon transport package called ARCHER-CT we have developed for fast CT imaging dose calculation. The package contains three components, ARCHER-CTCPU, ARCHER-CTGPU and ARCHER-CTCOP designed to be run on the multi-core CPU, GPU and coprocessor architectures respectively. A detailed GE LightSpeed Multi-Detector Computed Tomography (MDCT) scanner model and a family of voxel patient phantoms are included in the code to calculate absorbed dose to radiosensitive organs under user-specified scan protocols. The results from ARCHER agree well with those from the production code Monte Carlo N-Particle eXtended (MCNPX). It is found that all the code components are significantly faster than the parallel MCNPX run on 12 MPI processes, and that the GPU and coprocessor codes are 5.15–5.81 and 3.30–3.38 times faster than the parallel ARCHER-CTCPU, respectively. The M2090 GPU performs better than the 5110p coprocessor in our specific test. Besides, the heterogeneous computation mode in which the CPU and the hardware accelerator work concurrently can increase the overall performance by 13–18%

  11. Characterization by Monte Carlo of the dose after a glass shield lead for gamma ray; Caracterizacion por Monte Carlo de la dosis tras un blindaje de vidrio de plomo para rayos gamma

    Energy Technology Data Exchange (ETDEWEB)

    Esteve Sanchez, S.; Gil Conde, M.; Contreras Gonzalez, J. L.; Rosado, J.; Pazyi, V.

    2013-07-01

    When a gamma-ray beam crosses the border between two media characterized by atomic number very different is they produce effects on the distribution of doses near the border difficult to predict with simple models. The case of rays gamma affecting a lead glass is particularly interesting for its application to shielding of common use. interested in studying the importance of the residual dose after the shield. (Author)

  12. Dose Calculations for Lung Inhomogeneity in High-Energy Photon Beams and Small Beamlets: A Comparison between XiO and TiGRT Treatment Planning Systems and MCNPX Monte Carlo Code

    Directory of Open Access Journals (Sweden)

    Asghar Mesbahi

    2015-09-01

    Full Text Available Introduction Radiotherapy with small fields is used widely in newly developed techniques. Additionally, dose calculation accuracy of treatment planning systems in small fields plays a crucial role in treatment outcome. In the present study, dose calculation accuracy of two commercial treatment planning systems was evaluated against Monte Carlo method. Materials and Methods Siemens Once or linear accelerator was simulated, using MCNPX Monte Carlo code, according to manufacturer’s instructions. Three analytical algorithms for dose calculation including full scatter convolution (FSC in TiGRT, along with convolution and superposition in XiO system were evaluated for a small solid liver tumor. This solid tumor with a diameter of 1.8 cm was evaluated in a thorax phantom, and calculations were performed for different field sizes (1×1, 2×2, 3×3 and4×4 cm2. The results obtained in these treatment planning systems were compared with calculations by MC method (regarded as the most reliable method. Results For FSC and convolution algorithm, comparison with MC calculations indicated dose overestimations of up to 120%and 25% inside the lung and tumor, respectively in 1×1 cm2field size, using an 18 MV photon beam. Regarding superposition, a close agreement was seen with MC simulation in all studied field sizes. Conclusion The obtained results showed that FSC and convolution algorithm significantly overestimated doses of the lung and solid tumor; therefore, significant errors could arise in treatment plans of lung region, thus affecting the treatment outcomes. Therefore, use of MC-based methods and super position is recommended for lung treatments, using small fields and beamlets.

  13. Commissioning and Implementation of an EPID Based IMRT QA System "Dosimetry Check" for 3D Absolute Dose Measurements and Quantitative Comparisons to MapCheck

    Science.gov (United States)

    Patel, Jalpa A.

    The software package "Dosimetry Check" by MathResolutions, LLC, provides an absolute 3D volumetric dose measurement for IMRT QA using the existing Electronic Portal Imaging Device (EPID) mounted on most linear accelerators. This package provides a feedback loop using the patient's treatment planning CT data as the phantom for dose reconstruction. The aim of this work is to study the difference between point, planar and volumetric doses with MapCheck and Dosimetry Check via the use of the EPID and the diode array respectively. Evaluating tools such as point doses at isocenter, 1-D profiles, gamma volume histograms, and dose volume histograms are used for IMRT dose comparison in three types of cases: head and neck, prostate, and lung. Dosimetry Check can be a valuable tool for IMRT QA as it uses patient specific attenuation corrections and the superiority of the EPID as compared to the MapCheck diode array. This helps reduce the uncertainty in dose for less variability in delivery and a more realistic measured vs computed dose verification system as compared to MapCheck.

  14. Improving anatomical mapping of complexly deformed anatomy for external beam radiotherapy and brachytherapy dose accumulation in cervical cancer

    Energy Technology Data Exchange (ETDEWEB)

    Vásquez Osorio, Eliana M., E-mail: e.vasquezosorio@erasmusmc.nl; Kolkman-Deurloo, Inger-Karine K.; Schuring-Pereira, Monica; Zolnay, András; Heijmen, Ben J. M.; Hoogeman, Mischa S. [Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam 3075 (Netherlands)

    2015-01-15

    Purpose: In the treatment of cervical cancer, large anatomical deformations, caused by, e.g., tumor shrinkage, bladder and rectum filling changes, organ sliding, and the presence of the brachytherapy (BT) applicator, prohibit the accumulation of external beam radiotherapy (EBRT) and BT dose distributions. This work proposes a structure-wise registration with vector field integration (SW+VF) to map the largely deformed anatomies between EBRT and BT, paving the way for 3D dose accumulation between EBRT and BT. Methods: T2w-MRIs acquired before EBRT and as a part of the MRI-guided BT procedure for 12 cervical cancer patients, along with the manual delineations of the bladder, cervix-uterus, and rectum-sigmoid, were used for this study. A rigid transformation was used to align the bony anatomy in the MRIs. The proposed SW+VF method starts by automatically segmenting features in the area surrounding the delineated organs. Then, each organ and feature pair is registered independently using a feature-based nonrigid registration algorithm developed in-house. Additionally, a background transformation is calculated to account for areas far from all organs and features. In order to obtain one transformation that can be used for dose accumulation, the organ-based, feature-based, and the background transformations are combined into one vector field using a weighted sum, where the contribution of each transformation can be directly controlled by its extent of influence (scope size). The optimal scope sizes for organ-based and feature-based transformations were found by an exhaustive analysis. The anatomical correctness of the mapping was independently validated by measuring the residual distances after transformation for delineated structures inside the cervix-uterus (inner anatomical correctness), and for anatomical landmarks outside the organs in the surrounding region (outer anatomical correctness). The results of the proposed method were compared with the results of the

  15. Improving anatomical mapping of complexly deformed anatomy for external beam radiotherapy and brachytherapy dose accumulation in cervical cancer

    International Nuclear Information System (INIS)

    Purpose: In the treatment of cervical cancer, large anatomical deformations, caused by, e.g., tumor shrinkage, bladder and rectum filling changes, organ sliding, and the presence of the brachytherapy (BT) applicator, prohibit the accumulation of external beam radiotherapy (EBRT) and BT dose distributions. This work proposes a structure-wise registration with vector field integration (SW+VF) to map the largely deformed anatomies between EBRT and BT, paving the way for 3D dose accumulation between EBRT and BT. Methods: T2w-MRIs acquired before EBRT and as a part of the MRI-guided BT procedure for 12 cervical cancer patients, along with the manual delineations of the bladder, cervix-uterus, and rectum-sigmoid, were used for this study. A rigid transformation was used to align the bony anatomy in the MRIs. The proposed SW+VF method starts by automatically segmenting features in the area surrounding the delineated organs. Then, each organ and feature pair is registered independently using a feature-based nonrigid registration algorithm developed in-house. Additionally, a background transformation is calculated to account for areas far from all organs and features. In order to obtain one transformation that can be used for dose accumulation, the organ-based, feature-based, and the background transformations are combined into one vector field using a weighted sum, where the contribution of each transformation can be directly controlled by its extent of influence (scope size). The optimal scope sizes for organ-based and feature-based transformations were found by an exhaustive analysis. The anatomical correctness of the mapping was independently validated by measuring the residual distances after transformation for delineated structures inside the cervix-uterus (inner anatomical correctness), and for anatomical landmarks outside the organs in the surrounding region (outer anatomical correctness). The results of the proposed method were compared with the results of the

  16. Dose Optimization of IORT Model for Breast Cancer Based on Monte Carlo Algorithm%基于蒙卡算法的乳腺癌术中放疗模型的剂量学优化

    Institute of Scientific and Technical Information of China (English)

    杨波; 孔旭东; 魏贤顶; 孟东; 陈建江

    2014-01-01

    目的:探讨蒙特卡罗算法在乳腺癌术中放疗(IORT)模型剂量学优化中的应用价值。方法采用MCTP的MCBEAM程序建立乳腺癌术中放疗模型,利用MCSIM程序对患者术前CT模拟术中影像模型进行剂量计算,分析其剂量学特点,并对靶区剂量进行优化。结果通过蒙卡计算,优化的乳腺癌术中放疗模型方案为:靶区表面添加2~3 mm等效材料,靶区后缘添加5 mm等效材料再加2 mm铅板,这可以使90%以上等剂量线包绕整个靶区,同时可以消除>110%的热点区域,肺最大剂量<1 Gy。结论蒙特卡罗算法在乳腺癌IORT模型剂量学优化中的应用能显著提高IORT靶区剂量的计算精度,优化剂量分布,值得临床推广。%ObjectiveToexplorethevalueofMonteCarloalgorithminthedoseoptimizationofIORTmodel forbreastcancer. MethodsTheIORTmodelforbreastcancerwasestablishedwithMCTPMCBEAM program. Then the dose calculation of the intraoperative image simulated by CT was conducted with MCBEAM program to analyze the dosimetric characteristics and optimize the target dose. ResuIts Based on Monte Carlo calculation, the optimization scheme of IORT model for breast cancer was designed as the follow:adding 2~3mmequivalentmaterialonthetargetsurfaceandadding 5mmequivalentmaterialand 2mm leadplateonthetrailingedgeofthetarget.Thustheentiretargetregioncanbesurroundedbymorethan 90%isodoselineandmorethan 110%hotregioncanbeeliminatedwhilethemaxiumdoseofthelungislessthan 1 Gy. ConcIusion The application of Monte Carlo algorithm in the dose optimization of IORT model for breast cancer can significantly improve the calculation precision of the target dose and optimize the dose distribution, which indicates that Monte Carlo algorithm is worth to be promoted in clinic.

  17. Determination of the relationship between dose deposition and Cerenkov photons in homogeneous and heterogeneous phantoms during radiotherapy using Monte Carlo method

    International Nuclear Information System (INIS)

    To explore the response relationship between Cerenkov photons and dose deposition, which is the theoretical premise of dose measurement based on Cerenkov effect, Geant4 was used to simulate the process of homogeneous and heterogeneous phantoms irradiated with monoenergetic or clinical beam energy spectrum. Results showed certain response relationship between Cerenkov photons and dose deposition regardless of the phantom used under different irradiation conditions. However, deviation observed in the axial distribution of dose deposition as characterized by Cerenkov photons was larger under electron beam than under photon beam. (author)

  18. Effect of iodine contrast agent concentration on cerebrovascular dose for synchrotron radiation microangiography based on a simple mouse head model and a voxel mouse head phantom by Monte Carlo simulation.

    Science.gov (United States)

    Lin, Hui; Jing, Jia; Lu, Yi-Fan; Xie, Cong; Lin, Xiao-Jie; Yang, Guo-Yuan

    2016-01-01

    Effective setting strategies using Monte Carlo simulation are presented to mitigate the irradiation damage in synchrotron radiation microangiography (SRA). A one-dimensional mouse head model and a segmented voxel phantom mouse head were simulated using the EGSnrc/DOSXYZnrc code to investigate the dose enhancement effect of an iodine contrast agent irradiated by a monochromatic synchrotron radiation source. The influence of the iodine concentration, vessel width and depth, protection with and without the skull layer, and various incident X-ray energies were all simulated. The dose enhancement effect and the absolute dose based on the segmented voxel mouse head phantom were evaluated. The dose enhancement ratio depended little on the irradiation depth, but strongly and linearly increasing on iodine concentration. The protection given by the skull layer cannot be ignored in SRA because a 700 µm-thick skull can decrease the dose by 10%. The incident X-ray energy can affect the dose significantly. Compared with a dose of 33.2 keV for 50 mgI ml(-1), a dose of 32.7 keV decreased by 38%, whereas a dose of 33.7 keV increased by 69.2% and the variation strengthened more with enhanced iodine concentration. The segmented voxel mouse head phantom also showed that the average dose enhancement effect and the maximal voxel dose per photon depended little on the iodine voxel volume ratio but strongly on the iodine concentration. To decrease the damage caused by the dose in SRA, a high-Z contrast agent should be used as little as possible and irradiation of the injection site of the contrast agent should be avoided immediately after the injection. The fragile vessel containing iodine should avoid being closely irradiated. Avoiding irradiating through a thin (or no) skull region, or attaching a thin equivalent material on the outside for protection are better methods. An incident X-ray energy as low as possible should be used as long as the SRA image quality is ensured

  19. Surface activity distribution measurements and establishment of a dose rate map inside the destroyed Chernobyl reactor

    International Nuclear Information System (INIS)

    A Gamma Locator designed for contamination survey inside the reactor hall of the 4th unit of Chernobyl NNP has been developed. The device consists of a detector head and a remote control computer connected by a 150 m long cable. The detector head (dimensions: 500 mm by 500 mm by 400 mm; weight: about 40 kg) is a collimated scintillation gamma detector (the collimation angle is 10 deg.). It is installed on a scanning unit and was placed inside the reactor hall. The Gamma Locator scans all surfaces of the reactor hall with angular steps (≤ 1 deg. vertically as well as horizontally) and the particle fluence from the corresponding direction is recorded. The distance between the device head and the measured surface is instantaneously registered by a laser distance gauge. Inside the collimator there is a small CCD camera which makes it possible to obtain a visible image of the measured surface. The effective surface activity levels are presented in colour on the screen of the control computer. The gamma detector essentially consists of a CsI(TI) scintillator crystal (φ 8 mm in diameter, 2.5 mm in thickness) and a Si photodiode. The detector energy resolution is about 8% for radiation from 137Cs. The exposure dose rate distribution in the reactor hall is estimated from the measured effective surface activities /137Cs is the main gamma emitting isotope inside the reactor hall). The results of dose rate calculations are presented in colour superposed on a drawing of the reactor hall. (au)

  20. Surface activity distribution measurements and establishment of a dose rate map inside the destroyed Chernobyl reactor

    Energy Technology Data Exchange (ETDEWEB)

    Chesnokov, A.V.; Fedin, V.I.; Gulyaev, A.A. [RECOM Ltd., Moscow (Russian Federation)] [and others

    1999-02-01

    A Gamma Locator designed for contamination survey inside the reactor hall of the 4th unit of Chernobyl NNP has been developed. The device consists of a detector head and a remote control computer connected by a 150 m long cable. The detector head (dimensions: 500 mm by 500 mm by 400 mm; weight: about 40 kg) is a collimated scintillation gamma detector (the collimation angle is 10 deg.). It is installed on a scanning unit and was placed inside the reactor hall. The Gamma Locator scans all surfaces of the reactor hall with angular steps ({<=} 1 deg. vertically as well as horizontally) and the particle fluence from the corresponding direction is recorded. The distance between the device head and the measured surface is instantaneously registered by a laser distance gauge. Inside the collimator there is a small CCD camera which makes it possible to obtain a visible image of the measured surface. The effective surface activity levels are presented in colour on the screen of the control computer. The gamma detector essentially consists of a CsI(TI) scintillator crystal ({phi} 8 mm in diameter, 2.5 mm in thickness) and a Si photodiode. The detector energy resolution is about 8% for radiation from {sup 137}Cs. The exposure dose rate distribution in the reactor hall is estimated from the measured effective surface activities ({sup 137}Cs is the main gamma emitting isotope inside the reactor hall). The results of dose rate calculations are presented in colour superposed on a drawing of the reactor hall. (au) 1 tab., 28 ills., 16 refs.

  1. Comparison of 2 accelerators of Monte Carlo radiation transport calculations, NVIDIA tesla M2090 GPU and Intel Xeon Phi 5110p coprocessor: a case study for X-ray CT Imaging Dose calculation

    International Nuclear Information System (INIS)

    Hardware accelerators are currently becoming increasingly important in boosting high performance computing systems. In this study, we tested the performance of two accelerator models, NVIDIA Tesla M2090 GPU and Intel Xeon Phi 5110p coprocessor, using a new Monte Carlo photon transport package called ARCHER-CT we have developed for fast CT imaging dose calculation. The package contains three code variants, ARCHER-CT(CPU), ARCHER-CT(GPU) and ARCHER-CT(COP) to run in parallel on the multi-core CPU, GPU and coprocessor architectures respectively. A detailed GE LightSpeed Multi-Detector Computed Tomography (MDCT) scanner model and a family of voxel patient phantoms were included in the code to calculate absorbed dose to radiosensitive organs under specified scan protocols. The results from ARCHER agreed well with those from the production code Monte Carlo N-Particle eXtended (MCNPX). It was found that all the code variants were significantly faster than the parallel MCNPX running on 12 MPI processes, and that the GPU and coprocessor performed equally well, being 2.89-4.49 and 3.01-3.23 times faster than the parallel ARCHER-CT(CPU) running with 12 hyper-threads. (authors)

  2. A Monte Carlo approach to lung dose calculation in small fields used in intensity modulated radiation therapy and stereotactic body radiation therapy

    Directory of Open Access Journals (Sweden)

    Asghar Mesbahi

    2014-01-01

    Conclusion: Our study showed that the dose reduction with small fields in the lung was very enormous. Thus, inaccurate prediction of absorbed dose inside lung and also lung soft-tissue interfaces with small photon beams may lead to critical consequences for treatment outcome.

  3. Study of the distribution of radiation dose in radio sensible organs arising from dental X-ray devices using the Monte Carlo method

    International Nuclear Information System (INIS)

    This project used the MCNPX code to estimate the radiation doses from dental X-rays apparatus received for patients on the radiological services. On the research several steps were taken as: The construction of an input file to the MCNPX code containing related information: the geometries of dental X-ray apparatus and the ionizing chamber. To the input file was added a virtual model of head. However, was performed the validation of simulation with the code through experimental measurements directly into a real dental X-ray apparatus. With it conclude that the results are very representative, because the entrance skin dose obtained through simulation match with the results found in the literature. Also, we noted that entrance skin, the teeth and the upper and lower jaw presented the higher doses, and the radiosensitive organs did not receive relevant doses, this was due to good collimation of the equipment. (author)

  4. Monte Carlo simulation-based feasibility study of a dose-area product meter built into a collimator for diagnostic X-ray

    International Nuclear Information System (INIS)

    According to the International Electro-technical Commission, manufacturers of X-ray equipment should indicate the number of radiation doses to which a patient can be exposed. Dose-area product (DAP) meters are readily available devices that provide dose indices. Collimators are the most commonly employed radiation beam restrictors in X-ray equipment. DAP meters are attached to the lower surface of a collimator. A DAP meter consists of a chamber and electronics. This separation makes it difficult for operators to maintain the accuracy of a DAP meter. Developing a comprehensive system that has a DAP meter in place of a mirror in the collimator would be effective for measuring, recording the dose and maintaining the quality of the DAP meter. This study was conducted through experimental measurements and a simulation. A DAP meter built into a collimator was found to be feasible when its reading was multiplied by a correction factor. (authors)

  5. Effects Induced by Choosing Different Voxels on Dose Calculation Based on Monte Carlo Method%体元大小对基于Monte Carlo的剂量计算的影响

    Institute of Scientific and Technical Information of China (English)

    刘春燕; 刘乐乐; 侯氢; 勾成俊; 吴章文

    2012-01-01

    Objective: In treatment planning system, human density data should be voxelized before dose calculation. When using Monte Carlo method to simulate the procedure, if the free path steps over the interface of the voxel, the free path will be processed approximately. The smaller the voxel is, the more approximate processions there will be. The article is to simulate the reactions in the water phantom that caused by a virtual radiation source based on Monte Carlo method, and calculate the dose distribution in it. By comparing the distribution of the PDD and ORA under two cases, that is, when the water phantom is stratified, we deal with the free path of the particles approximately when it crossing the interfaces and when the water phantom isn't stratified. The impact of the distribution by choosing different sizes of voxels wll be discussed. Methods: Set 6 MeV electron square fields as external beam source, 3-dimensional water phantom as media and simulate the reactions between electron and material in the water phantom when electron beam enter into it vertically by using Penelope program. We stratify the water phantom and compare the central axis Percent Depth Dose (PDD) and Off-Axis Ratio (OAR). Results: Comparing the central axis Percent Depth Dose (PDD) and Off-Axis Ratio (OAR) in these two situations, the influence is little. Conclusions: Choosing different voxels has little influence on the dose accuracy when using Monte Carlo method to process the free path approximately. The results of the research have an instructive effect on the clinical radiotherapy based on Monte Carlo simulation.%目的:在放射治疗计划系统中,剂量计算之前需要对人体密度数据体元化.对于蒙特卡罗方法的模拟过程,当一个自由程跨过体元界面时,会应用自由程近似.选取的体元越小,将导致越多的自由程近似.本文采用蒙特卡罗方法模拟一个虚拟射线源入射到水箱中的反应,计算水箱中的剂量分布,通过比

  6. SU-E-T-579: On the Relative Sensitivity of Monte Carlo and Pencil Beam Dose Calculation Algorithms to CT Metal Artifacts in Volumetric-Modulated Arc Spine Radiosurgery (RS)

    Energy Technology Data Exchange (ETDEWEB)

    Wong, M; Lee, V; Leung, R; Lee, K; Law, G; Tung, S; Chan, M [Tuen Mun Hospital, Hong Kong, Hong Kong (S.A.R) (Hong Kong); Blanck, O [University Clinic Schleswig-Holstein, Kiel, Kiel (Germany)

    2015-06-15

    Purpose: Investigating the relative sensitivity of Monte Carlo (MC) and Pencil Beam (PB) dose calculation algorithms to low-Z (titanium) metallic artifacts is important for accurate and consistent dose reporting in post¬operative spinal RS. Methods: Sensitivity analysis of MC and PB dose calculation algorithms on the Monaco v.3.3 treatment planning system (Elekta CMS, Maryland Heights, MO, USA) was performed using CT images reconstructed without (plain) and with Orthopedic Metal Artifact Reduction (OMAR; Philips Healthcare system, Cleveland, OH, USA). 6MV and 10MV volumetric-modulated arc (VMAT) RS plans were obtained for MC and PB on the plain and OMAR images (MC-plain/OMAR and PB-plain/OMAR). Results: Maximum differences in dose to 0.2cc (D0.2cc) of spinal cord and cord +2mm for 6MV and 10MV VMAT plans were 0.1Gy between MC-OMAR and MC-plain, and between PB-OMAR and PB-plain. Planning target volume (PTV) dose coverage changed by 0.1±0.7% and 0.2±0.3% for 6MV and 10MV from MC-OMAR to MC-plain, and by 0.1±0.1% for both 6MV and 10 MV from PB-OMAR to PB-plain, respectively. In no case for both MC and PB the D0.2cc to spinal cord was found to exceed the planned tolerance changing from OMAR to plain CT in dose calculations. Conclusion: Dosimetric impacts of metallic artifacts caused by low-Z metallic spinal hardware (mainly titanium alloy) are not clinically important in VMAT-based spine RS, without significant dependence on dose calculation methods (MC and PB) and photon energy ≥ 6MV. There is no need to use one algorithm instead of the other to reduce uncertainty for dose reporting. The dose calculation method that should be used in spine RS shall be consistent with the usual clinical practice.

  7. Monte Carlo simulations of the secondary neutron ambient and effective dose equivalent rates from surface to suborbital altitudes and low Earth orbit

    Science.gov (United States)

    El-Jaby, Samy; Richardson, Richard B.

    2015-07-01

    Occupational exposures from ionizing radiation are currently regulated for airline travel (tourism vehicles will reach suborbital altitudes of approximately 100 km and, therefore, the annual occupational dose to flight crew during repeated transits is expected to fall somewhere between those observed for aircrew and astronauts. Unfortunately, measurements of the radiation environment at the high altitudes reached by suborbital vehicles are sparse, and modelling efforts have been similarly limited. In this paper, preliminary MCNPX radiation transport code simulations are developed of the secondary neutron flux profile in air from surface altitudes up to low Earth orbit at solar minimum conditions and excluding the effects of spacecraft shielding. These secondary neutrons are produced by galactic cosmic radiation interacting with Earth's atmosphere and are among the sources of radiation that can pose a health risk. Associated estimates of the operational neutron ambient dose equivalent, used for radiation protection purposes, and the neutron effective dose equivalent that is typically used for estimates of stochastic health risks, are provided in air. Simulations show that the neutron radiation dose rates received at suborbital altitudes are comparable to those experienced by aircrew flying at 7 to 14 km. We also show that the total neutron dose rate tails off beyond the Pfotzer maximum on ascension from surface up to low Earth orbit.

  8. CTC-ask: a new algorithm for conversion of CT numbers to tissue parameters for Monte Carlo dose calculations applying DICOM RS knowledge

    DEFF Research Database (Denmark)

    Ottosson, Rickard; Behrens, Claus F.

    2011-01-01

    conversion of CT number to density and proper differentiation between air and lung. Existing tools do not address this issue specifically. Moreover, their density conversion may depend on the number of media used. Differentiation between air and lung is an important task in MC treatment planning and...... generated for two clinical cases using a CT-conversion scheme implemented in both CTC-ask and the DICOM-RT toolbox. Full MC dose calculation was subsequently conducted and the resulting dose distributions were compared. The DICOM-RT toolbox inaccurately assigned lung in 9.9% and 12.2% of the voxels located...

  9. Determination of differential dose rates in a mixed beta and gamma field using shielded Al2O3:C : Results of Monte Carlo modelling

    DEFF Research Database (Denmark)

    Aznar, M.C.; Nathan, R.; Murray, A.S.;

    2003-01-01

    Mixed beta and gamma heterogeneous radiation fields are found in many circumstances, ranging from retrospective dosimetry to medical therapy treatments. It can be very important to provide a direct measurement of the contribution to dose rate from beta particles and gamma rays separately...... outline the results of our modelling of the most appropriate encapsulation for Al2O3: C luminescence dosimeters when used to measure the dose rate from natural radiation fields. We consider a configuration where one Al2O3: C chip of a pair is enclosed in a beta-thin light-tight package (which would allow...

  10. Comparison of organ doses for patients undergoing balloon brachytherapy of the breast with HDR {sup 192}Ir or electronic sources using Monte Carlo simulations in a heterogeneous human phantom

    Energy Technology Data Exchange (ETDEWEB)

    Mille, Matthew M.; Xu, X. George; Rivard, Mark J. [Nuclear Engineering and Engineering Physics Program, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States)

    2010-02-15

    Purpose: Accelerated partial breast irradiation via interstitial balloon brachytherapy is a fast and effective treatment method for certain early stage breast cancers. The radiation can be delivered using a conventional high-dose rate (HDR) {sup 192}Ir gamma-emitting source or a novel electronic brachytherapy (eBx) source which uses lower energy x rays that do not penetrate as far within the patient. A previous study [A. Dickler, M. C. Kirk, N. Seif, K. Griem, K. Dowlatshahi, D. Francescatti, and R. A. Abrams, ''A dosimetric comparison of MammoSite high-dose-rate brachytherapy and Xoft Axxent electronic brachytherapy,'' Brachytherapy 6, 164-168 (2007)] showed that the target dose is similar for HDR {sup 192}Ir and eBx. This study compares these sources based on the dose received by healthy organs and tissues away from the treatment site. Methods: A virtual patient with left breast cancer was represented by a whole-body, tissue-heterogeneous female voxel phantom. Monte Carlo methods were used to calculate the dose to healthy organs in a virtual patient undergoing balloon brachytherapy of the left breast with HDR {sup 192}Ir or eBx sources. The dose-volume histograms for a few organs which received large doses were also calculated. Additional simulations were performed with all tissues in the phantom defined as water to study the effect of tissue inhomogeneities. Results: For both HDR {sup 192}Ir and eBx, the largest mean organ doses were received by the ribs, thymus gland, left lung, heart, and sternum which were close to the brachytherapy source in the left breast. eBx yielded mean healthy organ doses that were more than a factor of {approx}1.4 smaller than for HDR {sup 192}Ir for all organs considered, except for the three closest ribs. Excluding these ribs, the average and median dose-reduction factors were {approx}28 and {approx}11, respectively. The volume distribution of doses in nearby soft tissue organs that were outside the PTV were also

  11. A practical guideline for the release of patients treated by I-131 based on Monte Carlo dose calculations for family members

    International Nuclear Information System (INIS)

    We recently published effective doses per time-integrated activity (mSv MBq−1 s−1) for paediatric and adult family members exposed to an adult patient released from hospital following I-131 therapy. In the present study, we intend to provide medical physicists with a methodology to estimate family member effective dose in daily clinical practice because the duration of post-radiation precautions for the patient–family member exposure scenario has not been explicitly delineated based on the effective dose. Four different exposure scenarios are considered in this study including (1) a patient and a family member standing face to face, (2) a patient and a family member lying side by side, (3) an adult female patient holding a newborn child to her chest and (4) a one-year-old child standing on the lap of an adult female patient following her I-131 therapy. The results of this study suggest that an adult female hyperthyroidism (HT) patient who was administered with 740 MBq should keep a distance of 100 cm from a 15-year-old child for six days and the same distance from other adults for seven days. The HT female patient should avoid holding a newborn against her chest for at least 16 days following hospital discharge, and a female patient treated with 5550 MBq for differentiated thyroid cancer should not hold her newborn child for at least 15 days following hospital discharge. This study also gives dose coefficients allowing one to predict age-specific effective doses to family members given the measured dose rate (mSv h−1) of the patient. In conclusion, effective dose-based patient release criteria with a modified NRC two-component model provide a site medical physicist with less restrictive and age-specific radiation precaution guidance as they fully consider a patient’s iodine biokinetics and photon attenuation within both the patient and the exposed family members. (note)

  12. Feasibility of a CdTe-based SPECT for high-resolution low-dose small animal imaging: a Monte Carlo simulation study

    International Nuclear Information System (INIS)

    Dedicated single-photon-emission computed tomography (SPECT) systems based on pixelated semiconductors such as cadmium telluride (CdTe) are in development to study small animal models of human disease. In an effort to develop a high-resolution, low-dose system for small animal imaging, we compared a CdTe-based SPECT system and a conventional NaI(Tl)-based SPECT system in terms of spatial resolution, sensitivity, contrast, and contrast-to-noise ratio (CNR). In addition, we investigated the radiation absorbed dose and calculated a figure of merit (FOM) for both SPECT systems. Using the conventional NaI(Tl)-based SPECT system, we achieved a spatial resolution of 1.66 mm at a 30 mm source-to-collimator distance, and a resolution of 2.4-mm hot-rods. Using the newly-developed CdTe-based SPECT system, we achieved a spatial resolution of 1.32 mm FWHM at a 30 mm source-to-collimator distance, and a resolution of 1.7-mm hot-rods. The sensitivities at a 30 mm source-to-collimator distance were 115.73 counts/sec/MBq and 83.38 counts/sec/MBq for the CdTe-based SPECT and conventional NaI(Tl)-based SPECT systems, respectively. To compare quantitative measurements in the mouse brain, we calculated the CNR for images from both systems. The CNR from the CdTe-based SPECT system was 4.41, while that from the conventional NaI(Tl)-based SPECT system was 3.11 when the injected striatal dose was 160 Bq/voxel. The CNR increased as a function of injected dose in both systems. The FOM of the CdTe-based SPECT system was superior to that of the conventional NaI(Tl)-based SPECT system, and the highest FOM was achieved with the CdTe-based SPECT at a dose of 40 Bq/voxel injected into the striatum. Thus, a CdTe-based SPECT system showed significant improvement in performance compared with a conventional system in terms of spatial resolution, sensitivity, and CNR, while reducing the radiation dose to the small animal subject. Herein, we discuss the feasibility of a CdTe-based SPECT system for high

  13. Monte Carlo techniques in radiation therapy

    CERN Document Server

    Verhaegen, Frank

    2013-01-01

    Modern cancer treatment relies on Monte Carlo simulations to help radiotherapists and clinical physicists better understand and compute radiation dose from imaging devices as well as exploit four-dimensional imaging data. With Monte Carlo-based treatment planning tools now available from commercial vendors, a complete transition to Monte Carlo-based dose calculation methods in radiotherapy could likely take place in the next decade. Monte Carlo Techniques in Radiation Therapy explores the use of Monte Carlo methods for modeling various features of internal and external radiation sources, including light ion beams. The book-the first of its kind-addresses applications of the Monte Carlo particle transport simulation technique in radiation therapy, mainly focusing on external beam radiotherapy and brachytherapy. It presents the mathematical and technical aspects of the methods in particle transport simulations. The book also discusses the modeling of medical linacs and other irradiation devices; issues specific...

  14. Dependence of Coronary 3-Dimensional Dose Maps on Coronary Topologies and Beam Set in Breast Radiation Therapy: A Study Based on CT Angiographies

    Energy Technology Data Exchange (ETDEWEB)

    Moignier, Alexandra, E-mail: alexandra.moignier@gmail.com [Institut de Radioprotection et de Sûreté Nucléaire, PRP-HOM/SDI/LEDI, Laboratoire d' Evaluation de la Dose Interne, Fontenay-aux-Roses (France); Broggio, David [Institut de Radioprotection et de Sûreté Nucléaire, PRP-HOM/SDI/LEDI, Laboratoire d' Evaluation de la Dose Interne, Fontenay-aux-Roses (France); Derreumaux, Sylvie [Institut de Radioprotection et de Sûreté Nucléaire, PRP-HOM/SER/UEM, Unité d' Expertise en radioprotection Médicale, Fontenay-aux-Roses (France); El Baf, Fida [Institut de Radioprotection et de Sûreté Nucléaire, PRP-HOM/SDI/LEDI, Laboratoire d' Evaluation de la Dose Interne, Fontenay-aux-Roses (France); Mandin, Anne-Marie [Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique - Hôpitaux de Paris, Service de Radiothérapie Oncologique, Paris (France); Girinsky, Théodore [Institut Gustave Roussy, Service de Radiothérapie Oncologique, Villejuif (France); Paul, Jean-François [Centre Chirurgical Marie-Lannelongue, Service de Radiologie, Le Plessis-Robinson (France); and others

    2014-05-01

    Purpose: In left-side breast radiation therapy (RT), doses to the left main (LM) and left anterior descending (LAD) coronary arteries are usually assessed after delineation by prior anatomic knowledge on the treatment planning computed tomography (CT) scan. In this study, dose sensitivity due to interindividual coronary topology variation was assessed, and hot spots were located. Methods and Materials: Twenty-two detailed heart models, created from heart computed tomography angiographies, were fitted into a single representative female thorax. Two breast RT protocols were then simulated into a treatment planning system: the first protocol comprised tangential and tumoral bed beams (TGs{sub T}B) at 50 + 16 Gy, the second protocol added internal mammary chain beams at 50 Gy to TGs{sub T}B (TGs{sub T}B{sub I}MC). For the heart, the LAD, and the LM, several dose indicators were calculated: dose-volume histograms, mean dose (D{sub mean}), minimal dose received by the most irradiated 2% of the volume (D{sub 2%}), and 3-dimensional (3D) dose maps. Variations of these indicators with anatomies were studied. Results: For the LM, the intermodel dispersion of D{sub mean} and D{sub 2%} was 10% and 11%, respectively, with TGs{sub T}B and 40% and 80%, respectively, with TGs{sub T}B{sub I}MC. For the LAD, these dispersions were 19% (D{sub mean}) and 49% (D{sub 2%}) with TGs{sub T}B and 35% (D{sub mean}) and 76% (D{sub 2%}) with TGs{sub T}B{sub I}MC. The 3D dose maps revealed that the internal mammary chain beams induced hot spots between 20 and 30 Gy on the LM and the proximal LAD for some coronary topologies. Without IMC beams, hot spots between 5 and 26 Gy are located on the middle and distal LAD. Conclusions: Coronary dose distributions with hot spot location and dose level can change significantly depending on coronary topology, as highlighted by 3D coronary dose maps. In clinical practice, coronary imaging may be required for a relevant coronary dose assessment

  15. An assessment of the efficiency of methods for measurement of the computed tomography dose index (CTDI) for cone beam (CBCT) dosimetry by Monte Carlo simulation

    Science.gov (United States)

    Abuhaimed, Abdullah; Martin, Colin J.; Sankaralingam, Marimuthu; Gentle, David J.; McJury, Mark

    2014-10-01

    The IEC has introduced a practical approach to overcome shortcomings of the CTDI100 for measurements on wide beams employed for cone beam (CBCT) scans. This study evaluated the efficiency of this approach (CTDIIEC) for different arrangements using Monte Carlo simulation techniques, and compared CTDIIEC to the efficiency of CTDI100 for CBCT. Monte Carlo EGSnrc/BEAMnrc and EGSnrc/DOSXYZnrc codes were used to simulate the kV imaging system mounted on a Varian TrueBeam linear accelerator. The Monte Carlo model was benchmarked against experimental measurements and good agreement shown. Standard PMMA head and body phantoms with lengths 150, 600, and 900 mm were simulated. Beam widths studied ranged from 20-300 mm, and four scanning protocols using two acquisition modes were utilized. The efficiency values were calculated at the centre (ɛc) and periphery (ɛp) of the phantoms and for the weighted CTDI (ɛw). The efficiency values for CTDI100 were approximately constant for beam widths 20-40 mm, where ɛc(CTDI100), ɛp(CTDI100), and ɛw(CTDI100) were 74.7  ±  0.6%, 84.6  ±  0.3%, and 80.9  ±  0.4%, for the head phantom and 59.7  ±  0.3%, 82.1  ±  0.3%, and 74.9  ±  0.3%, for the body phantom, respectively. When beam width increased beyond 40 mm, ɛ(CTDI100) values fell steadily reaching ~30% at a beam width of 300 mm. In contrast, the efficiency of the CTDIIEC was approximately constant over all beam widths, demonstrating its suitability for assessment of CBCT. ɛc(CTDIIEC), ɛp(CTDIIEC), and ɛw(CTDIIEC) were 76.1  ±  0.9%, 85.9  ±  1.0%, and 82.2  ±  0.9% for the head phantom and 60.6  ±  0.7%, 82.8  ±  0.8%, and 75.8  ±  0.7%, for the body phantom, respectively, within 2% of ɛ(CTDI100) values for narrower beam widths. CTDI100,w and CTDIIEC,w underestimate CTDI∞,w by ~55% and ~18% for the head phantom and by ~56% and ~24% for the body phantom, respectively, using a clinical beam width 198 mm. The

  16. Use of Monte Carlo Methods in brachytherapy; Uso del metodo de Monte Carlo en braquiterapia

    Energy Technology Data Exchange (ETDEWEB)

    Granero Cabanero, D.

    2015-07-01

    The Monte Carlo method has become a fundamental tool for brachytherapy dosimetry mainly because no difficulties associated with experimental dosimetry. In brachytherapy the main handicap of experimental dosimetry is the high dose gradient near the present sources making small uncertainties in the positioning of the detectors lead to large uncertainties in the dose. This presentation will review mainly the procedure for calculating dose distributions around a fountain using the Monte Carlo method showing the difficulties inherent in these calculations. In addition we will briefly review other applications of the method of Monte Carlo in brachytherapy dosimetry, as its use in advanced calculation algorithms, calculating barriers or obtaining dose applicators around. (Author)

  17. Establishment and assessment of Monte Carlo dose calculation algorithm for G4 Cyberknife%G4射波刀蒙特卡罗算法的建立与评价

    Institute of Scientific and Technical Information of China (English)

    徐慧军; 李玉; 张素静; 朴俊杰; 杨晓

    2012-01-01

    目的 建立G4射波刀照射剂量的蒙特卡罗算法并加以评价.方法 利用PTW M3水箱、PTW60012半导体光子探测器测量空气中输出因子、60 mm准直器百分深度剂量和开野剂量曲线得到源分布、注量分布和能谱,并以适当格式输入到射波刀数据库,建立加速器源模型.利用CT扫描CRIS 062密度模体,测量已知物质相对电子密度和质量密度,建立质量密度模型.利用蒙特卡罗算法模拟计算组织模体比、中心离轴比和输出因子,同时用高斯方法调整半高宽,使计算值与射线追踪算法测量值一致.结果 源分布、注量分布和能谱概率生成源模型,利用源模型和密度模型建立起蒙特卡罗算法,之后运用蒙特卡罗算法模拟计算出组织模体比、中心离轴比、输出因子,其结果与测量结果一致.结论 成功建立蒙特卡罗算法后,进行认真评价,即可用于计算剂量.%Objective To establish and assess Monte Carlo (MC) dose calculation algorithm on the exposure dose of G4 Cyberknife. Methods 3D Water phantom and PTW 60012 diode detector were adopted to measure in-air output factor, while 60 mm collimator percent depth dose and the opened field profile were used to generate source distribution, fluence distribution and energy spectrum. After importing the measured beam data to the Cyberknife Data Management System, a calculated source model for the LINAC radiation source was set up. The CRIS 062 density phantom was scanned by using CT, and the relative electron and mass density of the known materials were measured to create the CT density model. And the MC algorithm was used to simulate tissue phantom ratio (TPR) , off center ratio (OCR) and output factor (OF). The Gaussion source model was adopted by adjusting the full width half maximum (FWHM) in order to make the calculated value in accord with the measured value of the ray-tracing dose calculation. Results The source model was created by source

  18. SU-E-T-179: Exploring Appropriate Offset Values for Pencil Beam and Monte Carlo Dose Optimization in Lung Stereotactic Body Radiotherapy Encompassing the Effects of Respiration and Tumor Location

    Energy Technology Data Exchange (ETDEWEB)

    Evans, G [Boca Raton, FL (United States); Shang, C [Florida Atlantic University, Boca Raton, FL (United States); Leventouri, T [Lynn Cancer Institute, Boca Raton, FL (United States)

    2014-06-01

    Purpose: Exploring appropriate offset values in dose optimization with pencil beam (PB) algorithm to minimize dosimetric differences with plans calculated with Monte Carlo (MC) for lung cancer treatment with Stereotactic Body Radiotherapy (SBRT). Methods: 20 cases of Non-Small Cell Lung Cancer, treated with gated full motion range SBRT were selected. According to the proximity of the Gross Tumor Volume (GTV) to the chest wall, two groups are defined: peripherally located when GTV merges with the chest wall for at least 50% of the lesion diameter, and centrally located when the GTV is surrounded by lung tissue. Treatment plans were created on 4D average intensity projection (AIP) CT set with Brainlab iPlanDose 4.1.2 planning system. The D97 of PTV was normalized to 50Gy using the fast PB and compared with MC. The optimized plan was then recomputed over each 4D respiratory phase, and compared with MC using the same plan MU's. Results: The mean difference in the PB and MC D97 of the ITV was 10.5% (±0.8%) of the prescription dose (50Gy). PB algorithm showed 2.3–2.4% less overestimation to the D97 of the ITV, when comparing to MC, in the maximum exhalation phase than in the maximal inhalation phase. Significantly smaller dose difference between PB and MC is also shown in plans for peripheral lesions (7.7 ± 0.7%) versus for central lesions (12.7±0.8%) (p< 0.01). Conclusion: The dosimetric differences between PB and MC can be reasonably predicted depending on the location of lesion in the lung, and may be used as offset value in dose optimization with PB. Since the maximal exhalation phase demonstrates less dose discrepancy between the two algorithms than that in maximal inhalation phase, caution is suggested when the latter is included as a major phase portion in the respiration gated lung SBRT.

  19. Comparison of dose calculations between pencil-beam and Monte Carlo algorithms of the iPlan RT in arc therapy using a homogenous phantom with 3DVH software

    International Nuclear Information System (INIS)

    To create an arc therapy plan, certain current general calculation algorithms such as pencil-beam calculation (PBC) are based on discretizing the continuous arc into multiple fields to simulate an arc. The iPlan RT™ treatment planning system incorporates not only a PBC algorithm, but also a more recent Monte Carlo calculation (MCC) algorithm that does not need beam discretization. The objective of this study is to evaluate the dose differences in a homogenous phantom between PBC and MCC by using a three-dimensional (3D) diode array detector (ArcCHECK™) and 3DVH software. A cylindrically shaped ‘target’ region of interest (ROI) and a ‘periphery ROI’ surrounding the target were designed. An arc therapy plan was created to deliver 600 cGy to the target within a 350° rotation angle, calculated using the PBC and MCC algorithms. The radiation doses were measured by the ArcCHECK, and reproduced by the 3DVH software. Through this process, we could compare the accuracy of both algorithms with regard to the 3D gamma passing rate (for the entire area and for each ROI). Comparing the PBC and MCC planned dose distributions directly, the 3D gamma passing rates for the entire area were 97.7% with the gamma 3%/3 mm criterion. Comparing the planned dose to the measured dose, the 3D gamma passing rates were 98.8% under the PBC algorithm and 100% under the MCC algorithm. The difference was statistically significant (p = 0.034). Furthermore the gamma passing rate decreases 7.5% in the PBC when using the 2%/2 mm criterion compared to only a 0.4% decrease under the MCC. Each ROI as well as the entire area showed statistically significant higher gamma passing rates under the MCC algorithm. The failure points that did not satisfy the gamma criteria showed a regular pattern repeated every 10°. MCC showed better accuracy than the PBC of the iPlan RT in calculating the dose distribution in arc therapy, which was validated with the ArcCHECK and the 3DVH software. This may

  20. Application of Monte Carlo technology to fast dose calculation of radiation therapy%蒙特卡罗技术在放射诊断剂量快速计算中的应用

    Institute of Scientific and Technical Information of China (English)

    管永红; 黄娇凤; 刘进; 刘军

    2013-01-01

    The convolution core is the key factor to calculate dose with the convolution method in single-photon emission computed tomography (SPECT) diagnosis. The Monte Carlo (MO technology was used to investigate the dose characteristic of the SPECT diagnosis with the radioactive isotope 131I. The expression of the 131I decay was given and was used to achieve the simulation of the electron and the photon of one decay of the 131I. The SPECT object is a spherical water phantom. The MC simulation results not only show that 131I can cure the hypothyroid caner and almost has no harm to the normal tissue, but also verify that the requirement of the self-adaption convolution core is met, for the relationship between the deposited energy and the areal mass is nothing to the density. The convolution core is gained by the MC simulation and is very useful to fast dose calculation.%采用蒙特卡罗(MC)技术研究放射性核素131I的放疗特性.给出了131I衰变过程的MC抽样表达式,实现了含电子和光子的混合抽样模拟.对水客体中131I衰变的MC模拟结果表明:131I能够有效地治疗甲状腺肿瘤而几乎不影响正常组织.变密度客体的MC模拟结果表明:沉积能量与面密度之间的关系与密度无关,满足卷积核自适应的要求;并且MC模拟能够提供剂量卷积核函数,为快速剂量计算提供数据.

  1. A new method for evaluating annual absorbed gamma dose rates in an archaeological site by combining the SSNTD technique with Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Misdaq, M.A.; Fahde, K.; Erramli, H. [Nuclear Physics and Techniques Laboratory, Faculty of Sciences Semlalia, B.P. S15, University Cadi Ayyad, Marrakech (Morocco); Mikdad, A. [National Institute of Archaeology and Patrimony, Rabat (Morocco); Rzama, A.; Yousif Charif, M.L. [National Centre of Radioprotection, Rabat (Morocco)

    1998-10-01

    Uranium and thorium contents in different layers of an archaeological site have been determined by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTD) and calculating the probabilities for {alpha}-particles emitted by the uranium and thorium series to reach and be registered on the SSNTD films. A new method has been developed based on calculating the self-absorption coefficient of the gamma-photons emitted by the uranium ({sup 238}U), thorium ({sup 232}Th) and their corresponding decay products as well as the potassium-40 ({sup 40}K) isotope for evaluating the annual absorbed gamma dose rates in the considered material samples. Results obtained have been compared with data obtained by using the TL dosimetry and Bell's methods. Ceramic samples belonging to the studied archaeological site have been dated.

  2. A new method for evaluating annual absorbed gamma dose rates in an archaeological site by combining the SSNTD technique with Monte Carlo simulations

    CERN Document Server

    Misdaq, M A; Erramli, H; Mikdad, A; Rzama, A; Yousif-Charif, M L

    1998-01-01

    Uranium and thorium contents in different layers of an archaeological site have been determined by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTD) and calculating the probabilities for alpha-particles emitted by the uranium and thorium series to reach and be registered on the SSNTD films. A new method has been developed based on calculating the self-absorption coefficient of the gamma-photons emitted by the uranium ( sup 2 sup 3 sup 8 U), thorium ( sup 2 sup 3 sup 2 Th) and their corresponding decay products as well as the potassium-40 ( sup 4 sup 0 K) isotope for evaluating the annual absorbed gamma dose rates in the considered material samples. Results obtained have been compared with data obtained by using the TL dosimetry and Bell's methods. Ceramic samples belonging to the studied archaeological site have been dated.

  3. The effect of rib and lung heterogeneities on the computed dose to lung in Ir-192 High-Dose-Rate breast brachytherapy: Monte Carlo versus a treatment planning system

    Directory of Open Access Journals (Sweden)

    Hossein Salehi Yazdi

    2012-01-01

    Conclusions: Taking into account the ribs and entering the actual data for breasts, ribs, and lungs, revealed an average overestimation of the dose by a factor of 8% in the lung for TPS calculations. Therefore, the accuracy of the TPS results may be limited to regions near the implants where the treatment is planned, and is a more conservative approach for regions at boundaries with curvatures or tissues with a different material than that in the breast.

  4. Clinical evaluation of X-ray voxel Monte Carlo versus pencil beam-based dose calculation in stereotactic body radiotherapy of lung cancer under normal and deep inspiration breath hold.

    Science.gov (United States)

    Landoni, V; Borzì, G R; Strolin, S; Bruzzaniti, V; Soriani, A; D'Alessio, D; Ambesi, F; Di Grazia, A M; Strigari, L

    2015-06-01

    The purpose of this study is to evaluate the differences between dose distributions calculated with the pencil beam (PB) and X-ray voxel Monte Carlo (MC) algorithms for patients with lung cancer using intensity-modulated radiotherapy (IMRT) or HybridArc techniques. The 2 algorithms were compared in terms of dose-volume histograms, under normal and deep inspiration breath hold, and in terms of the tumor control probability (TCP). The dependence of the differences in tumor volume and location was investigated. Dosimetric validation was performed using Gafchromic EBT3 (International Specialty Products, ISP, Wayne, NJ). Forty-five Computed Tomography (CT) data sets were used for this study; 40 Gy at 8 Gy/fraction was prescribed with 5 noncoplanar 6-MV IMRT beams or 3 to 4 dynamic conformal arcs with 3 to 5 IMRT beams distributed per arc. The plans were first calculated with PB and then recalculated with MC. The difference between the mean tumor doses was approximately 10% ± 4%; these differences were even larger under deep inspiration breath hold. Differences between the mean tumor dose correlated with tumor volume and path length of the beams. The TCP values changed from 99.87% ± 0.24% to 96.78% ± 4.81% for both PB- and MC-calculated plans (P = .009). When a fraction of hypoxic cells was considered, the mean TCP values changed from 76.01% ± 5.83% to 34.78% ± 18.06% for the differently calculated plans (P < .0001). When the plans were renormalized to the same mean dose at the tumor, the mean TCP for oxic cells was 99.05% ± 1.59% and for hypoxic cells was 60.20% ± 9.53%. This study confirms that the MC algorithm adequately accounts for inhomogeneities. The inclusion of the MC in the process of IMRT optimization could represent a further step in the complex problem of determining the optimal treatment plan. PMID:25223324

  5. SU-E-CAMPUS-I-04: Automatic Skin-Dose Mapping for An Angiographic System with a Region-Of-Interest, High-Resolution Detector

    Energy Technology Data Exchange (ETDEWEB)

    Vijayan, S; Rana, V [Department of Physiology and Biophysics, Toshiba Stroke and Vascular Research Center (United States); Setlur Nagesh, S [Toshiba Stroke and Vascular Research Center (United States); Ionita, C [Department of Biomedical Engineering, University at Buffalo (State University of New York), Buffalo, NY (United States); Rudin, S [Department of Radiology, Department of Physiology and Biophysics, Toshiba Stroke and Vascular Research Center, Department of Biomedical Engineering, University at Buffalo (State University of New York), Buffalo, NY (United States); Bednarek, D [Department of Radiology, Department of Physiology and Biophysics, Toshiba Stroke and Vascular Research Center (United States)

    2014-06-15

    Purpose: Our real-time skin dose tracking system (DTS) has been upgraded to monitor dose for the micro-angiographic fluoroscope (MAF), a high-resolution, small field-of-view x-ray detector. Methods: The MAF has been mounted on a changer on a clinical C-Arm gantry so it can be used interchangeably with the standard flat-panel detector (FPD) during neuro-interventional procedures when high resolution is needed in a region-of-interest. To monitor patient skin dose when using the MAF, our DTS has been modified to automatically account for the change in scatter for the very small MAF FOV and to provide separated dose distributions for each detector. The DTS is able to provide a color-coded mapping of the cumulative skin dose on a 3D graphic model of the patient. To determine the correct entrance skin exposure to be applied by the DTS, a correction factor was determined by measuring the exposure at the entrance surface of a skull phantom with an ionization chamber as a function of entrance beam size for various beam filters and kVps. Entrance exposure measurements included primary radiation, patient backscatter and table forward scatter. To allow separation of the dose from each detector, a parameter log is kept that allows a replay of the procedure exposure events and recalculation of the dose components.The graphic display can then be constructed showing the dose distribution from the MAF and FPD separately or together. Results: The DTS is able to provide separate displays of dose for the MAF and FPD with field-size specific scatter corrections. These measured corrections change from about 49% down to 10% when changing from the FPD to the MAF. Conclusion: The upgraded DTS allows identification of the patient skin dose delivered when using each detector in order to achieve improved dose management as well as to facilitate peak skin-dose reduction through dose spreading. Research supported in part by Toshiba Medical Systems Corporation and NIH Grants R43FD0158401, R44FD

  6. Monte Carlo primer for health physicists

    International Nuclear Information System (INIS)

    The basic ideas and principles of Monte Carlo calculations are presented in the form of a primer for health physicists. A simple integral with a known answer is evaluated by two different Monte Carlo approaches. Random number, which underlie Monte Carlo work, are discussed, and a sample table of random numbers generated by a hand calculator is presented. Monte Carlo calculations of dose and linear energy transfer (LET) from 100-keV neutrons incident on a tissue slab are discussed. The random-number table is used in a hand calculation of the initial sequence of events for a 100-keV neutron entering the slab. Some pitfalls in Monte Carlo work are described. While this primer addresses mainly the bare bones of Monte Carlo, a final section briefly describes some of the more sophisticated techniques used in practice to reduce variance and computing time

  7. A critical evaluation of secondary cancer risk models applied to Monte Carlo dose distributions of 2-dimensional, 3-dimensional conformal and hybrid intensity-modulated radiation therapy for breast cancer.

    Science.gov (United States)

    Joosten, A; Bochud, F; Moeckli, R

    2014-08-21

    The comparison of radiotherapy techniques regarding secondary cancer risk has yielded contradictory results possibly stemming from the many different approaches used to estimate risk. The purpose of this study was to make a comprehensive evaluation of different available risk models applied to detailed whole-body dose distributions computed by Monte Carlo for various breast radiotherapy te