Monte Carlo systems used for treatment planning and dose verification
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Brualla, Lorenzo [Universitaetsklinikum Essen, NCTeam, Strahlenklinik, Essen (Germany); Rodriguez, Miguel [Centro Medico Paitilla, Balboa (Panama); Lallena, Antonio M. [Universidad de Granada, Departamento de Fisica Atomica, Molecular y Nuclear, Granada (Spain)
2017-04-15
General-purpose radiation transport Monte Carlo codes have been used for estimation of the absorbed dose distribution in external photon and electron beam radiotherapy patients since several decades. Results obtained with these codes are usually more accurate than those provided by treatment planning systems based on non-stochastic methods. Traditionally, absorbed dose computations based on general-purpose Monte Carlo codes have been used only for research, owing to the difficulties associated with setting up a simulation and the long computation time required. To take advantage of radiation transport Monte Carlo codes applied to routine clinical practice, researchers and private companies have developed treatment planning and dose verification systems that are partly or fully based on fast Monte Carlo algorithms. This review presents a comprehensive list of the currently existing Monte Carlo systems that can be used to calculate or verify an external photon and electron beam radiotherapy treatment plan. Particular attention is given to those systems that are distributed, either freely or commercially, and that do not require programming tasks from the end user. These systems are compared in terms of features and the simulation time required to compute a set of benchmark calculations. (orig.) [German] Seit mehreren Jahrzehnten werden allgemein anwendbare Monte-Carlo-Codes zur Simulation des Strahlungstransports benutzt, um die Verteilung der absorbierten Dosis in der perkutanen Strahlentherapie mit Photonen und Elektronen zu evaluieren. Die damit erzielten Ergebnisse sind meist akkurater als solche, die mit nichtstochastischen Methoden herkoemmlicher Bestrahlungsplanungssysteme erzielt werden koennen. Wegen des damit verbundenen Arbeitsaufwands und der langen Dauer der Berechnungen wurden Monte-Carlo-Simulationen von Dosisverteilungen in der konventionellen Strahlentherapie in der Vergangenheit im Wesentlichen in der Forschung eingesetzt. Im Bemuehen, Monte-Carlo
Application of a Monte Carlo linac model in routine verifications of dose calculations
International Nuclear Information System (INIS)
Linares Rosales, H. M.; Alfonso Laguardia, R.; Lara Mas, E.; Popescu, T.
2015-01-01
The analysis of some parameters of interest in Radiotherapy Medical Physics based on an experimentally validated Monte Carlo model of an Elekta Precise lineal accelerator, was performed for 6 and 15 Mv photon beams. The simulations were performed using the EGSnrc code. As reference for simulations, the optimal beam parameters values (energy and FWHM) previously obtained were used. Deposited dose calculations in water phantoms were done, on typical complex geometries commonly are used in acceptance and quality control tests, such as irregular and asymmetric fields. Parameters such as MLC scatter, maximum opening or closing position, and the separation between them were analyzed from calculations in water. Similarly simulations were performed on phantoms obtained from CT studies of real patients, making comparisons of the dose distribution calculated with EGSnrc and the dose distribution obtained from the computerized treatment planning systems (TPS) used in routine clinical plans. All the results showed a great agreement with measurements, finding all of them within tolerance limits. These results allowed the possibility of using the developed model as a robust verification tool for validating calculations in very complex situation, where the accuracy of the available TPS could be questionable. (Author)
Verification of the VEF photon beam model for dose calculations by the voxel-Monte-Carlo-algorithm
International Nuclear Information System (INIS)
Kriesen, S.; Fippel, M.
2005-01-01
The VEF linac head model (VEF, virtual energy fluence) was developed at the University of Tuebingen to determine the primary fluence for calculations of dose distributions in patients by the Voxel-Monte-Carlo-Algorithm (XVMC). This analytical model can be fitted to any therapy accelerator head by measuring only a few basic dose data; therefore, time-consuming Monte-Carlo simulations of the linac head become unnecessary. The aim of the present study was the verification of the VEF model by means of water-phantom measurements, as well as the comparison of this system with a common analytical linac head model of a commercial planning system (TMS, formerly HELAX or MDS Nordion, respectively). The results show that both the VEF and the TMS models can very well simulate the primary fluence. However, the VEF model proved superior in the simulations of scattered radiation and in the calculations of strongly irregular MLC fields. Thus, an accurate and clinically practicable tool for the determination of the primary fluence for Monte-Carlo-Simulations with photons was established, especially for the use in IMRT planning. (orig.)
Kriesen, Stephan; Fippel, Matthias
2005-01-01
The VEF linac head model (VEF, virtual energy fluence) was developed at the University of Tübingen to determine the primary fluence for calculations of dose distributions in patients by the Voxel-Monte-Carlo-Algorithm (XVMC). This analytical model can be fitted to any therapy accelerator head by measuring only a few basic dose data; therefore, time-consuming Monte-Carlo simulations of the linac head become unnecessary. The aim of the present study was the verification of the VEF model by means of water-phantom measurements, as well as the comparison of this system with a common analytical linac head model of a commercial planning system (TMS, formerly HELAX or MDS Nordion, respectively). The results show that both the VEF and the TMS models can very well simulate the primary fluence. However, the VEF model proved superior in the simulations of scattered radiation and in the calculations of strongly irregular MLC fields. Thus, an accurate and clinically practicable tool for the determination of the primary fluence for Monte-Carlo-Simulations with photons was established, especially for the use in IMRT planning.
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Fujita, Y [Tokai University School of Medicine, Isehara, Kanagawa (Japan)
2015-06-15
Purpose: Intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) are techniques that are widely used for treating cancer due to better target coverage and critical structure sparing. The increasing complexity of IMRT and VMAT plans leads to decreases in dose calculation accuracy. Monte Carlo simulations are the most accurate method for the determination of dose distributions in patients. However, the simulation settings for modeling an accurate treatment head are very complex and time consuming. The purpose of this work is to report our implementation of a simple Monte Carlo simulation system in a cloud-computing environment for dosimetric verification of IMRT and VMAT plans. Methods: Monte Carlo simulations of a Varian Clinac linear accelerator were performed using the BEAMnrc code, and dose distributions were calculated using the DOSXYZnrc code. Input files for the simulations were automatically generated from DICOM RT files by the developed web application. We therefore must only upload the DICOM RT files through the web interface, and the simulations are run in the cloud. The calculated dose distributions were exported to RT Dose files that can be downloaded through the web interface. The accuracy of the calculated dose distribution was verified by dose measurements. Results: IMRT and VMAT simulations were performed and good agreement results were observed for measured and MC dose comparison. Gamma analysis with a 3% dose and 3 mm DTA criteria shows a mean gamma index value of 95% for the studied cases. Conclusion: A Monte Carlo-based dose calculation system has been successfully implemented in a cloud environment. The developed system can be used for independent dose verification of IMRT and VMAT plans in routine clinical practice. The system will also be helpful for improving accuracy in beam modeling and dose calculation in treatment planning systems. This work was supported by JSPS KAKENHI Grant Number 25861057.
International Nuclear Information System (INIS)
Fujita, Y
2015-01-01
Purpose: Intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) are techniques that are widely used for treating cancer due to better target coverage and critical structure sparing. The increasing complexity of IMRT and VMAT plans leads to decreases in dose calculation accuracy. Monte Carlo simulations are the most accurate method for the determination of dose distributions in patients. However, the simulation settings for modeling an accurate treatment head are very complex and time consuming. The purpose of this work is to report our implementation of a simple Monte Carlo simulation system in a cloud-computing environment for dosimetric verification of IMRT and VMAT plans. Methods: Monte Carlo simulations of a Varian Clinac linear accelerator were performed using the BEAMnrc code, and dose distributions were calculated using the DOSXYZnrc code. Input files for the simulations were automatically generated from DICOM RT files by the developed web application. We therefore must only upload the DICOM RT files through the web interface, and the simulations are run in the cloud. The calculated dose distributions were exported to RT Dose files that can be downloaded through the web interface. The accuracy of the calculated dose distribution was verified by dose measurements. Results: IMRT and VMAT simulations were performed and good agreement results were observed for measured and MC dose comparison. Gamma analysis with a 3% dose and 3 mm DTA criteria shows a mean gamma index value of 95% for the studied cases. Conclusion: A Monte Carlo-based dose calculation system has been successfully implemented in a cloud environment. The developed system can be used for independent dose verification of IMRT and VMAT plans in routine clinical practice. The system will also be helpful for improving accuracy in beam modeling and dose calculation in treatment planning systems. This work was supported by JSPS KAKENHI Grant Number 25861057
SU-F-T-575: Verification of a Monte-Carlo Small Field SRS/SBRT Dose Calculation System
International Nuclear Information System (INIS)
Sudhyadhom, A; McGuinness, C; Descovich, M
2016-01-01
Purpose: To develop a methodology for validation of a Monte-Carlo dose calculation model for robotic small field SRS/SBRT deliveries. Methods: In a robotic treatment planning system, a Monte-Carlo model was iteratively optimized to match with beam data. A two-part analysis was developed to verify this model. 1) The Monte-Carlo model was validated in a simulated water phantom versus a Ray-Tracing calculation on a single beam collimator-by-collimator calculation. 2) The Monte-Carlo model was validated to be accurate in the most challenging situation, lung, by acquiring in-phantom measurements. A plan was created and delivered in a CIRS lung phantom with film insert. Separately, plans were delivered in an in-house created lung phantom with a PinPoint chamber insert within a lung simulating material. For medium to large collimator sizes, a single beam was delivered to the phantom. For small size collimators (10, 12.5, and 15mm), a robotically delivered plan was created to generate a uniform dose field of irradiation over a 2×2cm 2 area. Results: Dose differences in simulated water between Ray-Tracing and Monte-Carlo were all within 1% at dmax and deeper. Maximum dose differences occurred prior to dmax but were all within 3%. Film measurements in a lung phantom show high correspondence of over 95% gamma at the 2%/2mm level for Monte-Carlo. Ion chamber measurements for collimator sizes of 12.5mm and above were within 3% of Monte-Carlo calculated values. Uniform irradiation involving the 10mm collimator resulted in a dose difference of ∼8% for both Monte-Carlo and Ray-Tracing indicating that there may be limitations with the dose calculation. Conclusion: We have developed a methodology to validate a Monte-Carlo model by verifying that it matches in water and, separately, that it corresponds well in lung simulating materials. The Monte-Carlo model and algorithm tested may have more limited accuracy for 10mm fields and smaller.
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Paelinck, L; Reynaert, N; Thierens, H; Neve, W De; Wagter, C de
2005-01-01
The purpose of this study was to assess the absorbed dose in and around lung tissue by performing radiochromic film measurements, Monte Carlo simulations and calculations with superposition convolution algorithms. We considered a layered polystyrene phantom of 12 x 12 x 12 cm 3 containing a central cavity of 6 x 6 x 6 cm 3 filled with Gammex RMI lung-equivalent material. Two field configurations were investigated, a small 1 x 10 cm 2 field and a larger 10 x 10 cm 2 field. First, we performed Monte Carlo simulations to investigate the influence of radiochromic film itself on the measured dose distribution when the film intersects a lung-equivalent region and is oriented parallel to the central beam axis. To that end, the film and the lung-equivalent materials were modelled in detail, taking into account their specific composition. Next, measurements were performed with the film oriented both parallel and perpendicular to the central beam axis to verify the results of our Monte Carlo simulations. Finally, we digitized the phantom in two commercially available treatment planning systems, Helax-TMS version 6.1A and Pinnacle version 6.2b, and calculated the absorbed dose in the phantom with their incorporated superposition convolution algorithms to compare with the Monte Carlo simulations. Comparing Monte Carlo simulations with measurements reveals that radiochromic film is a reliable dosimeter in and around lung-equivalent regions when the film is positioned perpendicular to the central beam axis. Radiochromic film is also able to predict the absorbed dose accurately when the film is positioned parallel to the central beam axis through the lung-equivalent region. However, attention must be paid when the film is not positioned along the central beam axis, in which case the film gradually attenuates the beam and decreases the dose measured behind the cavity. This underdosage disappears by offsetting the film a few centimetres. We find deviations of about 3.6% between
Paelinck, L.; Reynaert, N.; Thierens, H.; DeNeve, W.; DeWagter, C.
2005-05-01
The purpose of this study was to assess the absorbed dose in and around lung tissue by performing radiochromic film measurements, Monte Carlo simulations and calculations with superposition convolution algorithms. We considered a layered polystyrene phantom of 12 × 12 × 12 cm3 containing a central cavity of 6 × 6 × 6 cm3 filled with Gammex RMI lung-equivalent material. Two field configurations were investigated, a small 1 × 10 cm2 field and a larger 10 × 10 cm2 field. First, we performed Monte Carlo simulations to investigate the influence of radiochromic film itself on the measured dose distribution when the film intersects a lung-equivalent region and is oriented parallel to the central beam axis. To that end, the film and the lung-equivalent materials were modelled in detail, taking into account their specific composition. Next, measurements were performed with the film oriented both parallel and perpendicular to the central beam axis to verify the results of our Monte Carlo simulations. Finally, we digitized the phantom in two commercially available treatment planning systems, Helax-TMS version 6.1A and Pinnacle version 6.2b, and calculated the absorbed dose in the phantom with their incorporated superposition convolution algorithms to compare with the Monte Carlo simulations. Comparing Monte Carlo simulations with measurements reveals that radiochromic film is a reliable dosimeter in and around lung-equivalent regions when the film is positioned perpendicular to the central beam axis. Radiochromic film is also able to predict the absorbed dose accurately when the film is positioned parallel to the central beam axis through the lung-equivalent region. However, attention must be paid when the film is not positioned along the central beam axis, in which case the film gradually attenuates the beam and decreases the dose measured behind the cavity. This underdosage disappears by offsetting the film a few centimetres. We find deviations of about 3.6% between
International Nuclear Information System (INIS)
Koch, Nicholas C; Newhauser, Wayne D
2010-01-01
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.
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Kuenzler, Thomas; Fotina, Irina; Stock, Markus; Georg, Dietmar
2009-01-01
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 x 10 cm 2 field at the first density interface from tissue to lung equivalent material. Small fields (2 x 2 cm 2 ) 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
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Kim, Tae-Hoon; Kim, Yong-Kyun; Lee, Cheol Ho; Son, Jaebum; Lee, Sangmin; Kim, Dong Geon; Choi, Joonbum; Jang, Jae Yeong [Hanyang University, Seoul (Korea, Republic of); Chung, Hyun-Tai [Seoul National University, Seoul (Korea, Republic of)
2016-10-15
Gamma Knife model C contains 201 {sup 60}Co sources located on a spherical surface, so that each beam is concentrated on the center of the sphere. In the last work, we simulated the Gamma Knife model C through Monte Carlo simulation code using Geant4. Instead of 201 multi-collimation system, we made one single collimation system that collects source parameter passing through the collimator helmet. Using the virtual source, we drastically reduced the simulation time to transport 201 gamma circle beams to the target. Gamma index has been widely used to compare two dose distributions in cancer radiotherapy. Gamma index pass rates were compared in two calculated results using the virtual source method and the original method and measured results obtained using radiocrhomic films. A virtual source method significantly reduces simulation time of a Gamma Knife Model C and provides equivalent absorbed dose distributions as that of the original method showing Gamma Index pass rate close to 100% under 1mm/3% criteria. On the other hand, it gives a little narrow dose distribution compared to the film measurement showing Gamma Index pass rate of 94%. More accurate and sophisticated examination on the accuracy of the simulation and film measurement is necessary.
International Nuclear Information System (INIS)
Wieslander, Elinore; Knoeoes, Tommy
2006-01-01
By introducing Monte Carlo (MC) techniques to the verification procedure of dose calculation algorithms in treatment planning systems (TPSs), problems associated with conventional measurements can be avoided and properties that are considered unmeasurable can be studied. The aim of the study is to implement a virtual accelerator, based on MC simulations, to evaluate the performance of a dose calculation algorithm for electron beams in a commercial TPS. The TPS algorithm is MC based and the virtual accelerator is used to study the accuracy of the algorithm in water phantoms. The basic test of the implementation of the virtual accelerator is successful for 6 and 12 MeV (γ < 1.0, 0.02 Gy/2 mm). For 18 MeV, there are problems in the profile data for some of the applicators, where the TPS underestimates the dose. For fields equipped with patient-specific inserts, the agreement is generally good. The exception is 6 MeV where there are slightly larger deviations. The concept of the virtual accelerator is shown to be feasible and has the potential to be a powerful tool for vendors and users
Monte Carlo simulations to replace film dosimetry in IMRT verification
International Nuclear Information System (INIS)
Goetzfried, Thomas; Trautwein, Marius; Koelbi, Oliver; Bogner, Ludwig; Rickhey, Mark
2011-01-01
Patient-specific verification of intensity-modulated radiation therapy (IMRT) plans can be done by dosimetric measurements or by independent dose or monitor unit calculations. The aim of this study was the clinical evaluation of IMRT verification based on a fast Monte Carlo (MC) program with regard to possible benefits compared to commonly used film dosimetry. 25 head-and-neck IMRT plans were recalculated by a pencil beam based treatment planning system (TPS) using an appropriate quality assurance (QA) phantom. All plans were verified both by film and diode dosimetry and compared to MC simulations. The irradiated films, the results of diode measurements and the computed dose distributions were evaluated, and the data were compared on the basis of gamma maps and dose-difference histograms. Average deviations in the high-dose region between diode measurements and point dose calculations performed with the TPS and MC program were 0.7 ± 2.7% and 1.2 ± 3.1%, respectively. For film measurements, the mean gamma values with 3% dose difference and 3 mm distance-to-agreement were 0.74 ± 0.28 (TPS as reference) with dose deviations up to 10%. Corresponding values were significantly reduced to 0.34 ± 0.09 for MC dose calculation. The total time needed for both verification procedures is comparable, however, by far less labor intensive in the case of MC simulations. The presented study showed that independent dose calculation verification of IMRT plans with a fast MC program has the potential to eclipse film dosimetry more and more in the near future. Thus, the linac-specific QA part will necessarily become more important. In combination with MC simulations and due to the simple set-up, point-dose measurements for dosimetric plausibility checks are recommended at least in the IMRT introduction phase. (orig.)
International Nuclear Information System (INIS)
Fragoso Valdez, F. R.; Alvarez Romero, J. T.
2001-01-01
It verifies, in a experimental way, the Monte Carlo simulation results (PENELOPE algorithm) for the water absorbed dose distribution, imparted by a 1 37 Cs - Amersham source (model CDCS-M-3). The feigned results are expressed in terms of the functions Α(r,z), g(r) and F(r,Θ) according to the recommendations of the AAPM TG 43 [es
SU-E-T-29: A Web Application for GPU-Based Monte Carlo IMRT/VMAT QA with Delivered Dose Verification
International Nuclear Information System (INIS)
Folkerts, M; Graves, Y; Tian, Z; Gu, X; Jia, X; Jiang, S
2014-01-01
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
SU-E-T-29: A Web Application for GPU-Based Monte Carlo IMRT/VMAT QA with Delivered Dose Verification
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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.
International Nuclear Information System (INIS)
Tansho, Ryohei; Takada, Yoshihisa; Mizutani, Shohei; Kohno, Ryosuke; Hotta, Kenji; Akimoto, Tetsuo; Hara, Yousuke
2013-01-01
A beam delivery system using a single-radius-beam-wobbling method has been used to form a conformal irradiation field for proton radiotherapy in Japan. A proton beam broadened by the beam-wobbling system provides a non-Gaussian distribution of projection angle different in two mutually orthogonal planes with a common beam central axis, at a certain position. However, the conventional initial beam model for dose calculations has been using an approximation of symmetric Gaussian angular distribution with the same variance in both planes (called here a Gaussian model with symmetric variance (GMSV)), instead of the accurate one. We have developed a more accurate initial beam model defined as a non-Gaussian model with asymmetric variance (NonGMAV), and applied it to dose calculations using the simplified Monte Carlo (SMC) method. The initial beam model takes into account the different distances of two beam-wobbling magnets from the iso-center and also the different amplitudes of kick angle given by each magnet. We have confirmed that the calculation using the SMC with NonGMAV reproduced the measured dose distribution formed in air by a mono-energetic proton beam passing through a square aperture collimator better than with the GMSV and with a Gaussian model with asymmetric variance (GMAV) in which different variances of angular distributions are used in the two mutually orthogonal planes. Measured dose distributions in a homogeneous phantom formed by a modulated proton beam passing through a range shifter and an L-shaped range compensator, were consistent with calculations using the SMC with GMAV and NonGMAV, but in disagreement with calculations using the SMC with GMSV. Measured lateral penumbrae in a lateral direction were reproduced better by calculations using the SMC with NonGMAV than by those with GMAV, when an aperture collimator with a smaller opening was used. We found that such a difference can be attributed to the non-Gaussian angular distribution of the
Monte Carlo investigation of collapsed versus rotated IMRT plan verification.
Conneely, Elaine; Alexander, Andrew; Ruo, Russell; Chung, Eunah; Seuntjens, Jan; Foley, Mark J
2014-05-08
IMRT QA requires, among other tests, a time-consuming process of measuring the absorbed dose, at least to a point, in a high-dose, low-dose-gradient region. Some clinics use a technique of measuring this dose with all beams delivered at a single gantry angle (collapsed delivery), as opposed to the beams delivered at the planned gantry angle (rotated delivery). We examined, established, and optimized Monte Carlo simulations of the dosimetry for IMRT verification of treatment plans for these two different delivery modes (collapsed versus rotated). The results of the simulations were compared to the treatment planning system dose calculations for the two delivery modes, as well as to measurements taken. This was done in order to investigate the validity of the use of a collapsed delivery technique for IMRT QA. The BEAMnrc, DOSXYZnrc, and egs_chamber codes were utilized for the Monte Carlo simulations along with the MMCTP system. A number of different plan complexity metrics were also used in the analysis of the dose distributions in a bid to qualify why verification in a collapsed delivery may or may not be optimal for IMRT QA. Following the Alfonso et al. formalism, the kfclin,frefQclin,Q correction factor was calculated to correct the deviation of small fields from the reference conditions used for beam calibration. We report on the results obtained for a cohort of 20 patients. The plan complexity was investigated for each plan using the complexity metrics of homogeneity index, conformity index, modulation complexity score, and the fraction of beams from a particular plan that intersect the chamber when performing the QA. Rotated QA gives more consistent results than the collapsed QA technique. The kfclin,frefQclin,Qfactor deviates less from 1 for rotated QA than for collapsed QA. If the homogeneity index is less than 0.05 then the kfclin,frefQclin,Q factor does not deviate from unity by more than 1%. A value this low for the homogeneity index can only be obtained
Monte Carlo calculations supporting patient plan verification in proton therapy
Directory of Open Access Journals (Sweden)
Thiago Viana Miranda Lima
2016-03-01
Full Text Available Patient’s treatment plan verification covers substantial amount of the quality assurance (QA resources, this is especially true for Intensity Modulated Proton Therapy (IMPT. The use of Monte Carlo (MC simulations in supporting QA has been widely discussed and several methods have been proposed. In this paper we studied an alternative approach from the one being currently applied clinically at Centro Nazionale di Adroterapia Oncologica (CNAO. We reanalysed the previously published data (Molinelli et al. 2013, where 9 patient plans were investigated in which the warning QA threshold of 3% mean dose deviation was crossed. The possibility that these differences between measurement and calculated dose were related to dose modelling (Treatment Planning Systems (TPS vs MC, limitations on dose delivery system or detectors mispositioning was originally explored but other factors such as the geometric description of the detectors were not ruled out. For the purpose of this work we compared ionisation-chambers measurements with different MC simulations results. It was also studied some physical effects introduced by this new approach for example inter detector interference and the delta ray thresholds. The simulations accounting for a detailed geometry typically are superior (statistical difference - p-value around 0.01 to most of the MC simulations used at CNAO (only inferior to the shift approach used. No real improvement were observed in reducing the current delta-ray threshold used (100 keV and no significant interference between ion chambers in the phantom were detected (p-value 0.81. In conclusion, it was observed that the detailed geometrical description improves the agreement between measurement and MC calculations in some cases. But in other cases position uncertainty represents the dominant uncertainty. The inter chamber disturbance was not detected for the therapeutic protons energies and the results from the current delta threshold are
Verification of Monte Carlo transport codes by activation experiments
Chetvertkova, Vera
2013-01-01
With the increasing energies and intensities of heavy-ion accelerator facilities, the problem of an excessive activation of the accelerator components caused by beam losses becomes more and more important. Numerical experiments using Monte Carlo transport codes are performed in order to assess the levels of activation. The heavy-ion versions of the codes were released approximately a decade ago, therefore the verification is needed to be sure that they give reasonable results. Present work is...
Monte Carlo dose distributions for radiosurgery
International Nuclear Information System (INIS)
Perucha, M.; Leal, A.; Rincon, M.; Carrasco, E.
2001-01-01
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.)
The Monte Carlo applied for calculation dose
International Nuclear Information System (INIS)
Peixoto, J.E.
1988-01-01
The Monte Carlo method is showed for the calculation of absorbed dose. The trajectory of the photon is traced simulating sucessive interaction between the photon and the substance that consist the human body simulator. The energy deposition in each interaction of the simulator organ or tissue per photon is also calculated. (C.G.C.) [pt
Development and verification of Monte Carlo burnup calculation system
International Nuclear Information System (INIS)
Ando, Yoshihira; Yoshioka, Kenichi; Mitsuhashi, Ishi; Sakurada, Koichi; Sakurai, Shungo
2003-01-01
Monte Carlo burnup calculation code system has been developed to evaluate accurate various quantities required in the backend field. From the Actinide Research in a Nuclear Element (ARIANE) program, by using, the measured nuclide compositions of fuel rods in the fuel assemblies irradiated in the commercial Netherlands BWR, the analyses have been performed for the code system verification. The code system developed in this paper has been verified through analysis for MOX and UO2 fuel rods. This system enables to reduce large margin assumed in the present criticality analysis for LWR spent fuels. (J.P.N.)
Verification of Monte Carlo transport codes by activation experiments
Energy Technology Data Exchange (ETDEWEB)
Chetvertkova, Vera
2012-12-18
With the increasing energies and intensities of heavy-ion accelerator facilities, the problem of an excessive activation of the accelerator components caused by beam losses becomes more and more important. Numerical experiments using Monte Carlo transport codes are performed in order to assess the levels of activation. The heavy-ion versions of the codes were released approximately a decade ago, therefore the verification is needed to be sure that they give reasonable results. Present work is focused on obtaining the experimental data on activation of the targets by heavy-ion beams. Several experiments were performed at GSI Helmholtzzentrum fuer Schwerionenforschung. The interaction of nitrogen, argon and uranium beams with aluminum targets, as well as interaction of nitrogen and argon beams with copper targets was studied. After the irradiation of the targets by different ion beams from the SIS18 synchrotron at GSI, the γ-spectroscopy analysis was done: the γ-spectra of the residual activity were measured, the radioactive nuclides were identified, their amount and depth distribution were detected. The obtained experimental results were compared with the results of the Monte Carlo simulations using FLUKA, MARS and SHIELD. The discrepancies and agreements between experiment and simulations are pointed out. The origin of discrepancies is discussed. Obtained results allow for a better verification of the Monte Carlo transport codes, and also provide information for their further development. The necessity of the activation studies for accelerator applications is discussed. The limits of applicability of the heavy-ion beam-loss criteria were studied using the FLUKA code. FLUKA-simulations were done to determine the most preferable from the radiation protection point of view materials for use in accelerator components.
Dose concentration and dose verification for radiotherapy of cancer
International Nuclear Information System (INIS)
Maruyama, Koichi
2005-01-01
The number of cancer treatments using radiation therapy is increasing. The background of this increase is the accumulated fact that the number of successful cases is comparative to or even better than surgery for some types of cancer due to the improvement in irradiation technology and radiation planning technology. This review describes the principles and technology of radiation therapy, its characteristics, particle therapy that improves the dose concentration, its historical background, the importance of dose concentration, present situation and future possibilities. There are serious problems that hinder the superior dose concentration of particle therapy. Recent programs and our efforts to solve these problems are described. A new concept is required to satisfy the notion of evidence based medicine, i.e., one has to develop a method of dose verification, which is not yet available. This review is for researchers, medical doctors and radiation technologists who are developing this field. (author)
ORANGE: a Monte Carlo dose engine for radiotherapy
International Nuclear Information System (INIS)
Zee, W van der; Hogenbirk, A; Marck, S C van der
2005-01-01
This study presents data for the verification of ORANGE, a fast MCNP-based dose engine for radiotherapy treatment planning. In order to verify the new algorithm, it has been benchmarked against DOSXYZ and against measurements. For the benchmarking, first calculations have been done using the ICCR-XIII benchmark. Next, calculations have been done with DOSXYZ and ORANGE in five different phantoms (one homogeneous, two with bone equivalent inserts and two with lung equivalent inserts). The calculations have been done with two mono-energetic photon beams (2 MeV and 6 MeV) and two mono-energetic electron beams (10 MeV and 20 MeV). Comparison of the calculated data (from DOSXYZ and ORANGE) against measurements was possible for a realistic 10 MV photon beam and a realistic 15 MeV electron beam in a homogeneous phantom only. For the comparison of the calculated dose distributions and dose distributions against measurements, the concept of the confidence limit (CL) has been used. This concept reduces the difference between two data sets to a single number, which gives the deviation for 90% of the dose distributions. Using this concept, it was found that ORANGE was always within the statistical bandwidth with DOSXYZ and the measurements. The ICCR-XIII benchmark showed that ORANGE is seven times faster than DOSXYZ, a result comparable with other accelerated Monte Carlo dose systems when no variance reduction is used. As shown for XVMC, using variance reduction techniques has the potential for further acceleration. Using modern computer hardware, this brings the total calculation time for a dose distribution with 1.5% (statistical) accuracy within the clinical range (less then 10 min). This means that ORANGE can be a candidate for a dose engine in radiotherapy treatment planning
Stability and Concentration Verification of Ammonium Perchlorate Dosing Solutions
National Research Council Canada - National Science Library
Tsui, David
1998-01-01
Stability and concentration verification was performed for the ammonium perchlorate dosing solutions used in the on-going 90-Day Oral Toxicity Study conducted by Springborn Laboratories, Inc. (SLI Study No. 3433.1...
Verification of IMRT dose distributions using a water beam imaging system
International Nuclear Information System (INIS)
Li, J.S.; Boyer, Arthur L.; Ma, C.-M.
2001-01-01
A water beam imaging system (WBIS) has been developed and used to verify dose distributions for intensity modulated radiotherapy using dynamic multileaf collimator. This system consisted of a water container, a scintillator screen, a charge-coupled device camera, and a portable personal computer. The scintillation image was captured by the camera. The pixel value in this image indicated the dose value in the scintillation screen. Images of radiation fields of known spatial distributions were used to calibrate the device. The verification was performed by comparing the image acquired from the measurement with a dose distribution from the IMRT plan. Because of light scattering in the scintillator screen, the image was blurred. A correction for this was developed by recognizing that the blur function could be fitted to a multiple Gaussian. The blur function was computed using the measured image of a 10 cmx10 cm x-ray beam and the result of the dose distribution calculated using the Monte Carlo method. Based on the blur function derived using this method, an iterative reconstruction algorithm was applied to recover the dose distribution for an IMRT plan from the measured WBIS image. The reconstructed dose distribution was compared with Monte Carlo simulation result. Reasonable agreement was obtained from the comparison. The proposed approach makes it possible to carry out a real-time comparison of the dose distribution in a transverse plane between the measurement and the reference when we do an IMRT dose verification
Adaptive anisotropic diffusion filtering of Monte Carlo dose distributions
International Nuclear Information System (INIS)
Miao Binhe; Jeraj, Robert; Bao Shanglian; Mackie, Thomas R
2003-01-01
The Monte Carlo method is the most accurate method for radiotherapy dose calculations, if used correctly. However, any Monte Carlo dose calculation is burdened with statistical noise. In this paper, denoising of Monte Carlo dose distributions with a three-dimensional adaptive anisotropic diffusion method was investigated. The standard anisotropic diffusion method was extended by changing the filtering parameters adaptively according to the local statistical noise. Smoothing of dose distributions with different noise levels in an inhomogeneous phantom, a conventional and an IMRT treatment case is shown. The resultant dose distributions were analysed using several evaluating criteria. It is shown that the adaptive anisotropic diffusion method can reduce statistical noise significantly (two to five times, corresponding to the reduction of simulation time by a factor of up to 20), while preserving important gradients of the dose distribution well. The choice of free parameters of the method was found to be fairly robust
Monte Carlo simulation and experimental verification of radiotherapy electron beams
International Nuclear Information System (INIS)
Griffin, J.; Deloar, H. M.
2007-01-01
Full text: Based on fundamental physics and statistics, the Monte Carlo technique is generally accepted as the accurate method for modelling radiation therapy treatments. A Monte Carlo simulation system has been installed, and models of linear accelerators in the more commonly used electron beam modes have been built and commissioned. A novel technique for radiation dosimetry is also being investigated. Combining the advantages of both water tank and solid phantom dosimetry, a hollow, thin walled shell or mask is filled with water and then raised above the natural water surface to produce a volume of water with the desired irregular shape.
Barbeiro, A R; Ureba, A; Baeza, J A; Linares, R; Perucha, M; Jiménez-Ortega, E; Velázquez, S; Mateos, J C; Leal, A
2016-01-01
A model based on a specific phantom, called QuAArC, has been designed for the evaluation of planning and verification systems of complex radiotherapy treatments, such as volumetric modulated arc therapy (VMAT). This model uses the high accuracy provided by the Monte Carlo (MC) simulation of log files and allows the experimental feedback from the high spatial resolution of films hosted in QuAArC. This cylindrical phantom was specifically designed to host films rolled at different radial distances able to take into account the entrance fluence and the 3D dose distribution. Ionization chamber measurements are also included in the feedback process for absolute dose considerations. In this way, automated MC simulation of treatment log files is implemented to calculate the actual delivery geometries, while the monitor units are experimentally adjusted to reconstruct the dose-volume histogram (DVH) on the patient CT. Prostate and head and neck clinical cases, previously planned with Monaco and Pinnacle treatment planning systems and verified with two different commercial systems (Delta4 and COMPASS), were selected in order to test operational feasibility of the proposed model. The proper operation of the feedback procedure was proved through the achieved high agreement between reconstructed dose distributions and the film measurements (global gamma passing rates > 90% for the 2%/2 mm criteria). The necessary discretization level of the log file for dose calculation and the potential mismatching between calculated control points and detection grid in the verification process were discussed. Besides the effect of dose calculation accuracy of the analytic algorithm implemented in treatment planning systems for a dynamic technique, it was discussed the importance of the detection density level and its location in VMAT specific phantom to obtain a more reliable DVH in the patient CT. The proposed model also showed enough robustness and efficiency to be considered as a pre
Phantoms for IMRT dose distribution measurement and treatment verification
International Nuclear Information System (INIS)
Low, Daniel A.; Gerber, Russell L.; Mutic, Sasa; Purdy, James A.
1998-01-01
Background: The verification of intensity-modulated radiation therapy (IMRT) patient treatment dose distributions is currently based on custom-built or modified dose measurement phantoms. The only commercially available IMRT treatment planning and delivery system (Peacock, NOMOS Corp.) is supplied with a film phantom that allows accurate spatial localization of the dose distribution using radiographic film. However, measurements using other dosimeters are necessary for the thorough verification of IMRT. Methods: We have developed a phantom to enable dose measurements using a cylindrical ionization chamber and the localization of prescription isodose curves using a matrix of thermoluminescent dosimetry (TLD) chips. The external phantom cross-section is identical to that of the commercial phantom, to allow direct comparisons of measurements. A supplementary phantom has been fabricated to verify the IMRT dose distributions for pelvis treatments. Results: To date, this phantom has been used for the verification of IMRT dose distributions for head and neck and prostate cancer treatments. Designs are also presented for a phantom insert to be used with polymerizing gels (e.g., BANG-2) to obtain volumetric dose distribution measurements. Conclusion: The phantoms have proven useful in the quantitative evaluation of IMRT treatments
SU-F-T-268: A Feasibility Study of Independent Dose Verification for Vero4DRT
International Nuclear Information System (INIS)
Yamashita, M; Kokubo, M; Takahashi, R; Takayama, K; Tanabe, H; Sueoka, M; Okuuchi, N; Ishii, M; Iwamoto, Y; Tachibana, H
2016-01-01
Purpose: Vero4DRT (Mitsubishi Heavy Industries Ltd.) has been released for a few years. The treatment planning system (TPS) of Vero4DRT is dedicated, so the measurement is the only method of dose verification. There have been no reports of independent dose verification using Clarksonbased algorithm for Vero4DRT. An independent dose verification software program of the general-purpose linac using a modified Clarkson-based algorithm was modified for Vero4DRT. In this study, we evaluated the accuracy of independent dose verification program and the feasibility of the secondary check for Vero4DRT. Methods: iPlan (Brainlab AG) was used as the TPS. PencilBeam Convolution was used for dose calculation algorithm of IMRT and X-ray Voxel Monte Carlo was used for the others. Simple MU Analysis (SMU, Triangle Products, Japan) was used as the independent dose verification software program in which CT-based dose calculation was performed using a modified Clarkson-based algorithm. In this study, 120 patients’ treatment plans were collected in our institute. The treatments were performed using the conventional irradiation for lung and prostate, SBRT for lung and Step and shoot IMRT for prostate. Comparison in dose between the TPS and the SMU was done and confidence limits (CLs, Mean ± 2SD %) were compared to those from the general-purpose linac. Results: As the results of the CLs, the conventional irradiation (lung, prostate), SBRT (lung) and IMRT (prostate) show 2.2 ± 3.5% (CL of the general-purpose linac: 2.4 ± 5.3%), 1.1 ± 1.7% (−0.3 ± 2.0%), 4.8 ± 3.7% (5.4 ± 5.3%) and −0.5 ± 2.5% (−0.1 ± 3.6%), respectively. The CLs for Vero4DRT show similar results to that for the general-purpose linac. Conclusion: The independent dose verification for the new linac is clinically available as a secondary check and we performed the check with the similar tolerance level of the general-purpose linac. This research is partially supported by Japan Agency for Medical Research and
SU-F-T-268: A Feasibility Study of Independent Dose Verification for Vero4DRT
Energy Technology Data Exchange (ETDEWEB)
Yamashita, M; Kokubo, M [Kobe City Medical Center General Hospital, Kobe, Hyogo (Japan); Institute of Biomedical Research and Innovation, Kobe, Hyogo (Japan); Takahashi, R [Cancer Institute Hospital of Japanese Foundation for Cancer Research, Koto, Tokyo (Japan); Takayama, K [Institute of Biomedical Research and Innovation, Kobe, Hyogo (Japan); Kobe City Medical Center General Hospital, Kobe, Hyogo (Japan); Tanabe, H; Sueoka, M; Okuuchi, N [Institute of Biomedical Research and Innovation, Kobe, Hyogo (Japan); Ishii, M; Iwamoto, Y [Kobe City Medical Center General Hospital, Kobe, Hyogo (Japan); Tachibana, H [National Cancer Center, Kashiwa, Chiba (Japan)
2016-06-15
Purpose: Vero4DRT (Mitsubishi Heavy Industries Ltd.) has been released for a few years. The treatment planning system (TPS) of Vero4DRT is dedicated, so the measurement is the only method of dose verification. There have been no reports of independent dose verification using Clarksonbased algorithm for Vero4DRT. An independent dose verification software program of the general-purpose linac using a modified Clarkson-based algorithm was modified for Vero4DRT. In this study, we evaluated the accuracy of independent dose verification program and the feasibility of the secondary check for Vero4DRT. Methods: iPlan (Brainlab AG) was used as the TPS. PencilBeam Convolution was used for dose calculation algorithm of IMRT and X-ray Voxel Monte Carlo was used for the others. Simple MU Analysis (SMU, Triangle Products, Japan) was used as the independent dose verification software program in which CT-based dose calculation was performed using a modified Clarkson-based algorithm. In this study, 120 patients’ treatment plans were collected in our institute. The treatments were performed using the conventional irradiation for lung and prostate, SBRT for lung and Step and shoot IMRT for prostate. Comparison in dose between the TPS and the SMU was done and confidence limits (CLs, Mean ± 2SD %) were compared to those from the general-purpose linac. Results: As the results of the CLs, the conventional irradiation (lung, prostate), SBRT (lung) and IMRT (prostate) show 2.2 ± 3.5% (CL of the general-purpose linac: 2.4 ± 5.3%), 1.1 ± 1.7% (−0.3 ± 2.0%), 4.8 ± 3.7% (5.4 ± 5.3%) and −0.5 ± 2.5% (−0.1 ± 3.6%), respectively. The CLs for Vero4DRT show similar results to that for the general-purpose linac. Conclusion: The independent dose verification for the new linac is clinically available as a secondary check and we performed the check with the similar tolerance level of the general-purpose linac. This research is partially supported by Japan Agency for Medical Research and
Monte Carlo dose calibration in CT scanner
International Nuclear Information System (INIS)
Yadav, Poonam; Ramasubramanian, V.; Subbaiah, K.V.; Thayalan, K.
2008-01-01
Computed Tomography (CT) scanner is a high radiation imaging modality compared to radiography. The dose from a CT examination can vary greatly depending on the particular CT scanner used, the area of the body examined, and the operating parameters of the scan. CT is a major contributor to collective effective dose in diagnostic radiology. Apart from the clinical benefits, the widespread use of multislice scanner is increasing radiation level to patient in comparison with conventional CT scanner. So, it becomes necessary to increase awareness about the CT scanner. (author)
Dosimetry investigation of MOSFET for clinical IMRT dose verification.
Deshpande, Sudesh; Kumar, Rajesh; Ghadi, Yogesh; Neharu, R M; Kannan, V
2013-06-01
In IMRT, patient-specific dose verification is followed regularly at each centre. Simple and efficient dosimetry techniques play a very important role in routine clinical dosimetry QA. The MOSFET dosimeter offers several advantages over the conventional dosimeters such as its small detector size, immediate readout, immediate reuse, multiple point dose measurements. To use the MOSFET as routine clinical dosimetry system for pre-treatment dose verification in IMRT, a comprehensive set of experiments has been conducted, to investigate its linearity, reproducibility, dose rate effect and angular dependence for 6 MV x-ray beam. The MOSFETs shows a linear response with linearity coefficient of 0.992 for a dose range of 35 cGy to 427 cGy. The reproducibility of the MOSFET was measured by irradiating the MOSFET for ten consecutive irradiations in the dose range of 35 cGy to 427 cGy. The measured reproducibility of MOSFET was found to be within 4% up to 70 cGy and within 1.4% above 70 cGy. The dose rate effect on the MOSFET was investigated in the dose rate range 100 MU/min to 600 MU/min. The response of the MOSFET varies from -1.7% to 2.1%. The angular responses of the MOSFETs were measured at 10 degrees intervals from 90 to 270 degrees in an anticlockwise direction and normalized at gantry angle zero and it was found to be in the range of 0.98 ± 0.014 to 1.01 ± 0.014. The MOSFETs were calibrated in a phantom which was later used for IMRT verification. The measured calibration coefficients were found to be 1 mV/cGy and 2.995 mV/cGy in standard and high sensitivity mode respectively. The MOSFETs were used for pre-treatment dose verification in IMRT. Nine dosimeters were used for each patient to measure the dose in different plane. The average variation between calculated and measured dose at any location was within 3%. Dose verification using MOSFET and IMRT phantom was found to quick and efficient and well suited for a busy radiotherapy
Proton Therapy Dose Characterization and Verification
2016-10-01
necrosis may be confined to the white matter, both grey and white matter is affected by vascular changes. It is very difficult to predict the severity of...treatment planning may contribute to the risk of late neurocognitive injury. Radiation dose-dependent subclinical vascular effects have been reported...changes in vascular perfusion, in spectroscopic parameters of neuronal injury, and in changes in the degree and directionality of tissue water
DOSE COEFFICIENTS FOR LIVER CHEMOEMBOLISATION PROCEDURES USING MONTE CARLO CODE.
Karavasilis, E; Dimitriadis, A; Gonis, H; Pappas, P; Georgiou, E; Yakoumakis, E
2016-12-01
The aim of the present study is the estimation of radiation burden during liver chemoembolisation procedures. Organ dose and effective dose conversion factors, normalised to dose-area product (DAP), were estimated for chemoembolisation procedures using a Monte Carlo transport code in conjunction with an adult mathematical phantom. Exposure data from 32 patients were used to determine the exposure projections for the simulations. Equivalent organ (H T ) and effective (E) doses were estimated using individual DAP values. The organs receiving the highest amount of doses during these exams were lumbar spine, liver and kidneys. The mean effective dose conversion factor was 1.4 Sv Gy -1 m -2 Dose conversion factors can be useful for patient-specific radiation burden during chemoembolisation procedures. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Dose verification by OSLDs in the irradiation of cell cultures
International Nuclear Information System (INIS)
Meca C, E. A.; Bourel, V.; Notcovich, C.; Duran, H.
2015-10-01
The determination of value of irradiation dose presents difficulties when targets are irradiated located in regions where electronic equilibrium of charged particle is not reached, as in the case of irradiation -in vitro- of cell lines monolayer-cultured, in culture dishes or flasks covered with culture medium. The present study aimed to implement a methodology for dose verification in irradiation of cells in culture media by optically stimulated luminescence dosimetry (OSLD). For the determination of the absorbed dose in terms of cell proliferation OSL dosimeters of aluminum oxide doped with carbon (Al 2 O 3 :C) were used, which were calibrated to the irradiation conditions of culture medium and at doses that ranged from 0.1 to 15 Gy obtained with a linear accelerator of 6 MV photons. Intercomparison measurements were performed with an ionization chamber of 6 cm 3 . Different geometries were evaluated by varying the thicknesses of solid water, air and cell culture medium. The results showed deviations below 2.2% when compared with the obtained doses of OSLDs and planning system used. Also deviations were observed below 3.4% by eccentric points of the irradiation plane, finding homogeneous dose distribution. Uncertainty in the readings was less than 2%. The proposed methodology contributes a contribution in the dose verification in this type of irradiations, eliminating from the calculation uncertainties, potential errors in settling irradiation or possible equipment failure with which is radiating. It also provides certainty about the survival curves to be plotted with the experimental data. (Author)
Beam intensity scanner system for three dimensional dose verification of IMRT
International Nuclear Information System (INIS)
Vahc, Young W.; Kwon, Ohyun; Park, Kwangyl; Park, Kyung R.; Yi, Byung Y.; Kim, Keun M.
2003-01-01
Patient dose verification is clinically one of the most important parts in the treatment delivery of radiation therapy. The three dimensional (3D) reconstruction of dose distribution delivered to target volume helps to verify patient dose and determine the physical characteristics of beams used in IMRT. Here we present beam intensity scanner (BInS) system for the pre-treatment dosimetric verification of two dimensional photon intensity. The BInS is a radiation detector with a custom-made software for dose conversion of fluorescence signals from scintillator. The scintillator is used to produce fluorescence from the irradiation of 6 MV photons on a Varian Clinac 21EX. The digitized fluoroscopic signals obtained by digital video camera-based scintillator (DVCS) will be processed by our custom made software to reproduce 3D- relative dose distribution. For the intensity modulated beam (IMB), the BInS calculates absorbed dose in absolute beam fluence which is used for the patient dose distribution. Using BInS, we performed various measurements related to IMRT and found the following: (1) The 3D-dose profiles of the IMBs measured by the BInS demonstrate good agreement with radiographic film, pin type ionization chamber and Monte Carlo simulation. (2) The delivered beam intensity is altered by the mechanical and dosimetric properties of the collimation of dynamic and/or step MLC system. This is mostly due to leaf transmission, leaf penumbra scattered photons from the round edges of leaves, and geometry of leaf. (3) The delivered dose depends on the operational detail of how to make multi leaf opening. These phenomena result in a fluence distribution that can be substantially different from the initial and calculated intensity modulation and therefore, should be taken into account by the treatment planning for accurate dose calculations delivered to the target volume in IMRT. (author)
Cornelius, Iwan; Guatelli, Susanna; Fournier, Pauline; Crosbie, Jeffrey C; Sanchez Del Rio, Manuel; Bräuer-Krisch, Elke; Rosenfeld, Anatoly; Lerch, Michael
2014-05-01
Microbeam radiation therapy (MRT) is a synchrotron-based radiotherapy modality that uses high-intensity beams of spatially fractionated radiation to treat tumours. The rapid evolution of MRT towards clinical trials demands accurate treatment planning systems (TPS), as well as independent tools for the verification of TPS calculated dose distributions in order to ensure patient safety and treatment efficacy. Monte Carlo computer simulation represents the most accurate method of dose calculation in patient geometries and is best suited for the purpose of TPS verification. A Monte Carlo model of the ID17 biomedical beamline at the European Synchrotron Radiation Facility has been developed, including recent modifications, using the Geant4 Monte Carlo toolkit interfaced with the SHADOW X-ray optics and ray-tracing libraries. The code was benchmarked by simulating dose profiles in water-equivalent phantoms subject to irradiation by broad-beam (without spatial fractionation) and microbeam (with spatial fractionation) fields, and comparing against those calculated with a previous model of the beamline developed using the PENELOPE code. Validation against additional experimental dose profiles in water-equivalent phantoms subject to broad-beam irradiation was also performed. Good agreement between codes was observed, with the exception of out-of-field doses and toward the field edge for larger field sizes. Microbeam results showed good agreement between both codes and experimental results within uncertainties. Results of the experimental validation showed agreement for different beamline configurations. The asymmetry in the out-of-field dose profiles due to polarization effects was also investigated, yielding important information for the treatment planning process in MRT. This work represents an important step in the development of a Monte Carlo-based independent verification tool for treatment planning in MRT.
RapidArc treatment verification in 3D using polymer gel dosimetry and Monte Carlo simulation
DEFF Research Database (Denmark)
Ceberg, Sofie; Gagne, Isabel; Gustafsson, Helen
2010-01-01
The aim of this study was to verify the advanced inhomogeneous dose distribution produced by a volumetric arc therapy technique (RapidArc™) using 3D gel measurements and Monte Carlo (MC) simulations. The TPS (treatment planning system)-calculated dose distribution was compared with gel measurements...
International Nuclear Information System (INIS)
Locke, C.; Zavgorodni, S.; British Columbia Cancer Agency, Vancouver Island Center, Victoria BC
2008-01-01
Monte Carlo (MC) methods provide the most accurate to-date dose calculations in heterogeneous media and complex geometries, and this spawns increasing interest in incorporating MC calculations into treatment planning quality assurance process. This involves MC dose calculations for clinically produced treatment plans. To perform these calculations, a number of treatment plan parameters specifying radiation beam
Monte Carlo estimation of the absorbed dose in computed tomography
Energy Technology Data Exchange (ETDEWEB)
Kim, Jin Woo; Youn, Han Bean; Kim, Ho Kyung [Pusan National University, Busan (Korea, Republic of)
2016-05-15
The purpose of this study is to devise an algorithm calculating absorbed dose distributions of patients based on Monte Carlo (MC) methods, and which includes the dose estimations due to primary and secondary (scattered) x-ray photons. Assessment of patient dose in computed tomography (CT) at the population level has become a subject of public attention and concern, and ultimate CT quality assurance and dose optimization have the goal of reducing radiation-induced cancer risks in the examined population. However, the conventional CT dose index (CTDI) concept is not a surrogate of risk but it has rather been designed to measure an average central dose. In addition, the CTDI or the dose-length product has showed troubles for helical CT with a wider beam collimation. Simple algorithms to estimate a patient specific CT dose based on the MCNP output data have been introduced. For numerical chest and head phantoms, the spatial dose distributions were calculated. The results were reasonable. The estimated dose distribution map can be readily converted into the effective dose. The important list for further studies includes the validation of the models with the experimental measurements and the acceleration of algorithms.
International Nuclear Information System (INIS)
Fraass, Benedick A.; Smathers, James; Deye, James
2003-01-01
Due to the significant interest in Monte Carlo dose calculations for external beam megavoltage radiation therapy from both the research and commercial communities, a workshop was held in October 2001 to assess the status of this computational method with regard to use for clinical treatment planning. The Radiation Research Program of the National Cancer Institute, in conjunction with the Nuclear Data and Analysis Group at the Oak Ridge National Laboratory, gathered a group of experts in clinical radiation therapy treatment planning and Monte Carlo dose calculations, and examined issues involved in clinical implementation of Monte Carlo dose calculation methods in clinical radiotherapy. The workshop examined the current status of Monte Carlo algorithms, the rationale for using Monte Carlo, algorithmic concerns, clinical issues, and verification methodologies. Based on these discussions, the workshop developed recommendations for future NCI-funded research and development efforts. This paper briefly summarizes the issues presented at the workshop and the recommendations developed by the group
Independent verification of the delivered dose in High-Dose Rate (HDR) brachytherapy
International Nuclear Information System (INIS)
Portillo, P.; Feld, D.; Kessler, J.
2009-01-01
An important aspect of a Quality Assurance program in Clinical Dosimetry is an independent verification of the dosimetric calculation done by the Treatment Planning System for each radiation treatment. The present paper is aimed at creating a spreadsheet for the verification of the dose recorded at a point of an implant with radioactive sources and HDR in gynecological injuries. An 192 Ir source automatic differed loading equipment, GammaMedplus model, Varian Medical System with HDR installed at the Angel H. Roffo Oncology Institute has been used. The planning system implemented for getting the dose distribution is the BraquiVision. The sources coordinates as well as those of the calculation point (Rectum) are entered into the Excel-devised verification program by assuming the existence of a point source in each one of the applicators' positions. Such calculation point has been selected as the rectum is an organ at risk, therefore determining the treatment planning. The dose verification is performed at points standing at a sources distance having at least twice the active length of such sources, so they may be regarded as point sources. Most of the sources used in HDR brachytherapy with 192 Ir have a 5 mm active length for all equipment brands. Consequently, the dose verification distance must be at least of 10 mm. (author)
Patient dose in image guided radiotherapy: Monte Carlo study of the CBCT dose contribution
Leotta, Salvatore; Amato, Ernesto; Settineri, Nicola; Basile, Emilia; Italiano, Antonio; Auditore, Lucrezia; Santacaterina, Anna; Pergolizzi, Stefano
2018-01-01
Image Guided RadioTherapy (IGRT) is a technique whose diffusion is growing thanks to the well-recognized gain in accuracy of dose delivery. However, multiple Cone Beam Computed Tomography (CBCT) scans add dose to patients, and its contribution has to be assessed and minimized. Aim of our work was to evaluate, through Monte Carlo simulations, organ doses in IGRT due to CBCT and therapeutic MV irradiation in head-neck, thorax and pelvis districts. We developed a Monte Carlo simulation in GAMOS ...
Applying Monte Carlo Simulation to Launch Vehicle Design and Requirements Verification
Hanson, John M.; Beard, Bernard B.
2010-01-01
This paper is focused on applying Monte Carlo simulation to probabilistic launch vehicle design and requirements verification. The approaches developed in this paper can be applied to other complex design efforts as well. Typically the verification must show that requirement "x" is met for at least "y" % of cases, with, say, 10% consumer risk or 90% confidence. Two particular aspects of making these runs for requirements verification will be explored in this paper. First, there are several types of uncertainties that should be handled in different ways, depending on when they become known (or not). The paper describes how to handle different types of uncertainties and how to develop vehicle models that can be used to examine their characteristics. This includes items that are not known exactly during the design phase but that will be known for each assembled vehicle (can be used to determine the payload capability and overall behavior of that vehicle), other items that become known before or on flight day (can be used for flight day trajectory design and go/no go decision), and items that remain unknown on flight day. Second, this paper explains a method (order statistics) for determining whether certain probabilistic requirements are met or not and enables the user to determine how many Monte Carlo samples are required. Order statistics is not new, but may not be known in general to the GN&C community. The methods also apply to determining the design values of parameters of interest in driving the vehicle design. The paper briefly discusses when it is desirable to fit a distribution to the experimental Monte Carlo results rather than using order statistics.
Generation and Verification of ENDF/B-VII.0 Cross section Libraries for Monte Carlo Calculations
International Nuclear Information System (INIS)
Park, Ho Jin; Kwak, Min Su; Joo, Han Gyu; Kim, Chang Hyo
2007-01-01
For Monte Carlo neutronics calculations, a continuous energy nuclear data library is needed. It can be generated from various evaluated nuclear data files such as ENDF/B using the ACER routine of the NJOY.code after a series of prior processing involving various other NJOY routines. Recently, a utility code, which generates the NJOY input decks in an automated mode, named ANJOYMC became available. The use of this code greatly reduces the user's effort and the possibility of input errors. In December 2006, the initial version of the ENDF/BVII nuclear data library was released. It was reported that the new data files have much better data which reduces the errors noted in the previous versions. Thus it is worthwhile to examine the performance of the new data files particularly using an independent Monte Carlo code, MCCARD and the ANJOYMC utility code. The verification of the newly generated library can be readily performed by analyzing numerous standard criticality benchmark problems
Investigation of the spatial resolution of an online dose verification device
International Nuclear Information System (INIS)
Asuni, G.; Rickey, D. W.; McCurdy, B. M. C.
2012-01-01
Purpose: The aim of this work is to characterize a new online dose verification device, COMPASS transmission detector array (IBA Dosimetry, Schwarzenbruck, Germany). The array is composed of 1600 cylindrical ionization chambers of 3.8 mm diameter, separated by 6.5 mm center-to-center spacing, in a 40 x 40 arrangement. Methods: The line spread function (LSF) of a single ion chamber in the detector was measured with a narrow slit collimator for a 6 MV photon beam. The 0.25 x 10 mm 2 slit was formed by two machined lead blocks. The LSF was obtained by laterally translating the detector in 0.25 mm steps underneath the slit over a range of 24 mm and taking a measurement at each step. This measurement was validated with Monte Carlo simulation using BEAMnrc and DOSXYZnrc. The presampling modulation transfer function (MTF), the Fourier transform of the line spread function, was determined and compared to calculated (Monte Carlo and analytical) MTFs. Two head-and-neck intensity modulated radiation therapy (IMRT) fields were measured using the device and were used to validate the LSF measurement. These fields were simulated with the BEAMnrc Monte Carlo model, and the Monte Carlo generated incident fluence was convolved with the 2D detector response function (derived from the measured LSF) to obtain calculated dose. The measured and calculated dose distributions were then quantitatively compared using χ-comparison criteria of 3% dose difference and 3 mm distance-to-agreement for in-field points (defined as those above the 10% maximum dose threshold). Results: The full width at half-maximum (FWHM) of the measured detector response for a single chamber is 4.3 mm, which is comparable to the chamber diameter of 3.8 mm. The pre-sampling MTF was calculated, and the resolution of one chamber was estimated as 0.25 lp/mm from the first zero crossing. For both examined IMRT fields, the χ-comparison between measured and calculated data show good agreement with 95.1% and 96.3% of in
A Monte Carlo dose calculation tool for radiotherapy treatment planning
International Nuclear Information System (INIS)
Ma, C.-M.; Li, J.S.; Pawlicki, T.; Jiang, S.B.; Deng, J.; Lee, M.C.; Koumrian, T.; Luxton, M.; Brain, S.
2002-01-01
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. (author)
Monte Carlo verification of polymer gel dosimetry applied to radionuclide therapy: a phantom study
International Nuclear Information System (INIS)
Gear, J I; Partridge, M; Flux, G D; Charles-Edwards, E
2011-01-01
This study evaluates the dosimetric performance of the polymer gel dosimeter 'Methacrylic and Ascorbic acid in Gelatin, initiated by Copper' and its suitability for quality assurance and analysis of I-131-targeted radionuclide therapy dosimetry. Four batches of gel were manufactured in-house and sets of calibration vials and phantoms were created containing different concentrations of I-131-doped gel. Multiple dose measurements were made up to 700 h post preparation and compared to equivalent Monte Carlo simulations. In addition to uniformly filled phantoms the cross-dose distribution from a hot insert to a surrounding phantom was measured. In this example comparisons were made with both Monte Carlo and a clinical scintigraphic dosimetry method. Dose-response curves generated from the calibration data followed a sigmoid function. The gels appeared to be stable over many weeks of internal irradiation with a delay in gel response observed at 29 h post preparation. This was attributed to chemical inhibitors and slow reaction rates of long-chain radical species. For this reason, phantom measurements were only made after 190 h of irradiation. For uniformly filled phantoms of I-131 the accuracy of dose measurements agreed to within 10% when compared to Monte Carlo simulations. A radial cross-dose distribution measured using the gel dosimeter compared well to that calculated with Monte Carlo. Small inhomogeneities were observed in the dosimeter attributed to non-uniform mixing of monomer during preparation. However, they were not detrimental to this study where the quantitative accuracy and spatial resolution of polymer gel dosimetry were far superior to that calculated using scintigraphy. The difference between Monte Carlo and gel measurements was of the order of a few cGy, whilst with the scintigraphic method differences of up to 8 Gy were observed. A manipulation technique is also presented which allows 3D scintigraphic dosimetry measurements to be compared to polymer
Monte Carlo dose calculation of microbeam in a lung phantom
International Nuclear Information System (INIS)
Company, F.Z.; Mino, C.; Mino, F.
1998-01-01
Full text: Recent advances in synchrotron generated X-ray beams with high fluence rate permit investigation of the application of an array of closely spaced, parallel or converging microplanar beams in radiotherapy. The proposed techniques takes advantage of the hypothesised repair mechanism of capillary cells between alternate microbeam zones, which regenerates the lethally irradiated endothelial cells. The lateral and depth doses of 100 keV microplanar beams are investigated for different beam dimensions and spacings in a tissue, lung and tissue/lung/tissue phantom. The EGS4 Monte Carlo code is used to calculate dose profiles at different depth and bundles of beams (up to 20x20cm square cross section). The maximum dose on the beam axis (peak) and the minimum interbeam dose (valley) are compared at different depths, bundles, heights, widths and beam spacings. Relatively high peak to valley ratios are observed in the lung region, suggesting an ideal environment for microbeam radiotherapy. For a single field, the ratio at the tissue/lung interface will set the maximum dose to the target volume. However, in clinical application, several fields would be involved allowing much greater doses to be applied for the elimination of cancer cells. We conclude therefore that multifield microbeam therapy has the potential to achieve useful therapeutic ratios for the treatment of lung cancer
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.
An improved Monte Carlo (MC) dose simulation for charged particle cancer therapy
International Nuclear Information System (INIS)
Ying, C. K.; Kamil, W. A.; Shuaib, I. L.; Matsufuji, Naruhiro
2014-01-01
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
An improved Monte Carlo (MC) dose simulation for charged particle cancer therapy
International Nuclear Information System (INIS)
Ying, C.K.; Kamil, W.A.; Shuaib, I.L.; Ying, C.K.; Kamil, W.A.
2013-01-01
Full-text: 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. (author)
Approach to 3D dose verification by utilizing autoactivation
Energy Technology Data Exchange (ETDEWEB)
Nakajima, Yasunori, E-mail: yasunori.nkjm@gmail.com [Tokyo Institute of Technology, Yokohama-shi (Japan); Kohno, Toshiyuki [Tokyo Institute of Technology, Yokohama-shi (Japan); Inaniwa, Taku; Sato, Shinji; Yoshida, Eiji; Yamaya, Taiga [National Institute of Radiological Sciences, Chiba-shi (Japan); Tsuruta, Yuki [Tokyo Institute of Technology, Yokohama-shi (Japan); Sihver, Lembit [Chalmers University of Technology, Gothenburg (Sweden)
2011-08-21
To evaluate the deposited dose distribution in a target, we have proposed to utilize the annihilation gamma-rays emitted from the positron emitters distributed in the target irradiated with stable heavy-ion beams. Verification of the one dimensional (1-D) dose distributions along and perpendicular to a beam axis was achieved through our previous works. The purpose of this work is to verify 3-D dose distributions. As the first attempt uniform PMMA targets were irradiated in simple rectangular parallelepiped shapes, and the annihilation gamma-rays were detected with a PET scanner. By comparing the detected annihilation gamma-ray distributions with the calculated ones the dose distributions were estimated. As a result the estimated positions of the distal edges of the dose distributions were in agreement with the measured ones within 1 mm. However, the estimated positions of the proximal edges were different from the measured ones by 5-9 mm depending on the thickness of the irradiation filed.
Verification of an effective dose equivalent model for neutrons
International Nuclear Information System (INIS)
Tanner, J.E.; Piper, R.K.; Leonowich, J.A.; Faust, L.G.
1992-01-01
Since the effective dose equivalent, based on the weighted sum of organ dose equivalents, is not a directly measurable quantity, it must be estimated with the assistance of computer modelling techniques and a knowledge of the incident radiation field. Although extreme accuracy is not necessary for radiation protection purposes, a few well chosen measurements are required to confirm the theoretical models. Neutron doses and dose equivalents were measured in a RANDO phantom at specific locations using thermoluminescence dosemeters, etched track dosemeters, and a 1.27 cm (1/2 in) tissue-equivalent proportional counter. The phantom was exposed to a bare and a D 2 O-moderated 252 Cf neutron source at the Pacific Northwest Laboratory's Low Scatter Facility. The Monte Carlo code MCNP with the MIRD-V mathematical phantom was used to model the human body and to calculate the organ doses and dose equivalents. The experimental methods are described and the results of the measurements are compared with the calculations. (author)
Verification of an effective dose equivalent model for neutrons
International Nuclear Information System (INIS)
Tanner, J.E.; Piper, R.K.; Leonowich, J.A.; Faust, L.G.
1991-10-01
Since the effective dose equivalent, based on the weighted sum of organ dose equivalents, is not a directly measurable quantity, it must be estimated with the assistance of computer modeling techniques and a knowledge of the radiation field. Although extreme accuracy is not necessary for radiation protection purposes, a few well-chosen measurements are required to confirm the theoretical models. Neutron measurements were performed in a RANDO phantom using thermoluminescent dosemeters, track etch dosemeters, and a 1/2-in. (1.27-cm) tissue equivalent proportional counter in order to estimate neutron doses and dose equivalents within the phantom at specific locations. The phantom was exposed to bare and D 2 O-moderated 252 Cf neutrons at the Pacific Northwest Laboratory's Low Scatter Facility. The Monte Carlo code MCNP with the MIRD-V mathematical phantom was used to model the human body and calculate organ doses and dose equivalents. The experimental methods are described and the results of the measurements are compared to the calculations. 8 refs., 3 figs., 3 tabs
Verification of eye lens dose in IMRT by MOSFET measurement.
Wang, Xuetao; Li, Guangjun; Zhao, Jianling; Song, Ying; Xiao, Jianghong; Bai, Sen
2018-04-17
The eye lens is recognized as one of the most radiosensitive structures in the human body. The widespread use of intensity-modulated radiotherapy (IMRT) complicates dose verification and necessitates high standards of dose computation. The purpose of this work was to assess the computed dose accuracy of eye lens through measurements using a metal-oxide-semiconductor field-effect transistor (MOSFET) dosimetry system. Sixteen clinical IMRT plans of head and neck patients were copied to an anthropomorphic head phantom. Measurements were performed using the MOSFET dosimetry system based on the head phantom. Two MOSFET detectors were imbedded in the eyes of the head phantom as the left and the right lens, covered by approximately 5-mm-thick paraffin wax. The measurement results were compared with the calculated values with a dose grid size of 1 mm. Sixteen IMRT plans were delivered, and 32 measured lens doses were obtained for analysis. The MOSFET dosimetry system can be used to verify the lens dose, and our measurements showed that the treatment planning system used in our clinic can provide adequate dose assessment in eye lenses. The average discrepancy between measurement and calculation was 6.7 ± 3.4%, and the largest discrepancy was 14.3%, which met the acceptability criterion set by the American Association of Physicists in Medicine Task Group 53 for external beam calculation for multileaf collimator-shaped fields in buildup regions. Copyright © 2018 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.
Monte Carlo calculations of patient doses from dental radiography
International Nuclear Information System (INIS)
Gibbs, S.J.; Pujol, A.; Chen, T.S.; Malcolm, A.W.
1984-01-01
A Monte Carlo computer program has been developed to calculate patient dose from diagnostic radiologic procedures. Input data include patient anatomy as serial CT scans at 1-cm intervals from a typical cadaver, beam spectrum, and projection geometry. The program tracks single photons, accounting for photoelectric effect, coherent (using atomic form factors) and incoherent (using scatter functions) scatter. Inhomogeneities (bone, teeth, muscle, fat, lung, air cavities, etc.) are accounted for as they are encountered. Dose is accumulated in a three-dimensional array of voxels, corresponding to the CT input. Output consists of isodose curves, doses to specific organs, and effective dose equivalent, H/sub E/, as defined by ICRP. Initial results, from dental bite-wing projections using 90-kVp, half-wave rectified dental spectra, have produced H/sub E/ values ranging from 3 to 17 microsieverts (0.3-1.7 mrem) per image, depending on image receptor and projection geometry. The probability of stochastic effect is estimated by ICRP as 10/sup -2//Sv, or about 10/sup -7/ to 10/sup -8/ per image
Monte Carlo simulation for radiation dose in children radiology
International Nuclear Information System (INIS)
Mendes, Hitalo R.; Tomal, Alessandra
2016-01-01
The dosimetry in pediatric radiology is essential due to the higher risk that children have in comparison to adults. The focus of this study is to present how the dose varies depending on the depth in a 10 year old and a newborn, for this purpose simulations are made using the Monte Carlo method. Potential differences were considered 70 and 90 kVp for the 10 year old and 70 and 80 kVp for the newborn. The results show that in both cases, the dose at the skin surface is larger for smaller potential value, however, it decreases faster for larger potential values. Another observation made is that because the newborn is less thick the ratio between the initial dose and the final is lower compared to the case of a 10 year old, showing that it is possible to make an image using a smaller entrance dose in the skin, keeping the same level of exposure at the detector. (author)
Monte Carlo dose calculation algorithm on a distributed system
International Nuclear Information System (INIS)
Chauvie, Stephane; Dominoni, Matteo; Marini, Piergiorgio; Stasi, Michele; Pia, Maria Grazia; Scielzo, Giuseppe
2003-01-01
The main goal of modern radiotherapy, such as 3D conformal radiotherapy and intensity-modulated radiotherapy is to deliver a high dose to the target volume sparing the surrounding healthy tissue. The accuracy of dose calculation in a treatment planning system is therefore a critical issue. Among many algorithms developed over the last years, those based on Monte Carlo proven to be very promising in terms of accuracy. The most severe obstacle in application to clinical practice is the high time necessary for calculations. We have studied a high performance network of Personal Computer as a realistic alternative to a high-costs dedicated parallel hardware to be used routinely as instruments of evaluation of treatment plans. We set-up a Beowulf Cluster, configured with 4 nodes connected with low-cost network and installed MC code Geant4 to describe our irradiation facility. The MC, once parallelised, was run on the Beowulf Cluster. The first run of the full simulation showed that the time required for calculation decreased linearly increasing the number of distributed processes. The good scalability trend allows both statistically significant accuracy and good time performances. The scalability of the Beowulf Cluster system offers a new instrument for dose calculation that could be applied in clinical practice. These would be a good support particularly in high challenging prescription that needs good calculation accuracy in zones of high dose gradient and great dishomogeneities
Density scaling of phantom materials for a 3D dose verification system.
Tani, Kensuke; Fujita, Yukio; Wakita, Akihisa; Miyasaka, Ryohei; Uehara, Ryuzo; Kodama, Takumi; Suzuki, Yuya; Aikawa, Ako; Mizuno, Norifumi; Kawamori, Jiro; Saitoh, Hidetoshi
2018-05-21
In this study, the optimum density scaling factors of phantom materials for a commercially available three-dimensional (3D) dose verification system (Delta4) were investigated in order to improve the accuracy of the calculated dose distributions in the phantom materials. At field sizes of 10 × 10 and 5 × 5 cm 2 with the same geometry, tissue-phantom ratios (TPRs) in water, polymethyl methacrylate (PMMA), and Plastic Water Diagnostic Therapy (PWDT) were measured, and TPRs in various density scaling factors of water were calculated by Monte Carlo simulation, Adaptive Convolve (AdC, Pinnacle 3 ), Collapsed Cone Convolution (CCC, RayStation), and AcurosXB (AXB, Eclipse). Effective linear attenuation coefficients (μ eff ) were obtained from the TPRs. The ratios of μ eff in phantom and water ((μ eff ) pl,water ) were compared between the measurements and calculations. For each phantom material, the density scaling factor proposed in this study (DSF) was set to be the value providing a match between the calculated and measured (μ eff ) pl,water . The optimum density scaling factor was verified through the comparison of the dose distributions measured by Delta4 and calculated with three different density scaling factors: the nominal physical density (PD), nominal relative electron density (ED), and DSF. Three plans were used for the verifications: a static field of 10 × 10 cm 2 and two intensity modulated radiation therapy (IMRT) treatment plans. DSF were determined to be 1.13 for PMMA and 0.98 for PWDT. DSF for PMMA showed good agreement for AdC and CCC with 6 MV x ray, and AdC for 10 MV x ray. DSF for PWDT showed good agreement regardless of the dose calculation algorithms and x-ray energy. DSF can be considered one of the references for the density scaling factor of Delta4 phantom materials and may help improve the accuracy of the IMRT dose verification using Delta4. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley
Monte Carlo dose calculations for phantoms with hip prostheses
International Nuclear Information System (INIS)
Bazalova, M; Verhaegen, F; Coolens, C; Childs, P; Cury, F; Beaulieu, L
2008-01-01
Computed tomography (CT) images of patients with hip prostheses are severely degraded by metal streaking artefacts. The low image quality makes organ contouring more difficult and can result in large dose calculation errors when Monte Carlo (MC) techniques are used. In this work, the extent of streaking artefacts produced by three common hip prosthesis materials (Ti-alloy, stainless steel, and Co-Cr-Mo alloy) was studied. The prostheses were tested in a hypothetical prostate treatment with five 18 MV photon beams. The dose distributions for unilateral and bilateral prosthesis phantoms were calculated with the EGSnrc/DOSXYZnrc MC code. This was done in three phantom geometries: in the exact geometry, in the original CT geometry, and in an artefact-corrected geometry. The artefact-corrected geometry was created using a modified filtered back-projection correction technique. It was found that unilateral prosthesis phantoms do not show large dose calculation errors, as long as the beams miss the artefact-affected volume. This is possible to achieve in the case of unilateral prosthesis phantoms (except for the Co-Cr-Mo prosthesis which gives a 3% error) but not in the case of bilateral prosthesis phantoms. The largest dose discrepancies were obtained for the bilateral Co-Cr-Mo hip prosthesis phantom, up to 11% in some voxels within the prostate. The artefact correction algorithm worked well for all phantoms and resulted in dose calculation errors below 2%. In conclusion, a MC treatment plan should include an artefact correction algorithm when treating patients with hip prostheses
A Monte Carlo estimation of effective dose in chest tomosynthesis
International Nuclear Information System (INIS)
Sabol, John M.
2009-01-01
Purpose: The recent introduction of digital tomosynthesis imaging into routine clinical use has enabled the acquisition of volumetric patient data within a standard radiographic examination. Tomosynthesis requires the acquisition of multiple projection views, requiring additional dose compared to a standard projection examination. Knowledge of the effective dose is needed to make an appropriate decision between standard projection, tomosynthesis, and CT for thoracic x-ray examinations. In this article, the effective dose to the patient of chest tomosynthesis is calculated and compared to a standard radiographic examination and to values published for thoracic CT. Methods: Radiographic technique data for posterior-anterior (PA) and left lateral (LAT) radiographic chest examinations of medium-sized adults was obtained from clinical sites. From these data, the average incident air kerma for the standard views was determined. A commercially available tomosynthesis system was used to define the acquisition technique and geometry for each projection view. Using Monte Carlo techniques, the effective dose of the PA, LAT, and each tomosynthesis projection view was calculated. The effective dose for all projections of the tomosynthesis sweep was summed and compared to the calculated PA and LAT values and to the published values for thoracic CT. Results: The average incident air kerma for the PA and left lateral clinical radiographic examinations were found to be 0.10 and 0.40 mGy, respectively. The effective dose for the PA view of a patient of the size of an average adult male was determined to be 0.017 mSv (ICRP 60) [0.018 mSv (ICRP 103)]. For the left lateral view of the same sized patient, the effective dose was determined to be 0.039 mSv (ICRP 60) [0.050 mSv (ICRP 103)]. The cumulative mA s for a tomosynthesis examination is recommended to be ten times the mA s of the PA image. With this technique, the effective dose for an average tomosynthesis examination was
TH-A-19A-06: Site-Specific Comparison of Analytical and Monte Carlo Based Dose Calculations
International Nuclear Information System (INIS)
Schuemann, J; Grassberger, C; Paganetti, H; Dowdell, S
2014-01-01
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
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
Verhaegen, Frank; Seuntjens, Jan
2008-03-01
Monte Carlo particle transport techniques offer exciting tools for radiotherapy research, where they play an increasingly important role. Topics of research related to clinical applications range from treatment planning, motion and registration studies, brachytherapy, verification imaging and dosimetry. The International Workshop on Monte Carlo Techniques in Radiotherapy Delivery and Verification took place in a hotel in Montreal in French Canada, from 29 May-1 June 2007, and was the third workshop to be held on a related topic, which now seems to have become a tri-annual event. About one hundred workers from many different countries participated in the four-day meeting. Seventeen experts in the field were invited to review topics and present their latest work. About half of the audience was made up by young graduate students. In a very full program, 57 papers were presented and 10 posters were on display during most of the meeting. On the evening of the third day a boat trip around the island of Montreal allowed participants to enjoy the city views, and to sample the local cuisine. The topics covered at the workshop included the latest developments in the most popular Monte Carlo transport algorithms, fast Monte Carlo, statistical issues, source modeling, MC treatment planning, modeling of imaging devices for treatment verification, registration and deformation of images and a sizeable number of contributions on brachytherapy. In this volume you will find 27 short papers resulting from the workshop on a variety of topics, some of them on very new stuff such as graphics processing units for fast computing, PET modeling, dual-energy CT, calculations in dynamic phantoms, tomotherapy devices, . . . . We acknowledge the financial support of the National Cancer Institute of Canada, the Institute of Cancer Research of the Canadian Institutes of Health Research, the Association Québécoise des Physicien(ne)s Médicaux Clinique, the Institute of Physics, and Medical
Feasibility of RACT for 3D dose measurement and range verification in a water phantom.
Alsanea, Fahed; Moskvin, Vadim; Stantz, Keith M
2015-02-01
The objective of this study is to establish the feasibility of using radiation-induced acoustics to measure the range and Bragg peak dose from a pulsed proton beam. Simulation studies implementing a prototype scanner design based on computed tomographic methods were performed to investigate the sensitivity to proton range and integral dose. Derived from thermodynamic wave equation, the pressure signals generated from the dose deposited from a pulsed proton beam with a 1 cm lateral beam width and a range of 16, 20, and 27 cm in water using Monte Carlo methods were simulated. The resulting dosimetric images were reconstructed implementing a 3D filtered backprojection algorithm and the pressure signals acquired from a 71-transducer array with a cylindrical geometry (30 × 40 cm) rotated over 2π about its central axis. Dependencies on the detector bandwidth and proton beam pulse width were performed, after which, different noise levels were added to the detector signals (using 1 μs pulse width and a 0.5 MHz cutoff frequency/hydrophone) to investigate the statistical and systematic errors in the proton range (at 20 cm) and Bragg peak dose (of 1 cGy). The reconstructed radioacoustic computed tomographic image intensity was shown to be linearly correlated to the dose within the Bragg peak. And, based on noise dependent studies, a detector sensitivity of 38 mPa was necessary to determine the proton range to within 1.0 mm (full-width at half-maximum) (systematic error ionizing radiation-induced acoustics can be used to verify dose distribution and proton range with centi-Gray sensitivity. Realizing this technology into the clinic has the potential to significantly impact beam commissioning, treatment verification during particle beam therapy and image guided techniques.
Gharehaghaji, Nahideh; Dadgar, Habib Alah
2018-01-01
The main purpose of this study was evaluate a polymer-gel-dosimeter (PGD) for three-dimensional verification of dose distributions in the lung that is called lung-equivalent gel (LEG) and then to compare its result with Monte Carlo (MC) method. In the present study, to achieve a lung density for PGD, gel is beaten until foam is obtained, and then sodium dodecyl sulfate is added as a surfactant to increase the surface tension of the gel. The foam gel was irradiated with 1 cm × 1 cm field size in the 6 MV photon beams of ONCOR SIEMENS LINAC, along the central axis of the gel. The LEG was then scanned on a 1.5 Tesla magnetic resonance imaging scanner after irradiation using a multiple-spin echo sequence. Least-square fitting the pixel values from 32 consecutive images using a single exponential decay function derived the R2 relaxation rates. Moreover, 6 and 18 MV photon beams of ONCOR SIEMENS LINAC are simulated using MCNPX MC Code. The MC model is used to calculate the depth dose water and low-density water resembling the soft tissue and lung, respectively. Percentages of dose reduction in the lung region relative to homogeneous phantom for 6 MV photon beam were 44.6%, 39%, 13%, and 7% for 0.5 cm × 0.5 cm, 1 cm × 1 cm, 2 cm × 2 cm, and 3 cm × 3 cm fields, respectively. For 18 MV photon beam, the results were found to be 82%, 69%, 46%, and 25.8% for the same field sizes, respectively. Preliminary results show good agreement between depth dose measured with the LEG and the depth dose calculated using MCNP code. Our study showed that the dose reduction with small fields in the lung was very high. Thus, inaccurate prediction of absorbed dose inside the lung and also lung/soft-tissue interfaces with small photon beams may lead to critical consequences for treatment outcome.
Patient dose in image guided radiotherapy: Monte Carlo study of the CBCT dose contribution
Directory of Open Access Journals (Sweden)
Salvatore Leotta
2018-02-01
Full Text Available Image Guided RadioTherapy (IGRT is a technique whose diffusion is growing thanks to the well-recognized gain in accuracy of dose delivery. However, multiple Cone Beam Computed Tomography (CBCT scans add dose to patients, and its contribution has to be assessed and minimized. Aim of our work was to evaluate, through Monte Carlo simulations, organ doses in IGRT due to CBCT and therapeutic MV irradiation in head-neck, thorax and pelvis districts. We developed a Monte Carlo simulation in GAMOS (Geant4-based Architecture for Medicine-Oriented Simulations, reproducing an Elekta Synergy medical linac operating at 6 and 10 MV photon energy, and we set up a scalable anthropomorphic model. After a validation by comparison with the experimental quality indexes, we evaluated the average doses to all organs and tissues belonging to the model for the three cases of irradiated district. Scattered radiation in therapy is larger than that diffused by CBCT by one to two orders of magnitude.
Satake, S; Park, J-K; Sugama, H; Kanno, R
2011-07-29
Neoclassical toroidal viscosities (NTVs) in tokamaks are investigated using a δf Monte Carlo simulation, and are successfully verified with a combined analytic theory over a wide range of collisionality. A Monte Carlo simulation has been required in the study of NTV since the complexities in guiding-center orbits of particles and their collisions cannot be fully investigated by any means of analytic theories alone. Results yielded the details of the complex NTV dependency on particle precessions and collisions, which were predicted roughly in a combined analytic theory. Both numerical and analytic methods can be utilized and extended based on these successful verifications.
International Nuclear Information System (INIS)
Sharma, Subhash; Ott, Joseph; Williams, Jamone; Dickow, Danny
2011-01-01
Monte Carlo dose calculation algorithms have the potential for greater accuracy than traditional model-based algorithms. This enhanced accuracy is particularly evident in regions of lateral scatter disequilibrium, which can develop during treatments incorporating small field sizes and low-density tissue. A heterogeneous slab phantom was used to evaluate the accuracy of several commercially available dose calculation algorithms, including Monte Carlo dose calculation for CyberKnife, Analytical Anisotropic Algorithm and Pencil Beam convolution for the Eclipse planning system, and convolution-superposition for the Xio planning system. The phantom accommodated slabs of varying density; comparisons between planned and measured dose distributions were accomplished with radiochromic film. The Monte Carlo algorithm provided the most accurate comparison between planned and measured dose distributions. In each phantom irradiation, the Monte Carlo predictions resulted in gamma analysis comparisons >97%, using acceptance criteria of 3% dose and 3-mm distance to agreement. In general, the gamma analysis comparisons for the other algorithms were <95%. The Monte Carlo dose calculation algorithm for CyberKnife provides more accurate dose distribution calculations in regions of lateral electron disequilibrium than commercially available model-based algorithms. This is primarily because of the ability of Monte Carlo algorithms to implicitly account for tissue heterogeneities, density scaling functions; and/or effective depth correction factors are not required.
Moteabbed, M.; España, S.; Paganetti, H.
2011-02-01
The purpose of this work was to compare the clinical adaptation of prompt gamma (PG) imaging and positron emission tomography (PET) as independent tools for non-invasive proton beam range verification and treatment validation. The PG range correlation and its differences with PET have been modeled for the first time in a highly heterogeneous tissue environment, using different field sizes and configurations. Four patients with different tumor locations (head and neck, prostate, spine and abdomen) were chosen to compare the site-specific behaviors of the PG and PET images, using both passive scattered and pencil beam fields. Accurate reconstruction of dose, PG and PET distributions was achieved by using the planning computed tomography (CT) image in a validated GEANT4-based Monte Carlo code capable of modeling the treatment nozzle and patient anatomy in detail. The physical and biological washout phenomenon and decay half-lives for PET activity for the most abundant isotopes such as 11C, 15O, 13N, 30P and 38K were taken into account in the data analysis. The attenuation of the gamma signal after traversing the patient geometry and respective detection efficiencies were estimated for both methods to ensure proper comparison. The projected dose, PG and PET profiles along many lines in the beam direction were analyzed to investigate the correlation consistency across the beam width. For all subjects, the PG method showed on average approximately 10 times higher gamma production rates than the PET method before, and 60 to 80 times higher production after including the washout correction and acquisition time delay. This rate strongly depended on tissue density and elemental composition. For broad passive scattered fields, it was demonstrated that large differences exist between PG and PET signal falloff positions and the correlation with the dose distribution for different lines in the beam direction. These variations also depended on the treatment site and the
International Nuclear Information System (INIS)
Pavon, Ester Carrasco; Sanchez-Doblado, Francisco; Leal, Antonio; Capote, Roberto; Lagares, Juan Ignacio; Perucha, Maria; Arrans, Rafael
2003-01-01
Total skin electron therapy (TSET) is a complex technique which requires non-standard measurements and dosimetric procedures. This paper investigates an essential first step towards TSET Monte Carlo (MC) verification. The non-standard 6 MeV 40 x 40 cm 2 electron beam at a source to surface distance (SSD) of 100 cm as well as its horizontal projection behind a polymethylmethacrylate (PMMA) screen to SSD = 380 cm were evaluated. The EGS4 OMEGA-BEAM code package running on a Linux home made 47 PCs cluster was used for the MC simulations. Percentage depth-dose curves and profiles were calculated and measured experimentally for the 40 x 40 cm 2 field at both SSD = 100 cm and patient surface SSD = 380 cm. The output factor (OF) between the reference 40 x 40 cm 2 open field and its horizontal projection as TSET beam at SSD = 380 cm was also measured for comparison with MC results. The accuracy of the simulated beam was validated by the good agreement to within 2% between measured relative dose distributions, including the beam characteristic parameters (R 50 , R 80 , R 100 , R p , E 0 ) and the MC calculated results. The energy spectrum, fluence and angular distribution at different stages of the beam (at SSD = 100 cm, at SSD = 364.2 cm, behind the PMMA beam spoiler screen and at treatment surface SSD = 380 cm) were derived from MC simulations. Results showed a final decrease in mean energy of almost 56% from the exit window to the treatment surface. A broader angular distribution (FWHM of the angular distribution increased from 13deg at SSD 100 cm to more than 30deg at the treatment surface) was fully attributable to the PMMA beam spoiler screen. OF calculations and measurements agreed to less than 1%. The effect of changing the electron energy cut-off from 0.7 MeV to 0.521 MeV and air density fluctuations in the bunker which could affect the MC results were shown to have a negligible impact on the beam fluence distributions. Results proved the applicability of using MC
Feasibility of RACT for 3D dose measurement and range verification in a water phantom
Energy Technology Data Exchange (ETDEWEB)
Alsanea, Fahed [School of Health Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, Indiana 47907-2051 (United States); Moskvin, Vadim [Radiation Oncology, Indiana University School of Medicine, 535 Barnhill Drive, RT 041, Indianapolis, Indiana 46202-5289 (United States); Stantz, Keith M., E-mail: kstantz@purdue.edu [School of Health Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, Indiana 47907-2051 and Radiology and Imaging Sciences, Indiana University School of Medicine, 950 West Walnut Street, Indianapolis, Indiana 46202-5289 (United States)
2015-02-15
Purpose: The objective of this study is to establish the feasibility of using radiation-induced acoustics to measure the range and Bragg peak dose from a pulsed proton beam. Simulation studies implementing a prototype scanner design based on computed tomographic methods were performed to investigate the sensitivity to proton range and integral dose. Methods: Derived from thermodynamic wave equation, the pressure signals generated from the dose deposited from a pulsed proton beam with a 1 cm lateral beam width and a range of 16, 20, and 27 cm in water using Monte Carlo methods were simulated. The resulting dosimetric images were reconstructed implementing a 3D filtered backprojection algorithm and the pressure signals acquired from a 71-transducer array with a cylindrical geometry (30 × 40 cm) rotated over 2π about its central axis. Dependencies on the detector bandwidth and proton beam pulse width were performed, after which, different noise levels were added to the detector signals (using 1 μs pulse width and a 0.5 MHz cutoff frequency/hydrophone) to investigate the statistical and systematic errors in the proton range (at 20 cm) and Bragg peak dose (of 1 cGy). Results: The reconstructed radioacoustic computed tomographic image intensity was shown to be linearly correlated to the dose within the Bragg peak. And, based on noise dependent studies, a detector sensitivity of 38 mPa was necessary to determine the proton range to within 1.0 mm (full-width at half-maximum) (systematic error < 150 μm) for a 1 cGy Bragg peak dose, where the integral dose within the Bragg peak was measured to within 2%. For existing hydrophone detector sensitivities, a Bragg peak dose of 1.6 cGy is possible. Conclusions: This study demonstrates that computed tomographic scanner based on ionizing radiation-induced acoustics can be used to verify dose distribution and proton range with centi-Gray sensitivity. Realizing this technology into the clinic has the potential to significantly
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Piao, J [PLA General Hospital, Beijing (China); PLA 302 Hospital, Beijing (China); Xu, S [PLA General Hospital, Beijing (China); Tsinghua University, Beijing (China); Wu, Z; Liu, Y [Tsinghua University, Beijing (China); Li, Y [Beihang University, Beijing (China); Qu, B [PLA General Hospital, Beijing (China); Duan, X [PLA 302 Hospital, Beijing (China)
2016-06-15
Purpose: This study will use Monte Carlo to simulate the Cyberknife system, and intend to develop the third-party tool to evaluate the dose verification of specific patient plans in TPS. Methods: By simulating the treatment head using the BEAMnrc and DOSXYZnrc software, the comparison between the calculated and measured data will be done to determine the beam parameters. The dose distribution calculated in the Raytracing, Monte Carlo algorithms of TPS (Multiplan Ver4.0.2) and in-house Monte Carlo simulation method for 30 patient plans, which included 10 head, lung and liver cases in each, were analyzed. The γ analysis with the combined 3mm/3% criteria would be introduced to quantitatively evaluate the difference of the accuracy between three algorithms. Results: More than 90% of the global error points were less than 2% for the comparison of the PDD and OAR curves after determining the mean energy and FWHM.The relative ideal Monte Carlo beam model had been established. Based on the quantitative evaluation of dose accuracy for three algorithms, the results of γ analysis shows that the passing rates (84.88±9.67% for head,98.83±1.05% for liver,98.26±1.87% for lung) of PTV in 30 plans between Monte Carlo simulation and TPS Monte Carlo algorithms were good. And the passing rates (95.93±3.12%,99.84±0.33% in each) of PTV in head and liver plans between Monte Carlo simulation and TPS Ray-tracing algorithms were also good. But the difference of DVHs in lung plans between Monte Carlo simulation and Ray-tracing algorithms was obvious, and the passing rate (51.263±38.964%) of γ criteria was not good. It is feasible that Monte Carlo simulation was used for verifying the dose distribution of patient plans. Conclusion: Monte Carlo simulation algorithm developed in the CyberKnife system of this study can be used as a reference tool for the third-party tool, which plays an important role in dose verification of patient plans. This work was supported in part by the grant
SU-E-T-762: Toward Volume-Based Independent Dose Verification as Secondary Check
International Nuclear Information System (INIS)
Tachibana, H; Tachibana, R
2015-01-01
Purpose: Lung SBRT plan has been shifted to volume prescription technique. However, point dose agreement is still verified using independent dose verification at the secondary check. The volume dose verification is more affected by inhomogeneous correction rather than point dose verification currently used as the check. A feasibility study for volume dose verification was conducted in lung SBRT plan. Methods: Six SBRT plans were collected in our institute. Two dose distributions with / without inhomogeneous correction were generated using Adaptive Convolve (AC) in Pinnacle3. Simple MU Analysis (SMU, Triangle Product, Ishikawa, JP) was used as the independent dose verification software program, in which a modified Clarkson-based algorithm was implemented and radiological path length was computed using CT images independently to the treatment planning system. The agreement in point dose and mean dose between the AC with / without the correction and the SMU were assessed. Results: In the point dose evaluation for the center of the GTV, the difference shows the systematic shift (4.5% ± 1.9 %) in comparison of the AC with the inhomogeneous correction, on the other hands, there was good agreement of 0.2 ± 0.9% between the SMU and the AC without the correction. In the volume evaluation, there were significant differences in mean dose for not only PTV (14.2 ± 5.1 %) but also GTV (8.0 ± 5.1 %) compared to the AC with the correction. Without the correction, the SMU showed good agreement for GTV (1.5 ± 0.9%) as well as PTV (0.9% ± 1.0%). Conclusion: The volume evaluation for secondary check may be possible in homogenous region. However, the volume including the inhomogeneous media would make larger discrepancy. Dose calculation algorithm for independent verification needs to be modified to take into account the inhomogeneous correction
An in vivo dose verification method for SBRT–VMAT delivery using the EPID
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McCowan, P. M., E-mail: peter.mccowan@cancercare.mb.ca [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); Medical Physics Department, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9 (Canada); Van Uytven, E.; Van Beek, T.; Asuni, G. [Medical Physics Department, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9 (Canada); McCurdy, B. M. C. [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); Medical Physics Department, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9 (Canada); Department of Radiology, University of Manitoba, 820 Sherbrook Street, Winnipeg, Manitoba R3A 1R9 (Canada)
2015-12-15
Purpose: Radiation treatments have become increasingly more complex with the development of volumetric modulated arc therapy (VMAT) and the use of stereotactic body radiation therapy (SBRT). SBRT involves the delivery of substantially larger doses over fewer fractions than conventional therapy. SBRT–VMAT treatments will strongly benefit from in vivo patient dose verification, as any errors in delivery can be more detrimental to the radiobiology of the patient as compared to conventional therapy. Electronic portal imaging devices (EPIDs) are available on most commercial linear accelerators (Linacs) and their documented use for dosimetry makes them valuable tools for patient dose verification. In this work, the authors customize and validate a physics-based model which utilizes on-treatment EPID images to reconstruct the 3D dose delivered to the patient during SBRT–VMAT delivery. Methods: The SBRT Linac head, including jaws, multileaf collimators, and flattening filter, were modeled using Monte Carlo methods and verified with measured data. The simulation provides energy spectrum data that are used by their “forward” model to then accurately predict fluence generated by a SBRT beam at a plane above the patient. This fluence is then transported through the patient and then the dose to the phosphor layer in the EPID is calculated. Their “inverse” model back-projects the EPID measured focal fluence to a plane upstream of the patient and recombines it with the extra-focal fluence predicted by the forward model. This estimate of total delivered fluence is then forward projected onto the patient’s density matrix and a collapsed cone convolution algorithm calculates the dose delivered to the patient. The model was tested by reconstructing the dose for two prostate, three lung, and two spine SBRT–VMAT treatment fractions delivered to an anthropomorphic phantom. It was further validated against actual patient data for a lung and spine SBRT–VMAT plan. The
Clinical implementation of full Monte Carlo dose calculation in proton beam therapy
International Nuclear Information System (INIS)
Paganetti, Harald; Jiang, Hongyu; Parodi, Katia; Slopsema, Roelf; Engelsman, Martijn
2008-01-01
The goal of this work was to facilitate the clinical use of Monte Carlo proton dose calculation to support routine treatment planning and delivery. The Monte Carlo code Geant4 was used to simulate the treatment head setup, including a time-dependent simulation of modulator wheels (for broad beam modulation) and magnetic field settings (for beam scanning). Any patient-field-specific setup can be modeled according to the treatment control system of the facility. The code was benchmarked against phantom measurements. Using a simulation of the ionization chamber reading in the treatment head allows the Monte Carlo dose to be specified in absolute units (Gy per ionization chamber reading). Next, the capability of reading CT data information was implemented into the Monte Carlo code to model patient anatomy. To allow time-efficient dose calculation, the standard Geant4 tracking algorithm was modified. Finally, a software link of the Monte Carlo dose engine to the patient database and the commercial planning system was established to allow data exchange, thus completing the implementation of the proton Monte Carlo dose calculation engine ('DoC++'). Monte Carlo re-calculated plans are a valuable tool to revisit decisions in the planning process. Identification of clinically significant differences between Monte Carlo and pencil-beam-based dose calculations may also drive improvements of current pencil-beam methods. As an example, four patients (29 fields in total) with tumors in the head and neck regions were analyzed. Differences between the pencil-beam algorithm and Monte Carlo were identified in particular near the end of range, both due to dose degradation and overall differences in range prediction due to bony anatomy in the beam path. Further, the Monte Carlo reports dose-to-tissue as compared to dose-to-water by the planning system. Our implementation is tailored to a specific Monte Carlo code and the treatment planning system XiO (Computerized Medical Systems Inc
Online 3D EPID-based dose verification: Proof of concept
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Spreeuw, Hanno; Rozendaal, Roel, E-mail: r.rozendaal@nki.nl; Olaciregui-Ruiz, Igor; González, Patrick; Mans, Anton; Mijnheer, Ben [Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam 1066 CX (Netherlands); Herk, Marcel van [University of Manchester, Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Manchester M20 4BX (United Kingdom)
2016-07-15
Purpose: Delivery errors during radiotherapy may lead to medical harm and reduced life expectancy for patients. Such serious incidents can be avoided by performing dose verification online, i.e., while the patient is being irradiated, creating the possibility of halting the linac in case of a large overdosage or underdosage. The offline EPID-based 3D in vivo dosimetry system clinically employed at our institute is in principle suited for online treatment verification, provided the system is able to complete 3D dose reconstruction and verification within 420 ms, the present acquisition time of a single EPID frame. It is the aim of this study to show that our EPID-based dosimetry system can be made fast enough to achieve online 3D in vivo dose verification. Methods: The current dose verification system was sped up in two ways. First, a new software package was developed to perform all computations that are not dependent on portal image acquisition separately, thus removing the need for doing these calculations in real time. Second, the 3D dose reconstruction algorithm was sped up via a new, multithreaded implementation. Dose verification was implemented by comparing planned with reconstructed 3D dose distributions delivered to two regions in a patient: the target volume and the nontarget volume receiving at least 10 cGy. In both volumes, the mean dose is compared, while in the nontarget volume, the near-maximum dose (D2) is compared as well. The real-time dosimetry system was tested by irradiating an anthropomorphic phantom with three VMAT plans: a 6 MV head-and-neck treatment plan, a 10 MV rectum treatment plan, and a 10 MV prostate treatment plan. In all plans, two types of serious delivery errors were introduced. The functionality of automatically halting the linac was also implemented and tested. Results: The precomputation time per treatment was ∼180 s/treatment arc, depending on gantry angle resolution. The complete processing of a single portal frame
Online 3D EPID-based dose verification: Proof of concept
International Nuclear Information System (INIS)
Spreeuw, Hanno; Rozendaal, Roel; Olaciregui-Ruiz, Igor; González, Patrick; Mans, Anton; Mijnheer, Ben; Herk, Marcel van
2016-01-01
Purpose: Delivery errors during radiotherapy may lead to medical harm and reduced life expectancy for patients. Such serious incidents can be avoided by performing dose verification online, i.e., while the patient is being irradiated, creating the possibility of halting the linac in case of a large overdosage or underdosage. The offline EPID-based 3D in vivo dosimetry system clinically employed at our institute is in principle suited for online treatment verification, provided the system is able to complete 3D dose reconstruction and verification within 420 ms, the present acquisition time of a single EPID frame. It is the aim of this study to show that our EPID-based dosimetry system can be made fast enough to achieve online 3D in vivo dose verification. Methods: The current dose verification system was sped up in two ways. First, a new software package was developed to perform all computations that are not dependent on portal image acquisition separately, thus removing the need for doing these calculations in real time. Second, the 3D dose reconstruction algorithm was sped up via a new, multithreaded implementation. Dose verification was implemented by comparing planned with reconstructed 3D dose distributions delivered to two regions in a patient: the target volume and the nontarget volume receiving at least 10 cGy. In both volumes, the mean dose is compared, while in the nontarget volume, the near-maximum dose (D2) is compared as well. The real-time dosimetry system was tested by irradiating an anthropomorphic phantom with three VMAT plans: a 6 MV head-and-neck treatment plan, a 10 MV rectum treatment plan, and a 10 MV prostate treatment plan. In all plans, two types of serious delivery errors were introduced. The functionality of automatically halting the linac was also implemented and tested. Results: The precomputation time per treatment was ∼180 s/treatment arc, depending on gantry angle resolution. The complete processing of a single portal frame
Online 3D EPID-based dose verification: Proof of concept.
Spreeuw, Hanno; Rozendaal, Roel; Olaciregui-Ruiz, Igor; González, Patrick; Mans, Anton; Mijnheer, Ben; van Herk, Marcel
2016-07-01
Delivery errors during radiotherapy may lead to medical harm and reduced life expectancy for patients. Such serious incidents can be avoided by performing dose verification online, i.e., while the patient is being irradiated, creating the possibility of halting the linac in case of a large overdosage or underdosage. The offline EPID-based 3D in vivo dosimetry system clinically employed at our institute is in principle suited for online treatment verification, provided the system is able to complete 3D dose reconstruction and verification within 420 ms, the present acquisition time of a single EPID frame. It is the aim of this study to show that our EPID-based dosimetry system can be made fast enough to achieve online 3D in vivo dose verification. The current dose verification system was sped up in two ways. First, a new software package was developed to perform all computations that are not dependent on portal image acquisition separately, thus removing the need for doing these calculations in real time. Second, the 3D dose reconstruction algorithm was sped up via a new, multithreaded implementation. Dose verification was implemented by comparing planned with reconstructed 3D dose distributions delivered to two regions in a patient: the target volume and the nontarget volume receiving at least 10 cGy. In both volumes, the mean dose is compared, while in the nontarget volume, the near-maximum dose (D2) is compared as well. The real-time dosimetry system was tested by irradiating an anthropomorphic phantom with three VMAT plans: a 6 MV head-and-neck treatment plan, a 10 MV rectum treatment plan, and a 10 MV prostate treatment plan. In all plans, two types of serious delivery errors were introduced. The functionality of automatically halting the linac was also implemented and tested. The precomputation time per treatment was ∼180 s/treatment arc, depending on gantry angle resolution. The complete processing of a single portal frame, including dose verification, took
Monte Carlo calculation of ''skyshine'' neutron dose from ALS [Advanced Light Source
International Nuclear Information System (INIS)
Moin-Vasiri, M.
1990-06-01
This report discusses the following topics on ''skyshine'' neutron dose from ALS: Sources of radiation; ALS modeling for skyshine calculations; MORSE Monte-Carlo; Implementation of MORSE; Results of skyshine calculations from storage ring; and Comparison of MORSE shielding calculations
International Nuclear Information System (INIS)
Lin, Hailei; Huang, Shaomin; Deng, Xiaowu; Zhu, Jinhan; Chen, Lixin
2014-01-01
The two-dimensional phantom dose verification (2D-PDV) using hybrid plan and planar dose measurement has been widely used for IMRT treatment QA. Due to the lack of information about the correlations between the verification results and the anatomical structure of patients, it is inadequate in clinical evaluation. A three-dimensional anatomical dose verification (3D-ADV) method was used in this study to evaluate the IMRT/VMAT treatment delivery for nasopharyngeal carcinoma and comparison with 2D-PDV was analyzed. Twenty nasopharyngeal carcinoma (NPC) patients treated with IMRT/VMAT were recruited in the study. A 2D ion-chamber array was used for the 2D-PDV in both single-gantry-angle composite (SGAC) and multi-gantry-angle composite (MGAC) verifications. Differences in the gamma pass rate between the 2 verification methods were assessed. Based on measurement of irradiation dose fluence, the 3D dose distribution was reconstructed for 3D-ADV in the above cases. The reconstructed dose homogeneity index (HI), conformity index (CI) of the planning target volume (PTV) were calculated. Gamma pass rate and deviations in the dose-volume histogram (DVH) of each PTV and organ at risk (OAR) were analyzed. In 2D-PDV, the gamma pass rate (3%, 3 mm) of SGAC (99.55% ± 0.83%) was significantly higher than that of MGAC (92.41% ± 7.19%). In 3D-ADV, the gamma pass rates (3%, 3 mm) were 99.75% ± 0.21% in global, 83.82% ± 16.98% to 93.71% ± 6.22% in the PTVs and 45.12% ± 32.78% to 98.08% ± 2.29% in the OARs. The maximum HI increment in PTVnx was 19.34%, while the maximum CI decrement in PTV1 and PTV2 were -32.45% and -6.93%, respectively. Deviations in dose volume of PTVs were all within ±5%. D2% of the brainstem, spinal cord, left/right optic nerves, and the mean doses to the left/right parotid glands maximally increased by 3.5%, 6.03%, 31.13%/26.90% and 4.78%/4.54%, respectively. The 2D-PDV and global gamma pass rate might be insufficient to provide an accurate assessment for
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Rodrigues, Bruno L.; Tomal, Alessandra [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Instituto de Fisica Gleb Wataghin
2016-07-01
Mammography is the main tool for breast cancer diagnosis, and it is based on the use of X-rays to obtain images. However, the glandular tissue present within the breast is highly sensitive to ionizing radiation, and therefore requires strict quality control in order to minimize the absorbed dose. The quantification of the absorbed dose in the breast tissue can be done by using Monte Carlo simulation, which allows a detailed study of the deposition of energy in different regions of the breast. Besides, the results obtained from the simulation can be associated with experimental data and provide values of dose interest, such as the dose deposited in glandular tissue. (author)
International Nuclear Information System (INIS)
Milosevic, M.; Cupac, S.; Pesic, M.
2005-01-01
The methodology for equivalent gamma dose rate determination on the outer surface of existing containers with the spent fuel elements of the RA reactor is briefly summarised, and experimental verification of this methodology in the field of gamma rays near the aluminium channel with spent fuel elements lifted from the stainless steel containers no. 275 in the RA reactor hall is presented. The proposed methodology is founded on: the existing fuel burnup data base; methods and models for the photon source determination in the RA reactor spent fuel elements developed in the Vinca Institute, and validated Monte Carlo codes for the equivalent gamma dose rate calculations. (author) [sr
A feasible method for clinical delivery verification and dose reconstruction in tomotherapy
International Nuclear Information System (INIS)
Kapatoes, J.M.; Olivera, G.H.; Ruchala, K.J.; Smilowitz, J.B.; Reckwerdt, P.J.; Mackie, T.R.
2001-01-01
Delivery verification is the process in which the energy fluence delivered during a treatment is verified. This verified energy fluence can be used in conjunction with an image in the treatment position to reconstruct the full three-dimensional dose deposited. A method for delivery verification that utilizes a measured database of detector signal is described in this work. This database is a function of two parameters, radiological path-length and detector-to-phantom distance, both of which are computed from a CT image taken at the time of delivery. Such a database was generated and used to perform delivery verification and dose reconstruction. Two experiments were conducted: a simulated prostate delivery on an inhomogeneous abdominal phantom, and a nasopharyngeal delivery on a dog cadaver. For both cases, it was found that the verified fluence and dose results using the database approach agreed very well with those using previously developed and proven techniques. Delivery verification with a measured database and CT image at the time of treatment is an accurate procedure for tomotherapy. The database eliminates the need for any patient-specific, pre- or post-treatment measurements. Moreover, such an approach creates an opportunity for accurate, real-time delivery verification and dose reconstruction given fast image reconstruction and dose computation tools
International Nuclear Information System (INIS)
Jacimovic, R.; Maucec, M.; Trkov, A.
2002-01-01
In this work experimental verification of Monte Carlo neutron flux calculations in the carousel facility (CF) of the 250 kW TRIGA Mark II reactor at the Jozef Stefan Institute is presented. Simulations were carried out using the Monte Carlo radiation-transport code, MCNP4B. The objective of the work was to model and verify experimentally the azimuthal variation of neutron flux in the CF for core No. 176, set up in April 2002. '1'9'8Au activities of Al-Au(0.1%) disks irradiated in 11 channels of the CF covering 180'0 around the perimeter of the core were measured. The comparison between MCNP calculation and measurement shows relatively good agreement and demonstrates the overall accuracy with which the detailed spectral characteristics can be predicted by calculations.(author)
SU-E-T-602: Patient-Specific Online Dose Verification Based On Transmission Detector Measurements
International Nuclear Information System (INIS)
Thoelking, J; Yuvaraj, S; Jens, F; Lohr, F; Wenz, F; Wertz, H; Wertz, H
2015-01-01
Purpose: Intensity modulated radiotherapy requires a comprehensive quality assurance program in general and ideally independent verification of dose delivery. Since conventional 2D detector arrays allow only pre-treatment verification, there is a debate concerning the need of online dose verification. This study presents the clinical performance, including dosimetric plan verification in 2D as well as in 3D and the error detection abilities of a new transmission detector (TD) for online dose verification of 6MV photon beam. Methods: To validate the dosimetric performance of the new device, dose reconstruction based on TD measurements were compared to a conventional pre-treatment verification method (reference) and treatment planning system (TPS) for 18 IMRT and VMAT treatment plans. Furthermore, dose reconstruction inside the patient based on TD read-out was evaluated by comparing various dose volume indices and 3D gamma evaluations against independent dose computation and TPS. To investigate the sensitivity of the new device, different types of systematic and random errors for leaf positions and linac output were introduced in IMRT treatment sequences. Results: The 2D gamma index evaluation of transmission detector based dose reconstruction showed an excellent agreement for all IMRT and VMAT plans compared to reference measurements (99.3±1.2)% and TPS (99.1±0.7)%. Good agreement was also obtained for 3D dose reconstruction based on TD read-out compared to dose computation (mean gamma value of PTV = 0.27±0.04). Only a minimal dose underestimation within the target volume was observed when analyzing DVH indices (<1%). Positional errors in leaf banks larger than 1mm and errors in linac output larger than 2% could clearly identified with the TD. Conclusion: Since 2D and 3D evaluations for all IMRT and VMAT treatment plans were in excellent agreement with reference measurements and dose computation, the new TD is suitable to qualify for routine treatment plan
SU-E-T-602: Patient-Specific Online Dose Verification Based On Transmission Detector Measurements
Energy Technology Data Exchange (ETDEWEB)
Thoelking, J; Yuvaraj, S; Jens, F; Lohr, F; Wenz, F; Wertz, H; Wertz, H [University Medical Center Mannheim, University of Heidelberg, Mannheim, Baden-Wuerttemberg (Germany)
2015-06-15
Purpose: Intensity modulated radiotherapy requires a comprehensive quality assurance program in general and ideally independent verification of dose delivery. Since conventional 2D detector arrays allow only pre-treatment verification, there is a debate concerning the need of online dose verification. This study presents the clinical performance, including dosimetric plan verification in 2D as well as in 3D and the error detection abilities of a new transmission detector (TD) for online dose verification of 6MV photon beam. Methods: To validate the dosimetric performance of the new device, dose reconstruction based on TD measurements were compared to a conventional pre-treatment verification method (reference) and treatment planning system (TPS) for 18 IMRT and VMAT treatment plans. Furthermore, dose reconstruction inside the patient based on TD read-out was evaluated by comparing various dose volume indices and 3D gamma evaluations against independent dose computation and TPS. To investigate the sensitivity of the new device, different types of systematic and random errors for leaf positions and linac output were introduced in IMRT treatment sequences. Results: The 2D gamma index evaluation of transmission detector based dose reconstruction showed an excellent agreement for all IMRT and VMAT plans compared to reference measurements (99.3±1.2)% and TPS (99.1±0.7)%. Good agreement was also obtained for 3D dose reconstruction based on TD read-out compared to dose computation (mean gamma value of PTV = 0.27±0.04). Only a minimal dose underestimation within the target volume was observed when analyzing DVH indices (<1%). Positional errors in leaf banks larger than 1mm and errors in linac output larger than 2% could clearly identified with the TD. Conclusion: Since 2D and 3D evaluations for all IMRT and VMAT treatment plans were in excellent agreement with reference measurements and dose computation, the new TD is suitable to qualify for routine treatment plan
Baptista, M.; Di Maria, S.; Vieira, S.; Vaz, P.
2017-11-01
Cone-Beam Computed Tomography (CBCT) enables high-resolution volumetric scanning of the bone and soft tissue anatomy under investigation at the treatment accelerator. This technique is extensively used in Image Guided Radiation Therapy (IGRT) for pre-treatment verification of patient position and target volume localization. When employed daily and several times per patient, CBCT imaging may lead to high cumulative imaging doses to the healthy tissues surrounding the exposed organs. This work aims at (1) evaluating the dose distribution during a CBCT scan and (2) calculating the organ doses involved in this image guiding procedure for clinically available scanning protocols. Both Monte Carlo (MC) simulations and measurements were performed. To model and simulate the kV imaging system mounted on a linear accelerator (Edge™, Varian Medical Systems) the state-of-the-art MC radiation transport program MCNPX 2.7.0 was used. In order to validate the simulation results, measurements of the Computed Tomography Dose Index (CTDI) were performed, using standard PMMA head and body phantoms, with 150 mm length and a standard pencil ionizing chamber (IC) 100 mm long. Measurements for head and pelvis scanning protocols, usually adopted in clinical environment were acquired, using two acquisition modes (full-fan and half fan). To calculate the organ doses, the implemented MC model of the CBCT scanner together with a male voxel phantom ("Golem") was used. The good agreement between the MCNPX simulations and the CTDIw measurements (differences up to 17%) presented in this work reveals that the CBCT MC model was successfully validated, taking into account the several uncertainties. The adequacy of the computational model to map dose distributions during a CBCT scan is discussed in order to identify ways to reduce the total CBCT imaging dose. The organ dose assessment highlights the need to evaluate the therapeutic and the CBCT imaging doses, in a more balanced approach, and the
Monte Carlo calculation of received dose from ingestion and inhalation of natural uranium
International Nuclear Information System (INIS)
Trobok, M.; Zupunski, Lj.; Spasic-Jokic, V.; Gordanic, V.; Sovilj, P.
2009-01-01
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) [sr
International Nuclear Information System (INIS)
Allam, Kh. A.
2017-01-01
In this work, a new methodology is developed based on Monte Carlo simulation for tunnels and mines external dose calculation. Tunnels external dose evaluation model of a cylindrical shape of finite thickness with an entrance and with or without exit. A photon transportation model was applied for exposure dose calculations. A new software based on Monte Carlo solution was designed and programmed using Delphi programming language. The variation of external dose due to radioactive nuclei in a mine tunnel and the corresponding experimental data lies in the range 7.3 19.9%. The variation of specific external dose rate with position in, tunnel building material density and composition were studied. The given new model has more flexible for real external dose in any cylindrical tunnel structure calculations. (authors)
A measurement-based generalized source model for Monte Carlo dose simulations of CT scans.
Ming, Xin; Feng, Yuanming; Liu, Ransheng; Yang, Chengwen; Zhou, Li; Zhai, Hezheng; Deng, Jun
2017-03-07
The goal of this study is to develop a generalized source model for accurate Monte Carlo dose simulations of CT scans based solely on the measurement data without a priori knowledge of scanner specifications. The proposed generalized source model consists of an extended circular source located at x-ray target level with its energy spectrum, source distribution and fluence distribution derived from a set of measurement data conveniently available in the clinic. Specifically, the central axis percent depth dose (PDD) curves measured in water and the cone output factors measured in air were used to derive the energy spectrum and the source distribution respectively with a Levenberg-Marquardt algorithm. The in-air film measurement of fan-beam dose profiles at fixed gantry was back-projected to generate the fluence distribution of the source model. A benchmarked Monte Carlo user code was used to simulate the dose distributions in water with the developed source model as beam input. The feasibility and accuracy of the proposed source model was tested on a GE LightSpeed and a Philips Brilliance Big Bore multi-detector CT (MDCT) scanners available in our clinic. In general, the Monte Carlo simulations of the PDDs in water and dose profiles along lateral and longitudinal directions agreed with the measurements within 4%/1 mm for both CT scanners. The absolute dose comparison using two CTDI phantoms (16 cm and 32 cm in diameters) indicated a better than 5% agreement between the Monte Carlo-simulated and the ion chamber-measured doses at a variety of locations for the two scanners. Overall, this study demonstrated that a generalized source model can be constructed based only on a set of measurement data and used for accurate Monte Carlo dose simulations of patients' CT scans, which would facilitate patient-specific CT organ dose estimation and cancer risk management in the diagnostic and therapeutic radiology.
A measurement-based generalized source model for Monte Carlo dose simulations of CT scans
Ming, Xin; Feng, Yuanming; Liu, Ransheng; Yang, Chengwen; Zhou, Li; Zhai, Hezheng; Deng, Jun
2017-03-01
The goal of this study is to develop a generalized source model for accurate Monte Carlo dose simulations of CT scans based solely on the measurement data without a priori knowledge of scanner specifications. The proposed generalized source model consists of an extended circular source located at x-ray target level with its energy spectrum, source distribution and fluence distribution derived from a set of measurement data conveniently available in the clinic. Specifically, the central axis percent depth dose (PDD) curves measured in water and the cone output factors measured in air were used to derive the energy spectrum and the source distribution respectively with a Levenberg-Marquardt algorithm. The in-air film measurement of fan-beam dose profiles at fixed gantry was back-projected to generate the fluence distribution of the source model. A benchmarked Monte Carlo user code was used to simulate the dose distributions in water with the developed source model as beam input. The feasibility and accuracy of the proposed source model was tested on a GE LightSpeed and a Philips Brilliance Big Bore multi-detector CT (MDCT) scanners available in our clinic. In general, the Monte Carlo simulations of the PDDs in water and dose profiles along lateral and longitudinal directions agreed with the measurements within 4%/1 mm for both CT scanners. The absolute dose comparison using two CTDI phantoms (16 cm and 32 cm in diameters) indicated a better than 5% agreement between the Monte Carlo-simulated and the ion chamber-measured doses at a variety of locations for the two scanners. Overall, this study demonstrated that a generalized source model can be constructed based only on a set of measurement data and used for accurate Monte Carlo dose simulations of patients’ CT scans, which would facilitate patient-specific CT organ dose estimation and cancer risk management in the diagnostic and therapeutic radiology.
Sharma, Sunil D; Kumar, Rajesh; Akhilesh, Philomina; Pendse, Anil M; Deshpande, Sudesh; Misra, Basant K
2012-01-01
Dose verification to cochlea using metal oxide semiconductor field effect transistor (MOSFET) dosimeter using a specially designed multi slice head and neck phantom during the treatment of acoustic schwannoma by Gamma Knife radiosurgery unit. A multi slice polystyrene head phantom was designed and fabricated for measurement of dose to cochlea during the treatment of the acoustic schwannoma. The phantom has provision to position the MOSFET dosimeters at the desired location precisely. MOSFET dosimeters of 0.2 mm x 0.2 mm x 0.5 μm were used to measure the dose to the cochlea. CT scans of the phantom with MOSFETs in situ were taken along with Leksell frame. The treatment plans of five patients treated earlier for acoustic schwannoma were transferred to the phantom. Dose and coordinates of maximum dose point inside the cochlea were derived. The phantom along with the MOSFET dosimeters was irradiated to deliver the planned treatment and dose received by cochlea were measured. The treatment planning system (TPS) estimated and measured dose to the cochlea were in the range of 7.4 - 8.4 Gy and 7.1 - 8 Gy, respectively. The maximum variation between TPS calculated and measured dose to cochlea was 5%. The measured dose values were found in good agreement with the dose values calculated using the TPS. The MOSFET dosimeter can be a suitable choice for routine dose verification in the Gamma Knife radiosurgery.
Evaluation of GafChromic EBT prototype B for external beam dose verification
International Nuclear Information System (INIS)
Todorovic, M.; Fischer, M.; Cremers, F.; Thom, E.; Schmidt, R.
2006-01-01
The capability of the new GafChromic EBT prototype B for external beam dose verification is investigated in this paper. First the general characteristics of this film (dose response, postirradiation coloration, influence of calibration field size) were derived using a flat-bed scanner. In the dose range from 0.1 to 8 Gy, the sensitivity of the EBT prototype B film is ten times higher than the response of the GafChromic HS, which so far was the GafChromic film with the highest sensitivity. Compared with the Kodak EDR2 film, the response of the EBT is higher by a factor of 3 in the dose range from 0.1 to 8 Gy. The GafChromic EBT almost does not show a temporal growth of the optical density and there is no influence of the chosen calibration field size on the dose response curve obtained from this data. A MatLab program was written to evaluate the two-dimensional dose distributions from treatment planning systems and GafChromic EBT film measurements. Verification of external beam therapy (SRT, IMRT) using the above-mentioned approach resulted in very small differences between the planned and the applied dose. The GafChromic EBT prototype B together with the flat-bed scanner and MatLab is a successful approach for making the advantages of the GafChromic films applicable for verification of external beam therapy
International Nuclear Information System (INIS)
Ibrahim, Ahmad M.; Peplow, Douglas E.; Peterson, Joshua L.; Grove, Robert E.
2014-01-01
Highlights: •Develop the novel Multi-Step CADIS (MS-CADIS) hybrid Monte Carlo/deterministic method for multi-step shielding analyses. •Accurately calculate shutdown dose rates using full-scale Monte Carlo models of fusion energy systems. •Demonstrate the dramatic efficiency improvement of the MS-CADIS method for the rigorous two step calculations of the shutdown dose rate in fusion reactors. -- Abstract: The rigorous 2-step (R2S) computational system uses three-dimensional Monte Carlo transport simulations to calculate the shutdown dose rate (SDDR) in fusion reactors. Accurate full-scale R2S calculations are impractical in fusion reactors because they require calculating space- and energy-dependent neutron fluxes everywhere inside the reactor. The use of global Monte Carlo variance reduction techniques was suggested for accelerating the R2S neutron transport calculation. However, the prohibitive computational costs of these approaches, which increase with the problem size and amount of shielding materials, inhibit their ability to accurately predict the SDDR in fusion energy systems using full-scale modeling of an entire fusion plant. This paper describes a novel hybrid Monte Carlo/deterministic methodology that uses the Consistent Adjoint Driven Importance Sampling (CADIS) method but focuses on multi-step shielding calculations. The Multi-Step CADIS (MS-CADIS) methodology speeds up the R2S neutron Monte Carlo calculation using an importance function that represents the neutron importance to the final SDDR. Using a simplified example, preliminary results showed that the use of MS-CADIS enhanced the efficiency of the neutron Monte Carlo simulation of an SDDR calculation by a factor of 550 compared to standard global variance reduction techniques, and that the efficiency enhancement compared to analog Monte Carlo is higher than a factor of 10,000
Local dose enhancement in radiation therapy: Monte Carlo simulation study
International Nuclear Information System (INIS)
Silva, Laura E. da; Nicolucci, Patricia
2014-01-01
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)
SU-F-T-267: A Clarkson-Based Independent Dose Verification for the Helical Tomotherapy
Energy Technology Data Exchange (ETDEWEB)
Nagata, H [Shonan Kamakura General Hospital, Kamakura, Kanagawa, (Japan); Juntendo University, Hongo, Tokyo (Japan); Hongo, H [Shonan Kamakura General Hospital, Kamakura, Kanagawa, (Japan); Tsukuba University, Tsukuba, Ibaraki (Japan); Kawai, D [Kanagawa Cancer Center, Yokohama, Kanagawa (Japan); Takahashi, R [Cancer Institute Hospital of Japanese Foundation for Cancer Research, Koto, Tokyo (Japan); Hashimoto, H [Shonan Fujisawa Tokushukai Hospital, Fujisawa, Kanagawa (Japan); Tachibana, H [National Cancer Center, Kashiwa, Chiba (Japan)
2016-06-15
Purpose: There have been few reports for independent dose verification for Tomotherapy. We evaluated the accuracy and the effectiveness of an independent dose verification system for the Tomotherapy. Methods: Simple MU Analysis (SMU, Triangle Product, Ishikawa, Japan) was used as the independent verification system and the system implemented a Clarkson-based dose calculation algorithm using CT image dataset. For dose calculation in the SMU, the Tomotherapy machine-specific dosimetric parameters (TMR, Scp, OAR and MLC transmission factor) were registered as the machine beam data. Dose calculation was performed after Tomotherapy sinogram from DICOM-RT plan information was converted to the information for MU and MLC location at more segmented control points. The performance of the SMU was assessed by a point dose measurement in non-IMRT and IMRT plans (simple target and mock prostate plans). Subsequently, 30 patients’ treatment plans for prostate were compared. Results: From the comparison, dose differences between the SMU and the measurement were within 3% for all cases in non-IMRT plans. In the IMRT plan for the simple target, the differences (Average±1SD) were −0.70±1.10% (SMU vs. TPS), −0.40±0.10% (measurement vs. TPS) and −1.20±1.00% (measurement vs. SMU), respectively. For the mock prostate, the differences were −0.40±0.60% (SMU vs. TPS), −0.50±0.90% (measurement vs. TPS) and −0.90±0.60% (measurement vs. SMU), respectively. For patients’ plans, the difference was −0.50±2.10% (SMU vs. TPS). Conclusion: A Clarkson-based independent dose verification for the Tomotherapy can be clinically available as a secondary check with the similar tolerance level of AAPM Task group 114. This research is partially supported by Japan Agency for Medical Research and Development (AMED)
International Nuclear Information System (INIS)
Mazonakis, Michalis; Tzedakis, Antonis; Damilakis, John; Varveris, Haris; Kachris, Stefanos; Gourtsoyiannis, Nicholas
2006-01-01
The purpose of this study was to estimate the scattered dose to thyroid from prophylactic cranial irradiation during childhood. The MCNP transport code and mathematical phantoms representing the average individual at ages 3, 5, 10, 15 and 18 years old were employed to simulate cranial radiotherapy using two lateral opposed fields. The mean radiation dose received by the thyroid gland was calculated. A 10 cm thick lead block placed on the patient's couch to shield the thyroid was simulated by MCNP code. The Monte Carlo model was validated by measuring the scattered dose to the unshielded and shielded thyroid using three different humanoid phantoms and thermoluminescense dosimetry. For a cranial dose of 18 Gy, the thyroid dose obtained by Monte Carlo calculations varied from 47 to 79 cGy depending upon the age of the child. Appropriate placement of the couch block resulted in a thyroid dose reduction by 39 to 54%. Thyroid dose values at all possible positions of the radiosensitive gland with respect to the inferior field edge at five different patient ages were found. The mean difference between Monte Carlo results and thyroid dose measurements was 9.6%. (note)
Experimental validation of Monte Carlo calculations for organ dose
International Nuclear Information System (INIS)
Yalcintas, M.G.; Eckerman, K.F.; Warner, G.G.
1980-01-01
The problem of validating estimates of absorbed dose due to photon energy deposition is examined. The computational approaches used for the estimation of the photon energy deposition is examined. The limited data for validation of these approaches is discussed and suggestions made as to how better validation information might be obtained
Dose verification for respiratory-gated volumetric modulated arc therapy
Energy Technology Data Exchange (ETDEWEB)
Qian Jianguo; Xing Lei; Liu Wu; Luxton, Gary, E-mail: gluxton@stanford.edu [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305 (United States)
2011-08-07
A novel commercial medical linac system (TrueBeam(TM), Varian Medical Systems, Palo Alto, CA) allows respiratory-gated volumetric modulated arc therapy (VMAT), a new modality for treating moving tumors with high precision and improved accuracy by allowing for regular motion associated with a patient's breathing during VMAT delivery. The purpose of this work is to adapt a previously-developed dose reconstruction technique to evaluate the fidelity of VMAT treatment during gated delivery under clinic-relevant periodic motion related to patient breathing. A Varian TrueBeam system was used in this study. VMAT plans were created for three patients with lung or pancreas tumors. Conventional 6 and 15 MV beams with flattening filter and high-dose-rate 10 MV beams with no flattening filter were used in these plans. Each patient plan was delivered to a phantom first without gating and then with gating for three simulated respiratory periods (3, 4.5 and 6 s). Using the adapted log-file-based dose reconstruction procedure supplemented with ion chamber array (Seven29(TM), PTW, Freiburg, Germany) measurements, the delivered dose was used to evaluate the fidelity of gated VMAT delivery. Comparison of Seven29 measurements with and without gating showed good agreement with gamma-index passing rates above 99% for 1%/1 mm dose accuracy/distance-to-agreement criteria. With original plans as reference, gamma-index passing rates were 100% for the reconstituted plans (1%/1 mm criteria) and 93.5-100% for gated Seven29 measurements (3%/3 mm criteria). In the presence of leaf error deliberately introduced into the gated delivery of a pancreas patient plan, both dose reconstruction and Seven29 measurement consistently indicated substantial dosimetric differences from the original plan. In summary, a dose reconstruction procedure was demonstrated for evaluating the accuracy of respiratory-gated VMAT delivery. This technique showed that under clinical operation, the TrueBeam system
SU-E-T-49: A Multi-Institutional Study of Independent Dose Verification for IMRT
International Nuclear Information System (INIS)
Baba, H; Tachibana, H; Kamima, T; Takahashi, R; Kawai, D; Sugawara, Y; Yamamoto, T; Sato, A; Yamashita, M
2015-01-01
Purpose: AAPM TG114 does not cover the independent verification for IMRT. We conducted a study of independent dose verification for IMRT in seven institutes to show the feasibility. Methods: 384 IMRT plans in the sites of prostate and head and neck (HN) were collected from the institutes, where the planning was performed using Eclipse and Pinnacle3 with the two techniques of step and shoot (S&S) and sliding window (SW). All of the institutes used a same independent dose verification software program (Simple MU Analysis: SMU, Triangle Product, Ishikawa, JP), which is Clarkson-based and CT images were used to compute radiological path length. An ion-chamber measurement in a water-equivalent slab phantom was performed to compare the doses computed using the TPS and an independent dose verification program. Additionally, the agreement in dose computed in patient CT images between using the TPS and using the SMU was assessed. The dose of the composite beams in the plan was evaluated. Results: The agreement between the measurement and the SMU were −2.3±1.9 % and −5.6±3.6 % for prostate and HN sites, respectively. The agreement between the TPSs and the SMU were −2.1±1.9 % and −3.0±3.7 for prostate and HN sites, respectively. There was a negative systematic difference with similar standard deviation and the difference was larger in the HN site. The S&S technique showed a statistically significant difference between the SW. Because the Clarkson-based method in the independent program underestimated (cannot consider) the dose under the MLC. Conclusion: The accuracy would be improved when the Clarkson-based algorithm should be modified for IMRT and the tolerance level would be within 5%
Modelling of electron contamination in clinical photon beams for Monte Carlo dose calculation
International Nuclear Information System (INIS)
Yang, J; Li, J S; Qin, L; Xiong, W; Ma, C-M
2004-01-01
The purpose of this work is to model electron contamination in clinical photon beams and to commission the source model using measured data for Monte Carlo treatment planning. In this work, a planar source is used to represent the contaminant electrons at a plane above the upper jaws. The source size depends on the dimensions of the field size at the isocentre. The energy spectra of the contaminant electrons are predetermined using Monte Carlo simulations for photon beams from different clinical accelerators. A 'random creep' method is employed to derive the weight of the electron contamination source by matching Monte Carlo calculated monoenergetic photon and electron percent depth-dose (PDD) curves with measured PDD curves. We have integrated this electron contamination source into a previously developed multiple source model and validated the model for photon beams from Siemens PRIMUS accelerators. The EGS4 based Monte Carlo user code BEAM and MCSIM were used for linac head simulation and dose calculation. The Monte Carlo calculated dose distributions were compared with measured data. Our results showed good agreement (less than 2% or 2 mm) for 6, 10 and 18 MV photon beams
Absorbed dose in fibrotic microenvironment models employing Monte Carlo simulation
International Nuclear Information System (INIS)
Zambrano Ramírez, O.D.; Rojas Calderón, E.L.; Azorín Vega, E.P.; Ferro Flores, G.; Martínez Caballero, E.
2015-01-01
The presence or absence of fibrosis and yet more, the multimeric and multivalent nature of the radiopharmaceutical have recently been reported to have an effect on the radiation absorbed dose in tumor microenvironment models. Fibroblast and myofibroblast cells produce the extracellular matrix by the secretion of proteins which provide structural and biochemical support to cells. The reactive and reparative mechanisms triggered during the inflammatory process causes the production and deposition of extracellular matrix proteins, the abnormal excessive growth of the connective tissue leads to fibrosis. In this work, microenvironment (either not fibrotic or fibrotic) models composed of seven spheres representing cancer cells of 10 μm in diameter each with a 5 μm diameter inner sphere (cell nucleus) were created in two distinct radiation transport codes (PENELOPE and MCNP). The purpose of creating these models was to determine the radiation absorbed dose in the nucleus of cancer cells, based on previously reported radiopharmaceutical retain (by HeLa cells) percentages of the 177 Lu-Tyr 3 -octreotate (monomeric) and 177 Lu-Tyr 3 -octreotate-AuNP (multimeric) radiopharmaceuticals. A comparison in the results between the PENELOPE and MCNP was done. We found a good agreement in the results of the codes. The percent difference between the increase percentages of the absorbed dose in the not fibrotic model with respect to the fibrotic model of the codes PENELOPE and MCNP was found to be under 1% for both radiopharmaceuticals. (authors)
Toltz, Allison; Hoesl, Michaela; Schuemann, Jan; Seuntjens, Jan; Lu, Hsiao-Ming; Paganetti, Harald
2017-11-01
Our group previously introduced an in vivo proton range verification methodology in which a silicon diode array system is used to correlate the dose rate profile per range modulation wheel cycle of the detector signal to the water-equivalent path length (WEPL) for passively scattered proton beam delivery. The implementation of this system requires a set of calibration data to establish a beam-specific response to WEPL fit for the selected 'scout' beam (a 1 cm overshoot of the predicted detector depth with a dose of 4 cGy) in water-equivalent plastic. This necessitates a separate set of measurements for every 'scout' beam that may be appropriate to the clinical case. The current study demonstrates the use of Monte Carlo simulations for calibration of the time-resolved diode dosimetry technique. Measurements for three 'scout' beams were compared against simulated detector response with Monte Carlo methods using the Tool for Particle Simulation (TOPAS). The 'scout' beams were then applied in the simulation environment to simulated water-equivalent plastic, a CT of water-equivalent plastic, and a patient CT data set to assess uncertainty. Simulated detector response in water-equivalent plastic was validated against measurements for 'scout' spread out Bragg peaks of range 10 cm, 15 cm, and 21 cm (168 MeV, 177 MeV, and 210 MeV) to within 3.4 mm for all beams, and to within 1 mm in the region where the detector is expected to lie. Feasibility has been shown for performing the calibration of the detector response for three 'scout' beams through simulation for the time-resolved diode dosimetry technique in passive scattered proton delivery. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.
Monte-Carlo Method Python Library for dose distribution Calculation in Brachytherapy
Energy Technology Data Exchange (ETDEWEB)
Randriantsizafy, R D; Ramanandraibe, M J [Madagascar Institut National des Sciences et Techniques Nucleaires, Antananarivo (Madagascar); Raboanary, R [Institut of astro and High-Energy Physics Madagascar, University of Antananarivo, Antananarivo (Madagascar)
2007-07-01
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.
Monte-Carlo Method Python Library for dose distribution Calculation in Brachytherapy
International Nuclear Information System (INIS)
Randriantsizafy, R.D.; Ramanandraibe, M.J.; Raboanary, R.
2007-01-01
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.
An IMRT dose distribution study using commercial verification software
International Nuclear Information System (INIS)
Grace, M.; Liu, G.; Fernando, W.; Rykers, K.
2004-01-01
Full text: The introduction of IMRT requires users to confirm that the isodose distributions and relative doses calculated by their planning system match the doses delivered by their linear accelerators. To this end the commercially available software, VeriSoft TM (PTW-Freiburg, Germany) was trialled to determine if the tools and functions it offered would be of benefit to this process. The CMS Xio (Computer Medical System) treatment planning system was used to generate IMRT plans that were delivered with an upgraded Elekta SL15 linac. Kodak EDR2 film sandwiched in RW3 solid water (PTW-Freiburg, Germany) was used to measure the IMRT fields delivered with 6 MV photons. The isodose and profiles measured with the film generally agreed to within ± 3% or ± 3 mm with the planned doses, in some regions (outside the IMRT field) the match fell to within ± 5%. The isodose distributions of the planning system and the film could be compared on screen and allows for electronic records of the comparison to be kept if so desired. The features and versatility of this software has been of benefit to our IMRT QA program. Furthermore, the VeriSoft TM software allows for quick and accurate, automated planar film analysis.Copyright (2004) Australasian College of Physical Scientists and Engineers in Medicine
Verification of the shift Monte Carlo code with the C5G7 reactor benchmark
International Nuclear Information System (INIS)
Sly, N. C.; Mervin, B. T.; Mosher, S. W.; Evans, T. M.; Wagner, J. C.; Maldonado, G. I.
2012-01-01
Shift is a new hybrid Monte Carlo/deterministic radiation transport code being developed at Oak Ridge National Laboratory. At its current stage of development, Shift includes a parallel Monte Carlo capability for simulating eigenvalue and fixed-source multigroup transport problems. This paper focuses on recent efforts to verify Shift's Monte Carlo component using the two-dimensional and three-dimensional C5G7 NEA benchmark problems. Comparisons were made between the benchmark eigenvalues and those output by the Shift code. In addition, mesh-based scalar flux tally results generated by Shift were compared to those obtained using MCNP5 on an identical model and tally grid. The Shift-generated eigenvalues were within three standard deviations of the benchmark and MCNP5-1.60 values in all cases. The flux tallies generated by Shift were found to be in very good agreement with those from MCNP. (authors)
International Nuclear Information System (INIS)
Pelagade, S.M.; Bopche, T.T.; Namitha, K.; Munshi, M.; Bhola, S.; Sharma, H.; Patel, B.K.; Vyas, R.K.
2008-01-01
The outcome of stereotactic radiotherapy (SRT) and stereotactic radiosurgery (SRS) in both benign and malignant tumors within the cranial region highly depends on precision in dosimetry, dose delivery and the accuracy assessment of stereotaxy associated with the unit. The frames BRW (Brown-Roberts-Wells) and GTC (Gill- Thomas-Cosman) can facilitate accurate patient positioning as well as precise targeting of tumours. The implementation of this technique may result in a significant benefit as compared to conventional therapy. As the target localization accuracy is improved, the demand for treatment planning accuracy of a TPS is also increased. The accuracy of stereotactic X Knife treatment planning system has two components to verify: (i) the dose delivery verification and the accuracy assessment of stereotaxy; (ii) to ensure that the Cartesian coordinate system associated is well established within the TPS for accurate determination of a target position. Both dose delivery verification and target positional accuracy affect dose delivery accuracy to a defined target. Hence there is a need to verify these two components in quality assurance protocol. The main intention of this paper is to present our dose delivery verification procedure using cylindrical wax phantom and accuracy assessment (target position) of stereotaxy using Geometric Phantom on Elekta's Precise linear accelerator for stereotactic installation
International Nuclear Information System (INIS)
Chen Ying; Luo Yisheng; Cao Zhenshan; Liu Xiulin
2006-01-01
To estimate accurately biological dose of the victims exposed to high dose, the dose-response curves of chromosome aberration induced by 6-22 Gy 60 Co γ-ray were established. Human peripheral blood in vitro was irradiated, then lymphocytes were concentrated, cultured 52h, 68h and 72h and harvested. The frequencies of dicentrics (multi-centrics) and rings were counted and compared between different culture times. The dose-response curves and equations were established, as well as verified with high dose exposure accidents. The experiment showed that the culture time should be prolonged properly after high dose exposure, and no significant differences were observed between 52-72h culture. The dose-response curve of 6-22 Gy fitted to linear-square model Y=-2.269 + 0.776D - 7.868 x 10 -3 D 2 and is reliable through verification of the accident dose estimations. In this study, the dose-response curve and equation of chromosome dic + r after 6-22 Gy high dose irradiation were established firstly, and exact dose estimation can be achieved according to it. (authors)
International Nuclear Information System (INIS)
Homma, Y.; Moriwaki, H.; Ikeda, K.; Ohdi, S.
2013-01-01
This paper deals with the verification of the 3 dimensional triangular prismatic discrete ordinates transport calculation code ENSEMBLE-TRIZ by comparison with the multi-group Monte Carlo calculation code GMVP in a large fast breeder reactor. The reactor is a 750 MWe electric power sodium cooled reactor. Nuclear characteristics are calculated at the beginning of cycle of an initial core and at the beginning and the end of cycle of an equilibrium core. According to the calculations, the differences between the two methodologies are smaller than 0.0002 Δk in the multiplication factor, relatively about 1% in the control rod reactivity, and 1% in the sodium void reactivity. (authors)
International Nuclear Information System (INIS)
Sempau, J.; Bielajew, A.F.
2000-01-01
The Monte Carlo calculation of dose for radiotherapy treatment planning purposes introduces unavoidable statistical noise into the prediction of dose in a given volume element (voxel). When the doses in these voxels are summed to produce dose volume histograms (DVHs), this noise translates into a broadening of differential DVHs and correspondingly flatter DVHs. A brute force approach would entail calculating dose for long periods of time - enough to ensure that the DVHs had converged. In this paper we introduce an approach for deconvolving the statistical noise from DVHs, thereby obtaining estimates for converged DVHs obtained about 100 times faster than the brute force approach described above. There are two important implications of this work: (a) decisions based upon DVHs may be made much more economically using the new approach and (b) inverse treatment planning or optimization methods may employ Monte Carlo dose calculations at all stages of the iterative procedure since the prohibitive cost of Monte Carlo calculations at the intermediate calculation steps can be practically eliminated. (author)
Gamma irradiator dose mapping: a Monte Carlo simulation and experimental measurements
International Nuclear Information System (INIS)
Rodrigues, Rogerio R.; Ribeiro, Mariana A.; Grynberg, Suely E.; Ferreira, Andrea V.; Meira-Belo, Luiz Claudio; Sousa, Romulo V.; Sebastiao, Rita de C.O.
2009-01-01
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 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)
International Nuclear Information System (INIS)
Cumak, V.; Morgun, A.; Bakhanova, O.; Loganovs'kij, K.; Loganovs'ka, T.; Marazziti, D.
2015-01-01
This study aimed at investigating radiation exposure of hippocampus in interventional medical professionals irradiated in the operating room, and to compare doses in the hippocampus with the effective dose (protection quantity), as well as with the doses measured by individual dosimeter, in order to estimate probability of reaching levels of radiation induced cognitive and other neuropsychiatric alterations during their working career, through a Monte Carlo simulation. The results showed that cranial irradiation was very heterogeneous and depended on the projection: doses of left and right hippocampi may be different up to a factor of 2.5; under certain conditions, the dose of the left hippocampus may be twice the effective dose, estimated by conventional double dosimetry algorithm. The professional span doses of the irradiated hippocampus may overcome the threshold able to provoke possible cognitive and emotional-behavioral impairment. Therefore, in-depth studies of the effects of brain irradiation in occupationally exposed interventional medical personnel appear urgently needed and crucial
Effects of physics change in Monte Carlo code on electron pencil beam dose distributions
International Nuclear Information System (INIS)
Toutaoui, Abdelkader; Khelassi-Toutaoui, Nadia; Brahimi, Zakia; Chami, Ahmed Chafik
2012-01-01
Pencil beam algorithms used in computerized electron beam dose planning are usually described using the small angle multiple scattering theory. Alternatively, the pencil beams can be generated by Monte Carlo simulation of electron transport. In a previous work, the 4th version of the Electron Gamma Shower (EGS) Monte Carlo code was used to obtain dose distributions from monoenergetic electron pencil beam, with incident energy between 1 MeV and 50 MeV, interacting at the surface of a large cylindrical homogeneous water phantom. In 2000, a new version of this Monte Carlo code has been made available by the National Research Council of Canada (NRC), which includes various improvements in its electron-transport algorithms. In the present work, we were interested to see if the new physics in this version produces pencil beam dose distributions very different from those calculated with oldest one. The purpose of this study is to quantify as well as to understand these differences. We have compared a series of pencil beam dose distributions scored in cylindrical geometry, for electron energies between 1 MeV and 50 MeV calculated with two versions of the Electron Gamma Shower Monte Carlo Code. Data calculated and compared include isodose distributions, radial dose distributions and fractions of energy deposition. Our results for radial dose distributions show agreement within 10% between doses calculated by the two codes for voxels closer to the pencil beam central axis, while the differences are up to 30% for longer distances. For fractions of energy deposition, the results of the EGS4 are in good agreement (within 2%) with those calculated by EGSnrc at shallow depths for all energies, whereas a slightly worse agreement (15%) is observed at deeper distances. These differences may be mainly attributed to the different multiple scattering for electron transport adopted in these two codes and the inclusion of spin effect, which produces an increase of the effective range of
International Nuclear Information System (INIS)
Sankar, A.; Gopalkrishna Kurup, P.G.; Murali, V.; Ayyangar, Komanduri M.; Mothilal Nehru, R.; Velmurugan, J.
2006-01-01
This work was undertaken with the intention of investigating the possibility of clinical use of commercially available self-developing radiochromic film - Gafchromic EBT film - for IMRT dose verification. The dose response curves were generated for the films using VXR-16 film scanner. The results obtained with EBT films were compared with the results of Kodak EDR2 films. It was found that the EBT film has a linear response between the dose ranges of 0 and 600 cGy. The dose-related characteristics of the EBT film, like post-irradiation color growth with time, film uniformity and effect of scanning orientation, were studied. There is up to 8.6% increase in the color density between 2 and 40 h after irradiation. There was a considerable variation, up to 8.5%, in the film uniformity over its sensitive region. The quantitative difference between calculated and measured dose distributions was analyzed using Gamma index with the tolerance of 3% dose difference and 3 mm distance agreement. EDR2 films showed good and consistent results with the calculated dose distribution, whereas the results obtained using EBT were inconsistent. The variation in the film uniformity limits the use of EBT film for conventional large field IMRT verification. For IMRT of smaller field size (4.5 x 4.5 cm), the results obtained with EBT were comparable with results of EDR2 films. (author)
Simulation studies for the in-vivo dose verification of particle therapy
International Nuclear Information System (INIS)
Rohling, Heide
2015-01-01
An increasing number of cancer patients is treated with proton beams or other light ion beams which allow to deliver dose precisely to the tumor. However, the depth dose distribution of these particles, which enables this precision, is sensitive to deviations from the treatment plan, as e.g. anatomical changes. Thus, to assure the quality of the treatment, a non-invasive in-vivo dose verification is highly desired. This monitoring of particle therapy relies on the detection of secondary radiation which is produced by interactions between the beam particles and the nuclei of the patient's tissue. Up to now, the only clinically applied method for in-vivo dosimetry is Positron Emission Tomography which makes use of the β + -activity produced during the irradiation (PT-PET). Since from a PT-PET measurement the applied dose cannot be directly deduced, the simulated distribution of β + -emitting nuclei is used as a basis for the analysis of the measured PT-PET data. Therefore, the reliable modeling of the production rates and the spatial distribution of the β + -emitters is required. PT-PET applied during instead of after the treatment is referred to as in-beam PET. A challenge concerning in-beam PET is the design of the PET camera, because a standard full-ring scanner is not feasible. Thus, for in-beam PET and PGI dedicated detection systems and, moreover, profound knowledge about the corresponding radiation fields are required. Using various simulation codes, this thesis contributes to the modelling of the β + -emitters and photons produced during particle irradiation, as well as to the evaluation and optimization of hardware for both techniques. Concerning the modeling of the production of the relevant β + -emitters, the abilities of the Monte Carlo simulation code PHITS and of the deterministic, one-dimensional code HIBRAC were assessed. HIBRAC was substantially extended to enable the modeling of the depth-dependent yields of specific nuclides. For proton
Energy Technology Data Exchange (ETDEWEB)
Bonzoumet, S P.J.; Braz, D; Lopes, R T [Nuclear Instrumentation Laboratory, COPPE/UFRJ, Rio de Janeiro (Brazil); Anjos, M J [Nuclear Instrumentation Laboratory, COPPE/UFRJ, Rio de Janeiro (Brazil); Universidade do Estado do Rio de Janeiro, Rio de Janeiro (Brazil). Instituto de Fisica; Barroso, R C.S. [Universidade do Estado do Rio de Janeiro, Rio de Janeiro (Brazil). Instituto de Fisica
2003-11-15
Full text: The purpose of this study was to study the absorbed dose in mouth due to scattering in teeth in dental radiography using the monte carlo simulation. The Electron Gamma Shower (EGS-4) system of computer codes was used, which is a general purpose package for monte carlo simulation of the coupled transport of electrons and photons in an arbitrary geometry for particles with energies above a few keV up to several TeV. In the case of a X ray dental the low energy photons beam, are removed of the spectrum by the filtration. These low energy photons beam do not contribute in the obtaining of the radiographic image, but they will be contribute in the dose to the patient, however when the incident radiation crosses the tooth it generates a scattering radiation that contributes in the dose received by the patient in the oral cavity (cheek, tooth and oral cavity). Dental radiography is one of the largest single groups of radiographic examination accounting for 32% of radiographs taken in the Brazil. A number of relatively recent improvements in technology, equipment and techniques have the potential to reduce patient radiation dose and improve image quality. To optimize radiation protection all reasonable means should be employed to minimize the dose of each exposure. Dentists therefore need to keep up to date with changes in techniques and equipment and modify their own practice. In preliminary analysis could be notice that the energy below the 30 keV (low energy) is deposited in the cheek. To 30 keV photons there is the maximum absorbed energy in the tooth (about 60%). In 40 keV could be notice that deposited energy is same to teeth and cheek, but up to 40 keV just a small part of energy is deposited, e.g., the great part of energy is transmitted to the inner mouth (oral cavity). (orig.)
Monte Carlo simulation of dose enhancement effect of X-ray at Au/Si interface
International Nuclear Information System (INIS)
Wu Zhengxin; He Chengfa; Lu Wu; Guo Qi; Yu Xin; Zhang Lei; Deng Wei; Zheng Qiwen; ARKIN Abulim
2013-01-01
Background: The dose enhancement factor of X-ray was found in 1970s, because of its bad damage to electronic devices. Purpose: This paper is mainly to calculate the dose-enhancement factor at Au/Si interfaces. Methods: The gradient distribution of dose with X-rays has been studied at and near the interface of Au/Si by Monte-Carlo simulation of particle transportation. The mechanism of dose enhancement is discussed based on the principles of interaction of photon with matter. A 3D Au/Si model has been established by MCNP5 program and the dose-enhancement factors of different thicknesses Au/Si interfaces were calculated by Monte Carlo method. Results: The calculated results demonstrate that there exists a stronger dose-enhancement in the Si side near the interface when the energy of X-ray is 30-300 keV. Conclusions: When the thickness of Au is 0-10 μm, dose-enhancement factor of X-ray increases along with the increase of the thickness of Au, when the thickness of Au exceeds 10 μm, dose-enhancement factor of X-ray decreases along with the increase of the thickness of Au. (authors)
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...
Monte Carlo characterisation of the Dose Magnifying Glass for proton therapy quality assurance
Merchant, A. H.; Guatelli, S.; Petesecca, M.; Jackson, M.; Rozenfeld, A. B.
2017-01-01
A Geant4 Monte Carlo simulation study was carried out to characterise a novel silicon strip detector, the Dose Magnifying Glass (DMG), for use in proton therapy Quality Assurance. We investigated the possibility to use DMG to determine the energy of the incident proton beam. The advantages of DMG are quick response, easy operation and high spatial resolution. In this work we theoretically proved that DMG can be used for QA in the determination of the energy of the incident proton beam, for ocular and prostate cancer therapy. The study was performed by means of Monte Carlo simulations Experimental measurements are currently on their way to confirm the results of this simulation study.
SU-F-T-122: 4Dand 5D Proton Dose Evaluation with Monte Carlo
Energy Technology Data Exchange (ETDEWEB)
Titt, U; Mirkovic, D; Yepes, P; Liu, A; Peeler, C; Randenyia, S; Mohan, R [UT MD Anderson Cancer Center, Houston, TX (United States)
2016-06-15
Purpose: We evaluated uncertainties in therapeutic proton doses of a lung treatment, taking into account intra-fractional geometry changes, such as breathing, and inter-fractional changes, such as tumor shrinkage and weight loss. Methods: A Monte Carlo study was performed using four dimensional CT image sets (4DCTs) and weekly repeat imaging (5DCTs) to compute fixed RBE (1.1) and variable RBE weighted dose in an actual lung treatment geometry. The MC2 Monte Carlo system was employed to simulate proton energy deposition and LET distributions according to a thoracic cancer treatment plan developed with a 3D-CT in a commercial treatment planning system, as well as in each of the phases of 4DCT sets which were recorded weekly throughout the course of the treatment. A cumulative dose distribution in relevant structures was computed and compared to the predictions of the treatment planning system. Results: Using the Monte Carlo method, dose deposition estimates with the lowest possible uncertainties were produced. Comparison with treatment planning predictions indicates that significant uncertainties may be associated with therapeutic lung dose prediction from treatment planning systems, depending on the magnitude of inter- and intra-fractional geometry changes. Conclusion: As this is just a case study, a more systematic investigation accounting for a cohort of patients is warranted; however, this is less practical because Monte Carlo simulations of such cases require enormous computational resources. Hence our study and any future case studies may serve as validation/benchmarking data for faster dose prediction engines, such as the track repeating algorithm, FDC.
Effective dose in individuals from exposure the patients treated with 131I using Monte Carlo method
International Nuclear Information System (INIS)
Carvalho Junior, Alberico B. de; Silva, Ademir X.
2007-01-01
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 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)
SU-E-J-60: Efficient Monte Carlo Dose Calculation On CPU-GPU Heterogeneous Systems
Energy Technology Data Exchange (ETDEWEB)
Xiao, K; Chen, D. Z; Hu, X. S [University of Notre Dame, Notre Dame, IN (United States); Zhou, B [Altera Corp., San Jose, CA (United States)
2014-06-01
Purpose: It is well-known that the performance of GPU-based Monte Carlo dose calculation implementations is bounded by memory bandwidth. One major cause of this bottleneck is the random memory writing patterns in dose deposition, which leads to several memory efficiency issues on GPU such as un-coalesced writing and atomic operations. We propose a new method to alleviate such issues on CPU-GPU heterogeneous systems, which achieves overall performance improvement for Monte Carlo dose calculation. Methods: Dose deposition is to accumulate dose into the voxels of a dose volume along the trajectories of radiation rays. Our idea is to partition this procedure into the following three steps, which are fine-tuned for CPU or GPU: (1) each GPU thread writes dose results with location information to a buffer on GPU memory, which achieves fully-coalesced and atomic-free memory transactions; (2) the dose results in the buffer are transferred to CPU memory; (3) the dose volume is constructed from the dose buffer on CPU. We organize the processing of all radiation rays into streams. Since the steps within a stream use different hardware resources (i.e., GPU, DMA, CPU), we can overlap the execution of these steps for different streams by pipelining. Results: We evaluated our method using a Monte Carlo Convolution Superposition (MCCS) program and tested our implementation for various clinical cases on a heterogeneous system containing an Intel i7 quad-core CPU and an NVIDIA TITAN GPU. Comparing with a straightforward MCCS implementation on the same system (using both CPU and GPU for radiation ray tracing), our method gained 2-5X speedup without losing dose calculation accuracy. Conclusion: The results show that our new method improves the effective memory bandwidth and overall performance for MCCS on the CPU-GPU systems. Our proposed method can also be applied to accelerate other Monte Carlo dose calculation approaches. This research was supported in part by NSF under Grants CCF
SU-E-T-202: Impact of Monte Carlo Dose Calculation Algorithm On Prostate SBRT Treatments
Energy Technology Data Exchange (ETDEWEB)
Venencia, C; Garrigo, E; Cardenas, J; Castro Pena, P [Instituto de Radioterapia - Fundacion Marie Curie, Cordoba (Argentina)
2014-06-01
Purpose: The purpose of this work was to quantify the dosimetric impact of using Monte Carlo algorithm on pre calculated SBRT prostate treatment with pencil beam dose calculation algorithm. Methods: A 6MV photon beam produced by a Novalis TX (BrainLAB-Varian) linear accelerator equipped with HDMLC was used. Treatment plans were done using 9 fields with Iplanv4.5 (BrainLAB) and dynamic IMRT modality. Institutional SBRT protocol uses a total dose to the prostate of 40Gy in 5 fractions, every other day. Dose calculation is done by pencil beam (2mm dose resolution), heterogeneity correction and dose volume constraint (UCLA) for PTV D95%=40Gy and D98%>39.2Gy, Rectum V20Gy<50%, V32Gy<20%, V36Gy<10% and V40Gy<5%, Bladder V20Gy<40% and V40Gy<10%, femoral heads V16Gy<5%, penile bulb V25Gy<3cc, urethra and overlap region between PTV and PRV Rectum Dmax<42Gy. 10 SBRT treatments plans were selected and recalculated using Monte Carlo with 2mm spatial resolution and mean variance of 2%. DVH comparisons between plans were done. Results: The average difference between PTV doses constraints were within 2%. However 3 plans have differences higher than 3% which does not meet the D98% criteria (>39.2Gy) and should have been renormalized. Dose volume constraint differences for rectum, bladder, femoral heads and penile bulb were les than 2% and within tolerances. Urethra region and overlapping between PTV and PRV Rectum shows increment of dose in all plans. The average difference for urethra region was 2.1% with a maximum of 7.8% and for the overlapping region 2.5% with a maximum of 8.7%. Conclusion: Monte Carlo dose calculation on dynamic IMRT treatments could affects on plan normalization. Dose increment in critical region of urethra and PTV overlapping region with PTV could have clinical consequences which need to be studied. The use of Monte Carlo dose calculation algorithm is limited because inverse planning dose optimization use only pencil beam.
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
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...... for water. This represents the case that our “detector” is an infinitesimal small non-perturbing entity made of water, where charged particle equilibrium can be assumed following the Bragg-Gray cavity theory. Dw and Dm are calculated for typical materials such as bone, brain, lung and soft-tissues using...
Monte Carlo MCNP-4B-based absorbed dose distribution estimates for patient-specific dosimetry.
Yoriyaz, H; Stabin, M G; dos Santos, A
2001-04-01
This study was intended to verify the capability of the Monte Carlo MCNP-4B code to evaluate spatial dose distribution based on information gathered from CT or SPECT. A new three-dimensional (3D) dose calculation approach for internal emitter use in radioimmunotherapy (RIT) was developed using the Monte Carlo MCNP-4B code as the photon and electron transport engine. It was shown that the MCNP-4B computer code can be used with voxel-based anatomic and physiologic data to provide 3D dose distributions. This study showed that the MCNP-4B code can be used to develop a treatment planning system that will provide such information in a time manner, if dose reporting is suitably optimized. If each organ is divided into small regions where the average energy deposition is calculated with a typical volume of 0.4 cm(3), regional dose distributions can be provided with reasonable central processing unit times (on the order of 12-24 h on a 200-MHz personal computer or modest workstation). Further efforts to provide semiautomated region identification (segmentation) and improvement of marrow dose calculations are needed to supply a complete system for RIT. It is envisioned that all such efforts will continue to develop and that internal dose calculations may soon be brought to a similar level of accuracy, detail, and robustness as is commonly expected in external dose treatment planning. For this study we developed a code with a user-friendly interface that works on several nuclear medicine imaging platforms and provides timely patient-specific dose information to the physician and medical physicist. Future therapy with internal emitters should use a 3D dose calculation approach, which represents a significant advance over dose information provided by the standard geometric phantoms used for more than 20 y (which permit reporting of only average organ doses for certain standardized individuals)
Poster - 43: Analysis of SBRT and SRS dose verification results using the Octavius 1000SRS detector
Energy Technology Data Exchange (ETDEWEB)
Cherpak, Amanda [Nova Scotia Cancer Centre, Nova Scotia Health Authority, Halifax, NS, Department of Radiation Oncology, Dalhousie University, Halifax, NS, Department of Physics and Atmospheric Sciences, Dalhousie University, Halifax, NS (Canada)
2016-08-15
Purpose: The Octavius 1000{sup SRS} detector was commissioned in December 2014 and is used routinely for verification of all SRS and SBRT plans. Results of verifications were analyzed to assess trends and limitations of the device and planning methods. Methods: Plans were delivered using a True Beam STx and results were evaluated using gamma analysis (95%, 3%/3mm) and absolute dose difference (5%). Verification results were analyzed based on several plan parameters including tumour volume, degree of modulation and prescribed dose. Results: During a 12 month period, a total of 124 patient plans were verified using the Octavius detector. Thirteen plans failed the gamma criteria, while 7 plans failed based on the absolute dose difference. When binned according to degree of modulation, a significant correlation was found between MU/cGy and both mean dose difference (r=0.78, p<0.05) and gamma (r=−0.60, p<0.05). When data was binned according to tumour volume, the standard deviation of average gamma dropped from 2.2% – 3.7% for the volumes less than 30 cm{sup 3} to below 1% for volumes greater than 30 cm{sup 3}. Conclusions: The majority of plans and verification failures involved tumour volumes smaller than 30 cm{sup 3}. This was expected due to the nature of disease treated with SBRT and SRS techniques and did not increase rate of failure. Correlations found with MU/cGy indicate that as modulation increased, results deteriorated but not beyond the previously set thresholds.
Energy Technology Data Exchange (ETDEWEB)
Sampaio, E V.M.
1986-12-31
Using the MIRD 5 phantom and Monte Carlo technique, organ doses in patients undergoing external dental examination were calculated taking into account the different x-ray beam geometries and the various possible positions of x-ray source with regard to the head of the patient. It was necessary to introduce in the original computer program a new source description specific for dental examinations. To have a realistic evaluation of organ doses during dental examination it was necessary to introduce a new region in the phantom heat which characterizes the teeth and salivary glands. The attenuation of the x-ray beam by the lead shield of the radiographic film was also introduced in the calculation. (author).
International Nuclear Information System (INIS)
Vautrin, M.
2011-01-01
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) [fr
Comparison of ONETRAN calculations of electron beam dose profiles with Monte Carlo and experiment
International Nuclear Information System (INIS)
Garth, J.C.; Woolf, S.
1987-01-01
Electron beam dose profiles have been calculated using a multigroup, discrete ordinates solution of the Spencer-Lewis electron transport equation. This was accomplished by introducing electron transport cross-sections into the ONETRAN code in a simple manner. The authors' purpose is to ''benchmark'' this electron transport model and to demonstrate its accuracy and capabilities over the energy range from 30 keV to 20 MeV. Many of their results are compared with the extensive measurements and TIGER Monte Carlo data. In general the ONETRAN results are smoother, agree with TIGER within the statistical error of the Monte Carlo histograms and require about one tenth the running time of Monte Carlo
SU-E-T-455: Impact of Different Independent Dose Verification Software Programs for Secondary Check
International Nuclear Information System (INIS)
Itano, M; Yamazaki, T; Kosaka, M; Kobayashi, N; Yamashita, M; Ishibashi, S; Higuchi, Y; Tachibana, H
2015-01-01
Purpose: There have been many reports for different dose calculation algorithms for treatment planning system (TPS). Independent dose verification program (IndpPro) is essential to verify clinical plans from the TPS. However, the accuracy of different independent dose verification programs was not evident. We conducted a multi-institutional study to reveal the impact of different IndpPros using different TPSs. Methods: Three institutes participated in this study. They used two different IndpPros (RADCALC and Simple MU Analysis (SMU), which implemented the Clarkson algorithm. RADCALC needed the input of radiological path length (RPL) computed by the TPSs (Eclipse or Pinnacle3). SMU used CT images to compute the RPL independently from TPS). An ion-chamber measurement in water-equivalent phantom was performed to evaluate the accuracy of two IndpPros and the TPS in each institute. Next, the accuracy of dose calculation using the two IndpPros compared to TPS was assessed in clinical plan. Results: The accuracy of IndpPros and the TPSs in the homogenous phantom was +/−1% variation to the measurement. 1543 treatment fields were collected from the patients treated in the institutes. The RADCALC showed better accuracy (0.9 ± 2.2 %) than the SMU (1.7 ± 2.1 %). However, the accuracy was dependent on the TPS (Eclipse: 0.5%, Pinnacle3: 1.0%). The accuracy of RADCALC with Eclipse was similar to that of SMU in one of the institute. Conclusion: Depending on independent dose verification program, the accuracy shows systematic dose accuracy variation even though the measurement comparison showed a similar variation. The variation was affected by radiological path length calculation. IndpPro with Pinnacle3 has different variation because Pinnacle3 computed the RPL using physical density. Eclipse and SMU uses electron density, though
3D dose distribution calculation in a voxelized human phantom by means of Monte Carlo method
International Nuclear Information System (INIS)
Abella, V.; Miro, R.; Juste, B.; Verdu, G.
2010-01-01
The aim of this work is to provide the reconstruction of a real human voxelized phantom by means of a MatLab program and the simulation of the irradiation of such phantom with the photon beam generated in a Theratron 780 (MDS Nordion) 60 Co radiotherapy unit, by using the Monte Carlo transport code MCNP (Monte Carlo N-Particle), version 5. The project results in 3D dose mapping calculations inside the voxelized antropomorphic head phantom. The program provides the voxelization by first processing the CT slices; the process follows a two-dimensional pixel and material identification algorithm on each slice and three-dimensional interpolation in order to describe the phantom geometry via small cubic cells, resulting in an MCNP input deck format output. Dose rates are calculated by using the MCNP5 tool FMESH, superimposed mesh tally, which gives the track length estimation of the particle flux in units of particles/cm 2 . Furthermore, the particle flux is converted into dose by using the conversion coefficients extracted from the NIST Physical Reference Data. The voxelization using a three-dimensional interpolation technique in combination with the use of the FMESH tool of the MCNP Monte Carlo code offers an optimal simulation which results in 3D dose mapping calculations inside anthropomorphic phantoms. This tool is very useful in radiation treatment assessments, in which voxelized phantoms are widely utilized.
Performance characteristics of an independent dose verification program for helical tomotherapy
Directory of Open Access Journals (Sweden)
Isaac C. F. Chang
2017-01-01
Full Text Available Helical tomotherapy with its advanced method of intensity-modulated radiation therapy delivery has been used clinically for over 20 years. The standard delivery quality assurance procedure to measure the accuracy of delivered radiation dose from each treatment plan to a phantom is time-consuming. RadCalc®, a radiotherapy dose verification software, has released specifically for beta testing a module for tomotherapy plan dose calculations. RadCalc®'s accuracy for tomotherapy dose calculations was evaluated through examination of point doses in ten lung and ten prostate clinical plans. Doses calculated by the TomoHDA™ tomotherapy treatment planning system were used as the baseline. For lung cases, RadCalc® overestimated point doses in the lung by an average of 13%. Doses within the spinal cord and esophagus were overestimated by 10%. Prostate plans showed better agreement, with overestimations of 6% in the prostate, bladder, and rectum. The systematic overestimation likely resulted from limitations of the pencil beam dose calculation algorithm implemented by RadCalc®. Limitations were more severe in areas of greater inhomogeneity and less prominent in regions of homogeneity with densities closer to 1 g/cm3. Recommendations for RadCalc® dose calculation algorithms and anatomical representation were provided based on the results of the study.
Independent calculation-based verification of IMRT plans using a 3D dose-calculation engine
International Nuclear Information System (INIS)
Arumugam, Sankar; Xing, Aitang; Goozee, Gary; Holloway, Lois
2013-01-01
Independent monitor unit verification of intensity-modulated radiation therapy (IMRT) plans requires detailed 3-dimensional (3D) dose verification. The aim of this study was to investigate using a 3D dose engine in a second commercial treatment planning system (TPS) for this task, facilitated by in-house software. Our department has XiO and Pinnacle TPSs, both with IMRT planning capability and modeled for an Elekta-Synergy 6 MV photon beam. These systems allow the transfer of computed tomography (CT) data and RT structures between them but do not allow IMRT plans to be transferred. To provide this connectivity, an in-house computer programme was developed to convert radiation therapy prescription (RTP) files as generated by many planning systems into either XiO or Pinnacle IMRT file formats. Utilization of the technique and software was assessed by transferring 14 IMRT plans from XiO and Pinnacle onto the other system and performing 3D dose verification. The accuracy of the conversion process was checked by comparing the 3D dose matrices and dose volume histograms (DVHs) of structures for the recalculated plan on the same system. The developed software successfully transferred IMRT plans generated by 1 planning system into the other. Comparison of planning target volume (TV) DVHs for the original and recalculated plans showed good agreement; a maximum difference of 2% in mean dose, − 2.5% in D95, and 2.9% in V95 was observed. Similarly, a DVH comparison of organs at risk showed a maximum difference of +7.7% between the original and recalculated plans for structures in both high- and medium-dose regions. However, for structures in low-dose regions (less than 15% of prescription dose) a difference in mean dose up to +21.1% was observed between XiO and Pinnacle calculations. A dose matrix comparison of original and recalculated plans in XiO and Pinnacle TPSs was performed using gamma analysis with 3%/3 mm criteria. The mean and standard deviation of pixels passing
Comparison of EGS4 and MCNP Monte Carlo codes when calculating radiotherapy depth doses.
Love, P A; Lewis, D G; Al-Affan, I A; Smith, C W
1998-05-01
The Monte Carlo codes EGS4 and MCNP have been compared when calculating radiotherapy depth doses in water. The aims of the work were to study (i) the differences between calculated depth doses in water for a range of monoenergetic photon energies and (ii) the relative efficiency of the two codes for different electron transport energy cut-offs. The depth doses from the two codes agree with each other within the statistical uncertainties of the calculations (1-2%). The relative depth doses also agree with data tabulated in the British Journal of Radiology Supplement 25. A discrepancy in the dose build-up region may by attributed to the different electron transport algorithims used by EGS4 and MCNP. This discrepancy is considerably reduced when the improved electron transport routines are used in the latest (4B) version of MCNP. Timing calculations show that EGS4 is at least 50% faster than MCNP for the geometries used in the simulations.
Monte Carlo Calculated Effective Dose to Teenage Girls from Computed Tomography Examinations
International Nuclear Information System (INIS)
Caon, M.; Bibbo, G.; Pattison, J.
2000-01-01
Effective doses from CT to paediatric patients are not common in the literature. This article reports some effective doses to teenage girls from CT examinations. The voxel computational model ADELAIDE, representative of a 14-year-old girl, was scaled in size by ±5% to represent also 11-12-year-old and 16-year-old girls. The EGS4 Monte Carlo code was used to calculate the effective dose from chest, abdomen and whole torso CT examinations to the three version of ADELAIDE using a 120 kV spectrum. For the whole torso CT examination, in order of increasing model size, the effective doses were 9.0, 8.2 and 7.8 mSv per 100 mA.s. Data are presented that allow the estimation of effective dose from CT examinations of the torso for girls between the ages of 11 and 16. (author)
International Nuclear Information System (INIS)
Valente, Mauro; Botta, Francesca; Pedroli, Guido
2012-01-01
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)
De Vries, Rowen J; Marsh, Steven
2015-11-08
Internal lead shielding is utilized during superficial electron beam treatments of the head and neck, such as lip carcinoma. Methods for predicting backscattered dose include the use of empirical equations or performing physical measurements. The accuracy of these empirical equations required verification for the local electron beams. In this study, a Monte Carlo model of a Siemens Artiste linac was developed for 6, 9, 12, and 15 MeV electron beams using the EGSnrc MC package. The model was verified against physical measurements to an accuracy of better than 2% and 2mm. Multiple MC simulations of lead interfaces at different depths, corresponding to mean electron energies in the range of 0.2-14 MeV at the interfaces, were performed to calculate electron backscatter values. The simulated electron backscatter was compared with current empirical equations to ascertain their accuracy. The major finding was that the current set of backscatter equations does not accurately predict electron backscatter, particularly in the lower energies region. A new equation was derived which enables estimation of electron backscatter factor at any depth upstream from the interface for the local treatment machines. The derived equation agreed to within 1.5% of the MC simulated electron backscatter at the lead interface and upstream positions. Verification of the equation was performed by comparing to measurements of the electron backscatter factor using Gafchromic EBT2 film. These results show a mean value of 0.997 ± 0.022 to 1σ of the predicted values of electron backscatter. The new empirical equation presented can accurately estimate electron backscatter factor from lead shielding in the range of 0.2 to 14 MeV for the local linacs.
Validation and verification of the ORNL Monte Carlo codes for nuclear safety analysis
International Nuclear Information System (INIS)
Emmett, M.B.
1993-01-01
The process of ensuring the quality of computer codes can be very time consuming and expensive. The Oak Ridge National Laboratory (ORNL) Monte Carlo codes all predate the existence of quality assurance (QA) standards and configuration control. The number of person-years and the amount of money spent on code development make it impossible to adhere strictly to all the current requirements. At ORNL, the Nuclear Engineering Applications Section of the Computing Applications Division is responsible for the development, maintenance, and application of the Monte Carlo codes MORSE and KENO. The KENO code is used for doing criticality analyses; the MORSE code, which has two official versions, CGA and SGC, is used for radiation transport analyses. Because KENO and MORSE were very thoroughly checked out over the many years of extensive use both in the United States and in the international community, the existing codes were open-quotes baselined.close quotes This means that the versions existing at the time the original configuration plan is written are considered to be validated and verified code systems based on the established experience with them
Monte Carlo assessment of the dose rates produced by spent fuel from CANDU reactors
International Nuclear Information System (INIS)
Pantazi, Doina; Mateescu, Silvia; Stanciu, Marcela
2003-01-01
One of the technical measures considered for biological protection is radiation shielding. The implementation process of a spent fuel intermediate storage system at Cernavoda NPP includes an evolution in computation methods related to shielding evaluation: from using simpler computer codes, like MicroShield and QAD, to systems of codes, like SCALE (which contains few independent modules) and the multipurpose and multi-particles transport code MCNP, based on Monte Carlo method. The Monte Carlo assessment of the dose rates produced by CANDU type spent fuel, during its handling for the intermediate storage, is the main objective of this paper. The work had two main features: -establishing of geometrical models according to description mode used in code MCNP, capable to account for the specific characteristics of CANDU nuclear fuel; - confirming the correctness of proposed models, by comparing MCNP results and the related results obtained with other computer codes for shielding evaluation and dose rates calculations. (authors)
Radiation doses in volume-of-interest breast computed tomography—A Monte Carlo simulation study
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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
A novel dose uncertainty model and its application for dose verification
International Nuclear Information System (INIS)
Jin Hosang; Chung Heetaek; Liu Chihray; Palta, Jatinder; Suh, Tae-Suk; Kim, Siyong
2005-01-01
Based on statistical approach, a novel dose uncertainty model was introduced considering both nonspatial and spatial dose deviations. Non-space-oriented uncertainty is mainly caused by dosimetric uncertainties, and space-oriented dose uncertainty is the uncertainty caused by all spatial displacements. Assuming these two parts are independent, dose difference between measurement and calculation is a linear combination of nonspatial and spatial dose uncertainties. Two assumptions were made: (1) the relative standard deviation of nonspatial dose uncertainty is inversely proportional to the dose standard deviation σ, and (2) the spatial dose uncertainty is proportional to the gradient of dose. The total dose uncertainty is a quadratic sum of the nonspatial and spatial uncertainties. The uncertainty model provides the tolerance dose bound for comparison between calculation and measurement. In the statistical uncertainty model based on a Gaussian distribution, a confidence level of 3σ theoretically confines 99.74% of measurements within the bound. By setting the confidence limit, the tolerance bound for dose comparison can be made analogous to that of existing dose comparison methods (e.g., a composite distribution analysis, a γ test, a χ evaluation, and a normalized agreement test method). However, the model considers the inherent dose uncertainty characteristics of the test points by taking into account the space-specific history of dose accumulation, while the previous methods apply a single tolerance criterion to the points, although dose uncertainty at each point is significantly different from others. Three types of one-dimensional test dose distributions (a single large field, a composite flat field made by two identical beams, and three-beam intensity-modulated fields) were made to verify the robustness of the model. For each test distribution, the dose bound predicted by the uncertainty model was compared with simulated measurements. The simulated
Energy Technology Data Exchange (ETDEWEB)
Cusumano, Davide, E-mail: davide.cusumano@unimi.it [School of Medical Physics, University of Milan, Milan (Italy); Fumagalli, Maria L. [Health Department, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan (Italy); Marchetti, Marcello; Fariselli, Laura [Department of Neurosurgery, Radiotherapy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan (Italy); De Martin, Elena [Health Department, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan (Italy)
2015-10-01
Aim of this study is to examine the feasibility of using the new Gafchromic EBT3 film in a high-dose stereotactic radiosurgery and radiotherapy quality assurance procedure. Owing to the reduced dimensions of the involved lesions, the feasibility of scanning plan verification films on the scanner plate area with the best uniformity rather than using a correction mask was evaluated. For this purpose, signal values dispersion and reproducibility of film scans were investigated. Uniformity was then quantified in the selected area and was found to be within 1.5% for doses up to 8 Gy. A high-dose threshold level for analyses using this procedure was established evaluating the sensitivity of the irradiated films. Sensitivity was found to be of the order of centiGray for doses up to 6.2 Gy and decreasing for higher doses. The obtained results were used to implement a procedure comparing dose distributions delivered with a CyberKnife system to planned ones. The procedure was validated through single beam irradiation on a Gafchromic film. The agreement between dose distributions was then evaluated for 13 patients (brain lesions, 5 Gy/die prescription isodose ~80%) using gamma analysis. Results obtained using Gamma test criteria of 5%/1 mm show a pass rate of 94.3%. Gamma frequency parameters calculation for EBT3 films showed to strongly depend on subtraction of unexposed film pixel values from irradiated ones. In the framework of the described dosimetric procedure, EBT3 films proved to be effective in the verification of high doses delivered to lesions with complex shapes and adjacent to organs at risk.
International Nuclear Information System (INIS)
Wieslander, Elinore; Knoeoes, Tommy
2003-01-01
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
International Nuclear Information System (INIS)
Rojas C, E.L.; Varon T, C.F.; Pedraza N, R.
2007-01-01
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)
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.
Evaluation of radiation dose to patients in intraoral dental radiography using Monte Carlo Method
International Nuclear Information System (INIS)
Park, Il; Kim, Kyeong Ho; Oh, Seung Chul; Song, Ji Young
2016-01-01
The use of dental radiographic examinations is common although radiation dose resulting from the dental radiography is relatively small. Therefore, it is required to evaluate radiation dose from the dental radiography for radiation safety purpose. The objectives of the present study were to develop dosimetry method for intraoral dental radiography using a Monte Carlo method based radiation transport code and to calculate organ doses and effective doses of patients from different types of intraoral radiographies. Radiological properties of dental radiography equipment were characterized for the evaluation of patient radiation dose. The properties including x-ray energy spectrum were simulated using MCNP code. Organ doses and effective doses to patients were calculated by MCNP simulation with computational adult phantoms. At the typical equipment settings (60 kVp, 7 mA, and 0.12 sec), the entrance air kerma was 1.79 mGy and the measured half value layer was 1.82 mm. The half value layer calculated by MCNP simulation was well agreed with the measurement values. Effective doses from intraoral radiographies ranged from 1 μSv for maxilla premolar to 3 μSv for maxilla incisor. Oral cavity layer (23⁓82 μSv) and salivary glands (10⁓68 μSv) received relatively high radiation dose. Thyroid also received high radiation dose (3⁓47 μSv) for examinations. The developed dosimetry method and evaluated radiation doses in this study can be utilized for policy making, patient dose management, and development of low-dose equipment. In addition, this study can ultimately contribute to decrease radiation dose to patients for radiation safety
Evaluation of radiation dose to patients in intraoral dental radiography using Monte Carlo Method
Energy Technology Data Exchange (ETDEWEB)
Park, Il; Kim, Kyeong Ho; Oh, Seung Chul; Song, Ji Young [Dept. of Nuclear Engineering, Kyung Hee University, Yongin (Korea, Republic of)
2016-11-15
The use of dental radiographic examinations is common although radiation dose resulting from the dental radiography is relatively small. Therefore, it is required to evaluate radiation dose from the dental radiography for radiation safety purpose. The objectives of the present study were to develop dosimetry method for intraoral dental radiography using a Monte Carlo method based radiation transport code and to calculate organ doses and effective doses of patients from different types of intraoral radiographies. Radiological properties of dental radiography equipment were characterized for the evaluation of patient radiation dose. The properties including x-ray energy spectrum were simulated using MCNP code. Organ doses and effective doses to patients were calculated by MCNP simulation with computational adult phantoms. At the typical equipment settings (60 kVp, 7 mA, and 0.12 sec), the entrance air kerma was 1.79 mGy and the measured half value layer was 1.82 mm. The half value layer calculated by MCNP simulation was well agreed with the measurement values. Effective doses from intraoral radiographies ranged from 1 μSv for maxilla premolar to 3 μSv for maxilla incisor. Oral cavity layer (23⁓82 μSv) and salivary glands (10⁓68 μSv) received relatively high radiation dose. Thyroid also received high radiation dose (3⁓47 μSv) for examinations. The developed dosimetry method and evaluated radiation doses in this study can be utilized for policy making, patient dose management, and development of low-dose equipment. In addition, this study can ultimately contribute to decrease radiation dose to patients for radiation safety.
A simulation study of a C-shaped in-beam PET system for dose verification in carbon ion therapy
International Nuclear Information System (INIS)
Jung An, Su; Beak, Cheol-Ha; Lee, Kisung; Hyun Chung, Yong
2013-01-01
The application of hadrons such as carbon ions is being developed for the treatment of cancer. The effectiveness of such a technique is due to the eligibility of charged particles in delivering most of their energy near the end of the range, called the Bragg peak. However, accurate verification of dose delivery is required since misalignment of the hadron beam can cause serious damage to normal tissue. PET scanners can be utilized to track the carbon beam to the tumor by imaging the trail of the hadron-induced positron emitters in the irradiated volume. In this study, we designed and evaluated (through Monte Carlo simulations) an in-beam PET scanner for monitoring patient dose in carbon beam therapy. A C-shaped PET and a partial-ring PET were designed to avoid interference between the PET detectors and the therapeutic carbon beam delivery. Their performance was compared with that of a full-ring PET scanner. The C-shaped, partial-ring, and full-ring scanners consisted of 14, 12, and 16 detector modules, respectively, with a 30.2 cm inner diameter for brain imaging. Each detector module was composed of a 13×13 array of 4.0 mm×4.0 mm×20.0 mm LYSO crystals and four round 25.4 mm diameter PMTs. To estimate the production yield of positron emitters such as 10 C, 11 C, and 15 O, a cylindrical PMMA phantom (diameter, 20 cm; thickness, 20 cm) was irradiated with 170, 290, and 350 AMeV 12 C beams using the GATE code. Phantom images of the three types of scanner were evaluated by comparing the longitudinal profile of the positron emitters, measured along the carbon beam as it passed a simulated positron emitter distribution. The results demonstrated that the development of a C-shaped PET scanner to characterize carbon dose distribution for therapy planning is feasible.
International Nuclear Information System (INIS)
Chang, Eric L.; Wong Peifong; Forster, Kenneth M.; Petru, Mark D.; Kowalski, Alexander V.; Maor, Moshe H.
2003-01-01
A modified 3-field technique was designed with opposed cranial fields and a single spinal field encompassing the entire spinal axis. Two methods of plan verifications were performed before the first treatment. First, a system of orthogonal rulers plus the thermoplastic head holder was used to visualize the light fields at the craniospinal junction. Second, film phantom measurements were taken to visualize the gap between the fields at the level of the spinal cord. Treatment verification entailed use of a posterior-anterior (PA) portal film and placement of radiopaque wire on the inferior border of the cranial field. More rigorous verification required a custom-fabricated orthogonal film holder. The isocenter positions of both fields when they matched were recorded using a record-and-verify system. A single extended distance spinal field collimated at 42 degree sign encompassed the entire spinal neuraxis. Data were collected from 40 fractions of craniospinal irradiation (CSI). The systematic error observed for the actual daily treatments was -0.5 mm (underlap), while the stochastic error was represented by a standard deviation of 5.39 mm. Measured data across the gapped craniospinal junction with junction shifts included revealed a dose ranging from 89.3% to 108%. CSI can be performed without direct visualization of the craniospinal junction by using the verification methods described. While the use of rigorous film verification for supine technique may have reduced the systematic error, the inability to visualize the supine craniospinal junction on skin appears to have increased the stochastic error compared to published data on such errors associated with prone craniospinal irradiation
NEUTRON GENERATOR FACILITY AT SFU: GEANT4 DOSE RATE PREDICTION AND VERIFICATION.
Williams, J; Chester, A; Domingo, T; Rizwan, U; Starosta, K; Voss, P
2016-11-01
Detailed dose rate maps for a neutron generator facility at Simon Fraser University were produced via the GEANT4 Monte Carlo framework. Predicted neutron dose rates throughout the facility were compared with radiation survey measurements made during the facility commissioning process. When accounting for thermal neutrons, the prediction and measurement agree within a factor of 2 or better in most survey locations, and within 10 % inside the vault housing the neutron generator. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Directory of Open Access Journals (Sweden)
Takahashi Wataru
2012-02-01
Full Text Available Abstract Background The purpose of this study was to compare dose distributions from three different algorithms with the x-ray Voxel Monte Carlo (XVMC calculations, in actual computed tomography (CT scans for use in stereotactic radiotherapy (SRT of small lung cancers. Methods Slow CT scan of 20 patients was performed and the internal target volume (ITV was delineated on Pinnacle3. All plans were first calculated with a scatter homogeneous mode (SHM which is compatible with Clarkson algorithm using Pinnacle3 treatment planning system (TPS. The planned dose was 48 Gy in 4 fractions. In a second step, the CT images, structures and beam data were exported to other treatment planning systems (TPSs. Collapsed cone convolution (CCC from Pinnacle3, superposition (SP from XiO, and XVMC from Monaco were used for recalculating. The dose distributions and the Dose Volume Histograms (DVHs were compared with each other. Results The phantom test revealed that all algorithms could reproduce the measured data within 1% except for the SHM with inhomogeneous phantom. For the patient study, the SHM greatly overestimated the isocenter (IC doses and the minimal dose received by 95% of the PTV (PTV95 compared to XVMC. The differences in mean doses were 2.96 Gy (6.17% for IC and 5.02 Gy (11.18% for PTV95. The DVH's and dose distributions with CCC and SP were in agreement with those obtained by XVMC. The average differences in IC doses between CCC and XVMC, and SP and XVMC were -1.14% (p = 0.17, and -2.67% (p = 0.0036, respectively. Conclusions Our work clearly confirms that the actual practice of relying solely on a Clarkson algorithm may be inappropriate for SRT planning. Meanwhile, CCC and SP were close to XVMC simulations and actual dose distributions obtained in lung SRT.
Dose distribution close to metal implants in Gamma Knife Radiosurgery: A Monte Carlo study
International Nuclear Information System (INIS)
Cheung, Joel Y.C.; Yu, K.N.; Chan, Josie F.K.; Ho, Robert T.K.; Yu, C.P.
2003-01-01
Materials with high atomic numbers favor the occurrence of the photoelectric effect when they are irradiated with gamma rays. Therefore, the photoelectric effects of metal implants within the target regions in Gamma Knife Radiosurgery are worth studying. In the present work, Monte Carlo simulations using EGS4 were employed to investigate the resulting dose enhancements. A dose enhancement as high as 10% was observed close to a platinum implant along the x and y axes, while no significant dose enhancements were observed for silver, stainless steel 301, and titanium ones. A dose enhancement as high as 20% was observed close to the platinum implant along the z axis at the superior position of the metal-phantom interface and was 10% higher for other metal implants
International Nuclear Information System (INIS)
Yanez, R.; Dempsey, J. F.
2007-01-01
We present studies in support of the development of a magnetic resonance imaging (MRI) guided intensity modulated radiation therapy (IMRT) device for the treatment of cancer patients. Fast and accurate computation of the absorbed ionizing radiation dose delivered in the presence of the MRI magnetic field are required for clinical implementation. The fast Monte Carlo simulation code DPM, optimized for radiotherapy treatment planning, is modified to simulate absorbed doses in uniform, static magnetic fields, and benchmarked against PENELOPE. Simulations of dose deposition in inhomogeneous phantoms in which a low density material is sandwiched in water shows that a lower MRI field strength (0.3 T) is to prefer in order to avoid dose build-up near material boundaries. (authors)
Monte Carlo dose calculations for BNCT treatment of diffuse human lung tumours
International Nuclear Information System (INIS)
Altieri, S.; Bortolussi, S.; Bruschi, P.
2006-01-01
In order to test the possibility to apply BNCT in the core of diffuse lung tumours, dose distribution calculations were made. The simulations were performed with the Monte Carlo code MCNP.4c2, using the male computational phantom Adam, version 07/94. Volumes of interest were voxelized for the tally requests, and results were obtained for tissues with and without Boron. Different collimated neutron sources were tested in order to establish the proper energies, as well as single and multiple beams to maximize neutron flux uniformity inside the target organs. Flux and dose distributions are reported. The use of two opposite epithermal neutron collimated beams insures good levels of dose homogeneity inside the lungs, with a substantially lower radiation dose delivered to surrounding structures. (author)
An automatic dose verification system for adaptive radiotherapy for helical tomotherapy
International Nuclear Information System (INIS)
Mo, Xiaohu; Chen, Mingli; Parnell, Donald; Olivera, Gustavo; Galmarini, Daniel; Lu, Weiguo
2014-01-01
dose verification system that quantifies treatment doses, and provides necessary information for adaptive planning without impeding clinical workflows.
Monte Carlo investigation of the low-dose envelope from scanned proton pencil beams
International Nuclear Information System (INIS)
Sawakuchi, Gabriel O; Titt, Uwe; Mirkovic, Dragan; Ciangaru, George; Zhu, X Ronald; Sahoo, Narayan; Gillin, Michael T; Mohan, Radhe
2010-01-01
Scanned proton pencil beams carry a low-dose envelope that extends several centimeters from the individual beam's central axis. Thus, the total delivered dose depends on the size of the target volume and the corresponding number and intensity of beams necessary to cover the target volume uniformly. This dependence must be considered in dose calculation algorithms used by treatment planning systems. In this work, we investigated the sources of particles contributing to the low-dose envelope using the Monte Carlo technique. We used a validated model of our institution's scanning beam line to determine the contributions to the low-dose envelope from secondary particles created in a water phantom and particles scattered in beam line components. Our results suggested that, for high-energy beams, secondary particles produced by nuclear interactions in the water phantom are the major contributors to the low-dose envelope. For low-energy beams, the low-dose envelope is dominated by particles undergoing multiple Coulomb scattering in the beam line components and water phantom. Clearly, in the latter situation, the low-dose envelope depends directly on beam line design features. Finally, we investigated the dosimetric consequences of the low-dose envelope. Our results showed that if not modeled properly the low-dose envelope may cause clinically relevant dose disturbance in the target volume. This work suggested that this low-dose envelope is beam line specific for low-energy beams, should be thoroughly experimentally characterized and validated during commissioning of the treatment planning system, and therefore is of great concern for accurate delivery of proton scanning beam doses.
Independent Monte-Carlo dose calculation for MLC based CyberKnife radiotherapy
Mackeprang, P.-H.; Vuong, D.; Volken, W.; Henzen, D.; Schmidhalter, D.; Malthaner, M.; Mueller, S.; Frei, D.; Stampanoni, M. F. M.; Dal Pra, A.; Aebersold, D. M.; Fix, M. K.; Manser, P.
2018-01-01
This work aims to develop, implement and validate a Monte Carlo (MC)-based independent dose calculation (IDC) framework to perform patient-specific quality assurance (QA) for multi-leaf collimator (MLC)-based CyberKnife® (Accuray Inc., Sunnyvale, CA) treatment plans. The IDC framework uses an XML-format treatment plan as exported from the treatment planning system (TPS) and DICOM format patient CT data, an MC beam model using phase spaces, CyberKnife MLC beam modifier transport using the EGS++ class library, a beam sampling and coordinate transformation engine and dose scoring using DOSXYZnrc. The framework is validated against dose profiles and depth dose curves of single beams with varying field sizes in a water tank in units of cGy/Monitor Unit and against a 2D dose distribution of a full prostate treatment plan measured with Gafchromic EBT3 (Ashland Advanced Materials, Bridgewater, NJ) film in a homogeneous water-equivalent slab phantom. The film measurement is compared to IDC results by gamma analysis using 2% (global)/2 mm criteria. Further, the dose distribution of the clinical treatment plan in the patient CT is compared to TPS calculation by gamma analysis using the same criteria. Dose profiles from IDC calculation in a homogeneous water phantom agree within 2.3% of the global max dose or 1 mm distance to agreement to measurements for all except the smallest field size. Comparing the film measurement to calculated dose, 99.9% of all voxels pass gamma analysis, comparing dose calculated by the IDC framework to TPS calculated dose for the clinical prostate plan shows 99.0% passing rate. IDC calculated dose is found to be up to 5.6% lower than dose calculated by the TPS in this case near metal fiducial markers. An MC-based modular IDC framework was successfully developed, implemented and validated against measurements and is now available to perform patient-specific QA by IDC.
Kirkby, Charles; Ghasroddashti, Esmaeel; Kovalchuk, Anna; Kolb, Bryan; Kovalchuk, Olga
2013-09-01
In radiation biology, rats are often irradiated, but the precise dose distributions are often lacking, particularly in areas that receive scatter radiation. We used a non-dedicated set of resources to calculate detailed dose distributions, including doses to peripheral organs well outside of the primary field, in common rat exposure settings. We conducted a detailed dose reconstruction in a rat through an analog to the conventional human treatment planning process. The process consisted of: (i) Characterizing source properties of an X-ray irradiator system, (ii) acquiring a computed tomography (CT) scan of a rat model, and (iii) using a Monte Carlo (MC) dose calculation engine to generate the dose distribution within the rat model. We considered cranial and liver irradiation scenarios where the rest of the body was protected by a lead shield. Organs of interest were the brain, liver and gonads. The study also included paired scenarios where the dose to adjacent, shielded rats was determined as a potential control for analysis of bystander effects. We established the precise doses and dose distributions delivered to the peripheral organs in single and paired rats. Mean doses to non-targeted organs in irradiated rats ranged from 0.03-0.1% of the reference platform dose. Mean doses to the adjacent rat peripheral organs were consistent to within 10% those of the directly irradiated rat. This work provided details of dose distributions in rat models under common irradiation conditions and established an effective scenario for delivering only scattered radiation consistent with that in a directly irradiated rat.
Evaluation of equivalent doses in 18F PET/CT using the Monte Carlo method with MCNPX code
International Nuclear Information System (INIS)
Belinato, Walmir; Santos, William Souza; Perini, Ana Paula; Neves, Lucio Pereira; Souza, Divanizia N.
2017-01-01
The present work used the Monte Carlo method (MMC), specifically the Monte Carlo NParticle - MCNPX, to simulate the interaction of radiation involving photons and particles, such as positrons and electrons, with virtual adult anthropomorphic simulators on PET / CT scans and to determine absorbed and equivalent doses in adult male and female patients
International Nuclear Information System (INIS)
Lee, C; Lin, H; Chao, T; Hsiao, I; Chuang, K
2015-01-01
Purpose: Predicted PET images on the basis of analytical filtering approach for proton range verification has been successful developed and validated using FLUKA Monte Carlo (MC) codes and phantom measurements. The purpose of the study is to validate the effectiveness of analytical filtering model for proton range verification on GATE/GEANT4 Monte Carlo simulation codes. Methods: In this study, we performed two experiments for validation of predicted β+-isotope by the analytical model with GATE/GEANT4 simulations. The first experiments to evaluate the accuracy of predicting β+-yields as a function of irradiated proton energies. In second experiment, we simulate homogeneous phantoms of different materials irradiated by a mono-energetic pencil-like proton beam. The results of filtered β+-yields distributions by the analytical model is compared with those of MC simulated β+-yields in proximal and distal fall-off ranges. Results: The results investigate the distribution between filtered β+-yields and MC simulated β+-yields distribution in different conditions. First, we found that the analytical filtering can be applied over the whole range of the therapeutic energies. Second, the range difference between filtered β+-yields and MC simulated β+-yields at the distal fall-off region are within 1.5mm for all materials used. The findings validated the usefulness of analytical filtering model on range verification of proton therapy on GATE Monte Carlo simulations. In addition, there is a larger discrepancy between filtered prediction and MC simulated β+-yields using GATE code, especially in proximal region. This discrepancy might Result from the absence of wellestablished theoretical models for predicting the nuclear interactions. Conclusion: Despite the fact that large discrepancies of the distributions between MC-simulated and predicted β+-yields were observed, the study prove the effectiveness of analytical filtering model for proton range verification using
Monte Carlo verification of control-rod worth for the Savannah River K reactor
International Nuclear Information System (INIS)
Mosteller, R.D.
1992-01-01
The Savannah River K Reactor is a heavy-water reactor that relies on control-rod movement to control its reactivity and power distribution during normal operations. It is necessary, therefore, to have an accurate estimate of the reactivity worth of its control rods in order to predict the behavior of the reactor. Westinghouse Savannah River Company (WSRC) uses the GLASS lattice-physics code to calculate few-group cross sections for fuel and control-rod assemblies in the K reactor. This paper compares the control-rod worth calculated by GLASS to that calculated by the MCNP Monte Carlo program. The GLASS calculations utilize its standard 37-group cross-section library, while the MCNP calculations employ continuous-energy isotopic cross-section libraries derived from ENDF/B-V. The MCNP calculations therefore combine the most rigorous analytical model and the most accurate cross sections currently available for thermal-reactor analysis. Consequently, the MCNP results comprise a computational benchmark against which the accuracy of the GLASS code can be evaluated
Verification of the Monte Carlo differential operator technique for MCNP trademark
International Nuclear Information System (INIS)
McKinney, G.W.; Iverson, J.L.
1996-02-01
The differential operator perturbation technique has been incorporated into the Monte Carlo N-Particle transport code MCNP and will become a standard feature of future releases. This feature includes first and second order terms of the Taylor series expansion for response perturbations related to cross-section data (i.e., density, composition, etc.). Perturbation and sensitivity analyses can benefit from this technique in that predicted changes in one or more tally responses may be obtained for multiple perturbations in a single run. The user interface is intuitive, yet flexible enough to allow for changes in a specific microscopic cross section over a specified energy range. With this technique, a precise estimate of a small change in response is easily obtained, even when the standard deviation of the unperturbed tally is greater than the change. Furthermore, results presented in this report demonstrate that first and second order terms can offer acceptable accuracy, to within a few percent, for up to 20-30% changes in a response
Verification of Transformer Restricted Earth Fault Protection by using the Monte Carlo Method
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KRSTIVOJEVIC, J. P.
2015-08-01
Full Text Available The results of a comprehensive investigation of the influence of current transformer (CT saturation on restricted earth fault (REF protection during power transformer magnetization inrush are presented. Since the inrush current during switch-on of unloaded power transformer is stochastic, its values are obtained by: (i laboratory measurements and (ii calculations based on the input data obtained by the Monte Carlo (MC simulation. To make a detailed assessment of the current transformer performance the uncertain input data for the CT model were obtained by applying the MC method. In this way, different levels of remanent flux in CT core are taken into consideration. By the generated CT secondary currents, the algorithm for REF protection based on phase comparison in time domain is tested. On the basis of the obtained results, a method of adjustment of the triggering threshold in order to ensure safe operation during transients, and thereby improve the algorithm security, has been proposed. The obtained results indicate that power transformer REF protection would be enhanced by using the proposed adjustment of triggering threshold in the algorithm which is based on phase comparison in time domain.
Evaluation of a new commercial Monte Carlo dose calculation algorithm for electron beams.
Vandervoort, Eric J; Tchistiakova, Ekaterina; La Russa, Daniel J; Cygler, Joanna E
2014-02-01
In this report the authors present the validation of a Monte Carlo dose calculation algorithm (XiO EMC from Elekta Software) for electron beams. Calculated and measured dose distributions were compared for homogeneous water phantoms and for a 3D heterogeneous phantom meant to approximate the geometry of a trachea and spine. Comparisons of measurements and calculated data were performed using 2D and 3D gamma index dose comparison metrics. Measured outputs agree with calculated values within estimated uncertainties for standard and extended SSDs for open applicators, and for cutouts, with the exception of the 17 MeV electron beam at extended SSD for cutout sizes smaller than 5 × 5 cm(2). Good agreement was obtained between calculated and experimental depth dose curves and dose profiles (minimum number of measurements that pass a 2%/2 mm agreement 2D gamma index criteria for any applicator or energy was 97%). Dose calculations in a heterogeneous phantom agree with radiochromic film measurements (>98% of pixels pass a 3 dimensional 3%/2 mm γ-criteria) provided that the steep dose gradient in the depth direction is considered. Clinically acceptable agreement (at the 2%/2 mm level) between the measurements and calculated data for measurements in water are obtained for this dose calculation algorithm. Radiochromic film is a useful tool to evaluate the accuracy of electron MC treatment planning systems in heterogeneous media.
Monte Carlo calculations of lung dose in ORNL phantom for boron neutron capture therapy
International Nuclear Information System (INIS)
Krstic, D.; Markovic, V.M.; Jovanovic, Z.; Milenkovic, B.; Nikezic, D.; Atanackovic, J.
2014-01-01
Monte Carlo simulations were performed to evaluate dose for possible treatment of cancers by boron neutron capture therapy (BNCT). The computational model of male Oak Ridge National Laboratory (ORNL) phantom was used to simulate tumours in the lung. Calculations have been performed by means of the MCNP5/X code. In this simulation, two opposite neutron beams were considered, in order to obtain uniform neutron flux distribution inside the lung. The obtained results indicate that the lung cancer could be treated by BNCT under the assumptions of calculations. The difference in evaluated dose in cancer and normal lung tissue suggests that BNCT could be applied for the treatment of cancers. The difference in exposure of cancer and healthy tissue can be observed, so the healthy tissue can be spared from damage. An absorbed dose ratio of metastatic tissue-to-the healthy tissue was ∼5. Absorbed dose to all other organs was low when compared with the lung dose. Absorbed dose depth distribution shows that BNC therapy can be very useful in the treatments for tumour. The ratio of the tumour absorbed dose and irradiated healthy tissue absorbed dose was also ∼5. It was seen that an elliptical neutron field was better irradiation choice. (authors)
A clinical study of lung cancer dose calculation accuracy with Monte Carlo simulation.
Zhao, Yanqun; Qi, Guohai; Yin, Gang; Wang, Xianliang; Wang, Pei; Li, Jian; Xiao, Mingyong; Li, Jie; Kang, Shengwei; Liao, Xiongfei
2014-12-16
The accuracy of dose calculation is crucial to the quality of treatment planning and, consequently, to the dose delivered to patients undergoing radiation therapy. Current general calculation algorithms such as Pencil Beam Convolution (PBC) and Collapsed Cone Convolution (CCC) have shortcomings in regard to severe inhomogeneities, particularly in those regions where charged particle equilibrium does not hold. The aim of this study was to evaluate the accuracy of the PBC and CCC algorithms in lung cancer radiotherapy using Monte Carlo (MC) technology. Four treatment plans were designed using Oncentra Masterplan TPS for each patient. Two intensity-modulated radiation therapy (IMRT) plans were developed using the PBC and CCC algorithms, and two three-dimensional conformal therapy (3DCRT) plans were developed using the PBC and CCC algorithms. The DICOM-RT files of the treatment plans were exported to the Monte Carlo system to recalculate. The dose distributions of GTV, PTV and ipsilateral lung calculated by the TPS and MC were compared. For 3DCRT and IMRT plans, the mean dose differences for GTV between the CCC and MC increased with decreasing of the GTV volume. For IMRT, the mean dose differences were found to be higher than that of 3DCRT. The CCC algorithm overestimated the GTV mean dose by approximately 3% for IMRT. For 3DCRT plans, when the volume of the GTV was greater than 100 cm(3), the mean doses calculated by CCC and MC almost have no difference. PBC shows large deviations from the MC algorithm. For the dose to the ipsilateral lung, the CCC algorithm overestimated the dose to the entire lung, and the PBC algorithm overestimated V20 but underestimated V5; the difference in V10 was not statistically significant. PBC substantially overestimates the dose to the tumour, but the CCC is similar to the MC simulation. It is recommended that the treatment plans for lung cancer be developed using an advanced dose calculation algorithm other than PBC. MC can accurately
International Nuclear Information System (INIS)
Berger, Lucie
2006-01-01
Today, amorphous silicon electronic portal imaging devices (aSi EPID) are currently used to check the accuracy of patient positioning. However, they are not use for dose reconstruction yet and more investigations are required to allow the use of an aSi EPID for routine dosimetric verification. The aim of this work is first to study the dosimetric characteristics of the EPID available at the Institut Curie and then, to check patient dose during treatment using these EPID. First, performance optimization of the Varian aS500 EPID system is studied. Then, a quality assurance system is set up in order to certify the image quality on a daily basis. An additional study on the dosimetric performance of the aS500 EPID is monitored to assess operational stability for dosimetry applications. Electronic portal imaging device is also a useful tool to improve IMRT quality control. The validation and the quality assurance of a portal dose image prediction system for IMRT pre-treatment quality control are performed. All dynamic IMRT fields are verified in clinical routine with the new method based on portal dosimetry. Finally, a new formalism for in vivo dosimetry using transit dose measured with EPID is developed and validated. The absolute dose measurement issue using aSi EPID is described and the midplane dose determination using in vivo dose measurements in combination with portal imaging is used with 3D-conformal-radiation therapy. (author) [fr
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Chibani, Omar, E-mail: omar.chibani@fccc.edu; C-M Ma, Charlie [Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111 (United States)
2014-05-15
Purpose: To present a new accelerated Monte Carlo code for CT-based dose calculations in high dose rate (HDR) brachytherapy. The new code (HDRMC) accounts for both tissue and nontissue heterogeneities (applicator and contrast medium). Methods: HDRMC uses a fast ray-tracing technique and detailed physics algorithms to transport photons through a 3D mesh of voxels representing the patient anatomy with applicator and contrast medium included. A precalculated phase space file for the{sup 192}Ir source is used as source term. HDRM is calibrated to calculated absolute dose for real plans. A postprocessing technique is used to include the exact density and composition of nontissue heterogeneities in the 3D phantom. Dwell positions and angular orientations of the source are reconstructed using data from the treatment planning system (TPS). Structure contours are also imported from the TPS to recalculate dose-volume histograms. Results: HDRMC was first benchmarked against the MCNP5 code for a single source in homogenous water and for a loaded gynecologic applicator in water. The accuracy of the voxel-based applicator model used in HDRMC was also verified by comparing 3D dose distributions and dose-volume parameters obtained using 1-mm{sup 3} versus 2-mm{sup 3} phantom resolutions. HDRMC can calculate the 3D dose distribution for a typical HDR cervix case with 2-mm resolution in 5 min on a single CPU. Examples of heterogeneity effects for two clinical cases (cervix and esophagus) were demonstrated using HDRMC. The neglect of tissue heterogeneity for the esophageal case leads to the overestimate of CTV D90, CTV D100, and spinal cord maximum dose by 3.2%, 3.9%, and 3.6%, respectively. Conclusions: A fast Monte Carlo code for CT-based dose calculations which does not require a prebuilt applicator model is developed for those HDR brachytherapy treatments that use CT-compatible applicators. Tissue and nontissue heterogeneities should be taken into account in modern HDR
SU-F-T-370: A Fast Monte Carlo Dose Engine for Gamma Knife
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Song, T; Zhou, L [Southern Medical University, Guangzhou, Guangdong (China); Li, Y [Beihang University, Beijing, Beijing (China)
2016-06-15
Purpose: To develop a fast Monte Carlo dose calculation algorithm for Gamma Knife. Methods: To make the simulation more efficient, we implemented the track repeating technique on GPU. We first use EGSnrc to pre-calculate the photon and secondary electron tracks in water from two mono-energy photons of 60Co. The total photon mean free paths for different materials and energies are obtained from NIST. During simulation, each entire photon track was first loaded to shared memory for each block, the incident original photon was then splitted to Nthread sub-photons, each thread transport one sub-photon, the Russian roulette technique was applied for scattered and bremsstrahlung photons. The resultant electrons from photon interactions are simulated by repeating the recorded electron tracks. The electron step length is stretched/shrunk proportionally based on the local density and stopping power ratios of the local material. Energy deposition in a voxel is proportional to the fraction of the equivalent step length in that voxel. To evaluate its accuracy, dose deposition in a 300mm*300mm*300mm water phantom is calculated, and compared to EGSnrc results. Results: Both PDD and OAR showed great agreements (within 0.5%) between our dose engine result and the EGSnrc result. It only takes less than 1 min for every simulation, being reduced up to ∼40 times compared to EGSnrc simulations. Conclusion: We have successfully developed a fast Monte Carlo dose engine for Gamma Knife.
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Nordenfors, C
1999-02-01
To determine dose rate in a gamma radiation field, based on measurements with a semiconductor detector, it is necessary to know how the detector effects the field. This work aims to describe this effect with Monte Carlo simulations and calculations, that is to identify the detector response function. This is done for a germanium gamma detector. The detector is normally used in the in-situ measurements that is carried out regularly at the department. After the response function is determined it is used to reconstruct a spectrum from an in-situ measurement, a so called unfolding. This is done to be able to calculate fluence rate and dose rate directly from a measured (and unfolded) spectrum. The Monte Carlo code used in this work is EGS4 developed mainly at Stanford Linear Accelerator Center. It is a widely used code package to simulate particle transport. The results of this work indicates that the method could be used as-is since the accuracy of this method compares to other methods already in use to measure dose rate. Bearing in mind that this method provides the nuclide specific dose it is useful, in radiation protection, since knowing what the relations between different nuclides are and how they change is very important when estimating the risks
Dose verification with different ion chambers for SRT/SBRT plans
Durmus, I. F.; Tas, B.; Okumus, A.; Uzel, O. E.
2017-02-01
Verification of patient plan is very important in stereotactic treatments. VMAT plans were prepared with 6MV-FFF or 10MV-FFF energies for 25 intracranial and extracranial stereotactic patients. Absolute dose was measured for dose verification in each plans. Iba® CC01, Iba® CC04, Iba® CC13 ion chambers placed at a depth of 5cm in solid phantom (RW3). Also we scanned this phantom with ion chambers by Siemens® Biograph mCT. QA plans were prepared by transferring twenty five patient plans to phantom assemblies for three ion chambers. All plans were performed separately for three ion chambers at Elekta® Versa HD linear accelerator. Statistical analysis of results were made by Wilcoxon signed-rank test. Difference between dose values were determined %1.84±3.4 (p: 0.001) with Iba CC13 ion chamber, %1.80±3.4 (p: 0.002) with Iba CC04 ion chamber and %0.29±4.6 (p: 0.667) with Iba CC01 ion chamber. In stereotactic treatments, dosimetric uncertainty increases in small areas. We determined more accurate results with small sized detectors. Difference between TPS calculations and all measurements were founded lower than %2.
Verification of absorbed dose calculation with XIO Radiotherapy Treatment Planning System
International Nuclear Information System (INIS)
Bokulic, T.; Budanec, M.; Frobe, A.; Gregov, M.; Kusic, Z.; Mlinaric, M.; Mrcela, I.
2013-01-01
Modern radiotherapy relies on computerized treatment planning systems (TPS) for absorbed dose calculation. Most TPS require a detailed model of a given machine and therapy beams. International Atomic Energy Agency (IAEA) recommends acceptance testing for the TPS (IAEA-TECDOC-1540). In this study we present customization of those tests for measurements with the purpose of verification of beam models intended for clinical use in our department. Elekta Synergy S linear accelerator installation and data acquisition for Elekta CMS XiO 4.62 TPS was finished in 2011. After the completion of beam modelling in TPS, tests were conducted in accordance with the IAEA protocol for TPS dose calculation verification. The deviations between the measured and calculated dose were recorded for 854 points and 11 groups of tests in a homogenous phantom. Most of the deviations were within tolerance. Similar to previously published results, results for irregular L shaped field and asymmetric wedged fields were out of tolerance for certain groups of points.(author)
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Davidson, Scott E., E-mail: sedavids@utmb.edu [Radiation Oncology, The University of Texas Medical Branch, Galveston, Texas 77555 (United States); Cui, Jing [Radiation Oncology, University of Southern California, Los Angeles, California 90033 (United States); Kry, Stephen; Ibbott, Geoffrey S.; Followill, David S. [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States); Deasy, Joseph O. [Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York 10065 (United States); Vicic, Milos [Department of Applied Physics, University of Belgrade, Belgrade 11000 (Serbia); White, R. Allen [Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States)
2016-08-15
Purpose: A dose calculation tool, which combines the accuracy of the dose planning method (DPM) Monte Carlo code and the versatility of a practical analytical multisource model, which was previously reported has been improved and validated for the Varian 6 and 10 MV linear accelerators (linacs). The calculation tool can be used to calculate doses in advanced clinical application studies. One shortcoming of current clinical trials that report dose from patient plans is the lack of a standardized dose calculation methodology. Because commercial treatment planning systems (TPSs) have their own dose calculation algorithms and the clinical trial participant who uses these systems is responsible for commissioning the beam model, variation exists in the reported calculated dose distributions. Today’s modern linac is manufactured to tight specifications so that variability within a linac model is quite low. The expectation is that a single dose calculation tool for a specific linac model can be used to accurately recalculate dose from patient plans that have been submitted to the clinical trial community from any institution. The calculation tool would provide for a more meaningful outcome analysis. Methods: The analytical source model was described by a primary point source, a secondary extra-focal source, and a contaminant electron source. Off-axis energy softening and fluence effects were also included. The additions of hyperbolic functions have been incorporated into the model to correct for the changes in output and in electron contamination with field size. A multileaf collimator (MLC) model is included to facilitate phantom and patient dose calculations. An offset to the MLC leaf positions was used to correct for the rudimentary assumed primary point source. Results: Dose calculations of the depth dose and profiles for field sizes 4 × 4 to 40 × 40 cm agree with measurement within 2% of the maximum dose or 2 mm distance to agreement (DTA) for 95% of the data
International Nuclear Information System (INIS)
Lee, Choonsik; Kim, Kwang Pyo; Long, Daniel J.; Bolch, Wesley E.
2012-01-01
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 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 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 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 differences up to
Monte Carlo characterisation of the Dose Magnifying Glass for proton therapy quality assurance
International Nuclear Information System (INIS)
Merchant, A H; Guatelli, S; Petesecca, M; Jackson, M; Rozenfeld, A B
2017-01-01
A Geant4 Monte Carlo simulation study was carried out to characterise a novel silicon strip detector, the Dose Magnifying Glass (DMG), for use in proton therapy Quality Assurance. We investigated the possibility to use DMG to determine the energy of the incident proton beam. The advantages of DMG are quick response, easy operation and high spatial resolution. In this work we theoretically proved that DMG can be used for QA in the determination of the energy of the incident proton beam, for ocular and prostate cancer therapy. The study was performed by means of Monte Carlo simulations Experimental measurements are currently on their way to confirm the results of this simulation study. (paper)
3D calculation of absorbed dose for 131I-targeted radiotherapy: A Monte Carlo study
International Nuclear Information System (INIS)
Saeedzadeh, E.; Sarkar, S.; Abbaspour Tehrani-Fard, A.; Ay, M. R.; Khosravi, H. R.; Loudos, G.
2008-01-01
Various methods, such as those developed by the Medical Internal Radiation Dosimetry (MIRD) Committee of the Society of Nuclear Medicine or employing dose point kernels, have been applied to the radiation dosimetry of 131 I radionuclide therapy. However, studies have not shown a strong relationship between tumour absorbed dose and its overall therapeutic response, probably due in part to inaccuracies in activity and dose estimation. In the current study, the GATE Monte Carlo computer code was used to facilitate voxel-level radiation dosimetry for organ activities measured in an. 131 I-treated thyroid cancer patient. This approach allows incorporation of the size, shape and composition of organs (in the current study, in the Zubal anthropomorphic phantom) and intra-organ and intra-tumour inhomogeneities in the activity distributions. The total activities of the tumours and their heterogeneous distributions were measured from the SPECT images to calculate the dose maps. For investigating the effect of activity distribution on dose distribution, a hypothetical homogeneous distribution of the same total activity was considered in the tumours. It was observed that the tumour mean absorbed dose rates per unit cumulated activity were 0.65 E-5 and 0.61 E-5 mGY MBq -1 s -1 for the uniform and non-uniform distributions in the tumour, respectively, which do not differ considerably. However, the dose-volume histograms (DVH) show that the tumour non-uniform activity distribution decreases the absorbed dose to portions of the tumour volume. In such a case, it can be misleading to quote the mean or maximum absorbed dose, because overall response is likely limited by the tumour volume that receives low (i.e. non-cytocidal) doses. Three-dimensional radiation dosimetry, and calculation of tumour DVHs, may lead to the derivation of clinically reliable dose-response relationships and therefore may ultimately improve treatment planning as well as response assessment for radionuclide
A Monte Carlo Study of dose enhancement according to the enhancement agents
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Kim, Jung Hoon; Kim, Chang Soo [Dept. of Radiological Science, College of Health Sciences, Catholic University of Pusan, Busan (Korea, Republic of); Hwang, Chul Hwan [Dept. of Radiation Oncology, Pusan National University Hospital, Busan (Korea, Republic of)
2017-03-15
Dose enhancement effects at megavoltage (MV) X and γ-ray energies, and the effects of different energy levels on incident energy, dose enhancement agents, and concentrations were analyzed using Monte Carlo simulations. Gold, gadolinium, Iodine, and iron oxide (Fe2O3) were compared as dose enhancement agents. For incident energy, 4, 6, 10 and 15 MV X-ray spectra produced by a linear accelerator and a Co60 γ-ray were used. The dose enhancement factor (DEF) was calculated using an ICRU Slab phantom for concentrations of 7, 18, and 30 mg/g. The DEF was higher at higher concentrations of dose enhancement agents and at lower incident energies. The calculated DEF ranged from 1.035 to 1.079, and dose enhancement effects were highest for iron oxide, followed by iodine, gadolinium, and gold. Thus, this study contributes to improving the therapeutic ratio by delivering larger doses of radiation to tumor volume, and provides data to support further in vivo and in vitro studies.
Dose-image quality study in digital chest radiography using Monte Carlo simulation
International Nuclear Information System (INIS)
Correa, S.C.A.; Souza, E.M.; Silva, A.X.; Lopes, R.T.; Yoriyaz, H.
2008-01-01
One of the main preoccupations of diagnostic radiology is to guarantee a good image-sparing dose to the patient. In the present study, Monte Carlo simulations, with MCNPX code, coupled with an adult voxel female model (FAX) were performed to investigate how image quality and dose in digital chest radiography vary with tube voltage (80-150 kV) using air-gap technique and a computed radiography system. Calculated quantities were normalized to a fixed value of entrance skin exposure (ESE) of 0.0136 R. The results of the present analysis show that the image quality for chest radiography with imaging plate is improved and the dose reduced at lower tube voltage
Online pretreatment verification of high-dose rate brachytherapy using an imaging panel
Fonseca, Gabriel P.; Podesta, Mark; Bellezzo, Murillo; Van den Bosch, Michiel R.; Lutgens, Ludy; Vanneste, Ben G. L.; Voncken, Robert; Van Limbergen, Evert J.; Reniers, Brigitte; Verhaegen, Frank
2017-07-01
Brachytherapy is employed to treat a wide variety of cancers. However, an accurate treatment verification method is currently not available. This study describes a pre-treatment verification system that uses an imaging panel (IP) to verify important aspects of the treatment plan. A detailed modelling of the IP was only possible with an extensive calibration performed using a robotic arm. Irradiations were performed with a high dose rate (HDR) 192Ir source within a water phantom. An empirical fit was applied to measure the distance between the source and the detector so 3D Cartesian coordinates of the dwell positions can be obtained using a single panel. The IP acquires 7.14 fps to verify the dwell times, dwell positions and air kerma strength (Sk). A gynecological applicator was used to create a treatment plan that was registered with a CT image of the water phantom used during the experiments for verification purposes. Errors (shifts, exchanged connections and wrong dwell times) were simulated to verify the proposed verification system. Cartesian source positions (panel measurement plane) have a standard deviation of about 0.02 cm. The measured distance between the source and the panel (z-coordinate) have a standard deviation up to 0.16 cm and maximum absolute error of ≈0.6 cm if the signal is close to sensitive limit of the panel. The average response of the panel is very linear with Sk. Therefore, Sk measurements can be performed with relatively small errors. The measured dwell times show a maximum error of 0.2 s which is consistent with the acquisition rate of the panel. All simulated errors were clearly identified by the proposed system. The use of IPs is not common in brachytherapy, however, it provides considerable advantages. It was demonstrated that the IP can accurately measure Sk, dwell times and dwell positions.
International Nuclear Information System (INIS)
Jarry, G; De Marco, J J; Beifuss, U; Cagnon, C H; McNitt-Gray, M F
2003-01-01
The purpose of this work is to develop and test a method to estimate the relative and absolute absorbed radiation dose from axial and spiral CT scans using a Monte Carlo approach. Initial testing was done in phantoms and preliminary results were obtained from a standard mathematical anthropomorphic model (MIRD V) and voxelized patient data. To accomplish this we have modified a general purpose Monte Carlo transport code (MCNP4B) to simulate the CT x-ray source and movement, and then to calculate absorbed radiation dose in desired objects. The movement of the source in either axial or spiral modes was modelled explicitly while the CT system components were modelled using published information about x-ray spectra as well as information provided by the manufacturer. Simulations were performed for single axial scans using the head and body computed tomography dose index (CTDI) polymethylmethacrylate phantoms at both central and peripheral positions for all available beam energies and slice thicknesses. For comparison, corresponding physical measurements of CTDI in phantom were made with an ion chamber. To obtain absolute dose values, simulations and measurements were performed in air at the scanner isocentre for each beam energy. To extend the verification, the CT scanner model was applied to the MIRD V model and compared with published results using similar technical factors. After verification of the model, the generalized source was simulated and applied to voxelized models of patient anatomy. The simulated and measured absolute dose data in phantom agreed to within 2% for the head phantom and within 4% for the body phantom at 120 and 140 kVp; this extends to 8% for the head and 9% for the body phantom across all available beam energies and positions. For the head phantom, the simulated and measured absolute dose data agree to within 2% across all slice thicknesses at 120 kVp. Our results in the MIRD phantom agree within 11% of all the different organ dose values
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Kramer, R.; Zankl, M.; Williams, G.; Drexler, G.
1982-12-01
By the help of a Monte-Carlo program the dose that single organs, organ groups and bigger or smaller parts of body would receive on an average, caused by an irradiation definitely fixed by the geometry of irradiation and photon energy, can be determined. Thus the phantom in connection with the Monte-Carlo program can be used for several considerations as for example - calculation of dose from occupational exposures - calculation of dose from diagnostic procedures - calculation of dose from radiotherapy procedures. (orig.)
Studying the potential of point detectors in time-resolved dose verification of dynamic radiotherapy
International Nuclear Information System (INIS)
Beierholm, A.R.; Behrens, C.F.; Andersen, C.E.
2015-01-01
Modern megavoltage x-ray radiotherapy with high spatial and temporal dose gradients puts high demands on the entire delivery system, including not just the linear accelerator and the multi-leaf collimator, but also algorithms used for optimization and dose calculations, and detectors used for quality assurance and dose verification. In this context, traceable in-phantom dosimetry using a well-characterized point detector is often an important supplement to 2D-based quality assurance methods based on radiochromic film or detector arrays. In this study, an in-house developed dosimetry system based on fiber-coupled plastic scintillator detectors was evaluated and compared with a Farmer-type ionization chamber and a small-volume ionization chamber. An important feature of scintillator detectors is that the sensitive volume of the detector can easily be scaled, and five scintillator detectors of different scintillator length were thus employed to quantify volume averaging effects by direct measurement. The dosimetric evaluation comprised several complex-shape static fields as well as simplified dynamic deliveries using RapidArc, a volumetric-modulated arc therapy modality often used at the participating clinic. The static field experiments showed that the smallest scintillator detectors were in the best agreement with dose calculations, while needing the smallest volume averaging corrections. Concerning total dose measured during RapidArc, all detectors agreed with dose calculations within 1.1 ± 0.7% when positioned in regions of high homogenous dose. Larger differences were observed for high dose gradient and organ at risk locations, were differences between measured and calculated dose were as large as 8.0 ± 5.5%. The smallest differences were generally seen for the small-volume ionization chamber and the smallest scintillators. The time-resolved RapidArc dose profiles revealed volume-dependent discrepancies between scintillator and ionization chamber response
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.
Oliver, P. A. K.; Thomson, Rowan M.
2017-02-01
This work investigates how doses to cellular targets depend on cell morphology, as well as relations between cellular doses and doses to bulk tissues and water. Multicellular models of five healthy and cancerous soft tissues are developed based on typical values of cell compartment sizes, elemental compositions and number densities found in the literature. Cells are modelled as two concentric spheres with nucleus and cytoplasm compartments. Monte Carlo simulations are used to calculate the absorbed dose to the nucleus and cytoplasm for incident photon energies of 20-370 keV, relevant for brachytherapy, diagnostic radiology, and out-of-field radiation in higher-energy external beam radiotherapy. Simulations involving cell clusters, single cells and single nuclear cavities are carried out for cell radii between 5 and 10~μ m, and nuclear radii between 2 and 9~μ m. Seven nucleus and cytoplasm elemental compositions representative of animal cells are considered. The presence of a cytoplasm, extracellular matrix and surrounding cells can affect the nuclear dose by up to 13 % . Differences in cell and nucleus size can affect dose to the nucleus (cytoplasm) of the central cell in a cluster of 13 cells by up to 13 % (8 % ). Furthermore, the results of this study demonstrate that neither water nor bulk tissue are reliable substitutes for subcellular targets for incident photon energies <50 keV: nuclear (cytoplasm) doses differ from dose-to-medium by up to 32 % (18 % ), and from dose-to-water by up to 21 % (8 % ). The largest differences between dose descriptors are seen for the lowest incident photon energies; differences are less than 3 % for energies ≥slant 90 keV. The sensitivity of results with regard to the parameters of the microscopic tissue structure model and cell model geometry, and the importance of the nucleus and cytoplasm as targets for radiation-induced cell death emphasize the importance of accurate models for cellular dosimetry studies.
Study of the IMRT interplay effect using a 4DCT Monte Carlo dose calculation.
Jensen, Michael D; Abdellatif, Ady; Chen, Jeff; Wong, Eugene
2012-04-21
Respiratory motion may lead to dose errors when treating thoracic and abdominal tumours with radiotherapy. The interplay between complex multileaf collimator patterns and patient respiratory motion could result in unintuitive dose changes. We have developed a treatment reconstruction simulation computer code that accounts for interplay effects by combining multileaf collimator controller log files, respiratory trace log files, 4DCT images and a Monte Carlo dose calculator. Two three-dimensional (3D) IMRT step-and-shoot plans, a concave target and integrated boost were delivered to a 1D rigid motion phantom. Three sets of experiments were performed with 100%, 50% and 25% duty cycle gating. The log files were collected, and five simulation types were performed on each data set: continuous isocentre shift, discrete isocentre shift, 4DCT, 4DCT delivery average and 4DCT plan average. Analysis was performed using 3D gamma analysis with passing criteria of 2%, 2 mm. The simulation framework was able to demonstrate that a single fraction of the integrated boost plan was more sensitive to interplay effects than the concave target. Gating was shown to reduce the interplay effects. We have developed a 4DCT Monte Carlo simulation method that accounts for IMRT interplay effects with respiratory motion by utilizing delivery log files.
Commissioning of a MOSFET in-vivo patient dose verification system
International Nuclear Information System (INIS)
Jenetsky, G.O.; Brown, R.L.
2004-01-01
Full text: TLD dosimetry has long been used for in-vivo measurements in estimating absorbed dose to critical structures on patients. Preparing TLDs for measurement, and then obtaining the results is a time consuming process taking many hours. The Thomson-Neilson 'MOSFET 20' (Metal Oxide Semiconducting Field Effect Transistor) dose assessment system, allows for in-vivo measurements (preparation and results) within minutes. Before being used clinically for dose verification, the MOSFETs were tested against the manufacturer's technical specifications, and compared with results from TLDs measured under controlled experiments and patient measurements. Standard sensitivity MOSFETs (TN-502RD) were used with the bias supply set to High sensitivity range. MOSFETs were tested for linearity (5-100cGy) and their calibration factors obtained for all energies (6MV, 18MV, 6MeV, 12MeV, 16MeV, 20MeV) using the method described by Ramani. MOSFETs and TLDs were exposed to a 6MV beam for 50MU at various depths (RW3 solid water phantom) and field sizes and compared to results taken with an ion chamber. Measurements using both systems were also taken at beam edge and 5mm and 10mm out of the field. Eleven patients, who had lens dose assessment requests were measured with both TLDs and MOSFETs and a paired t-test was performed on the results. On two patients, multiple (nine and four) MOSFET measurements were taken and the range of results compared to the range obtained from the TLDs. MOSFET linearity obtained co-efficients of R 2 ≥ 0.996 for all energies, this compared to R 2 ≥ 0.996 recorded by both Ramani and Chaung. The y-intercept values varied from 0 to -2.0mV. Greatest variation between calibration factors, measured for each energy, was 7.5%, this is substantially greater than 3.8% quoted by the manufacturer. For the measurements taken at varying depths and field sizes both TLDs and MOSFETs agreed with the ion chamber results ±IcGy. Measurements taken at beam edge varied ±6c
International Nuclear Information System (INIS)
Esnaashari, K. N.; Allahverdi, M.; Gharaati, H.; Shahriari, M.
2007-01-01
Stereotactic radiosurgery is an important clinical tool for the treatment of small lesions in the brain, including benign conditions, malignant and localized metastatic tumors. A dosimetry study was performed for Elekta 'Synergy S' as a dedicated Stereotactic radiosurgery unit, capable of generating circular radiation fields with diameters of 1-5 cm at iso centre using the BEAM/EGS4 Monte Carlo code. Materials and Methods: The linear accelerator Elekta Synergy S equipped with a set of 5 circular collimators from 10 mm to 50 mm in diameter at iso centre distance was used. The cones were inserted in a base plate mounted on the collimator linac head. A PinPoint chamber and Wellhofer water tank chamber were selected for clinical dosimetry of 6 MV photon beams. The results of simulations using the Monte Carlo system BEAM/EGS4 to model the beam geometry were compared with dose measurements. Results: An excellent agreement was found between Monte Carlo calculated and measured percentage depth dose and lateral dose profiles which were performed in water phantom for circular cones with 1, 2, 3, 4 and 5 cm in diameter. The comparison between calculation and measurements showed up to 0.5 % or 1 m m difference for all field sizes. The penumbra (80-20%) results at 5 cm depth in water phantom and SSD=95 ranged from 1.5 to 2.1 mm for circular collimators with diameter 1 to 5 cm. Conclusion: This study showed that BEAMnrc code has been accurate in modeling Synergy S linear accelerator equipped with circular collimators
International Nuclear Information System (INIS)
Bilodid, Y.; Kotlyar, D.; Margulis, M.; Fridman, E.; Shwageraus, E.
2015-01-01
Highlights: • Pu-239 based spectral history method was tested on 3D BWR single assembly case. • Burnup of a BWR fuel assembly was performed with the nodal code DYN3D. • Reference solution was obtained by coupled Monte-Carlo thermal-hydraulic code BGCore. • The proposed method accurately reproduces moderator density history effect for BWR test case. - Abstract: This research focuses on the verification of a recently developed methodology accounting for spectral history effects in 3D full core nodal simulations. The traditional deterministic core simulation procedure includes two stages: (1) generation of homogenized macroscopic cross section sets and (2) application of these sets to obtain a full 3D core solution with nodal codes. The standard approach adopts the branch methodology in which the branches represent all expected combinations of operational conditions as a function of burnup (main branch). The main branch is produced for constant, usually averaged, operating conditions (e.g. coolant density). As a result, the spectral history effects that associated with coolant density variation are not taken into account properly. Number of methods to solve this problem (such as micro-depletion and spectral indexes) were developed and implemented in modern nodal codes. Recently, we proposed a new and robust method to account for history effects. The methodology was implemented in DYN3D and involves modification of the few-group cross section sets. The method utilizes the local Pu-239 concentration as an indicator of spectral history. The method was verified for PWR and VVER applications. However, the spectrum variation in BWR core is more pronounced due to the stronger coolant density change. The purpose of the current work is investigating the applicability of the method to BWR analysis. The proposed methodology was verified against recently developed BGCore system, which couples Monte Carlo neutron transport with depletion and thermal-hydraulic solvers and
Doses determination in UCCA treatments with LDR brachytherapy using Monte Carlo methods
International Nuclear Information System (INIS)
Benites R, J. L.; Vega C, H. R.
2017-10-01
Using Monte Carlo methods, with the code MCNP5, a gynecological mannequin and a vaginal cylinder were modeled. The spatial distribution of absorbed dose rate in uterine cervical cancer (UCCA) treatments was determined under the modality of manual brachytherapy of low dose rate (B-LDR). The design of the model included the gynecological liquid water mannequin, a vaginal cylinder applicator of Lucite (PMMA) with hemisphere termination. The applicator was formed by a vaginal cylinder 10.3 cm long and 2 cm in diameter. This cylinder was mounted on a stainless steel tube 15.2 cm long by 0.6 cm in diameter. A linear array of four radioactive sources of Cesium 137 was inserted into the tube. 13 water cells of 0.5 cm in diameter were modeled around the vaginal cylinder and the absorbed dose was calculated in these. The distribution of the fluence of gamma photons in the mesh was calculated. It was found that the distribution of the absorbed dose is symmetric for cells located in the upper and lower part of the vaginal cylinder. The values of the absorbed dose rate were estimated for the date of manufacture of the sources. This result allows the use of the law of radioactive decay to determine the dose rate at any date of a gynecological treatment of B-LDR. (Author)
Application of the Monte Carlo method to estimate doses in a radioactive waste drum environment
International Nuclear Information System (INIS)
Rodenas, J.; Garcia, T.; Burgos, M.C.; Felipe, A.; Sanchez-Mayoral, M.L.
2002-01-01
During refuelling operation in a Nuclear Power Plant, filtration is used to remove non-soluble radionuclides contained in the water from reactor pool. Filter cartridges accumulate a high radioactivity, so that they are usually placed into a drum. When the operation ends up, the drum is filled with concrete and stored along with other drums containing radioactive wastes. Operators working in the refuelling plant near these radwaste drums can receive high dose rates. Therefore, it is convenient to estimate those doses to prevent risks in order to apply ALARA criterion for dose reduction to workers. The Monte Carlo method has been applied, using MCNP 4B code, to simulate the drum containing contaminated filters and estimate doses produced in the drum environment. In the paper, an analysis of the results obtained with the MCNP code has been performed. Thus, the influence on the evaluated doses of distance from drum and interposed shielding barriers has been studied. The source term has also been analysed to check the importance of the isotope composition. Two different geometric models have been considered in order to simplify calculations. Results have been compared with dose measurements in plant in order to validate the calculation procedure. This work has been developed at the Nuclear Engineering Department of the Polytechnic University of Valencia in collaboration with IBERINCO in the frame of an RD project sponsored by IBERINCO
Postimplant Dosimetry Using a Monte Carlo Dose Calculation Engine: A New Clinical Standard
International Nuclear Information System (INIS)
Carrier, Jean-Francois; D'Amours, Michel; Verhaegen, Frank; Reniers, Brigitte; Martin, Andre-Guy; Vigneault, Eric; Beaulieu, Luc
2007-01-01
Purpose: To use the Monte Carlo (MC) method as a dose calculation engine for postimplant dosimetry. To compare the results with clinically approved data for a sample of 28 patients. Two effects not taken into account by the clinical calculation, interseed attenuation and tissue composition, are being specifically investigated. Methods and Materials: An automated MC program was developed. The dose distributions were calculated for the target volume and organs at risk (OAR) for 28 patients. Additional MC techniques were developed to focus specifically on the interseed attenuation and tissue effects. Results: For the clinical target volume (CTV) D 90 parameter, the mean difference between the clinical technique and the complete MC method is 10.7 Gy, with cases reaching up to 17 Gy. For all cases, the clinical technique overestimates the deposited dose in the CTV. This overestimation is mainly from a combination of two effects: the interseed attenuation (average, 6.8 Gy) and tissue composition (average, 4.1 Gy). The deposited dose in the OARs is also overestimated in the clinical calculation. Conclusions: The clinical technique systematically overestimates the deposited dose in the prostate and in the OARs. To reduce this systematic inaccuracy, the MC method should be considered in establishing a new standard for clinical postimplant dosimetry and dose-outcome studies in a near future
Monte Carlo simulation of secondary neutron dose for scanning proton therapy using FLUKA.
Directory of Open Access Journals (Sweden)
Chaeyeong Lee
Full Text Available Proton therapy is a rapidly progressing field for cancer treatment. Globally, many proton therapy facilities are being commissioned or under construction. Secondary neutrons are an important issue during the commissioning process of a proton therapy facility. The purpose of this study is to model and validate scanning nozzles of proton therapy at Samsung Medical Center (SMC by Monte Carlo simulation for beam commissioning. After the commissioning, a secondary neutron ambient dose from proton scanning nozzle (Gantry 1 was simulated and measured. This simulation was performed to evaluate beam properties such as percent depth dose curve, Bragg peak, and distal fall-off, so that they could be verified with measured data. Using the validated beam nozzle, the secondary neutron ambient dose was simulated and then compared with the measured ambient dose from Gantry 1. We calculated secondary neutron dose at several different points. We demonstrated the validity modeling a proton scanning nozzle system to evaluate various parameters using FLUKA. The measured secondary neutron ambient dose showed a similar tendency with the simulation result. This work will increase the knowledge necessary for the development of radiation safety technology in medical particle accelerators.
Monte Carlo 20 and 45 MeV Bremsstrahlung and dose-reduction calculations
Energy Technology Data Exchange (ETDEWEB)
Goosman, D.R.
1984-08-14
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.
Monte Carlo 20 and 45 MeV Bremsstrahlung and dose-reduction calculations
International Nuclear Information System (INIS)
Goosman, D.R.
1984-01-01
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
Monte Carlo simulation of dose calculation in voxel and geometric phantoms using GEANT4 code
International Nuclear Information System (INIS)
Martins, Maximiano C.; Santos, Denison de S.; Queiroz Filho, Pedro P. de; Silva, Rosana de S. e; Begalli, Marcia
2009-01-01
Monte Carlo simulation techniques have become a valuable tool for scientific purposes. In radiation protection many quantities are obtained by means of the simulation of particles passing through human body models, also known as phantoms, allowing the calculation of doses deposited in an individual's organs exposed to ionizing radiation. These information are very useful from the medical viewpoint, as they are used in the planning of external beam radiotherapy and brachytherapy treatments. The goal of this work is the implementation of a voxel phantom and a geometrical phantom in the framework of the Geant4 tool kit, aiming at a future use of this code by professionals in the medical area. (author)
Image quality and dose assessment in digital breast tomosynthesis: A Monte Carlo study
International Nuclear Information System (INIS)
Baptista, M.; Di Maria, S.; Oliveira, N.; Matela, N.; Janeiro, L.; Almeida, P.; Vaz, P.
2014-01-01
Mammography is considered a standard technique for the early detection of breast cancer. However, its sensitivity is limited essentially due to the issue of the overlapping breast tissue. This limitation can be partially overcome, with a relatively new technique, called digital breast tomosynthesis (DBT). For this technique, optimization of acquisition parameters which maximize image quality, whilst complying with the ALARA principle, continues to be an area of considerable research. The aim of this work was to study the best quantum energies that optimize the image quality with the lowest achievable dose in DBT and compare these results with the digital mammography (DM) ones. Monte Carlo simulations were performed using the state-of-the-art computer program MCNPX 2.7.0 in order to generate several 2D cranio-caudal (CC) projections obtained during an acquisition of a standard DBT examination. Moreover, glandular absorbed doses and photon flux calculations, for each projection image, were performed. A homogeneous breast computational phantom with 50%/50% glandular/adipose tissue composition was used and two compressed breast thicknesses were evaluated: 4 cm and 8 cm. The simulated projection images were afterwards reconstructed with an algebraic reconstruction tool and the signal difference to noise ratio (SDNR) was calculated in order to evaluate the image quality in DBT and DM. Finally, a thorough comparison between the results obtained in terms of SDNR and dose assessment in DBT and DM was performed. - Highlights: • Optimization of the image quality in digital breast tomosynthesis. • Calculation of photon energies that maximize the signal difference to noise ratio. • Projections images and dose calculations through the Monte Carlo (MC) method. • Tumor masses and microcalcifications included in the MC model. • A dose saving of about 30% can be reached if optimal photon energies are used
International Nuclear Information System (INIS)
Yang, Bo; Qiu, Rui; Li, JunLi; Lu, Wei; Wu, Zhen; Li, Chunyan
2017-01-01
When a strong laser beam irradiates a solid target, a hot plasma is produced and high-energy electrons are usually generated (the so-called “hot electrons”). These energetic electrons subsequently generate hard X-rays in the solid target through the Bremsstrahlung process. To date, only limited studies have been conducted on this laser-induced radiological protection issue. In this study, extensive literature reviews on the physics and properties of hot electrons have been conducted. On the basis of these information, the photon dose generated by the interaction between hot electrons and a solid target was simulated with the Monte Carlo code FLUKA. With some reasonable assumptions, the calculated dose can be regarded as the upper boundary of the experimental results over the laser intensity ranging from 10 19 to 10 21 W/cm 2 . Furthermore, an equation to estimate the photon dose generated from ultraintense laser–solid interactions based on the normalized laser intensity is derived. The shielding effects of common materials including concrete and lead were also studied for the laser-driven X-ray source. The dose transmission curves and tenth-value layers (TVLs) in concrete and lead were calculated through Monte Carlo simulations. These results could be used to perform a preliminary and fast radiation safety assessment for the X-rays generated from ultraintense laser–solid interactions. - Highlights: • The laser–driven X-ray ionizing radiation source was analyzed in this study. • An equation to estimate the photon dose based on the laser intensity is given. • The shielding effects of concrete and lead were studied for this new X-ray source. • The aim of this study is to analyze and mitigate the laser–driven X-ray hazard.
Application of Monte Carlo method for dose calculation in thyroid follicle
International Nuclear Information System (INIS)
Silva, Frank Sinatra Gomes da
2008-02-01
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)
Correction of CT artifacts and its influence on Monte Carlo dose calculations
International Nuclear Information System (INIS)
Bazalova, Magdalena; Beaulieu, Luc; Palefsky, Steven; Verhaegen, Frank
2007-01-01
Computed tomography (CT) images of patients having metallic implants or dental fillings exhibit severe streaking artifacts. These artifacts may disallow tumor and organ delineation and compromise dose calculation outcomes in radiotherapy. We used a sinogram interpolation metal streaking artifact correction algorithm on several phantoms of exact-known compositions and on a prostate patient with two hip prostheses. We compared original CT images and artifact-corrected images of both. To evaluate the effect of the artifact correction on dose calculations, we performed Monte Carlo dose calculation in the EGSnrc/DOSXYZnrc code. For the phantoms, we performed calculations in the exact geometry, in the original CT geometry and in the artifact-corrected geometry for photon and electron beams. The maximum errors in 6 MV photon beam dose calculation were found to exceed 25% in original CT images when the standard DOSXYZnrc/CTCREATE calibration is used but less than 2% in artifact-corrected images when an extended calibration is used. The extended calibration includes an extra calibration point for a metal. The patient dose volume histograms of a hypothetical target irradiated by five 18 MV photon beams in a hypothetical treatment differ significantly in the original CT geometry and in the artifact-corrected geometry. This was found to be mostly due to miss-assignment of tissue voxels to air due to metal artifacts. We also developed a simple Monte Carlo model for a CT scanner and we simulated the contribution of scatter and beam hardening to metal streaking artifacts. We found that whereas beam hardening has a minor effect on metal artifacts, scatter is an important cause of these artifacts
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.
Dose measurement using radiochromic lms and Monte Carlo simulation for hadron-therapy
International Nuclear Information System (INIS)
Zahra, N.
2010-06-01
Because of the increase in dose at the end of the range of ions, dose delivery during patient treatment with hadron-therapy should be controlled with high precision. Monte Carlo codes are now considered mandatory for validation of clinical treatment planning and as a new tool for dosimetry of ion beams. In this work, we aimed to calculate the absorbed dose using Monte Carlo simulation Geant4/Gate. The effect on the dose calculation accuracy of different Geant4 parameters has been studied for mono-energetic carbon ion beams of 300 MeV/u in water. The parameters are: the production threshold of secondary particles and the maximum step limiter of the particle track. Tolerated criterion were chosen to meet the precision required in radiotherapy in term of value and dose localisation (2%, 2 mm respectively) and to obtain the best compromise on dose distribution and computational time. We propose here the values of parameters in order to satisfy the precision required. In the second part of this work, we study the response of radiochromic films MD-v2-55 for quality control in proton and carbon ion beams. We have particularly observed and studied the quenching effect of dosimetric films for high LET (≥20 keV/μm) irradiation in homogeneous and heterogeneous media. This effect is due to the high ionization density around the track of the particle. We have developed a method to predict the response of radiochromic films taking into account the saturation effect. This model is called the RADIS model for 'Radiochromic films Dosimetry for Ions using Simulations'. It is based on the response of films under photon irradiations and the saturation of films due to high linear energy deposit calculated by Monte Carlo. Different beams were used in this study and aimed to validate the model for hadron-therapy applications: carbon ions, protons and photons at different energies. Experiments were performed at Grand Accelerateur National d'Ions Lourds (GANIL), Proton therapy center of
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Liu, X; Yin, Y; Lin, X [Shandong Cancer Hospital and Institute, China, Jinan, Shandong (China)
2016-06-15
Purpose: To assess the preliminary feasibility of automated treatment planning verification system in cervical cancer IMRT pre-treatment dose verification. Methods: The study selected randomly clinical IMRT treatment planning data for twenty patients with cervical cancer, all IMRT plans were divided into 7 fields to meet the dosimetric goals using a commercial treatment planning system(PianncleVersion 9.2and the EclipseVersion 13.5). The plans were exported to the Mobius 3D (M3D)server percentage differences of volume of a region of interest (ROI) and dose calculation of target region and organ at risk were evaluated, in order to validate the accuracy automated treatment planning verification system. Results: The difference of volume for Pinnacle to M3D was less than results for Eclipse to M3D in ROI, the biggest difference was 0.22± 0.69%, 3.5±1.89% for Pinnacle and Eclipse respectively. M3D showed slightly better agreement in dose of target and organ at risk compared with TPS. But after recalculating plans by M3D, dose difference for Pinnacle was less than Eclipse on average, results were within 3%. Conclusion: The method of utilizing the automated treatment planning system to validate the accuracy of plans is convenientbut the scope of differences still need more clinical patient cases to determine. At present, it should be used as a secondary check tool to improve safety in the clinical treatment planning.
Faught, Austin M; Davidson, Scott E; Fontenot, Jonas; Kry, Stephen F; Etzel, Carol; Ibbott, Geoffrey S; Followill, David S
2017-09-01
The Imaging and Radiation Oncology Core Houston (IROC-H) (formerly the Radiological Physics Center) has reported varying levels of agreement in their anthropomorphic phantom audits. There is reason to believe one source of error in this observed disagreement is the accuracy of the dose calculation algorithms and heterogeneity corrections used. To audit this component of the radiotherapy treatment process, an independent dose calculation tool is needed. Monte Carlo multiple source models for Elekta 6 MV and 10 MV therapeutic x-ray beams were commissioned based on measurement of central axis depth dose data for a 10 × 10 cm 2 field size and dose profiles for a 40 × 40 cm 2 field size. The models were validated against open field measurements consisting of depth dose data and dose profiles for field sizes ranging from 3 × 3 cm 2 to 30 × 30 cm 2 . The models were then benchmarked against measurements in IROC-H's anthropomorphic head and neck and lung phantoms. Validation results showed 97.9% and 96.8% of depth dose data passed a ±2% Van Dyk criterion for 6 MV and 10 MV models respectively. Dose profile comparisons showed an average agreement using a ±2%/2 mm criterion of 98.0% and 99.0% for 6 MV and 10 MV models respectively. Phantom plan comparisons were evaluated using ±3%/2 mm gamma criterion, and averaged passing rates between Monte Carlo and measurements were 87.4% and 89.9% for 6 MV and 10 MV models respectively. Accurate multiple source models for Elekta 6 MV and 10 MV x-ray beams have been developed for inclusion in an independent dose calculation tool for use in clinical trial audits. © 2017 American Association of Physicists in Medicine.
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
IMRT implementation and patient specific dose verification with film and ion chamber array detectors
International Nuclear Information System (INIS)
Saminathan, S.; Manickam, R.; Chandraraj, V.; Supe, S. S.; Keshava, S. L.
2009-01-01
Implementation of Intensity Modulation Radiotherapy (IMRT) and patient dose verification was carried out with film and I'mariXX using linear accelerator with 120-leaf Millennium dynamic multi leaf collimator (dMLC). The basic mechanical and electrical commissioning and quality assurance tests of linear accelerator were carried out. The leaf position accuracy and leaf position repeatability checks were performed for static MLC positions. Picket fence test and garden fence test were performed to check the stability of the dMLC and the reproducibility of the gap between leaves. The radiation checks were performed to verify the position accuracy of MLCs in the collimator system. The dMLC dosimetric checks like output stability, average leaf transmission and dosimetric leaf separation were also investigated. The variation of output with gravitation at different gantry angles was found to be within 0.9%. The measured average leaf transmission for 6 MV was 1.6% and 1.8% for 18 MV beam. The dosimetric leaf separation was found to be 2.2 mm and 2.3 mm for 6 MV and 18 MV beams. In order to check the consistency of the stability and the precision of the dMLC, it is necessary to carryout regular weekly and monthly checks. The dynalog files analysis for Garden fence, leaf gap width and step wedge test patterns carried out weekly were in good agreement. Pretreatment verification was performed for 50 patients with ion chamber and I'matiXX device. The variations of calculated absolute dose for all treatment fields with the ion chamber measurement were within the acceptable criterion. Treatment Planning System (TPS) calculated dose distribution pattern was comparable with the I'matriXX measured dose distribution pattern. Out of 50 patients for which the comparison was made, 36 patients were agreed with the gamma pixel match of>95% and 14 patients were with the gamma pixel match of 90-95% with the criteria of 3% delta dose (DD) and 3 mm distance-to-agreement (DTA). Commissioning and
Estimation of skyshine dose from turbine building of BWR plant using Monte Carlo code
Energy Technology Data Exchange (ETDEWEB)
Yuji, Nemoto; Toshihisa, Tsukiyama; Shigeki, Nemezawa [Hitachi. Ltd., Saiwai-cho, Hitachi (Japan); Tadashi, Yamasaki; Hidetsugu, Okada [Chubu Electric Power Company, Inc., Odaka-cho, Midori-ku Nagoya (Japan)
2007-07-01
The Monte Carlo N-Particle transport code (MCNP) was adopted to calculate the skyshine dose from the turbine building of a BWR plant for obtaining precise estimations at the site boundary. In MCNP calculation, the equipment and piping arranged on the operating floor of the turbine building were considered and modeled in detail. The inner and outer walls of the turbine building, the shielding materials around the high-pressure turbine, and the piping connected from the moisture separator to the low-pressure turbine were all considered. A three-step study was conducted to estimate the applicability of MCNP code. The first step is confirming the propriety of calculation models. The atmospheric relief diaphragms, which are installed on top of the low-pressure turbine exhaust hood, are not considered in the calculation model. There was little difference between the skyshine dose distributions that were considered when using and not using the atmospheric relief diaphragms. The calculated dose rates agreed well with the measurements taken around the turbine. The second step is estimating the dose rates on the outer roof surface of the turbine building. This calculation was made to confirm the dose distribution of gamma-rays on the turbine roof before being scattered into the air. The calculated dose rates agreed well with the measured data. The third step is making a final confirmation by comparing the calculations and measurements of skyshine dose rates around the turbine building. The source terms of the main steam system are based on the measured activity data of N-16 and C-15. As a conclusion, we were able to calculate reasonable skyshine dose rates by using MCNP code. (authors)
Monte Carlo dosimetry of the IRAsource high dose rate 192Ir brachytherapy source
International Nuclear Information System (INIS)
Sarabiasl, Akbar; Ayoobian, Navid; Jabbari, Iraj; Poorbaygi, Hossein; Javanshir, Mohammad Reza
2016-01-01
High-dose-rate (HDR) brachytherapy is a common method for cancer treatment in clinical brachytherapy. Because of the different source designs, there is a need for specific dosimetry data set for each HDR model. The purpose of this study is to obtain detailed dose rate distributions in water phantom for a first prototype HDR 192 Ir brachytherapy source model, IRAsource, and compare with the other published works. In this study, Monte Carlo N-particle (MCNP version 4C) code was used to simulate the dose rate distributions around the HDR source. A full set of dosimetry parameters reported by the American Association of Physicists in Medicine Task Group No. 43U1 was evaluated. Also, the absorbed dose rate distributions in water, were obtained in an along-away look-up table. The dose rate constant, Λ, of the IRAsource was evaluated to be equal to 1.112 ± 0.005 cGy h −1 U −1 . The results of dosimetry parameters are presented in tabulated and graphical formats and compared with those reported from other commercially available HDR 192 Ir sources, which are in good agreement. This justifies the use of specific data sets for this new source. The results obtained in this study can be used as input data in the conventional treatment planning systems.
The denoising of Monte Carlo dose distributions using convolution superposition calculations
International Nuclear Information System (INIS)
El Naqa, I; Cui, J; Lindsay, P; Olivera, G; Deasy, J O
2007-01-01
Monte Carlo (MC) dose calculations can be accurate but are also computationally intensive. In contrast, convolution superposition (CS) offers faster and smoother results but by making approximations. We investigated MC denoising techniques, which use available convolution superposition results and new noise filtering methods to guide and accelerate MC calculations. Two main approaches were developed to combine CS information with MC denoising. In the first approach, the denoising result is iteratively updated by adding the denoised residual difference between the result and the MC image. Multi-scale methods were used (wavelets or contourlets) for denoising the residual. The iterations are initialized by the CS data. In the second approach, we used a frequency splitting technique by quadrature filtering to combine low frequency components derived from MC simulations with high frequency components derived from CS components. The rationale is to take the scattering tails as well as dose levels in the high-dose region from the MC calculations, which presumably more accurately incorporates scatter; high-frequency details are taken from CS calculations. 3D Butterworth filters were used to design the quadrature filters. The methods were demonstrated using anonymized clinical lung and head and neck cases. The MC dose distributions were calculated by the open-source dose planning method MC code with varying noise levels. Our results indicate that the frequency-splitting technique for incorporating CS-guided MC denoising is promising in terms of computational efficiency and noise reduction. (note)
NOTE: The denoising of Monte Carlo dose distributions using convolution superposition calculations
El Naqa, I.; Cui, J.; Lindsay, P.; Olivera, G.; Deasy, J. O.
2007-09-01
Monte Carlo (MC) dose calculations can be accurate but are also computationally intensive. In contrast, convolution superposition (CS) offers faster and smoother results but by making approximations. We investigated MC denoising techniques, which use available convolution superposition results and new noise filtering methods to guide and accelerate MC calculations. Two main approaches were developed to combine CS information with MC denoising. In the first approach, the denoising result is iteratively updated by adding the denoised residual difference between the result and the MC image. Multi-scale methods were used (wavelets or contourlets) for denoising the residual. The iterations are initialized by the CS data. In the second approach, we used a frequency splitting technique by quadrature filtering to combine low frequency components derived from MC simulations with high frequency components derived from CS components. The rationale is to take the scattering tails as well as dose levels in the high-dose region from the MC calculations, which presumably more accurately incorporates scatter; high-frequency details are taken from CS calculations. 3D Butterworth filters were used to design the quadrature filters. The methods were demonstrated using anonymized clinical lung and head and neck cases. The MC dose distributions were calculated by the open-source dose planning method MC code with varying noise levels. Our results indicate that the frequency-splitting technique for incorporating CS-guided MC denoising is promising in terms of computational efficiency and noise reduction.
International Nuclear Information System (INIS)
Lee, Hyun Cheol; Yoo, Do Hyeon; Testa, Mauro; Shin, Wook-Geun; Choi, Hyun Joon; Ha, Wi-Ho; Yoo, Jaeryong; Yoon, Seokwon; Min, Chul Hee
2016-01-01
The aim of this study is to evaluate the potential hazard of naturally occurring radioactive material (NORM) added consumer products. Using the Monte Carlo method, the radioactive products were simulated with ICRP reference phantom and the organ doses were calculated with the usage scenario. Finally, the annual effective doses were evaluated as lower than the public dose limit of 1 mSv y"−"1 for 44 products. It was demonstrated that NORM-added consumer products could be quantitatively assessed for the safety regulation. - Highlights: • Consumer products considered that NORM would be included should be regulated. • 44 products were collected and its gamma activities were measured with HPGe detector. • Through Monte Carlo simulation, organ equivalent doses and effective doses on human phantom were calculated. • All annual effective doses for the products were evaluated as lower than dose limit for the public.
Monte Carlo calculations for doses in organs and tissues to oral radiography
International Nuclear Information System (INIS)
Sampaio, E.V.M.
1985-01-01
Using the MIRD 5 phantom and Monte Carlo technique, organ doses in patients undergoing external dental examination were calculated taking into account the different x-ray beam geometries and the various possible positions of x-ray source with regard to the head of the patient. It was necessary to introduce in the original computer program a new source description specific for dental examinations. To have a realistic evaluation of organ doses during dental examination it was necessary to introduce a new region in the phantom heat which characterizes the teeth and salivary glands. The attenuation of the x-ray beam by the lead shield of the radiographic film was also introduced in the calculation. (author)
Absorbed dose measurements in mammography using Monte Carlo method and ZrO2+PTFE dosemeters
International Nuclear Information System (INIS)
Duran M, H. A.; Hernandez O, M.; Salas L, M. A.; Hernandez D, V. M.; Vega C, H. R.; Pinedo S, A.; Ventura M, J.; Chacon, F.; Rivera M, T.
2009-10-01
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 2 +PTFE thermoluminescent dosemeters, this calculation was completed with calculating the absorbed dose. (author)
Characterization of 60Co dose distribution using BEAMnrc Monte Carlo code
International Nuclear Information System (INIS)
Abuissa, M. I. M.
2012-12-01
In this study BEAMnrc based on EGSnrc as Monte Carlo code has been used for modeling and simulating 6 0C o 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 6 0C o machine and to investigate the effect of increasing the surface to skin distance (SSD) on the 6 0C o 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)
International Nuclear Information System (INIS)
Badel, Jean-Noel
2009-01-01
This research thesis addresses the dosimetric control of radiotherapy treatments by using amorphous silicon digital portal imagery. In a first part, the author reports the analysis of the dosimetric abilities of the imager (iViewGT) which is used in the radiotherapy department. The stability of the imager response on a short and on a long term has been studied. A relationship between the image grey level and the dose has been established for a reference irradiation field. The influence of irradiation parameters on the grey level variation with respect to the dose has been assessed. The obtained results show the possibility to use this system for dosimetry provided that a precise calibration is performed while taking the most influencing irradiation parameters into account, i.e. photon beam nominal energy, field size, and patient thickness. The author reports the development of a Monte Carlo simulation to model the imager response. It models the accelerator head by a generalized source point. Space and energy distributions of photons are calculated. This modelling can also be applied to the calculation of dose distribution within a patient, or to study physical interactions in the accelerator head. Then, the author explores a new approach to dose portal image prediction within the frame of an in vivo dosimetric control. He computes the image transmitted through the patient by Monte Carlo simulation, and measures the portal image of the irradiation field without the patient. Validation experiments are reported, and problems to be solved are highlighted (computation time, improvement of the collimator simulation) [fr
Dose estimation of patients in CT examinations using EGS4 Monte-Carlo simulation of voxel phantom
International Nuclear Information System (INIS)
Akahane, K.; Kai, M.; Kusama, T.; Saito, K.
2002-01-01
A voxel phantom based on CT images of one Japanese male have developed in Japan Atomic Energy Research Institute. Dose calculations of patients in X-ray CT examinations were performed using the voxel phantom and EGS4 Monte-Carlo simulation code. The organ doses of the patients were estimated
Dose estimation of patients in CT examinations using EGS4 Monte-Carlo simulation of voxel phantom
Energy Technology Data Exchange (ETDEWEB)
Akahane, K.; Kai, M.; Kusama, T. [Oita Univ., of Nursing and Health Sciences, Oita-Ken (Japan); Saito, K. [JAERI, Ibaraki-ken (Japan)
2002-07-01
A voxel phantom based on CT images of one Japanese male have developed in Japan Atomic Energy Research Institute. Dose calculations of patients in X-ray CT examinations were performed using the voxel phantom and EGS4 Monte-Carlo simulation code. The organ doses of the patients were estimated.
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Baltas, D; Geramani, K N; Ioannidis, G T; Kolotas, C; Zamboglou, N [Strahlenklinik, Stadtische Kliniken Offenbach, Offenbach (Germany); Giannouli, S [Department of Electrical and Computer Engineering, National Technical University of Athens, Athens (Greece)
1999-12-31
Source anisotropy is a very important factor in brachytherapy quality assurance of high dose rate HDR Ir 192 afterloading stepping sources. If anisotropy is not taken into account then doses received by a brachytherapy patient in certain directions can be in error by a clinically significant amount. Experimental measurements of anisotropy are very labour intensive. We have shown that within acceptable limits of accuracy, Monte Carlo integration (MCI) of a modified Sievert integral (3D generalisation) can provide the necessary data within a much shorter time scale than can experiments. Hence MCI can be used for routine quality assurance schedules whenever a new design of HDR or PDR Ir 192 is used for brachytherapy afterloading. Our MCI calculation results are comparable with published experimental data and Monte Carlo simulation data for microSelectron and VariSource Ir 192 sources. We have shown not only that MCI offers advantages over alternative numerical integration methods, but also that treating filtration coefficients as radial distance-dependent functions improves Sievert integral accuracy at low energies. This paper also provides anisotropy data for three new Ir 192 sources, one for microSelectron-HDR and two for the microSelectron-PDR, for which data currently is not available. The information we have obtained in this study can be incorporated into clinical practice.
Schneider, Wilfried; Bortfeld, Thomas; Schlegel, Wolfgang
2000-02-01
We describe a new method to convert CT numbers into mass density and elemental weights of tissues required as input for dose calculations with Monte Carlo codes such as EGS4. As a first step, we calculate the CT numbers for 71 human tissues. To reduce the effort for the necessary fits of the CT numbers to mass density and elemental weights, we establish four sections on the CT number scale, each confined by selected tissues. Within each section, the mass density and elemental weights of the selected tissues are interpolated. For this purpose, functional relationships between the CT number and each of the tissue parameters, valid for media which are composed of only two components in varying proportions, are derived. Compared with conventional data fits, no loss of accuracy is accepted when using the interpolation functions. Assuming plausible values for the deviations of calculated and measured CT numbers, the mass density can be determined with an accuracy better than 0.04 g cm-3 . The weights of phosphorus and calcium can be determined with maximum uncertainties of 1 or 2.3 percentage points (pp) respectively. Similar values can be achieved for hydrogen (0.8 pp) and nitrogen (3 pp). For carbon and oxygen weights, errors up to 14 pp can occur. The influence of the elemental weights on the results of Monte Carlo dose calculations is investigated and discussed.
Monte Carlo dose calculation improvements for low energy electron beams using eMC
International Nuclear Information System (INIS)
Fix, Michael K; Frei, Daniel; Volken, Werner; Born, Ernst J; Manser, Peter; Neuenschwander, Hans
2010-01-01
The electron Monte Carlo (eMC) dose calculation algorithm in Eclipse (Varian Medical Systems) is based on the macro MC method and is able to predict dose distributions for high energy electron beams with high accuracy. However, there are limitations for low energy electron beams. This work aims to improve the accuracy of the dose calculation using eMC for 4 and 6 MeV electron beams of Varian linear accelerators. Improvements implemented into the eMC include (1) improved determination of the initial electron energy spectrum by increased resolution of mono-energetic depth dose curves used during beam configuration; (2) inclusion of all the scrapers of the applicator in the beam model; (3) reduction of the maximum size of the sphere to be selected within the macro MC transport when the energy of the incident electron is below certain thresholds. The impact of these changes in eMC is investigated by comparing calculated dose distributions for 4 and 6 MeV electron beams at source to surface distance (SSD) of 100 and 110 cm with applicators ranging from 6 x 6 to 25 x 25 cm 2 of a Varian Clinac 2300C/D with the corresponding measurements. Dose differences between calculated and measured absolute depth dose curves are reduced from 6% to less than 1.5% for both energies and all applicators considered at SSD of 100 cm. Using the original eMC implementation, absolute dose profiles at depths of 1 cm, d max and R50 in water lead to dose differences of up to 8% for applicators larger than 15 x 15 cm 2 at SSD 100 cm. Those differences are now reduced to less than 2% for all dose profiles investigated when the improved version of eMC is used. At SSD of 110 cm the dose difference for the original eMC version is even more pronounced and can be larger than 10%. Those differences are reduced to within 2% or 2 mm with the improved version of eMC. In this work several enhancements were made in the eMC algorithm leading to significant improvements in the accuracy of the dose calculation
Monte Carlo dose calculation improvements for low energy electron beams using eMC.
Fix, Michael K; Frei, Daniel; Volken, Werner; Neuenschwander, Hans; Born, Ernst J; Manser, Peter
2010-08-21
The electron Monte Carlo (eMC) dose calculation algorithm in Eclipse (Varian Medical Systems) is based on the macro MC method and is able to predict dose distributions for high energy electron beams with high accuracy. However, there are limitations for low energy electron beams. This work aims to improve the accuracy of the dose calculation using eMC for 4 and 6 MeV electron beams of Varian linear accelerators. Improvements implemented into the eMC include (1) improved determination of the initial electron energy spectrum by increased resolution of mono-energetic depth dose curves used during beam configuration; (2) inclusion of all the scrapers of the applicator in the beam model; (3) reduction of the maximum size of the sphere to be selected within the macro MC transport when the energy of the incident electron is below certain thresholds. The impact of these changes in eMC is investigated by comparing calculated dose distributions for 4 and 6 MeV electron beams at source to surface distance (SSD) of 100 and 110 cm with applicators ranging from 6 x 6 to 25 x 25 cm(2) of a Varian Clinac 2300C/D with the corresponding measurements. Dose differences between calculated and measured absolute depth dose curves are reduced from 6% to less than 1.5% for both energies and all applicators considered at SSD of 100 cm. Using the original eMC implementation, absolute dose profiles at depths of 1 cm, d(max) and R50 in water lead to dose differences of up to 8% for applicators larger than 15 x 15 cm(2) at SSD 100 cm. Those differences are now reduced to less than 2% for all dose profiles investigated when the improved version of eMC is used. At SSD of 110 cm the dose difference for the original eMC version is even more pronounced and can be larger than 10%. Those differences are reduced to within 2% or 2 mm with the improved version of eMC. In this work several enhancements were made in the eMC algorithm leading to significant improvements in the accuracy of the dose
International Nuclear Information System (INIS)
Georg, Dietmar; Stock, Markus; Kroupa, Bernhard; Olofsson, Joergen; Nyholm, Tufve; Ahnesjoe, Anders; Karlsson, Mikael
2007-01-01
Experimental methods are commonly used for patient-specific intensity-modulated radiotherapy (IMRT) verification. The purpose of this study was to investigate the accuracy and performance of independent dose calculation software (denoted as 'MUV' (monitor unit verification)) for patient-specific quality assurance (QA). 52 patients receiving step-and-shoot IMRT were considered. IMRT plans were recalculated by the treatment planning systems (TPS) in a dedicated QA phantom, in which an experimental 1D and 2D verification (0.3 cm 3 ionization chamber; films) was performed. Additionally, an independent dose calculation was performed. The fluence-based algorithm of MUV accounts for collimator transmission, rounded leaf ends, tongue-and-groove effect, backscatter to the monitor chamber and scatter from the flattening filter. The dose calculation utilizes a pencil beam model based on a beam quality index. DICOM RT files from patient plans, exported from the TPS, were directly used as patient-specific input data in MUV. For composite IMRT plans, average deviations in the high dose region between ionization chamber measurements and point dose calculations performed with the TPS and MUV were 1.6 ± 1.2% and 0.5 ± 1.1% (1 S.D.). The dose deviations between MUV and TPS slightly depended on the distance from the isocentre position. For individual intensity-modulated beams (total 367), an average deviation of 1.1 ± 2.9% was determined between calculations performed with the TPS and with MUV, with maximum deviations up to 14%. However, absolute dose deviations were mostly less than 3 cGy. Based on the current results, we aim to apply a confidence limit of 3% (with respect to the prescribed dose) or 6 cGy for routine IMRT verification. For off-axis points at distances larger than 5 cm and for low dose regions, we consider 5% dose deviation or 10 cGy acceptable. The time needed for an independent calculation compares very favourably with the net time for an experimental approach
International Nuclear Information System (INIS)
Delis, H.; Spyrou, G.; Costaridou, L.; Tzanakos, G.; Panayiotakis, G.
2006-01-01
Mammography is the technique with the highest sensitivity and specificity, for the early detection of nonpalpable lesions associated with breast cancer. As screening mammography refers to asymptomatic women, the task of optimization between the image quality and the radiation dose is critical. A way toward optimization could be the introduction of new anode materials. A method for producing the x-ray spectra of different anode/filter combinations is proposed. The performance of several mammographic spectra, produced by both existing and theoretical anode materials, is evaluated, with respect to their dose and subject contrast characteristics, using a Monte Carlo simulation.The mammographic performance is evaluated utilizing a properly designed mathematical phantom with embedded inhomogeneities, irradiated with different spectra, based on combinations of conventional and new (Ru, Ag) anode materials, with several filters (Mo, Rh, Ru, Ag, Nb, Al). An earlier developed and validated Monte Carlo model, for deriving both image and dose characteristics in mammography, was utilized and overall performance results were derived in terms of subject contrast to dose ratio and squared subject contrast to dose ratio. Results demonstrate that soft spectra, mainly produced from Mo, Rh, and Ru anodes and filtered with k-edge filters, provide increased subject contrast for inhomogeneities of both small size, simulating microcalcifications and low density, simulating masses. The harder spectra (W and Ag anode) come short in the discrimination task but demonstrate improved performance when considering the dose delivered to the breast tissue. As far as the overall performance is concerned, new theoretical spectra demonstrate a noticeable good performance that is similar, and in some cases better compared to commonly used systems, stressing the possibility of introducing new materials in mammographic practice as a possible contribution to its optimization task. In the overall
Energy Technology Data Exchange (ETDEWEB)
Silva-Rodríguez, Jesús, E-mail: jesus.silva.rodriguez@sergas.es; Aguiar, Pablo, E-mail: pablo.aguiar.fernandez@sergas.es [Fundación Ramón Domínguez, Santiago de Compostela, Galicia (Spain); Servicio de Medicina Nuclear, Complexo Hospitalario Universidade de Santiago de Compostela (USC), 15782, Galicia (Spain); Grupo de Imaxe Molecular, Instituto de Investigación Sanitarias (IDIS), Santiago de Compostela, 15706, Galicia (Spain); Sánchez, Manuel; Mosquera, Javier; Luna-Vega, Víctor [Servicio de Radiofísica y Protección Radiológica, Complexo Hospitalario Universidade de Santiago de Compostela (USC), 15782, Galicia (Spain); Cortés, Julia; Garrido, Miguel [Servicio de Medicina Nuclear, Complexo Hospitalario Universitario de Santiago de Compostela, 15706, Galicia, Spain and Grupo de Imaxe Molecular, Instituto de Investigación Sanitarias (IDIS), Santiago de Compostela, 15706, Galicia (Spain); Pombar, Miguel [Servicio de Radiofísica y Protección Radiológica, Complexo Hospitalario Universitario de Santiago de Compostela, 15706, Galicia (Spain); Ruibal, Álvaro [Servicio de Medicina Nuclear, Complexo Hospitalario Universidade de Santiago de Compostela (USC), 15782, Galicia (Spain); Grupo de Imaxe Molecular, Instituto de Investigación Sanitarias (IDIS), Santiago de Compostela, 15706, Galicia (Spain); Fundación Tejerina, 28003, Madrid (Spain)
2014-05-15
Purpose: Current procedure guidelines for whole body [18F]fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) state that studies with visible dose extravasations should be rejected for quantification protocols. Our work is focused on the development and validation of methods for estimating extravasated doses in order to correct standard uptake value (SUV) values for this effect in clinical routine. Methods: One thousand three hundred sixty-seven consecutive whole body FDG-PET studies were visually inspected looking for extravasation cases. Two methods for estimating the extravasated dose were proposed and validated in different scenarios using Monte Carlo simulations. All visible extravasations were retrospectively evaluated using a manual ROI based method. In addition, the 50 patients with higher extravasated doses were also evaluated using a threshold-based method. Results: Simulation studies showed that the proposed methods for estimating extravasated doses allow us to compensate the impact of extravasations on SUV values with an error below 5%. The quantitative evaluation of patient studies revealed that paravenous injection is a relatively frequent effect (18%) with a small fraction of patients presenting considerable extravasations ranging from 1% to a maximum of 22% of the injected dose. A criterion based on the extravasated volume and maximum concentration was established in order to identify this fraction of patients that might be corrected for paravenous injection effect. Conclusions: The authors propose the use of a manual ROI based method for estimating the effectively administered FDG dose and then correct SUV quantification in those patients fulfilling the proposed criterion.
TU-AB-BRC-12: Optimized Parallel MonteCarlo Dose Calculations for Secondary MU Checks
Energy Technology Data Exchange (ETDEWEB)
French, S; Nazareth, D [Roswell Park Cancer Institute, Buffalo, NY (United States); Bellor, M [Lockheed Martin, Manassas, VA (United States)
2016-06-15
Purpose: Secondary MU checks are an important tool used during a physics review of a treatment plan. Commercial software packages offer varying degrees of theoretical dose calculation accuracy, depending on the modality involved. Dose calculations of VMAT plans are especially prone to error due to the large approximations involved. Monte Carlo (MC) methods are not commonly used due to their long run times. We investigated two methods to increase the computational efficiency of MC dose simulations with the BEAMnrc code. Distributed computing resources, along with optimized code compilation, will allow for accurate and efficient VMAT dose calculations. Methods: The BEAMnrc package was installed on a high performance computing cluster accessible to our clinic. MATLAB and PYTHON scripts were developed to convert a clinical VMAT DICOM plan into BEAMnrc input files. The BEAMnrc installation was optimized by running the VMAT simulations through profiling tools which indicated the behavior of the constituent routines in the code, e.g. the bremsstrahlung splitting routine, and the specified random number generator. This information aided in determining the most efficient compiling parallel configuration for the specific CPU’s available on our cluster, resulting in the fastest VMAT simulation times. Our method was evaluated with calculations involving 10{sup 8} – 10{sup 9} particle histories which are sufficient to verify patient dose using VMAT. Results: Parallelization allowed the calculation of patient dose on the order of 10 – 15 hours with 100 parallel jobs. Due to the compiler optimization process, further speed increases of 23% were achieved when compared with the open-source compiler BEAMnrc packages. Conclusion: Analysis of the BEAMnrc code allowed us to optimize the compiler configuration for VMAT dose calculations. In future work, the optimized MC code, in conjunction with the parallel processing capabilities of BEAMnrc, will be applied to provide accurate
Moradi, F.; Ung, N. M.; Khandaker, M. U.; Mahdiraji, G. A.; Saad, M.; Malik, R. Abdul; Bustam, A. Z.; Zaili, Z.; Bradley, D. A.
2017-08-01
The relatively new treatment modality electronic intraoperative radiotherapy (IORT) is gaining popularity, irradiation being obtained within a surgically produced cavity being delivered via a low-energy x-ray source and spherical applicators, primarily for early stage breast cancer. Due to the spatially dramatic dose-rate fall off with radial distance from the source and effects related to changes in the beam quality of the low keV photon spectra, dosimetric account of the Intrabeam system is rather complex. Skin dose monitoring in IORT is important due to the high dose prescription per treatment fraction. In this study, modeling of the x-ray source and related applicators were performed using the Monte Carlo N-Particle transport code. The dosimetric characteristics of the model were validated against measured data obtained using an ionization chamber and EBT3 film as dosimeters. By using a simulated breast phantom, absorbed doses to the skin for different combinations of applicator size (1.5-5 cm) and treatment depth (0.5-3 cm) were calculated. Simulation results showed overdosing of the skin (>30% of prescribed dose) at a treatment depth of 0.5 cm using applicator sizes larger than 1.5 cm. Skin doses were significantly increased with applicator size, insofar as delivering 12 Gy (60% of the prescribed dose) to skin for the largest sized applicator (5 cm diameter) and treatment depth of 0.5 cm. It is concluded that the recommended 0.5-1 cm distance between the skin and applicator surface does not guarantee skin safety and skin dose is generally more significant in cases with the larger applicators. Highlights: • Intrabeam x-ray source and spherical applicators were simulated and skin dose was calculated. • Skin dose for constant skin to applicator distance strongly depends on applicator size. • Use of larger applicators generally results in higher skin dose. • The recommended 0.5-1 cm skin to applicator distance does not guarantee skin
International Nuclear Information System (INIS)
Perisinakis, Kostas; Tzedakis, Antonis; Damilakis, John
2008-01-01
The purpose of this work was to investigate the applicability and appropriateness of Monte Carlo-derived normalized data to provide accurate estimations of patient dose from computed tomography (CT) exposures. Monte Carlo methodology and mathematical anthropomorphic phantoms were used to simulate standard patient CT examinations of the head, thorax, abdomen, and trunk performed on a multislice CT scanner. Phantoms were generated to simulate the average adult individual and two individuals with different body sizes. Normalized dose values for all radiosensitive organs and normalized effective dose values were calculated for standard axial and spiral CT examinations. Discrepancies in CT dosimetry using Monte Carlo-derived coefficients originating from the use of: (a) Conversion coefficients derived for axial CT exposures, (b) a mathematical anthropomorphic phantom of standard body size to derive conversion coefficients, and (c) data derived for a specific CT scanner to estimate patient dose from CT examinations performed on a different scanner, were separately evaluated. The percentage differences between the normalized organ dose values derived for contiguous axial scans and the corresponding values derived for spiral scans with pitch=1 and the same total scanning length were up to 10%, while the corresponding percentage differences in normalized effective dose values were less than 0.7% for all standard CT examinations. The normalized organ dose values for standard spiral CT examinations with pitch 0.5-1.5 were found to differ from the corresponding values derived for contiguous axial scans divided by the pitch, by less than 14% while the corresponding percentage differences in normalized effective dose values were less than 1% for all standard CT examinations. Normalized effective dose values for the standard contiguous axial CT examinations derived by Monte Carlo simulation were found to considerably decrease with increasing body size of the mathematical phantom
Dose rate evaluation of body phantom behind ITER bio-shield wall using Monte Carlo method
International Nuclear Information System (INIS)
Beheshti, A.; Jabbari, I.; Karimian, A.; Abdi, M.
2012-01-01
One of the most critical risks to humans in reactors environment is radiation exposure. Around the tokamak hall personnel are exposed to a wide range of particles, including neutrons and photons. International Thermonuclear Experimental Reactor (ITER) is a nuclear fusion research and engineering project, which is the most advanced experimental tokamak nuclear fusion reactor. Dose rates assessment and photon radiation due to the neutron activation of the solid structures in ITER is important from the radiological point of view. Therefore, the dosimetry considered in this case is based on the Deuterium-Tritium (DT) plasma burning with neutrons production rate at 14.1 MeV. The aim of this study is assessment the amount of radiation behind bio-shield wall that a human received during normal operation of ITER by considering neutron activation and delay gammas. To achieve the aim, the ITER system and its components were simulated by Monte Carlo method. Also to increase the accuracy and precision of the absorbed dose assessment a body phantom were considered in the simulation. The results of this research showed that total dose rates level near the outside of bio-shield wall of the tokamak hall is less than ten percent of the annual occupational dose limits during normal operation of ITER and It is possible to learn how long human beings can remain in that environment before the body absorbs dangerous levels of radiation. (authors)
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Gomes B, W. O., E-mail: wilsonottobatista@gmail.com [Instituto Federal da Bahia, Rua Emidio dos Santos s/n, Barbalho 40301-015, Salvador de Bahia (Brazil)
2016-10-15
This study aimed to develop a geometry of irradiation applicable to the software PCXMC and the consequent calculation of effective dose in applications of the Computed Tomography Cone Beam (CBCT). We evaluated two different CBCT equipment s for dental applications: Care stream Cs 9000 3-dimensional tomograph; i-CAT and GENDEX GXCB-500. Initially characterize each protocol measuring the surface kerma input and the product kerma air-area, P{sub KA}, with solid state detectors RADCAL and PTW transmission chamber. Then we introduce the technical parameters of each preset protocols and geometric conditions in the PCXMC software to obtain the values of effective dose. The calculated effective dose is within the range of 9.0 to 15.7 μSv for 3-dimensional computer 9000 Cs; within the range 44.5 to 89 μSv for GXCB-500 equipment and in the range of 62-111 μSv for equipment Classical i-CAT. These values were compared with results obtained dosimetry using TLD implanted in anthropomorphic phantom and are considered consistent. Os effective dose results are very sensitive to the geometry of radiation (beam position in mathematical phantom). This factor translates to a factor of fragility software usage. But it is very useful to get quick answers to regarding process optimization tool conclusions protocols. We conclude that use software PCXMC Monte Carlo simulation is useful assessment protocols for CBCT tests in dental applications. (Author)
Fast CPU-based Monte Carlo simulation for radiotherapy dose calculation
Ziegenhein, Peter; Pirner, Sven; Kamerling, Cornelis Ph; Oelfke, Uwe
2015-08-01
Monte-Carlo (MC) simulations are considered to be the most accurate method for calculating dose distributions in radiotherapy. Its clinical application, however, still is limited by the long runtimes conventional implementations of MC algorithms require to deliver sufficiently accurate results on high resolution imaging data. In order to overcome this obstacle we developed the software-package PhiMC, which is capable of computing precise dose distributions in a sub-minute time-frame by leveraging the potential of modern many- and multi-core CPU-based computers. PhiMC is based on the well verified dose planning method (DPM). We could demonstrate that PhiMC delivers dose distributions which are in excellent agreement to DPM. The multi-core implementation of PhiMC scales well between different computer architectures and achieves a speed-up of up to 37× compared to the original DPM code executed on a modern system. Furthermore, we could show that our CPU-based implementation on a modern workstation is between 1.25× and 1.95× faster than a well-known GPU implementation of the same simulation method on a NVIDIA Tesla C2050. Since CPUs work on several hundreds of GB RAM the typical GPU memory limitation does not apply for our implementation and high resolution clinical plans can be calculated.
International Nuclear Information System (INIS)
Quade, U.
1994-01-01
Neutron- und Gamma dose rate calculations were performed for the storage containers filled with plutonium nitrate of the MOX fabrication facility of Siemens. For the particle transport calculations the Monte Carlo Code MCNP 4.2 was used. The calculated results were compared with experimental dose rate measurements. It can be stated that the choice of the code system was appropriate since all aspects of the many facettes of the problem were well reproduced in the calculations. The position dependency as well as the influence of the shieldings, the reflections and the mutual influences of the sources were well described by the calculations for the gamma and for the neutron dose rates. However, good agreement with the experimental results on the gamma dose rates could only be reached when the lead shielding of the detector was integrated into the geometry modelling of the calculations. For some few cases of thick shieldings and soft gamma ray sources the statistics of the calculational results were not sufficient. In such cases more elaborate variance reduction methods must be applied in future calculations. Thus the MCNP code in connection with NGSRC has been proven as an effective tool for the solution of this type of problems. (orig./HP) [de
Monte Carlo Estimation of Absorbed Dose Distributions Obtained from Heterogeneous 106Ru Eye Plaques.
Zaragoza, Francisco J; Eichmann, Marion; Flühs, Dirk; Sauerwein, Wolfgang; Brualla, Lorenzo
2017-09-01
The distribution of the emitter substance in 106 Ru eye plaques is usually assumed to be homogeneous for treatment planning purposes. However, this distribution is never homogeneous, and it widely differs from plaque to plaque due to manufacturing factors. By Monte Carlo simulation of radiation transport, we study the absorbed dose distribution obtained from the specific CCA1364 and CCB1256 106 Ru plaques, whose actual emitter distributions were measured. The idealized, homogeneous CCA and CCB plaques are also simulated. The largest discrepancy in depth dose distribution observed between the heterogeneous and the homogeneous plaques was 7.9 and 23.7% for the CCA and CCB plaques, respectively. In terms of isodose lines, the line referring to 100% of the reference dose penetrates 0.2 and 1.8 mm deeper in the case of heterogeneous CCA and CCB plaques, respectively, with respect to the homogeneous counterpart. The observed differences in absorbed dose distributions obtained from heterogeneous and homogeneous plaques are clinically irrelevant if the plaques are used with a lateral safety margin of at least 2 mm. However, these differences may be relevant if the plaques are used in eccentric positioning.
Moving from organ dose to microdosimetry: contribution of the Monte Carlo simulations
Directory of Open Access Journals (Sweden)
Christophe Champion
2005-10-01
Full Text Available When living cells are irradiated by charged particles, a wide variety of interactions occurs that leads to a deep modification of the biological material. To understand the fine structure of the microscopic distribution of the energy deposits, Monte Carlo event-by-event simulations are particularly suitable. However, the development of these track structure codes needs accurate interaction cross sections for all the electronic processes: ionization, excitation, Positronium formation (for incident positrons and even elastic scattering. Under these conditions, we have recently developed a Monte Carlo code for electrons and positrons in water, this latter being commonly used to simulate the biological medium. All the processes are studied in detail via theoretical differential and total cross sections calculated by using partial wave methods. Comparisons with existing theoretical and experimental data show very good agreements. Moreover, this kind of detailed description allows one access to a useful microdosimetry, which can be coupled to a geometrical modelling of the target organ and then provide a detailed dose calculation at the nanometric scale.Quando células vivas são irradiadas por partículas carregadas, ocorre uma grande variedade de interações, o que leva a uma modificação profunda do material biológico. Para entender a delicada estrutura da distribuição microscópica dos depósitos de energia, as simulações de Monte Carlo são particularmente adequadas. Entretanto, o desenvolvimento destes códigos necessitam de amostras representativa de interações perfeitas para todos os processos eletrônicos: ionização, excitação, formação de positrônico (para pósitrons incidentes e mesmo espalhamento elástico. Nessas condições, nós desenvolvemos recentemente um código Monte Carlo para elétrons e pósitrons em água usada posteriormente para simular o meio biológico. Todos os processos são estudados detalhadamente via se
Landry, Guillaume; Reniers, Brigitte; Pignol, Jean-Philippe; Beaulieu, Luc; Verhaegen, Frank
2011-03-01
The goal of this work is to compare D(m,m) (radiation transported in medium; dose scored in medium) and D(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 ap plying 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. 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: 125I, 103Pd, and 131Cs seeds, as well as an EBS operating at 50 kV. Ratios of D(w,m) over D(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 103Pd) and prostate (using 125I) brachytherapy seed implants are considered. MC dose calculations are performed based on postimplant CT scans using prostate and breast tissue compositions. PTV D90 values are compared for D(w,m) and D(m,m). (1) Differences (D(w,m)/D(m,m)-1) of -3% to 70% are observed for the investigated tissues. For a given tissue, D(w,m)/D(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 D90(w,m) over D90(m,m) for clinical implants matches D(w,m)/D(m,m) at 1 cm from the single point sources, Given
International Nuclear Information System (INIS)
Tateoka, Kunihiko; Hareyama, Masato; Oouchi, Atsushi; Nakata, Kensei; Nagase, Daiki; Saikawa, Tsunehiko; Shimizume, Kazunari; Sugimoto, Harumi; Waka, Masaaki
2003-01-01
Intensity-modulated radiation therapy (IMRT) was developed to irradiate the target are more conformally, sparing organs at risk (OARs). Since the beams are sequentially delivered by many, small, irregular, and off-center fields in IMRT, dosimetric quality assurance (QA) is an extremely important issue. QA is performed by verifying both the dose distribution and doses at arbitrary points. In this work, we describe the verification of doses at arbitrary points in our hospital for Segmental multileaf collimator (SMLC)-IMRT. In general, verification of the absolute doses for IMRT is performed by comparison between the calculated doses using Radiation Treatment Planning Systems (RTP) and the measured doses using an ionization chamber with a small volume at arbitrary points in relatively flat regions of the dose gradients. However, no clear definitions of the dose gradients and the flat regions have yet been reported. We carried out verification by comparison of the measured doses with the average dose and the central point dose in a virtual Farmer type ionization chamber (V-F) and a virtual PinPoint ionization chamber (V-P) equal to the Farmer-type ionization chamber volume and PinPoint ionization chamber volumes using the RTP. Furthermore, we defined the dose gradients as the deviation of the maximum dose from the minimum dose in the virtual ionization chamber volume. In IMRT, the dose gradients may be as high as 80% or more in the virtual ionization chamber volume. Therefore, it is thought that the effective center of the ionization chamber varies by segment for IMRT fields (i.e., the variation of the ionization chamber replacement effect). Additionally, in regions with a higher dose gradient, uncertainty in the measured doses is influenced by the variations in the ionization chamber replacement effect and the ionization chamber positioning error. We more objectively examined the verification method for the absolute dose in IMRT using the virtual ionization chamber
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.
SU-F-T-494: A Multi-Institutional Study of Independent Dose Verification Using Golden Beam Data
Energy Technology Data Exchange (ETDEWEB)
Itano, M; Yamazaki, T [Inagi Municipal Hospital, Inagi, Tokyo (Japan); Tachibana, R; Uchida, Y [National Cancer Center Hospital East, Kashiwa, Chiba (Japan); Yamashita, M [Kobe City Medical Center General Hospital, Kobe, Hyogo (Japan); Shimizu, H [Kitasato University Medical Center, Kitamoto, Saitama (Japan); Sugawara, Y; Kotabe, K [National Center for Global Health and Medicine, Shinjuku, Tokyo (Japan); Kamima, T [Cancer Institute Hospital Japanese Foundation for Cancer Research, Koto, Tokyo (Japan); Takahashi, R [Cancer Institute Hospital of Japanese Foundation for Cancer Research, Koto, Tokyo (Japan); Ishibashi, S [Sasebo City General Hospital, Sasebo, Nagasaki (Japan); Tachibana, H [National Cancer Center, Kashiwa, Chiba (Japan)
2016-06-15
Purpose: In general, beam data of individual linac is measured for independent dose verification software program and the verification is performed as a secondary check. In this study, independent dose verification using golden beam data was compared to that using individual linac’s beam data. Methods: Six institutions were participated and three different beam data were prepared. The one was individual measured data (Original Beam Data, OBD) .The others were generated by all measurements from same linac model (Model-GBD) and all linac models (All-GBD). The three different beam data were registered to the independent verification software program for each institute. Subsequently, patient’s plans in eight sites (brain, head and neck, lung, esophagus, breast, abdomen, pelvis and bone) were analyzed using the verification program to compare doses calculated using the three different beam data. Results: 1116 plans were collected from six institutes. Compared to using the OBD, the results shows the variation using the Model-GBD based calculation and the All-GBD was 0.0 ± 0.3% and 0.0 ± 0.6%, respectively. The maximum variations were 1.2% and 2.3%, respectively. The plans with the variation over 1% shows the reference points were located away from the central axis with/without physical wedge. Conclusion: The confidence limit (2SD) using the Model-GBD and the All-GBD was within 0.6% and 1.2%, respectively. Thus, the use of golden beam data may be feasible for independent verification. In addition to it, the verification using golden beam data provide quality assurance of planning from the view of audit. This research is partially supported by Japan Agency for Medical Research and Development(AMED)
SU-F-T-494: A Multi-Institutional Study of Independent Dose Verification Using Golden Beam Data
International Nuclear Information System (INIS)
Itano, M; Yamazaki, T; Tachibana, R; Uchida, Y; Yamashita, M; Shimizu, H; Sugawara, Y; Kotabe, K; Kamima, T; Takahashi, R; Ishibashi, S; Tachibana, H
2016-01-01
Purpose: In general, beam data of individual linac is measured for independent dose verification software program and the verification is performed as a secondary check. In this study, independent dose verification using golden beam data was compared to that using individual linac’s beam data. Methods: Six institutions were participated and three different beam data were prepared. The one was individual measured data (Original Beam Data, OBD) .The others were generated by all measurements from same linac model (Model-GBD) and all linac models (All-GBD). The three different beam data were registered to the independent verification software program for each institute. Subsequently, patient’s plans in eight sites (brain, head and neck, lung, esophagus, breast, abdomen, pelvis and bone) were analyzed using the verification program to compare doses calculated using the three different beam data. Results: 1116 plans were collected from six institutes. Compared to using the OBD, the results shows the variation using the Model-GBD based calculation and the All-GBD was 0.0 ± 0.3% and 0.0 ± 0.6%, respectively. The maximum variations were 1.2% and 2.3%, respectively. The plans with the variation over 1% shows the reference points were located away from the central axis with/without physical wedge. Conclusion: The confidence limit (2SD) using the Model-GBD and the All-GBD was within 0.6% and 1.2%, respectively. Thus, the use of golden beam data may be feasible for independent verification. In addition to it, the verification using golden beam data provide quality assurance of planning from the view of audit. This research is partially supported by Japan Agency for Medical Research and Development(AMED)
Three dimensional dose verification for clinical treatments of small intracranial tumours
International Nuclear Information System (INIS)
Taylor, M.L.; Dunn, L.; Kairn, L.; Jenny, J.; Knight, R.; Trapp, J.; Smith, R.; Ackerly, T.
2010-01-01
Full text: Cancers of the brain and central nervous system account for 1.6% of new cancers and 1.8% of cancer deaths globally. The highest rates of all developed nations are observed in Australia and New Zealand. There are known complexities associated with dose measurement of very small radiation fields. Here, 3D dosimetric verification of treatments for small intracranial tumours using gel dosimetry was investigated. An anthropomorphic head phantom with a 43 mm diameter and 63 mm long gel container was filled with PAGAT normoxic radiosensitive gel. In this work, we show results for a 12-field stereotactic radiotherapy treatment delivered using a Varian 21EX with BrainLAB mini-multi leaf collimator. The gel was read out using an Octopus-1Q laser optical CT scanner. Generally good agreement was observed between the measured doses and those calculated with the iPlan treatment planning system (pencil beam convolution); see Fig. I. For gamma criteria of 5%/5 mm the percentage of gamma values less than unity was 95% above the 80% isodose line, indicating good PTV coverage. For lower isodose regions approaching the boundaries of the container poorer agreement was observed. The feasibility of three-dimensional measurement of small field dose distributions in clinical contexts has been demonstrated. Development of this methodology has the potential to overcome many shortcomings of other dosimetric methods, such as limitations of spatial information (typically one- and two-dimensions), volume-averaging effects and perturbation due to poor mediamatching. (author)
Image registration of BANG[reg] gel dose maps for quantitative dosimetry verification
International Nuclear Information System (INIS)
Meeks, Sanford L.; Bova, Frank J.; Maryanski, Marek J.; Kendrick, Lance A.; Ranade, Manisha K.; Buatti, John M.; Friedman, William A.
1999-01-01
the pixel resolution of the MRI dose maps is 1.56 x 1.56 mm, and the treatment-planning dose distributions were calculated on a 1-mm dose grid. All points within the dose distribution were well within the tolerances set forth for commissioning and quality assurance of stereotactic treatment-planning systems. Moreover, the quantitative evaluation presented here tests the accuracy of the entire treatment-planning and delivery process, including stereotactic frame rigidity, CT localization, CT/MR correlation, dose calculation, and radiation delivery. Conclusion: BANG[reg] polymer gel dosimetry coupled with image correlation provides quantitative verification of the accuracy of 3D dose distributions. Such quantitative evaluation is imperative to ensure the high quality of the 3D dose distributions generated and delivered by stereotactic and other conformal irradiation systems
Energy Technology Data Exchange (ETDEWEB)
Ding, G [Vanderbilt University Nashville, TN (United States); Yin, F; Ren, L [Duke University Medical Center, Durham, NC (United States)
2016-06-15
Purpose: In order to track the tumor movement for patient positioning verification during arc treatment delivery or in between 3D/IMRT beams for stereotactic body radiation therapy (SBRT), the limited-angle kV projections acquisition simultaneously during arc treatment delivery or in-between static treatment beams as the gantry moves to the next beam angle was proposed. The purpose of this study is to estimate additional imaging dose resulting from multiple tomosynthesis acquisitions in-between static treatment beams and to compare with that of a conventional kV-CBCT acquisition. Methods: kV imaging system integrated into Varian TrueBeam accelerators was modeled using EGSnrc Monte Carlo user code, BEAMnrc and DOSXYZnrc code was used in dose calculations. The simulated realistic kV beams from the Varian TrueBeam OBI 1.5 system were used to calculate dose to patient based on CT images. Organ doses were analyzed using DVHs. The imaging dose to patient resulting from realistic multiple tomosynthesis acquisitions with each 25–30 degree kV source rotation between 6 treatment beam gantry angles was studied. Results: For a typical lung SBRT treatment delivery much lower (20–50%) kV imaging doses from the sum of realistic six tomosynthesis acquisitions with each 25–30 degree x-ray source rotation between six treatment beam gantry angles were observed compared to that from a single CBCT image acquisition. Conclusion: This work indicates that the kV imaging in this proposed Limited-angle Intra-fractional Verification (LIVE) System for SBRT Treatments has a negligible imaging dose increase. It is worth to note that the MV imaging dose caused by MV projection acquisition in-between static beams in LIVE can be minimized by restricting the imaging to the target region and reducing the number of projections acquired. For arc treatments, MV imaging acquisition in LIVE does not add additional imaging dose as the MV images are acquired from treatment beams directly during the
TH-AB-201-01: A Feasibility Study of Independent Dose Verification for CyberKnife
International Nuclear Information System (INIS)
Sato, A; Noda, T; Keduka, Y; Kawajiri, T; Itano, M; Yamazaki, T; Tachibana, H
2016-01-01
Purpose: CyberKnife irradiation is composed of tiny-size, multiple and intensity-modulated beams compared to conventional linacs. Few of the publications for Independent dose calculation verification for CyberKnife have been reported. In this study, we evaluated the feasibility of independent dose verification for CyberKnife treatment as Secondary check. Methods: The followings were measured: test plans using some static and single beams, clinical plans in a phantom and using patient’s CT. 75 patient plans were collected from several treatment sites of brain, lung, liver and bone. In the test plans and the phantom plans, a pinpoint ion-chamber measurement was performed to assess dose deviation for a treatment planning system (TPS) and an independent verification program of Simple MU Analysis (SMU). In the clinical plans, dose deviation between the SMU and the TPS was performed. Results: In test plan, the dose deviations were 3.3±4.5%, and 4.1±4.4% for the TPS and the SMU, respectively. In the phantom measurements for the clinical plans, the dose deviations were −0.2±3.6% for the TPS and −2.3±4.8% for the SMU. In the clinical plans using the patient’s CT, the dose deviations were −3.0±2.1% (Mean±1SD). The systematic difference was partially derived from inverse square law and penumbra calculation. Conclusion: The independent dose calculation for CyberKnife shows −3.0±4.2% (Mean±2SD) and our study, the confidence limit was achieved within 5% of the tolerance level from AAPM task group 114 for non-IMRT treatment. Thus, it may be feasible to use independent dose calculation verification for CyberKnife treatment as the secondary check. This research is partially supported by Japan Agency for Medical Research and Development (AMED)
International Nuclear Information System (INIS)
Ji Gang; Guo Yong; Luo Yisheng; Zhang Wenzhong
2001-01-01
Objective: To provide useful parameters for neutron radiotherapy, the author presents results of a Monte Carlo simulation study investigating the dosimetric characteristics of linear 252 Cf fission neutron sources. Methods: A 252 Cf fission source and tissue equivalent phantom were modeled. The dose of neutron and gamma radiations were calculated using Monte Carlo Code. Results: The dose of neutron and gamma at several positions for 252 Cf in the phantom made of equivalent materials to water, blood, muscle, skin, bone and lung were calculated. Conclusion: The results by Monte Carlo methods were compared with the data by measurement and references. According to the calculation, the method using water phantom to simulate local tissues such as muscle, blood and skin is reasonable for the calculation and measurements of dose distribution for 252 Cf
International Nuclear Information System (INIS)
Yeh, Chi-Yuan; Tung, Chuan-Jung; Chao, Tsi-Chain; Lin, Mu-Han; Lee, Chung-Chi
2014-01-01
canal. Dose volume histogram (DVH) analyses revealed much smoother DVH curves for the dual resolution sandwich phantom when compared to the SR phantom. In conclusion, MBMC simulations using a dual resolution sandwich phantom improved simulation spatial resolution for skull base IMRS therapy. More detailed dose analyses for small critical structures can be made available to help in clinical judgment. - Highlights: • The measurement-based Monte Carlo (MBMC) simulation can serve as a standard reference for dose verification in intensity-modulated radiosurgery. • This study is the first in literature to describe a dual resolution sandwich phantom for Monte Carlo simulation. • MBMC simulation using the sandwich phantom revealed more dose distribution details for small volume critical organs. • MBMC simulation using the sandwich phantom detected significant dose differences in small organs of the inner ear
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Ding, A; Han, B; Bush, K; Wang, L; Xing, L
2015-01-01
Purpose: Dosimetric verification of VMAT/SBRT is currently performed on one or two planes in a phantom with either film or array detectors. A robust and easy-to-use 3D dosimetric tool has been sought since the advent of conformal radiation therapy. Here we present such a strategy for independent 3D VMAT/SBRT plan verification system by a combined use of EPID and cloud-based Monte Carlo (MC) dose calculation. Methods: The 3D dosimetric verification proceeds in two steps. First, the plan was delivered with a high resolution portable EPID mounted on the gantry, and the EPID-captured gantry-angle-resolved VMAT/SBRT field images were converted into fluence by using the EPID pixel response function derived from MC simulations. The fluence was resampled and used as the input for an in-house developed Amazon cloud-based MC software to reconstruct the 3D dose distribution. The accuracy of the developed 3D dosimetric tool was assessed using a Delta4 phantom with various field sizes (square, circular, rectangular, and irregular MLC fields) and different patient cases. The method was applied to validate VMAT/SBRT plans using WFF and FFF photon beams (Varian TrueBeam STX). Results: It was found that the proposed method yielded results consistent with the Delta4 measurements. For points on the two detector planes, a good agreement within 1.5% were found for all the testing fields. Patient VMAT/SBRT plan studies revealed similar level of accuracy: an average γ-index passing rate of 99.2± 0.6% (3mm/3%), 97.4± 2.4% (2mm/2%), and 72.6± 8.4 % ( 1mm/1%). Conclusion: A valuable 3D dosimetric verification strategy has been developed for VMAT/SBRT plan validation. The technique provides a viable solution for a number of intractable dosimetry problems, such as small fields and plans with high dose gradient
Energy Technology Data Exchange (ETDEWEB)
Ding, A; Han, B; Bush, K; Wang, L; Xing, L [Stanford University School of Medicine, Stanford, CA (United States)
2015-06-15
Purpose: Dosimetric verification of VMAT/SBRT is currently performed on one or two planes in a phantom with either film or array detectors. A robust and easy-to-use 3D dosimetric tool has been sought since the advent of conformal radiation therapy. Here we present such a strategy for independent 3D VMAT/SBRT plan verification system by a combined use of EPID and cloud-based Monte Carlo (MC) dose calculation. Methods: The 3D dosimetric verification proceeds in two steps. First, the plan was delivered with a high resolution portable EPID mounted on the gantry, and the EPID-captured gantry-angle-resolved VMAT/SBRT field images were converted into fluence by using the EPID pixel response function derived from MC simulations. The fluence was resampled and used as the input for an in-house developed Amazon cloud-based MC software to reconstruct the 3D dose distribution. The accuracy of the developed 3D dosimetric tool was assessed using a Delta4 phantom with various field sizes (square, circular, rectangular, and irregular MLC fields) and different patient cases. The method was applied to validate VMAT/SBRT plans using WFF and FFF photon beams (Varian TrueBeam STX). Results: It was found that the proposed method yielded results consistent with the Delta4 measurements. For points on the two detector planes, a good agreement within 1.5% were found for all the testing fields. Patient VMAT/SBRT plan studies revealed similar level of accuracy: an average γ-index passing rate of 99.2± 0.6% (3mm/3%), 97.4± 2.4% (2mm/2%), and 72.6± 8.4 % ( 1mm/1%). Conclusion: A valuable 3D dosimetric verification strategy has been developed for VMAT/SBRT plan validation. The technique provides a viable solution for a number of intractable dosimetry problems, such as small fields and plans with high dose gradient.
Evaluation of an electron Monte Carlo dose calculation algorithm for treatment planning.
Chamberland, Eve; Beaulieu, Luc; Lachance, Bernard
2015-05-08
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
Energy Technology Data Exchange (ETDEWEB)
Khan, Rao; Zavan, Rodolfo; McGeachy, Philip; Madamesila, Joseph; Villarreal-Barajas, Jose Eduardo [Radiation Oncology, Washington University School of Medicine, St Louis, MO, USA, Instituto de Física de São Carlos, Universidade de São Paulo, SP, Brazil, CancerCare Manitoba, Winnipeg,Manitoba, Physics and Astronomy, University of Calgary, Calgary, Alberta (Canada)
2016-08-15
Purpose: Transport based dose calculation algorithm Acuros XB (AXB) has been shown to accurately account for heterogeneities mostly through comparisons with Monte Carlo simulations. This study aims at providing additional experimental verification for AXB for flattened and unflattened clinical energies in low density phantoms of the same material. Materials and Methods: Polystyrene slabs were created using a bench-top 3D printer. Six slabs were printed at varying densities from 0.23 g/cm{sup 3} to 0.68 g/cm{sup 3}, corresponding to different density humanoid tissues. The slabs were used to form different single and multilayer geometries. Dose was calculated with AXB 11.0.31 for 6MV, 15MV flattened and 6FFF (flattening filter free) energies for field sizes of 2×2 cm{sup 2} and 5×5 cm{sup 2}. The phantoms containing radiochromic EBT3 films were irradiated. Absolute dose profiles and 2D gamma analyses were performed for 96 dose planes. Results: For all single slab, multislab configurations and energies, absolute dose differences between the AXB calculation and film measurements remained <3% for both fields, with slightly poor disagreement in penumbra. The gamma index at 2% / 2mm averaged 98% in all combinations of fields, phantoms and photon energies. Conclusions: The transport based dose algorithm AXB is in good agreement with the experimental measurements for small field sizes using 6MV, 6FFF and 15MV beams adjacent to low density heterogeneous media. This work provides sufficient experimental ground to support the use of AXB for heterogeneous dose calculation purposes.
Monte Carlo method for dose calculation due to oral X-rays
International Nuclear Information System (INIS)
Loureiro, Eduardo Cesar de Miranda
1998-06-01
The increasing utilization of oral X-rays, especially in youngsters and children, calls for the assessment of equivalent doses in their organs and tissues. With this purpose, a Monte Carlo code was adapted to simulate an X-ray source irradiating phantoms of the MIRD-5 type with different ages (10, 15 and 40 years old) to calculate the conversion coefficients which transform the exposure at skin to equivalent doses at several organs and tissues of interest. In order to check the computer program, simulations were performed for adult patients using the original code (ADAM.FOR developed at the GSF-Germany) and the adapted program (MCDRO.PAS). Good agreement between results obtained with both codes was observed. Irradiations of the incisive, canine and molar teeth were simulated. The conversion factors were calculated for the following organs and tissues: thyroid, active bone narrow (head and whole body), bone (facial skeleton, cranium and whole body), skin (head and whole body) and crystalline. Based on the obtained results, it follows that the younger the patient and the larger the field area, the higher the dose in assessed organs and tissues. The variation of the source-skin distance does not change the conversion coefficients. On the other hand, the increase in the voltage applied to the X-ray tube causes an increase in the calculated conversion coefficients. (author)
Energy Technology Data Exchange (ETDEWEB)
Anusionwu, Princess [Medical Physics, CancerCare Manitoba, Winnipeg Canada (Canada); Department of Physics & Astronomy, University of Manitoba, Winnipeg Canada (Canada); Alpuche Aviles, Jorge E. [Medical Physics, CancerCare Manitoba, Winnipeg Canada (Canada); Pistorius, Stephen [Medical Physics, CancerCare Manitoba, Winnipeg Canada (Canada); Department of Physics & Astronomy, University of Manitoba, Winnipeg Canada (Canada); Department of Radiology, University of Manitoba, Winnipeg (Canada)
2016-08-15
Objective: Commissioning of a Monte Carlo based electron dose calculation algorithm requires percentage depth doses (PDDs) and beam profiles which can be measured with multiple detectors. Electron dosimetry is commonly performed with cylindrical chambers but parallel plate chambers and diodes can also be used. The purpose of this study was to determine the most appropriate detector to perform the commissioning measurements. Methods: PDDs and beam profiles were measured for beams with energies ranging from 6 MeV to 15 MeV and field sizes ranging from 6 cm × 6 cm to 40 cm × 40 cm. Detectors used included diodes, cylindrical and parallel plate ionization chambers. Beam profiles were measured in water (100 cm source to surface distance) and in air (95 cm source to detector distance). Results: PDDs for the cylindrical chambers were shallower (1.3 mm averaged over all energies and field sizes) than those measured with the parallel plate chambers and diodes. Surface doses measured with the diode and cylindrical chamber were on average larger by 1.6 % and 3% respectively than those of the parallel plate chamber. Profiles measured with a diode resulted in penumbra values smaller than those measured with the cylindrical chamber by 2 mm. Conclusion: The diode was selected as the most appropriate detector since PDDs agreed with those measured with parallel plate chambers (typically recommended for low energies) and results in sharper profiles. Unlike ion chambers, no corrections are needed to measure PDDs, making it more convenient to use.
Monte Carlo simulated dose to the human body due to neutrons emitted in laser-fusion
International Nuclear Information System (INIS)
Gileadi, A.E.; Cohen, M.O.
1977-01-01
Considering a point neutron source located at a given distance from the human body, modeled by a 'standard reference man' phantom, neutron doses to the whole body, as well as to selected organs thereof, are determined, using the SAM-CE system, a Monte Carlo computer code, written in Fortran and designed to solve time, space and energy dependent neutron and gamma ray transport equations in complex three-dimensional geometrice. Collision density, energy deposition and dose are treated in the SAM-CE system as flux functionals. A special feature of SAM-CE is its use of the 'Combinatorial Geometry' technique which affords the user geometric capabilities exceeding those available with other commonly used geometric packages. All neutron and gamma ray cross section data, as well as gamma ray production data, are derived from the ENDF libraries. Both resolved and unresolved resonance parameters from ENDF neutron data files are treated automatically and extremely precise and detailed descriptions of cross section behavior is permitted. Such treatment avoids the ambiguities usually associated with multi-group codes, which use flux-averaged cross sections based on assumed flux distributions which may or may not be appropriate. The 'standard reference man', a heterogeneous phantom, uses simple geometric forms to approximate the shape and dimensions of the human body. Materials composition of each subregion representing a certain 'organ' is given. Typical values of neutron doses to the whole body and to selected 'organs' of interest are presented
Dose estimation in the crystalline lens of industrial radiography personnel using Monte Carlo Method
International Nuclear Information System (INIS)
Lima, Alexandre Roza de
2014-01-01
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 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 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 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 that the new
A single-source photon source model of a linear accelerator for Monte Carlo dose calculation.
Nwankwo, Obioma; Glatting, Gerhard; Wenz, Frederik; Fleckenstein, Jens
2017-01-01
To introduce a new method of deriving a virtual source model (VSM) of a linear accelerator photon beam from a phase space file (PSF) for Monte Carlo (MC) dose calculation. A PSF of a 6 MV photon beam was generated by simulating the interactions of primary electrons with the relevant geometries of a Synergy linear accelerator (Elekta AB, Stockholm, Sweden) and recording the particles that reach a plane 16 cm downstream the electron source. Probability distribution functions (PDFs) for particle positions and energies were derived from the analysis of the PSF. These PDFs were implemented in the VSM using inverse transform sampling. To model particle directions, the phase space plane was divided into a regular square grid. Each element of the grid corresponds to an area of 1 mm2 in the phase space plane. The average direction cosines, Pearson correlation coefficient (PCC) between photon energies and their direction cosines, as well as the PCC between the direction cosines were calculated for each grid element. Weighted polynomial surfaces were then fitted to these 2D data. The weights are used to correct for heteroscedasticity across the phase space bins. The directions of the particles created by the VSM were calculated from these fitted functions. The VSM was validated against the PSF by comparing the doses calculated by the two methods for different square field sizes. The comparisons were performed with profile and gamma analyses. The doses calculated with the PSF and VSM agree to within 3% /1 mm (>95% pixel pass rate) for the evaluated fields. A new method of deriving a virtual photon source model of a linear accelerator from a PSF file for MC dose calculation was developed. Validation results show that the doses calculated with the VSM and the PSF agree to within 3% /1 mm.
A single-source photon source model of a linear accelerator for Monte Carlo dose calculation.
Directory of Open Access Journals (Sweden)
Obioma Nwankwo
Full Text Available To introduce a new method of deriving a virtual source model (VSM of a linear accelerator photon beam from a phase space file (PSF for Monte Carlo (MC dose calculation.A PSF of a 6 MV photon beam was generated by simulating the interactions of primary electrons with the relevant geometries of a Synergy linear accelerator (Elekta AB, Stockholm, Sweden and recording the particles that reach a plane 16 cm downstream the electron source. Probability distribution functions (PDFs for particle positions and energies were derived from the analysis of the PSF. These PDFs were implemented in the VSM using inverse transform sampling. To model particle directions, the phase space plane was divided into a regular square grid. Each element of the grid corresponds to an area of 1 mm2 in the phase space plane. The average direction cosines, Pearson correlation coefficient (PCC between photon energies and their direction cosines, as well as the PCC between the direction cosines were calculated for each grid element. Weighted polynomial surfaces were then fitted to these 2D data. The weights are used to correct for heteroscedasticity across the phase space bins. The directions of the particles created by the VSM were calculated from these fitted functions. The VSM was validated against the PSF by comparing the doses calculated by the two methods for different square field sizes. The comparisons were performed with profile and gamma analyses.The doses calculated with the PSF and VSM agree to within 3% /1 mm (>95% pixel pass rate for the evaluated fields.A new method of deriving a virtual photon source model of a linear accelerator from a PSF file for MC dose calculation was developed. Validation results show that the doses calculated with the VSM and the PSF agree to within 3% /1 mm.
International Nuclear Information System (INIS)
Koukorava, C.; Carinou, E.; Ferrari, P.; Krim, S.; Struelens, L.
2011-01-01
Measurements performed within the ORAMED project helped to evaluate the dose levels to the operators’ hands, wrists, legs and eye lenses, during several types of interventional radiology (IR) and cardiology (IC) procedures, and also to determine the parameters that affect the doses. However, the study of the effect of each parameter separately, was possible only through Monte Carlo (MC) simulations, as in clinical practice many of those parameters change simultaneously. The influence of the protective equipment, the beam projections, the beam quality, the field size and the position of the operator according to the position of access of the catheter was investigated, using anthropomorphic phantoms in setups that represent realistic IR/IC procedures. The proper use of protective shields was found to be the most important way of reducing extremity and eye lens exposure during such examinations. Ceiling suspended shields can reduce the doses to the eye lenses up to 97%, but they can also reduce hand doses about 70% when placed correctly. The highest exposure to the operator is observed for left anterior oblique (LAO) and cranial projections. Additionally, for overcouch irradiations the eyes and the hands are about 6 times more exposed compared to the cases where the tube is below the operating table. For the lateral LAO projection, placing the ceiling suspended shield at the left side of the operator is twice more effective for the protection of the eyes compared to the cases where it is placed above the patient. Finally, beam collimation was found to play an important role in the reduction of the hands and wrists doses, especially when the operator is close to the irradiation field.
International Nuclear Information System (INIS)
Fonseca, Gabriel Paiva; Yoriyaz, Hélio; Landry, Guillaume; White, Shane; Reniers, Brigitte; Verhaegen, Frank; D’Amours, Michel; Beaulieu, Luc
2014-01-01
Accounting for brachytherapy applicator attenuation is part of the recommendations from the recent report of AAPM Task Group 186. To do so, model based dose calculation algorithms require accurate modelling of the applicator geometry. This can be non-trivial in the case of irregularly shaped applicators such as the Fletcher Williamson gynaecological applicator or balloon applicators with possibly irregular shapes employed in accelerated partial breast irradiation (APBI) performed using electronic brachytherapy sources (EBS). While many of these applicators can be modelled using constructive solid geometry (CSG), the latter may be difficult and time-consuming. Alternatively, these complex geometries can be modelled using tessellated geometries such as tetrahedral meshes (mesh geometries (MG)). Recent versions of Monte Carlo (MC) codes Geant4 and MCNP6 allow for the use of MG. The goal of this work was to model a series of applicators relevant to brachytherapy using MG. Applicators designed for 192 Ir sources and 50 kV EBS were studied; a shielded vaginal applicator, a shielded Fletcher Williamson applicator and an APBI balloon applicator. All applicators were modelled in Geant4 and MCNP6 using MG and CSG for dose calculations. CSG derived dose distributions were considered as reference and used to validate MG models by comparing dose distribution ratios. In general agreement within 1% for the dose calculations was observed for all applicators between MG and CSG and between codes when considering volumes inside the 25% isodose surface. When compared to CSG, MG required longer computation times by a factor of at least 2 for MC simulations using the same code. MCNP6 calculation times were more than ten times shorter than Geant4 in some cases. In conclusion we presented methods allowing for high fidelity modelling with results equivalent to CSG. To the best of our knowledge MG offers the most accurate representation of an irregular APBI balloon applicator. (paper)
International Nuclear Information System (INIS)
Gu, J.; George Xu, X.; Caracappa, P. F.; Liu, B.
2013-01-01
To investigate the radiation dose to the fetus using retrospective tube current modulation (TCM) data selected from archived clinical records. This paper describes the calculation of fetal doses using retrospective TCM data and Monte Carlo (MC) simulations. Three TCM schemes were adopted for use with three pregnant patient phantoms. MC simulations were used to model CT scanners, TCM schemes and pregnant patients. Comparisons between organ doses from TCM schemes and those from non-TCM schemes show that these three TCM schemes reduced fetal doses by 14, 18 and 25 %, respectively. These organ doses were also compared with those from ImPACT calculation. It is found that the difference between the calculated fetal dose and the ImPACT reported dose is as high as 46 %. This work demonstrates methods to study organ doses from various TCM protocols and potential ways to improve the accuracy of CT dose calculation for pregnant patients. (authors)
Monte-Carlo calculation of irradiation dose content beyond shielding of high-energy accelerators
International Nuclear Information System (INIS)
Mokhov, N.V.; Frolov, V.V.
1975-01-01
The MARS programme, designed for calculating the three-dimensional internuclear cascade in defence of the accelerators by the Monte Carlo method, is described. The methods used to reduce the dispersion and the system of semi-empirical formulas made it possible to exceed the parameters of the existing programmes. By means of a synthesis of the results, registered by MARS and HAMLET programmes, the dosage fields for homogeneous and heterogeneous defence were evaluated. The results of the calculated absorbed and equivalent dose behind the barrier, irradiated by a proton beam, having the energy of Esub(o)=1/1000 GeV are exposed. The dependence of the high- and low-energy neutron, proton, pion, kaon, muonium and γ-quantum dosage on the initial energy and thickness, on the material and the composition of the defence is investigated
Monte Carlo dose calculation using a cell processor based PlayStation 3 system
International Nuclear Information System (INIS)
Chow, James C L; Lam, Phil; Jaffray, David A
2012-01-01
This study investigates the performance of the EGSnrc computer code coupled with a Cell-based hardware in Monte Carlo simulation of radiation dose in radiotherapy. Performance evaluations of two processor-intensive functions namely, HOWNEAR and RANMAR G ET in the EGSnrc code were carried out basing on the 20-80 rule (Pareto principle). The execution speeds of the two functions were measured by the profiler gprof specifying the number of executions and total time spent on the functions. A testing architecture designed for Cell processor was implemented in the evaluation using a PlayStation3 (PS3) system. The evaluation results show that the algorithms examined are readily parallelizable on the Cell platform, provided that an architectural change of the EGSnrc was made. However, as the EGSnrc performance was limited by the PowerPC Processing Element in the PS3, PC coupled with graphics processing units or GPCPU may provide a more viable avenue for acceleration.
Monte Carlo dose calculation using a cell processor based PlayStation 3 system
Chow, James C. L.; Lam, Phil; Jaffray, David A.
2012-02-01
This study investigates the performance of the EGSnrc computer code coupled with a Cell-based hardware in Monte Carlo simulation of radiation dose in radiotherapy. Performance evaluations of two processor-intensive functions namely, HOWNEAR and RANMAR_GET in the EGSnrc code were carried out basing on the 20-80 rule (Pareto principle). The execution speeds of the two functions were measured by the profiler gprof specifying the number of executions and total time spent on the functions. A testing architecture designed for Cell processor was implemented in the evaluation using a PlayStation3 (PS3) system. The evaluation results show that the algorithms examined are readily parallelizable on the Cell platform, provided that an architectural change of the EGSnrc was made. However, as the EGSnrc performance was limited by the PowerPC Processing Element in the PS3, PC coupled with graphics processing units or GPCPU may provide a more viable avenue for acceleration.
GATE Monte Carlo simulation of dose distribution using MapReduce in a cloud computing environment.
Liu, Yangchuan; Tang, Yuguo; Gao, Xin
2017-12-01
The GATE Monte Carlo simulation platform has good application prospects of treatment planning and quality assurance. However, accurate dose calculation using GATE is time consuming. The purpose of this study is to implement a novel cloud computing method for accurate GATE Monte Carlo simulation of dose distribution using MapReduce. An Amazon Machine Image installed with Hadoop and GATE is created to set up Hadoop clusters on Amazon Elastic Compute Cloud (EC2). Macros, the input files for GATE, are split into a number of self-contained sub-macros. Through Hadoop Streaming, the sub-macros are executed by GATE in Map tasks and the sub-results are aggregated into final outputs in Reduce tasks. As an evaluation, GATE simulations were performed in a cubical water phantom for X-ray photons of 6 and 18 MeV. The parallel simulation on the cloud computing platform is as accurate as the single-threaded simulation on a local server and the simulation correctness is not affected by the failure of some worker nodes. The cloud-based simulation time is approximately inversely proportional to the number of worker nodes. For the simulation of 10 million photons on a cluster with 64 worker nodes, time decreases of 41× and 32× were achieved compared to the single worker node case and the single-threaded case, respectively. The test of Hadoop's fault tolerance showed that the simulation correctness was not affected by the failure of some worker nodes. The results verify that the proposed method provides a feasible cloud computing solution for GATE.
Neutron dose rate analysis on HTGR-10 reactor using Monte Carlo code
Suwoto; Adrial, H.; Hamzah, A.; Zuhair; Bakhri, S.; Sunaryo, G. R.
2018-02-01
The HTGR-10 reactor is cylinder-shaped core fuelled with kernel TRISO coated fuel particles in the spherical pebble with helium cooling system. The outlet helium gas coolant temperature outputted from the reactor core is designed to 700 °C. One advantage HTGR type reactor is capable of co-generation, as an addition to generating electricity, the reactor was designed to produce heat at high temperature can be used for other processes. The spherical fuel pebble contains 8335 TRISO UO2 kernel coated particles with enrichment of 10% and 17% are dispersed in a graphite matrix. The main purpose of this study was to analysis the distribution of neutron dose rates generated from HTGR-10 reactors. The calculation and analysis result of neutron dose rate in the HTGR-10 reactor core was performed using Monte Carlo MCNP5v1.6 code. The problems of double heterogeneity in kernel fuel coated particles TRISO and spherical fuel pebble in the HTGR-10 core are modelled well with MCNP5v1.6 code. The neutron flux to dose conversion factors taken from the International Commission on Radiological Protection (ICRP-74) was used to determine the dose rate that passes through the active core, reflectors, core barrel, reactor pressure vessel (RPV) and a biological shield. The calculated results of neutron dose rate with MCNP5v1.6 code using a conversion factor of ICRP-74 (2009) for radiation workers in the radial direction on the outside of the RPV (radial position = 220 cm from the center of the patio HTGR-10) provides the respective value of 9.22E-4 μSv/h and 9.58E-4 μSv/h for enrichment 10% and 17%, respectively. The calculated values of neutron dose rates are compliant with BAPETEN Chairman’s Regulation Number 4 Year 2013 on Radiation Protection and Safety in Nuclear Energy Utilization which sets the limit value for the average effective dose for radiation workers 20 mSv/year or 10μSv/h. Thus the protection and safety for radiation workers to be safe from the radiation source has
Head-and-neck IMRT treatments assessed with a Monte Carlo dose calculation engine
International Nuclear Information System (INIS)
Seco, J; Adams, E; Bidmead, M; Partridge, M; Verhaegen, F
2005-01-01
IMRT is frequently used in the head-and-neck region, which contains materials of widely differing densities (soft tissue, bone, air-cavities). Conventional methods of dose computation for these complex, inhomogeneous IMRT cases involve significant approximations. In the present work, a methodology for the development, commissioning and implementation of a Monte Carlo (MC) dose calculation engine for intensity modulated radiotherapy (MC-IMRT) is proposed which can be used by radiotherapy centres interested in developing MC-IMRT capabilities for research or clinical evaluations. The method proposes three levels for developing, commissioning and maintaining a MC-IMRT dose calculation engine: (a) development of a MC model of the linear accelerator, (b) validation of MC model for IMRT and (c) periodic quality assurance (QA) of the MC-IMRT system. The first step, level (a), in developing an MC-IMRT system is to build a model of the linac that correctly predicts standard open field measurements for percentage depth-dose and off-axis ratios. Validation of MC-IMRT, level (b), can be performed in a rando phantom and in a homogeneous water equivalent phantom. Ultimately, periodic quality assurance of the MC-IMRT system is needed to verify the MC-IMRT dose calculation system, level (c). Once the MC-IMRT dose calculation system is commissioned it can be applied to more complex clinical IMRT treatments. The MC-IMRT system implemented at the Royal Marsden Hospital was used for IMRT calculations for a patient undergoing treatment for primary disease with nodal involvement in the head-and-neck region (primary treated to 65 Gy and nodes to 54 Gy), while sparing the spinal cord, brain stem and parotid glands. Preliminary MC results predict a decrease of approximately 1-2 Gy in the median dose of both the primary tumour and nodal volumes (compared with both pencil beam and collapsed cone). This is possibly due to the large air-cavity (the larynx of the patient) situated in the centre
Novel method based on Fricke gel dosimeters for dose verification in IMRT techniques
International Nuclear Information System (INIS)
Aon, E.; Brunetto, M.; Sansogne, R.; Castellano, G.; Valente, M.
2008-01-01
Modern radiotherapy is becoming increasingly complex. Conformal and intensity modulated (IMRT) techniques are nowadays available for achieving better tumour control. However, accurate methods for 3D dose verification for these modern irradiation techniques have not been adequately established yet. Fricke gel dosimeters consist, essentially, in a ferrous sulphate (Fricke) solution fixed to a gel matrix, which enables spatial resolution. A suitable radiochromic marker (xylenol orange) is added to the solution in order to produce radiochromic changes within the visible spectrum range, due to the chemical internal conversion (oxidation) of ferrous ions to ferric ions. In addition, xylenol orange has proved to slow down the internal diffusion effect of ferric ions. These dosimeters suitably shaped in form of thin layers and optically analyzed by means of visible light transmission imaging have recently been proposed as a method for 3D absorbed dose distribution determinations in radiotherapy, and tested in several IMRT applications employing a homogeneous plane (visible light) illuminator and a CCD camera with a monochromatic filter for sample analysis by means of transmittance images. In this work, the performance of an alternative read-out method is characterized, consisting on visible light images, acquired before and after irradiation by means of a commercially available flatbed-like scanner. Registered images are suitably converted to matrices and analyzed by means of dedicated 'in-house' software. The integral developed method allows performing 1D (profiles), 2D (surfaces) and 3D (volumes) dose mapping. In addition, quantitative comparisons have been performed by means of the Gamma composite criteria. Dose distribution comparisons between Fricke gel dosimeters and traditional standard dosimetric techniques for IMRT irradiations show an overall good agreement, supporting the suitability of the method. The agreement, quantified by the gamma index (that seldom
Palmer, Antony L.; Dimitriadis, Alexis; Nisbet, Andrew; Clark, Catharine H.
2015-11-01
There is renewed interest in film dosimetry for the verification of dose delivery of complex treatments, particularly small fields, compared to treatment planning system calculations. A new radiochromic film, Gafchromic EBT-XD, is available for high-dose treatment verification and we present the first published evaluation of its use. We evaluate the new film for MV photon dosimetry, including calibration curves, performance with single- and triple-channel dosimetry, and comparison to existing EBT3 film. In the verification of a typical 25 Gy stereotactic radiotherapy (SRS) treatment, compared to TPS planned dose distribution, excellent agreement was seen with EBT-XD using triple-channel dosimetry, in isodose overlay, maximum 1.0 mm difference over 200-2400 cGy, and gamma evaluation, mean passing rate 97% at 3% locally-normalised, 1.5 mm criteria. In comparison to EBT3, EBT-XD gave improved evaluation results for the SRS-plan, had improved calibration curve gradients at high doses, and had reduced lateral scanner effect. The dimensions of the two films are identical. The optical density of EBT-XD is lower than EBT3 for the same dose. The effective atomic number for both may be considered water-equivalent in MV radiotherapy. We have validated the use of EBT-XD for high-dose, small-field radiotherapy, for routine QC and a forthcoming multi-centre SRS dosimetry intercomparison.
International Nuclear Information System (INIS)
Palmer, Antony L; Dimitriadis, Alexis; Nisbet, Andrew; Clark, Catharine H
2015-01-01
There is renewed interest in film dosimetry for the verification of dose delivery of complex treatments, particularly small fields, compared to treatment planning system calculations. A new radiochromic film, Gafchromic EBT-XD, is available for high-dose treatment verification and we present the first published evaluation of its use. We evaluate the new film for MV photon dosimetry, including calibration curves, performance with single- and triple-channel dosimetry, and comparison to existing EBT3 film. In the verification of a typical 25 Gy stereotactic radiotherapy (SRS) treatment, compared to TPS planned dose distribution, excellent agreement was seen with EBT-XD using triple-channel dosimetry, in isodose overlay, maximum 1.0 mm difference over 200–2400 cGy, and gamma evaluation, mean passing rate 97% at 3% locally-normalised, 1.5 mm criteria. In comparison to EBT3, EBT-XD gave improved evaluation results for the SRS-plan, had improved calibration curve gradients at high doses, and had reduced lateral scanner effect. The dimensions of the two films are identical. The optical density of EBT-XD is lower than EBT3 for the same dose. The effective atomic number for both may be considered water-equivalent in MV radiotherapy. We have validated the use of EBT-XD for high-dose, small-field radiotherapy, for routine QC and a forthcoming multi-centre SRS dosimetry intercomparison. (paper)
Energy Technology Data Exchange (ETDEWEB)
Choi, Chang Heon [Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul (Korea, Republic of); Jung, Seongmoon [Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul (Korea, Republic of); Choi, Kanghyuk; Son, Kwang-Jae; Lee, Jun Sig [Hanaro Applications Research, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Ye, Sung-Joon, E-mail: sye@snu.ac.kr [Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul (Korea, Republic of); Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul (Korea, Republic of); Center for Convergence Research on Robotics, Advance Institutes of Convergence Technology, Seoul National University, Suwon (Korea, Republic of)
2016-04-21
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{sup −1} Bq{sup −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{sup −5} cGy s{sup −1} and 2.259×10{sup −5} cGy s{sup −1}, respectively. The calculated conversion factors of the two sources were 1.213×10{sup −8} cGy s{sup −1} Bq{sup −1} and 1.071×10{sup −8} cGy s{sup −1} Bq{sup −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.
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
International Nuclear Information System (INIS)
Conti, E.; Marconi, S.; Christiansen, J.; Placidi, P.; Hemperek, T.
2016-01-01
The simulation and verification framework developed by the RD53 collaboration is a powerful tool for global architecture optimization and design verification of next generation hybrid pixel readout chips. In this paper the framework is used for studying digital pixel chip architectures at behavioral level. This is carried out by simulating a dedicated, highly parameterized pixel chip description, which makes it possible to investigate different grouping strategies between pixels and different latency buffering and arbitration schemes. The pixel hit information used as simulation input can be either generated internally in the framework or imported from external Monte Carlo detector simulation data. The latter have been provided by both the CMS and ATLAS experiments, featuring HL-LHC operating conditions and the specifications related to the Phase 2 upgrade. Pixel regions and double columns were simulated using such Monte Carlo data as inputs: the performance of different latency buffering architectures was compared and the compliance of different link speeds with the expected column data rate was verified
Impact of thermoplastic mask on X-ray surface dose calculated with Monte Carlo code
International Nuclear Information System (INIS)
Zhao Yanqun; Li Jie; Wu Liping; Wang Pei; Lang Jinyi; Wu Dake; Xiao Mingyong
2010-01-01
Objective: To calculate the effects of thermoplastic mask on X-ray surface dose. Methods: The BEAMnrc Monte Carlo Code system, designed especially for computer simulation of radioactive sources, was performed to evaluate the effects of thermoplastic mask on X-ray surface dose.Thermoplastic mask came from our center with a material density of 1.12 g/cm 2 . The masks without holes, with holes size of 0.1 cm x 0.1 cm, and with holes size of 0. 1 cm x 0.2 cm, and masks with different depth (0.12 cm and 0.24 cm) were evaluated separately. For those with holes, the material width between adjacent holes was 0.1 cm. Virtual masks with a material density of 1.38 g/cm 3 without holes with two different depths were also evaluated. Results: Thermoplastic mask affected X-rays surface dose. When using a thermoplastic mask with the depth of 0.24 cm without holes, the surface dose was 74. 9% and 57.0% for those with the density of 1.38 g/cm 3 and 1.12 g/cm 3 respectively. When focusing on the masks with the density of 1.12 g/cm 3 , the surface dose was 41.2% for those with 0.12 cm depth without holes; 57.0% for those with 0. 24 cm depth without holes; 44.5% for those with 0.24 cm depth with holes size of 0.1 cm x 0.2 cm;and 54.1% for those with 0.24 cm depths with holes size of 0.1 cm x 0.1 cm.Conclusions: Using thermoplastic mask during the radiation increases patient surface dose. The severity is relative to the hole size and the depth of thermoplastic mask. The surface dose change should be considered in radiation planning to avoid severe skin reaction. (authors)
Target dose conversion modeling from pencil beam (PB) to Monte Carlo (MC) for lung SBRT
International Nuclear Information System (INIS)
Zheng, Dandan; Zhu, Xiaofeng; Zhang, Qinghui; Liang, Xiaoying; Zhen, Weining; Lin, Chi; Verma, Vivek; Wang, Shuo; Wahl, Andrew; Lei, Yu; Zhou, Sumin; Zhang, Chi
2016-01-01
A challenge preventing routine clinical implementation of Monte Carlo (MC)-based lung SBRT is the difficulty of reinterpreting historical outcome data calculated with inaccurate dose algorithms, because the target dose was found to decrease to varying degrees when recalculated with MC. The large variability was previously found to be affected by factors such as tumour size, location, and lung density, usually through sub-group comparisons. We hereby conducted a pilot study to systematically and quantitatively analyze these patient factors and explore accurate target dose conversion models, so that large-scale historical outcome data can be correlated with more accurate MC dose without recalculation. Twenty-one patients that underwent SBRT for early-stage lung cancer were replanned with 6MV 360° dynamic conformal arcs using pencil-beam (PB) and recalculated with MC. The percent D95 difference (PB-MC) was calculated for the PTV and GTV. Using single linear regression, this difference was correlated with the following quantitative patient indices: maximum tumour diameter (MaxD); PTV and GTV volumes; minimum distance from tumour to soft tissue (dmin); and mean density and standard deviation of the PTV, GTV, PTV margin, lung, and 2 mm, 15 mm, 50 mm shells outside the PTV. Multiple linear regression and artificial neural network (ANN) were employed to model multiple factors and improve dose conversion accuracy. Single linear regression with PTV D95 deficiency identified the strongest correlation on mean-density (location) indices, weaker on lung density, and the weakest on size indices, with the following R 2 values in decreasing orders: shell2mm (0.71), PTV (0.68), PTV margin (0.65), shell15mm (0.62), shell50mm (0.49), lung (0.40), dmin (0.22), GTV (0.19), MaxD (0.17), PTV volume (0.15), and GTV volume (0.08). A multiple linear regression model yielded the significance factor of 3.0E-7 using two independent features: mean density of shell2mm (P = 1.6E-7) and PTV volume
International Nuclear Information System (INIS)
Acquah, F.G.
2011-01-01
Brachytherapy, the use of radioactive sources for the treatment of tumours is an important tool in radiation oncology. Accurate calculations of dose delivered to malignant and normal tissues are the main responsibility of the Medical Physics staff. With the use of Treatment Planning System (TPS) computers now becoming a standard practice in the Radiation Oncology Departments, Independent calculations to certify the results of these commercial TPSs are important part of a good quality management system for brachytherapy implants. There are inherent errors in the dose distributions produced by these TPSs due to its failure to account for heterogeneity in the calculation algorithms and Monte Carlo (MC) method seems to be the panacea for these corrections. In this study, a fit functional form using MC output parameters was performed to reduce dose calculation uncertainty using the Matlab software curve fitting applications. This includes the modification of the AAPM TG-43 parameters to accommodate the new developments for a rapid brachytherapy dose rate calculation. Analytical computations were performed to hybridize the anisotropy function, F(r,θ) and radial dose function, g(r) into a single new function f(r,θ) for the Nucletron microSelectron High Dose Rate 'new or v2' (mHDRv2) 192 Ir brachytherapy source. In order to minimize computation time and to improve the accuracy of manual calculations, the dosimetry function f(r,θ) used fewer parameters and formulas for the fit. Using MC outputs as the standard, the percentage errors for the fits were calculated and used to evaluate the average and maximum uncertainties. Dose rate deviation between the MC data and fit were also quantified as errors(E), which showed minimal values. These results showed that the dosimetry parameters from this study as compared to those of MC outputs parameters were in good agreement and better than the results obtained from literature. The work confirms a lot of promise in building robust
Towards real-time photon Monte Carlo dose calculation in the cloud
Ziegenhein, Peter; Kozin, Igor N.; Kamerling, Cornelis Ph; Oelfke, Uwe
2017-06-01
Near real-time application of Monte Carlo (MC) dose calculation in clinic and research is hindered by the long computational runtimes of established software. Currently, fast MC software solutions are available utilising accelerators such as graphical processing units (GPUs) or clusters based on central processing units (CPUs). Both platforms are expensive in terms of purchase costs and maintenance and, in case of the GPU, provide only limited scalability. In this work we propose a cloud-based MC solution, which offers high scalability of accurate photon dose calculations. The MC simulations run on a private virtual supercomputer that is formed in the cloud. Computational resources can be provisioned dynamically at low cost without upfront investment in expensive hardware. A client-server software solution has been developed which controls the simulations and transports data to and from the cloud efficiently and securely. The client application integrates seamlessly into a treatment planning system. It runs the MC simulation workflow automatically and securely exchanges simulation data with the server side application that controls the virtual supercomputer. Advanced encryption standards were used to add an additional security layer, which encrypts and decrypts patient data on-the-fly at the processor register level. We could show that our cloud-based MC framework enables near real-time dose computation. It delivers excellent linear scaling for high-resolution datasets with absolute runtimes of 1.1 seconds to 10.9 seconds for simulating a clinical prostate and liver case up to 1% statistical uncertainty. The computation runtimes include the transportation of data to and from the cloud as well as process scheduling and synchronisation overhead. Cloud-based MC simulations offer a fast, affordable and easily accessible alternative for near real-time accurate dose calculations to currently used GPU or cluster solutions.
Modeling dose-rate on/over the surface of cylindrical radio-models using Monte Carlo methods
International Nuclear Information System (INIS)
Xiao Xuefu; Ma Guoxue; Wen Fuping; Wang Zhongqi; Wang Chaohui; Zhang Jiyun; Huang Qingbo; Zhang Jiaqiu; Wang Xinxing; Wang Jun
2004-01-01
Objective: To determine the dose-rates on/over the surface of 10 cylindrical radio-models, which belong to the Metrology Station of Radio-Geological Survey of CNNC. Methods: The dose-rates on/over the surface of 10 cylindrical radio-models were modeled using the famous Monte Carlo code-MCNP. The dose-rates on/over the surface of 10 cylindrical radio-models were measured by a high gas pressurized ionization chamber dose-rate meter, respectively. The values of dose-rate modeled using MCNP code were compared with those obtained by authors in the present experimental measurement, and with those obtained by other workers previously. Some factors causing the discrepancy between the data obtained by authors using MCNP code and the data obtained using other methods are discussed in this paper. Results: The data of dose-rates on/over the surface of 10 cylindrical radio-models, obtained using MCNP code, were in good agreement with those obtained by other workers using the theoretical method. They were within the discrepancy of ±5% in general, and the maximum discrepancy was less than 10%. Conclusions: As if each factor needed for the Monte Carlo code is correct, the dose-rates on/over the surface of cylindrical radio-models modeled using the Monte Carlo code are correct with an uncertainty of 3%
Wang, R; Li, X A
2001-02-01
The dose parameters for the beta-particle emitting 90Sr/90Y source for intravascular brachytherapy (IVBT) have been calculated by different investigators. At a distant distance from the source, noticeable differences are seen in these parameters calculated using different Monte Carlo codes. The purpose of this work is to quantify as well as to understand these differences. We have compared a series of calculations using an EGS4, an EGSnrc, and the MCNP Monte Carlo codes. Data calculated and compared include the depth dose curve for a broad parallel beam of electrons, and radial dose distributions for point electron sources (monoenergetic or polyenergetic) and for a real 90Sr/90Y source. For the 90Sr/90Y source, the doses at the reference position (2 mm radial distance) calculated by the three code agree within 2%. However, the differences between the dose calculated by the three codes can be over 20% in the radial distance range interested in IVBT. The difference increases with radial distance from source, and reaches 30% at the tail of dose curve. These differences may be partially attributed to the different multiple scattering theories and Monte Carlo models for electron transport adopted in these three codes. Doses calculated by the EGSnrc code are more accurate than those by the EGS4. The two calculations agree within 5% for radial distance <6 mm.
International Nuclear Information System (INIS)
Tian, Zhen; Jia, Xun; Jiang, Steve B; Graves, Yan Jiang
2014-01-01
Monte Carlo (MC) simulation is commonly considered as the most accurate method for radiation dose calculations. Commissioning of a beam model in the MC code against a clinical linear accelerator beam is of crucial importance for its clinical implementation. In this paper, we propose an automatic commissioning method for our GPU-based MC dose engine, gDPM. gDPM utilizes a beam model based on a concept of phase-space-let (PSL). A PSL contains a group of particles that are of the same type and close in space and energy. A set of generic PSLs was generated by splitting a reference phase-space file. Each PSL was associated with a weighting factor, and in dose calculations the particle carried a weight corresponding to the PSL where it was from. Dose for each PSL in water was pre-computed, and hence the dose in water for a whole beam under a given set of PSL weighting factors was the weighted sum of the PSL doses. At the commissioning stage, an optimization problem was solved to adjust the PSL weights in order to minimize the difference between the calculated dose and measured one. Symmetry and smoothness regularizations were utilized to uniquely determine the solution. An augmented Lagrangian method was employed to solve the optimization problem. To validate our method, a phase-space file of a Varian TrueBeam 6 MV beam was used to generate the PSLs for 6 MV beams. In a simulation study, we commissioned a Siemens 6 MV beam on which a set of field-dependent phase-space files was available. The dose data of this desired beam for different open fields and a small off-axis open field were obtained by calculating doses using these phase-space files. The 3D γ-index test passing rate within the regions with dose above 10% of d max dose for those open fields tested was improved averagely from 70.56 to 99.36% for 2%/2 mm criteria and from 32.22 to 89.65% for 1%/1 mm criteria. We also tested our commissioning method on a six-field head-and-neck cancer IMRT plan. The
Dose to drivers during drive-through cargo scanning using GEANT4 Monte Carlo simulation
International Nuclear Information System (INIS)
Gomes, Rogerio S.; Gomes, Joana D'Arc R.L.; Costa, Mara Lucia L.
2013-01-01
The use of radiation technologies to perform screening for cargo containers has been increased due to security issues, mainly, as a consequence of the United States (US) legislation which requires, from 2013, the scanning of all intermodal cargo containers which arrive at US ports. Currently, systems to cargo inspections, using accelerator-driven high energy X-rays, between 4 and 9 MeV, are available for scanning operations. It is expected that, in the future, the use of these systems will be widely spread on roads, ports and airports in Brazil. However, in order to improve the productivity and reduce the costs of acquisition, operation and maintenance these systems require that the driver drives its vehicle through irradiation area, in a situation where members of the public (the truck drivers) enter in controlled area and are deliberately exposed to high-energy beam. Some manufacturers justifies this procedure arguing that the drivers are exposed briefly, and only to the scattered beam, since there are safety systems in order to avoid that the drivers are exposed to direct beam. In this work, it is presented the preliminary results of Monte Carlo simulations concerning the dose of drivers during scanning operations, including the dose due to a failure of safety system, producing an exposure of drivers to the direct beam, as well as, an analysis of the justification of practice, mainly related to the drive-through operational procedure. (author)
PCXMC. A PC-based Monte Carlo program for calculating patient doses in medical x-ray examinations
International Nuclear Information System (INIS)
Tapiovaara, M.; Lakkisto, M.; Servomaa, A.
1997-02-01
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.)
Energy Technology Data Exchange (ETDEWEB)
Schwarz, G; Hoffman, F O
1980-01-01
An evaluation of the imprecision in dose predictions for radionuclides has been performed using correct dose assessment models and knowledge of model parameter value uncertainties. The propagation of parameter uncertainties is demonstrated using a Monte Carlo technique for elemental iodine 131 transported via the pasture-cow-milk-child pathway. Results indicated that when site-specific information is unavailable, the imprecision inherent in the predictions for this pathway is potentially large. (3 graphs, 25 references, 5 tables)
International Nuclear Information System (INIS)
Rubio Rivero, A.; Caballero Pinelo, R.; Gonzalez Perez, Y.
2015-01-01
To propose and evaluate a method for the central axis dose verification in patients treated with total body irradiation (TBI) of photons using images obtained through a Computed Radiography (CR) system. It was used the Computed Radiography (Fuji) portal imaging cassette readings and correlate with measured of absorbed dose in water using 10 x 10 irradiation fields with ionization chamber in the 60 Co equipment. The analytical and graphic expression is obtained through software 'Origin8', the TBI patient portal verification images were processed using software ImageJ, to obtain the patient dose. To validate the results, the absorbed dose in RW3 models was measured with ionization chamber with different thickness, simulating TBI real conditions. Finally it was performed a retrospective study over the last 4 years obtaining the patients absorbed dose based on the reading in the image and comparing with the planned dose. The analytical equation obtained permits estimate the absorbed dose using image pixel value and the dose measured with ionization chamber and correlated with patient clinical records. Those results are compared with reported evidence obtaining a difference less than 02%, the 3 methods were compared and the results are within 10%. (Author)
Wu, J; Liu, Y L; Chang, S J; Chao, M M; Tsai, S Y; Huang, D E
2012-11-01
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 (90)Y, (177)Lu and (103 m)Rh, 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.
A GPU-based Monte Carlo dose calculation code for photon transport in a voxel phantom
International Nuclear Information System (INIS)
Bellezzo, M.; Do Nascimento, E.; Yoriyaz, H.
2014-08-01
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)
Monte Carlo determination of dose in crystalline and thyroid during chest tomography examinations
International Nuclear Information System (INIS)
Quispe H, B.; Pena V, J. D.; Waldo B, G.; Leon M, M.; Ceron R, P.; Vallejo H, A.; Sosa A, M.; Vega C, H. R.
2017-10-01
Computed tomography is a diagnostic imaging method that deposits higher doses than other radio diagnosis methods. The knowledge of the spectrum of X-rays is important, since is in direct function with the dose absorbed by the patient. In this work we estimated the spectrum of X-rays, produced during the interaction of monoenergetic electrons of 130 KeV with Tungsten white, in order to determine their energetic characteristics at 50 cm from the focal point. The study was done using Monte Carlo methods with the code MCNP5 where the X-ray tube of a Siemens SOMATOM Perspective tomograph of the General Regional Hospital of Leon, Mexico was modeled. In the calculations, 3 x 10 8 stories were used and a relative uncertainty of less than 0.1% was obtained. Also, a neck manikin with thyroid, thorax and head that included the eye, the table and gantry with 70 cm opening of the tomography was modeled. The X-ray spectrum calculated with a cut thickness of 10 mm limited by Pb collimators was used as the source term. The radiological service routine scanning protocol was used for chest computed tomography; the step-by-step or instant trigger method was simulated by moving the manikin coordinates for each cut and 360 degree continuous rotation movement. 36 positions of the X-ray tube were used in steps of 10 degrees. The radiation dispersed in the thorax deposits a dose of 2.063 mGy in crystalline and 252 mGy in thyroid. (Author)
A GPU-based Monte Carlo dose calculation code for photon transport in a voxel phantom
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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)
International Nuclear Information System (INIS)
Petoussi, N.; Zankl, M.; Williams, G.; Veit, R.; Drexler, G.
1987-01-01
There has been some evidence that cervical cancer patients who were treated by radiotherapy, had an increased incidence of second primary cancers noticeable 15 years or more after the radiotherapy. The data suggested that high dose pelvic irradiation was associated with increase in cancers of the bladder, kidneys, rectum, ovaries, corpus uteri, and non-Hodgkin's lymphoma but not leukemia (Kleinerman et al., 1982, Morton 1973). The aim of the present work is to estimate the absorbed dose, due to radiotherapy treatment for cervival cancer, to various organs and tissues in the body. Monte Carlo calculations were performed to calculate the organ absorbed doses resulting from intracavitary sources such as ovoids and applicators filled or loaded with radium, Co-60 and Cs-137. For that purpose a routine which simulates an internal source was constructed and added to the existing Monte Carlo code (GSF-Bericht S-885, Kramer et al.). Calculations were also made for external beam therapy. Various anterior, posterior and lateral fields were applied, resulting from megavoltage, Co-60 and Cs-137 therapy machines. The calculated organ doses are tabulated in three different ways: as organ dose per air Kerma in the reference field, according to the recommendations of the International Commission on Radiation Units and Measurements (ICRU Report No 38, 1985); as organ dose per surface dose and as organ dose per tissue dose at Point B. (orig.)
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Wang, Y; Mazur, T; Green, O; Hu, Y; Wooten, H; Yang, D; Zhao, T; Mutic, S; Li, H [Washington University School of Medicine, St. Louis, MO (United States)
2015-06-15
Purpose: To build a fast, accurate and easily-deployable research platform for Monte-Carlo dose calculations. We port the dose calculation engine PENELOPE to C++, and accelerate calculations using GPU acceleration. Simulations of a Co-60 beam model provided by ViewRay demonstrate the capabilities of the platform. Methods: We built software that incorporates a beam model interface, CT-phantom model, GPU-accelerated PENELOPE engine, and GUI front-end. We rewrote the PENELOPE kernel in C++ (from Fortran) and accelerated the code on a GPU. We seamlessly integrated a Co-60 beam model (obtained from ViewRay) into our platform. Simulations of various field sizes and SSDs using a homogeneous water phantom generated PDDs, dose profiles, and output factors that were compared to experiment data. Results: With GPU acceleration using a dated graphics card (Nvidia Tesla C2050), a highly accurate simulation – including 100*100*100 grid, 3×3×3 mm3 voxels, <1% uncertainty, and 4.2×4.2 cm2 field size – runs 24 times faster (20 minutes versus 8 hours) than when parallelizing on 8 threads across a new CPU (Intel i7-4770). Simulated PDDs, profiles and output ratios for the commercial system agree well with experiment data measured using radiographic film or ionization chamber. Based on our analysis, this beam model is precise enough for general applications. Conclusions: Using a beam model for a Co-60 system provided by ViewRay, we evaluate a dose calculation platform that we developed. Comparison to measurements demonstrates the promise of our software for use as a research platform for dose calculations, with applications including quality assurance and treatment plan verification.
International Nuclear Information System (INIS)
Wang, Y; Mazur, T; Green, O; Hu, Y; Wooten, H; Yang, D; Zhao, T; Mutic, S; Li, H
2015-01-01
Purpose: To build a fast, accurate and easily-deployable research platform for Monte-Carlo dose calculations. We port the dose calculation engine PENELOPE to C++, and accelerate calculations using GPU acceleration. Simulations of a Co-60 beam model provided by ViewRay demonstrate the capabilities of the platform. Methods: We built software that incorporates a beam model interface, CT-phantom model, GPU-accelerated PENELOPE engine, and GUI front-end. We rewrote the PENELOPE kernel in C++ (from Fortran) and accelerated the code on a GPU. We seamlessly integrated a Co-60 beam model (obtained from ViewRay) into our platform. Simulations of various field sizes and SSDs using a homogeneous water phantom generated PDDs, dose profiles, and output factors that were compared to experiment data. Results: With GPU acceleration using a dated graphics card (Nvidia Tesla C2050), a highly accurate simulation – including 100*100*100 grid, 3×3×3 mm3 voxels, <1% uncertainty, and 4.2×4.2 cm2 field size – runs 24 times faster (20 minutes versus 8 hours) than when parallelizing on 8 threads across a new CPU (Intel i7-4770). Simulated PDDs, profiles and output ratios for the commercial system agree well with experiment data measured using radiographic film or ionization chamber. Based on our analysis, this beam model is precise enough for general applications. Conclusions: Using a beam model for a Co-60 system provided by ViewRay, we evaluate a dose calculation platform that we developed. Comparison to measurements demonstrates the promise of our software for use as a research platform for dose calculations, with applications including quality assurance and treatment plan verification
A Monte Carlo model for mean glandular dose evaluation in spot compression mammography.
Sarno, Antonio; Dance, David R; van Engen, Ruben E; Young, Kenneth C; Russo, Paolo; Di Lillo, Francesca; Mettivier, Giovanni; Bliznakova, Kristina; Fei, Baowei; Sechopoulos, Ioannis
2017-07-01
To characterize the dependence of normalized glandular dose (DgN) on various breast model and image acquisition parameters during spot compression mammography and other partial breast irradiation conditions, and evaluate alternative previously proposed dose-related metrics for this breast imaging modality. Using Monte Carlo simulations with both simple homogeneous breast models and patient-specific breasts, three different dose-related metrics for spot compression mammography were compared: the standard DgN, the normalized glandular dose to only the directly irradiated portion of the breast (DgNv), and the DgN obtained by the product of the DgN for full field irradiation and the ratio of the mid-height area of the irradiated breast to the entire breast area (DgN M ). How these metrics vary with field-of-view size, spot area thickness, x-ray energy, spot area and position, breast shape and size, and system geometry was characterized for the simple breast model and a comparison of the simple model results to those with patient-specific breasts was also performed. The DgN in spot compression mammography can vary considerably with breast area. However, the difference in breast thickness between the spot compressed area and the uncompressed area does not introduce a variation in DgN. As long as the spot compressed area is completely within the breast area and only the compressed breast portion is directly irradiated, its position and size does not introduce a variation in DgN for the homogeneous breast model. As expected, DgN is lower than DgNv for all partial breast irradiation areas, especially when considering spot compression areas within the clinically used range. DgN M underestimates DgN by 6.7% for a W/Rh spectrum at 28 kVp and for a 9 × 9 cm 2 compression paddle. As part of the development of a new breast dosimetry model, a task undertaken by the American Association of Physicists in Medicine and the European Federation of Organizations of Medical Physics
SU-F-T-371: Development of a Linac Monte Carlo Model to Calculate Surface Dose
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Prajapati, S; Yan, Y; Gifford, K [UT MD Anderson Cancer Center, Houston, TX (United States)
2016-06-15
Purpose: To generate and validate a linac Monte Carlo (MC) model for surface dose prediction. Methods: BEAMnrc V4-2.4.0 was used to model 6 and 18 MV photon beams for a commercially available linac. DOSXYZnrc V4-2.4.0 calculated 3D dose distributions in water. Percent depth dose (PDD) and beam profiles were extracted for comparison to measured data. Surface dose and at depths in the buildup region was measured with radiochromic film at 100 cm SSD for 4 × 4 cm{sup 2} and 10 × 10 cm{sup 2} collimator settings for open and MLC collimated fields. For the 6 MV beam, films were placed at depths ranging from 0.015 cm to 2 cm and for 18 MV, 0.015 cm to 3.5 cm in Solid Water™. Films were calibrated for both photon energies at their respective dmax. PDDs and profiles were extracted from the film and compared to the MC data. The MC model was adjusted to match measured PDD and profiles. Results: For the 6 MV beam, the mean error(ME) in PDD between film and MC for open fields was 1.9%, whereas it was 2.4% for MLC. For the 18 MV beam, the ME in PDD for open fields was 2% and was 3.5% for MLC. For the 6 MV beam, the average root mean square(RMS) deviation for the central 80% of the beam profile for open fields was 1.5%, whereas it was 1.6% for MLC. For the 18 MV beam, the maximum RMS for open fields was 3%, and was 3.1% for MLC. Conclusion: The MC model of a linac agreed to within 4% of film measurements for depths ranging from the surface to dmax. Therefore, the MC linac model can predict surface dose for clinical applications. Future work will focus on adjusting the linac MC model to reduce RMS error and improve accuracy.
Zhu, X R; Jursinic, P A; Grimm, D F; Lopez, F; Rownd, J J; Gillin, M T
2002-08-01
A new type of radiographic film, Kodak EDR2 film, was evaluated for dose verification of intensity modulated radiation therapy (IMRT) delivered by a static multileaf collimator (SMLC). A sensitometric curve of EDR2 film irradiated by a 6 MV x-ray beam was compared with that of Kodak X-OMAT V (XV) film. The effects of field size, depth and dose rate on the sensitometric curve were also studied. It is found that EDR2 film is much less sensitive than XV film. In high-energy x-ray beams, the double hit process is the dominant mechanism that renders the grains on EDR2 films developable. As a result, in the dose range that is commonly used for film dosimetry for IMRT and conventional external beam therapy, the sensitometric curves of EDR2 films cannot be approximated as a linear function, OD = c * D. Within experimental uncertainty, the film sensitivity does not depend on the dose rate (50 vs 300 MU/min) or dose per pulse (from 1.0 x 10(-4) to 4.21 x 10(-4) Gy/pulse). Field sizes and depths (up to field size of 10 x 10 cm2 and depth = 10 cm) have little effect on the sensitometric curves. Percent depth doses (PDDs) for both 6 and 23 MV x rays were measured with both EDR2 and XV films and compared with ion chamber data. Film data are within 2.5% of the ion chamber results. Dose profiles measured with EDR2 film are consistent with those measured with an ion chamber. Examples of measured IMRT isodose distributions versus calculated isodoses are presented. We have used EDR2 films for verification of all IMRT patients treated by SMLC in our clinic. In most cases, with EDR2 film, actual clinical daily fraction doses can be used for verification of composite isodose distributions of SMLC-based IMRT.
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Li, JS; Fan, J; Ma, C-M [Fox Chase Cancer Center, Philadelphia, PA (United States)
2015-06-15
Purpose: To improve the treatment efficiency and capabilities for full-body treatment, a robotic radiosurgery system has equipped with a multileaf collimator (MLC) to extend its accuracy and precision to radiation therapy. To model the MLC and include it in the Monte Carlo patient dose calculation is the goal of this work. Methods: The radiation source and the MLC were carefully modeled to consider the effects of the source size, collimator scattering, leaf transmission and leaf end shape. A source model was built based on the output factors, percentage depth dose curves and lateral dose profiles measured in a water phantom. MLC leaf shape, leaf end design and leaf tilt for minimizing the interleaf leakage and their effects on beam fluence and energy spectrum were all considered in the calculation. Transmission/leakage was added to the fluence based on the transmission factors of the leaf and the leaf end. The transmitted photon energy was tuned to consider the beam hardening effects. The calculated results with the Monte Carlo implementation was compared with measurements in homogeneous water phantom and inhomogeneous phantoms with slab lung or bone material for 4 square fields and 9 irregularly shaped fields. Results: The calculated output factors are compared with the measured ones and the difference is within 1% for different field sizes. The calculated dose distributions in the phantoms show good agreement with measurements using diode detector and films. The dose difference is within 2% inside the field and the distance to agreement is within 2mm in the penumbra region. The gamma passing rate is more than 95% with 2%/2mm criteria for all the test cases. Conclusion: Implementation of Monte Carlo dose calculation for a MLC equipped robotic radiosurgery system is completed successfully. The accuracy of Monte Carlo dose calculation with MLC is clinically acceptable. This work was supported by Accuray Inc.
International Nuclear Information System (INIS)
Li, JS; Fan, J; Ma, C-M
2015-01-01
Purpose: To improve the treatment efficiency and capabilities for full-body treatment, a robotic radiosurgery system has equipped with a multileaf collimator (MLC) to extend its accuracy and precision to radiation therapy. To model the MLC and include it in the Monte Carlo patient dose calculation is the goal of this work. Methods: The radiation source and the MLC were carefully modeled to consider the effects of the source size, collimator scattering, leaf transmission and leaf end shape. A source model was built based on the output factors, percentage depth dose curves and lateral dose profiles measured in a water phantom. MLC leaf shape, leaf end design and leaf tilt for minimizing the interleaf leakage and their effects on beam fluence and energy spectrum were all considered in the calculation. Transmission/leakage was added to the fluence based on the transmission factors of the leaf and the leaf end. The transmitted photon energy was tuned to consider the beam hardening effects. The calculated results with the Monte Carlo implementation was compared with measurements in homogeneous water phantom and inhomogeneous phantoms with slab lung or bone material for 4 square fields and 9 irregularly shaped fields. Results: The calculated output factors are compared with the measured ones and the difference is within 1% for different field sizes. The calculated dose distributions in the phantoms show good agreement with measurements using diode detector and films. The dose difference is within 2% inside the field and the distance to agreement is within 2mm in the penumbra region. The gamma passing rate is more than 95% with 2%/2mm criteria for all the test cases. Conclusion: Implementation of Monte Carlo dose calculation for a MLC equipped robotic radiosurgery system is completed successfully. The accuracy of Monte Carlo dose calculation with MLC is clinically acceptable. This work was supported by Accuray Inc
Radiation dose verification using real tissue phantom in modern radiotherapy techniques
International Nuclear Information System (INIS)
Gurjar, Om Prakash; Mishra, S.P.; Bhandari, Virendra; Pathak, Pankaj; Patel, Prapti; Shrivastav, Garima
2014-01-01
In vitro dosimetric verification prior to patient treatment has a key role in accurate and precision radiotherapy treatment delivery. Most of commercially available dosimetric phantoms have almost homogeneous density throughout their volume, while real interior of patient body has variable and varying densities inside. In this study an attempt has been made to verify the physical dosimetry in actual human body scenario by using goat head as 'head phantom' and goat meat as 'tissue phantom'. The mean percentage variation between planned and measured doses was found to be 2.48 (standard deviation (SD): 0.74), 2.36 (SD: 0.77), 3.62 (SD: 1.05), and 3.31 (SD: 0.78) for three-dimensional conformal radiotherapy (3DCRT) (head phantom), intensity modulated radiotherapy (IMRT; head phantom), 3DCRT (tissue phantom), and IMRT (tissue phantom), respectively. Although percentage variations in case of head phantom were within tolerance limit (< ± 3%), but still it is higher than the results obtained by using commercially available phantoms. And the percentage variations in most of cases of tissue phantom were out of tolerance limit. On the basis of these preliminary results it is logical and rational to develop radiation dosimetry methods based on real human body and also to develop an artificial phantom which should truly represent the interior of human body. (author)
Radiation dose verification using real tissue phantom in modern radiotherapy techniques
Directory of Open Access Journals (Sweden)
Om Prakash Gurjar
2014-01-01
Full Text Available In vitro dosimetric verification prior to patient treatment has a key role in accurate and precision radiotherapy treatment delivery. Most of commercially available dosimetric phantoms have almost homogeneous density throughout their volume, while real interior of patient body has variable and varying densities inside. In this study an attempt has been made to verify the physical dosimetry in actual human body scenario by using goat head as "head phantom" and goat meat as "tissue phantom". The mean percentage variation between planned and measured doses was found to be 2.48 (standard deviation (SD: 0.74, 2.36 (SD: 0.77, 3.62 (SD: 1.05, and 3.31 (SD: 0.78 for three-dimensional conformal radiotherapy (3DCRT (head phantom, intensity modulated radiotherapy (IMRT; head phantom, 3DCRT (tissue phantom, and IMRT (tissue phantom, respectively. Although percentage variations in case of head phantom were within tolerance limit (< ± 3%, but still it is higher than the results obtained by using commercially available phantoms. And the percentage variations in most of cases of tissue phantom were out of tolerance limit. On the basis of these preliminary results it is logical and rational to develop radiation dosimetry methods based on real human body and also to develop an artificial phantom which should truly represent the interior of human body.
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Benites R, J. L. [Centro Estatal de Cancerologia de Nayarit, Comite de Investigacion, Calz. de la Cruz 118 sur, 63000 Tepic, Nayarit (Mexico); Vega C, H. R., E-mail: neutronesrapidos@gmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico)
2017-10-15
Using Monte Carlo methods, with the code MCNP5, a gynecological mannequin and a vaginal cylinder were modeled. The spatial distribution of absorbed dose rate in uterine cervical cancer (UCCA) treatments was determined under the modality of manual brachytherapy of low dose rate (B-LDR). The design of the model included the gynecological liquid water mannequin, a vaginal cylinder applicator of Lucite (PMMA) with hemisphere termination. The applicator was formed by a vaginal cylinder 10.3 cm long and 2 cm in diameter. This cylinder was mounted on a stainless steel tube 15.2 cm long by 0.6 cm in diameter. A linear array of four radioactive sources of Cesium 137 was inserted into the tube. 13 water cells of 0.5 cm in diameter were modeled around the vaginal cylinder and the absorbed dose was calculated in these. The distribution of the fluence of gamma photons in the mesh was calculated. It was found that the distribution of the absorbed dose is symmetric for cells located in the upper and lower part of the vaginal cylinder. The values of the absorbed dose rate were estimated for the date of manufacture of the sources. This result allows the use of the law of radioactive decay to determine the dose rate at any date of a gynecological treatment of B-LDR. (Author)
Adjoint electron Monte Carlo calculations
International Nuclear Information System (INIS)
Jordan, T.M.
1986-01-01
Adjoint Monte Carlo is the most efficient method for accurate analysis of space systems exposed to natural and artificially enhanced electron environments. Recent adjoint calculations for isotropic electron environments include: comparative data for experimental measurements on electronics boxes; benchmark problem solutions for comparing total dose prediction methodologies; preliminary assessment of sectoring methods used during space system design; and total dose predictions on an electronics package. Adjoint Monte Carlo, forward Monte Carlo, and experiment are in excellent agreement for electron sources that simulate space environments. For electron space environments, adjoint Monte Carlo is clearly superior to forward Monte Carlo, requiring one to two orders of magnitude less computer time for relatively simple geometries. The solid-angle sectoring approximations used for routine design calculations can err by more than a factor of 2 on dose in simple shield geometries. For critical space systems exposed to severe electron environments, these potential sectoring errors demand the establishment of large design margins and/or verification of shield design by adjoint Monte Carlo/experiment
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Cheong, Kwang-Ho; Suh, Tae-Suk; Lee, Hyoung-Koo; Choe, Bo-Young [The Catholic Univ. of Korea, Seoul (Korea, Republic of); Kim, Hoi-Nam; Yoon, Sei-Chul [Kangnam St. Mary' s Hospital, Seoul (Korea, Republic of)
2002-07-01
Accurate dose calculation in radiation treatment planning is most important for successful treatment. Since human body is composed of various materials and not an ideal shape, it is not easy to calculate the accurate effective dose in the patients. Many methods have been proposed to solve inhomogeneity and surface contour problems. Monte Carlo simulations are regarded as the most accurate method, but it is not appropriate for routine planning because it takes so much time. Pencil beam kernel based convolution/superposition methods were also proposed to correct those effects. Nowadays, many commercial treatment planning systems have adopted this algorithm as a dose calculation engine. The purpose of this study is to verify the accuracy of the dose calculated from pencil beam kernel based treatment planning system comparing to Monte Carlo simulations and measurements especially in inhomogeneous region. Home-made inhomogeneous phantom, Helax-TMS ver. 6.0 and Monte Carlo code BEAMnrc and DOSXYZnrc were used in this study. In homogeneous media, the accuracy was acceptable but in inhomogeneous media, the errors were more significant. However in general clinical situation, pencil beam kernel based convolution algorithm is thought to be a valuable tool to calculate the dose.
International Nuclear Information System (INIS)
Yamaguchi, Yasuhiro
1991-01-01
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)
International Nuclear Information System (INIS)
Fulea, D.; Cosma, C.
2006-01-01
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 methods which
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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 methods which
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Sampson, Andrew; Le Yi; Williamson, Jeffrey F. [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia 23298 (United States)
2012-02-15
Purpose: To demonstrate potential of correlated sampling Monte Carlo (CMC) simulation to improve the calculation efficiency for permanent seed brachytherapy (PSB) implants without loss of accuracy. Methods: CMC was implemented within an in-house MC code family (PTRAN) and used to compute 3D dose distributions for two patient cases: a clinical PSB postimplant prostate CT imaging study and a simulated post lumpectomy breast PSB implant planned on a screening dedicated breast cone-beam CT patient exam. CMC tallies the dose difference, {Delta}D, between highly correlated histories in homogeneous and heterogeneous geometries. The heterogeneous geometry histories were derived from photon collisions sampled in a geometrically identical but purely homogeneous medium geometry, by altering their particle weights to correct for bias. The prostate case consisted of 78 Model-6711 {sup 125}I seeds. The breast case consisted of 87 Model-200 {sup 103}Pd seeds embedded around a simulated lumpectomy cavity. Systematic and random errors in CMC were unfolded using low-uncertainty uncorrelated MC (UMC) as the benchmark. CMC efficiency gains, relative to UMC, were computed for all voxels, and the mean was classified in regions that received minimum doses greater than 20%, 50%, and 90% of D{sub 90}, as well as for various anatomical regions. Results: Systematic errors in CMC relative to UMC were less than 0.6% for 99% of the voxels and 0.04% for 100% of the voxels for the prostate and breast cases, respectively. For a 1 x 1 x 1 mm{sup 3} dose grid, efficiency gains were realized in all structures with 38.1- and 59.8-fold average gains within the prostate and breast clinical target volumes (CTVs), respectively. Greater than 99% of the voxels within the prostate and breast CTVs experienced an efficiency gain. Additionally, it was shown that efficiency losses were confined to low dose regions while the largest gains were located where little difference exists between the homogeneous and
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
International Nuclear Information System (INIS)
Takahashi, R; Kamima, T; Tachibana, H; Baba, H; Itano, M; Yamazaki, T; Ishibashi, S; Higuchi, Y; Shimizu, H; Yamamoto, T; Yamashita, M; Sugawara, Y; Sato, A; Nishiyama, S; Kawai, D; Miyaoka, S
2015-01-01
Purpose: To show the results of a multi-institutional study of the independent dose verification for conventional, Stereotactic radiosurgery and body radiotherapy (SRS and SBRT) plans based on the action level of AAPM TG-114. Methods: This study was performed at 12 institutions in Japan. To eliminate the bias of independent dose verification program (Indp), all of the institutions used the same CT-based independent dose verification software (Simple MU Analysis, Triangle Products, JP) with the Clarkson-based algorithm. Eclipse (AAA, PBC), Pinnacle 3 (Adaptive Convolve) and Xio (Superposition) were used as treatment planning system (TPS). The confidence limits (CL, Mean±2SD) for 18 sites (head, breast, lung, pelvis, etc.) were evaluated in comparison in dose between the TPS and the Indp. Results: A retrospective analysis of 6352 treatment fields was conducted. The CLs for conventional, SRS and SBRT were 1.0±3.7 %, 2.0±2.5 % and 6.2±4.4 %, respectively. In conventional plans, most of the sites showed within 5 % of TG-114 action level. However, there were the systematic difference (4.0±4.0 % and 2.5±5.8 % for breast and lung, respectively). In SRS plans, our results showed good agreement compared to the action level. In SBRT plans, the discrepancy between the Indp was variable depending on dose calculation algorithms of TPS. Conclusion: The impact of dose calculation algorithms for the TPS and the Indp affects the action level. It is effective to set the site-specific tolerances, especially for the site where inhomogeneous correction can affect dose distribution strongly
Energy Technology Data Exchange (ETDEWEB)
Takahashi, R; Kamima, T [The Cancer Institute Hospital of JFCR, Koto-ku, Tokyo (Japan); Tachibana, H; Baba, H [National Cancer Center Hospital East, Kashiwa, Chiba (Japan); Itano, M; Yamazaki, T [Inagi Municipal Hospital, Inagi, Tokyo (Japan); Ishibashi, S; Higuchi, Y [Sasebo City General Hospital, Sasebo, Nagasaki (Japan); Shimizu, H [Kitasato University Medical Center, Kitamoto, Saitama (Japan); Yamamoto, T [Otemae Hospital, Chuou-ku, Osaka-city (Japan); Yamashita, M [Kobe City Medical Center General Hospital, Kobe, Hyogo (Japan); Sugawara, Y [The National Center for Global Health and Medicine, Shinjuku-ku, Tokyo (Japan); Sato, A [Itabashi Central General Hospital, Itabashi-ku, Tokyo (Japan); Nishiyama, S [Kuki General Hospital, Kuki, Saitama (Japan); Kawai, D [Kanagawa Cancer Center, Yokohama, Kanagawa-prefecture (Japan); Miyaoka, S [Kamitsuga General Hospital, Kanuma, Tochigi (Japan)
2015-06-15
Purpose: To show the results of a multi-institutional study of the independent dose verification for conventional, Stereotactic radiosurgery and body radiotherapy (SRS and SBRT) plans based on the action level of AAPM TG-114. Methods: This study was performed at 12 institutions in Japan. To eliminate the bias of independent dose verification program (Indp), all of the institutions used the same CT-based independent dose verification software (Simple MU Analysis, Triangle Products, JP) with the Clarkson-based algorithm. Eclipse (AAA, PBC), Pinnacle{sup 3} (Adaptive Convolve) and Xio (Superposition) were used as treatment planning system (TPS). The confidence limits (CL, Mean±2SD) for 18 sites (head, breast, lung, pelvis, etc.) were evaluated in comparison in dose between the TPS and the Indp. Results: A retrospective analysis of 6352 treatment fields was conducted. The CLs for conventional, SRS and SBRT were 1.0±3.7 %, 2.0±2.5 % and 6.2±4.4 %, respectively. In conventional plans, most of the sites showed within 5 % of TG-114 action level. However, there were the systematic difference (4.0±4.0 % and 2.5±5.8 % for breast and lung, respectively). In SRS plans, our results showed good agreement compared to the action level. In SBRT plans, the discrepancy between the Indp was variable depending on dose calculation algorithms of TPS. Conclusion: The impact of dose calculation algorithms for the TPS and the Indp affects the action level. It is effective to set the site-specific tolerances, especially for the site where inhomogeneous correction can affect dose distribution strongly.
WE-D-BRA-04: Online 3D EPID-Based Dose Verification for Optimum Patient Safety
International Nuclear Information System (INIS)
Spreeuw, H; Rozendaal, R; Olaciregui-Ruiz, I; Mans, A; Mijnheer, B; Herk, M van; Gonzalez, P
2015-01-01
Purpose: To develop an online 3D dose verification tool based on EPID transit dosimetry to ensure optimum patient safety in radiotherapy treatments. Methods: A new software package was developed which processes EPID portal images online using a back-projection algorithm for the 3D dose reconstruction. The package processes portal images faster than the acquisition rate of the portal imager (∼ 2.5 fps). After a portal image is acquired, the software seeks for “hot spots” in the reconstructed 3D dose distribution. A hot spot is in this study defined as a 4 cm 3 cube where the average cumulative reconstructed dose exceeds the average total planned dose by at least 20% and 50 cGy. If a hot spot is detected, an alert is generated resulting in a linac halt. The software has been tested by irradiating an Alderson phantom after introducing various types of serious delivery errors. Results: In our first experiment the Alderson phantom was irradiated with two arcs from a 6 MV VMAT H&N treatment having a large leaf position error or a large monitor unit error. For both arcs and both errors the linac was halted before dose delivery was completed. When no error was introduced, the linac was not halted. The complete processing of a single portal frame, including hot spot detection, takes about 220 ms on a dual hexacore Intel Xeon 25 X5650 CPU at 2.66 GHz. Conclusion: A prototype online 3D dose verification tool using portal imaging has been developed and successfully tested for various kinds of gross delivery errors. The detection of hot spots was proven to be effective for the timely detection of these errors. Current work is focused on hot spot detection criteria for various treatment sites and the introduction of a clinical pilot program with online verification of hypo-fractionated (lung) treatments
Lee, Hyun Cheol; Yoo, Do Hyeon; Testa, Mauro; Shin, Wook-Geun; Choi, Hyun Joon; Ha, Wi-Ho; Yoo, Jaeryong; Yoon, Seokwon; Min, Chul Hee
2016-04-01
The aim of this study is to evaluate the potential hazard of naturally occurring radioactive material (NORM) added consumer products. Using the Monte Carlo method, the radioactive products were simulated with ICRP reference phantom and the organ doses were calculated with the usage scenario. Finally, the annual effective doses were evaluated as lower than the public dose limit of 1mSv y(-1) for 44 products. It was demonstrated that NORM-added consumer products could be quantitatively assessed for the safety regulation. Copyright © 2016 Elsevier Ltd. All rights reserved.
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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)
International Nuclear Information System (INIS)
Yang Bo; Qiu Rui; Li Junli; Zhang Hui
2014-01-01
The X-ray dose produced in the interaction between high intensity laser and solid target was studied by simulation using Monte Carlo code. Compared with experimental results, the calculation model was verified. The calculation model was used to study the effect on X-ray dose with different electron temperatures, target materials (including Au, Cu and PE) and thicknesses. The results indicate that the X-ray dose is mainly determined by the electron temperature, and will be affected by the target parameters. X-ray dose of Au is about 1.2 times that of Cu, and is about 5 times that of PE (polyethylene). In addition, compared with other target thickness, when target thickness is the mean range of electron in the target, X-ray dose is relatively large. These results will provide references on evaluating the ionizing radiation dose for laser devices. (authors)
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.
Monte Carlo dose calculation using a cell processor based PlayStation 3 system
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Chow, James C L; Lam, Phil; Jaffray, David A, E-mail: james.chow@rmp.uhn.on.ca [Department of Radiation Oncology, University of Toronto and Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, Ontario M5G 2M9 (Canada)
2012-02-09
This study investigates the performance of the EGSnrc computer code coupled with a Cell-based hardware in Monte Carlo simulation of radiation dose in radiotherapy. Performance evaluations of two processor-intensive functions namely, HOWNEAR and RANMAR{sub G}ET in the EGSnrc code were carried out basing on the 20-80 rule (Pareto principle). The execution speeds of the two functions were measured by the profiler gprof specifying the number of executions and total time spent on the functions. A testing architecture designed for Cell processor was implemented in the evaluation using a PlayStation3 (PS3) system. The evaluation results show that the algorithms examined are readily parallelizable on the Cell platform, provided that an architectural change of the EGSnrc was made. However, as the EGSnrc performance was limited by the PowerPC Processing Element in the PS3, PC coupled with graphics processing units or GPCPU may provide a more viable avenue for acceleration.
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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)
International Nuclear Information System (INIS)
Janek, S; Svensson, R; Jonsson, C; Brahme, A
2006-01-01
A method for dose delivery monitoring after high energy photon therapy has been investigated based on positron emission tomography (PET). The technique is based on the activation of body tissues by high energy bremsstrahlung beams, preferably with energies well above 20 MeV, resulting primarily in 11 C and 15 O but also 13 N, all positron-emitting radionuclides produced by photoneutron reactions in the nuclei of 12 C, 16 O and 14 N. A PMMA phantom and animal tissue, a frozen hind leg of a pig, were irradiated to 10 Gy and the induced positron activity distributions were measured off-line in a PET camera a couple of minutes after irradiation. The accelerator used was a Racetrack Microtron at the Karolinska University Hospital using 50 MV scanned photon beams. From photonuclear cross-section data integrated over the 50 MV photon fluence spectrum the predicted PET signal was calculated and compared with experimental measurements. Since measured PET images change with time post irradiation, as a result of the different decay times of the radionuclides, the signals from activated 12 C, 16 O and 14 N within the irradiated volume could be separated from each other. Most information is obtained from the carbon and oxygen radionuclides which are the most abundant elements in soft tissue. The predicted and measured overall positron activities are almost equal (-3%) while the predicted activity originating from nitrogen is overestimated by almost a factor of two, possibly due to experimental noise. Based on the results obtained in this first feasibility study the great value of a combined radiotherapy-PET-CT unit is indicated in order to fully exploit the high activity signal from oxygen immediately after treatment and to avoid patient repositioning. With an RT-PET-CT unit a high signal could be collected even at a dose level of 2 Gy and the acquisition time for the PET could be reduced considerably. Real patient dose delivery verification by means of PET imaging seems to be
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
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.
International Nuclear Information System (INIS)
Ramm, U.; Licher, J.; Moog, J.; Scherf, C.; Kara, E.; Boettcher, H.D.; Roedel, C.; Mose, S.
2008-01-01
Background and purpose: for total-body irradiation (TBI) using the translation method, dose distribution cannot be computed with computer-assisted three-dimensional planning systems. Therefore, dose distribution has to be primarily estimated based on CT scans (beam-zone method) which is followed by in vivo measurements to ascertain a homogeneous dose delivery. The aim of this study was to clinically establish semiconductor probes as a simple and fast method to obtain an online verification of the dose at relevant points. Patients and methods: in 110 consecutively irradiated TBI patients (12.6 Gy, 2 x 1.8 Gy/day), six semiconductor probes were attached to the body surface at dose-relevant points (eye/head, neck, lung, navel). The mid-body point of the abdomen was defined as dose reference point. The speed of translation was optimized to definitively reach the prescribed dose in this point. Based on the entrance and exit doses, the mid-body doses at the other points were computed. The dose homogeneity in the entire target volume was determined comparing all measured data with the dose at the reference point. Results: after calibration of the semiconductor probes under treatment conditions the dose in selected points and the dose homogeneity in the target volume could be quantitatively specified. In the TBI patients, conformity of calculated and measured doses in the given points was achieved with small deviations of adequate accuracy. The data of 80% of the patients are within an uncertainty of ± 5%. Conclusion: during TBI using the translation method, dose distribution and dose homogeneity can be easily controlled in selected points by means of semiconductor probes. Semiconductor probes are recommended for further use in the physical evaluation of TBI. (orig.)
Kostyuchenko, V. I.; Makarova, A. S.; Ryazantsev, O. B.; Samarin, S. I.; Uglov, A. S.
2014-06-01
A great breakthrough in proton therapy has happened in the new century: several tens of dedicated centers are now operated throughout the world and their number increases every year. An important component of proton therapy is a treatment planning system. To make calculations faster, these systems usually use analytical methods whose reliability and accuracy do not allow the advantages of this method of treatment to implement to the full extent. Predictions by the Monte Carlo (MC) method are a "gold" standard for the verification of calculations with these systems. At the Institute of Experimental and Theoretical Physics (ITEP) which is one of the eldest proton therapy centers in the world, an MC code is an integral part of their treatment planning system. This code which is called IThMC was developed by scientists from RFNC-VNIITF (Snezhinsk) under ISTC Project 3563.
Vera-Sánchez, Juan Antonio; Ruiz-Morales, Carmen; González-López, Antonio
2018-03-01
To provide a multi-stage model to calculate uncertainty in radiochromic film dosimetry with Monte-Carlo techniques. This new approach is applied to single-channel and multichannel algorithms. Two lots of Gafchromic EBT3 are exposed in two different Varian linacs. They are read with an EPSON V800 flatbed scanner. The Monte-Carlo techniques in uncertainty analysis provide a numerical representation of the probability density functions of the output magnitudes. From this numerical representation, traditional parameters of uncertainty analysis as the standard deviations and bias are calculated. Moreover, these numerical representations are used to investigate the shape of the probability density functions of the output magnitudes. Also, another calibration film is read in four EPSON scanners (two V800 and two 10000XL) and the uncertainty analysis is carried out with the four images. The dose estimates of single-channel and multichannel algorithms show a Gaussian behavior and low bias. The multichannel algorithms lead to less uncertainty in the final dose estimates when the EPSON V800 is employed as reading device. In the case of the EPSON 10000XL, the single-channel algorithms provide less uncertainty in the dose estimates for doses higher than four Gy. A multi-stage model has been presented. With the aid of this model and the use of the Monte-Carlo techniques, the uncertainty of dose estimates for single-channel and multichannel algorithms are estimated. The application of the model together with Monte-Carlo techniques leads to a complete characterization of the uncertainties in radiochromic film dosimetry. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
Sankar, A; Ayyangar, Komanduri M; Nehru, R Mothilal; Kurup, P G Gopalakrishna; Murali, V; Enke, Charles A; Velmurugan, J
2006-01-01
The quantitative dose validation of intensity-modulated radiation therapy (IMRT) plans require 2-dimensional (2D) high-resolution dosimetry systems with uniform response over its sensitive region. The present work deals with clinical use of commercially available self-developing Radio Chromic Film, Gafchromic EBT film, for IMRT dose verification. Dose response curves were generated for the films using a VXR-16 film scanner. The results obtained with EBT films were compared with the results of Kodak extended dose range 2 (EDR2) films. The EBT film had a linear response between the dose range of 0 to 600 cGy. The dose-related characteristics of the EBT film, such as post irradiation color growth with time, film uniformity, and effect of scanning orientation, were studied. There was up to 8.6% increase in the color density between 2 to 40 hours after irradiation. There was a considerable variation, up to 8.5%, in the film uniformity over its sensitive region. The quantitative differences between calculated and measured dose distributions were analyzed using DTA and Gamma index with the tolerance of 3% dose difference and 3-mm distance agreement. The EDR2 films showed consistent results with the calculated dose distributions, whereas the results obtained using EBT were inconsistent. The variation in the film uniformity limits the use of EBT film for conventional large-field IMRT verification. For IMRT of smaller field sizes (4.5 x 4.5 cm), the results obtained with EBT were comparable with results of EDR2 films.
International Nuclear Information System (INIS)
Sankar, A.; Ayyangar, Komanduri M.; Nehru, R. Mothilal; Gopalakrishna Kurup, P.G.; Murali, V.; Enke, Charles A.; Velmurugan, J.
2006-01-01
The quantitative dose validation of intensity-modulated radiation therapy (IMRT) plans require 2-dimensional (2D) high-resolution dosimetry systems with uniform response over its sensitive region. The present work deals with clinical use of commercially available self-developing Radio Chromic Film, Gafchromic EBT film, for IMRT dose verification. Dose response curves were generated for the films using a VXR-16 film scanner. The results obtained with EBT films were compared with the results of Kodak extended dose range 2 (EDR2) films. The EBT film had a linear response between the dose range of 0 to 600 cGy. The dose-related characteristics of the EBT film, such as post irradiation color growth with time, film uniformity, and effect of scanning orientation, were studied. There was up to 8.6% increase in the color density between 2 to 40 hours after irradiation. There was a considerable variation, up to 8.5%, in the film uniformity over its sensitive region. The quantitative differences between calculated and measured dose distributions were analyzed using DTA and Gamma index with the tolerance of 3% dose difference and 3-mm distance agreement. The EDR2 films showed consistent results with the calculated dose distributions, whereas the results obtained using EBT were inconsistent. The variation in the film uniformity limits the use of EBT film for conventional large-field IMRT verification. For IMRT of smaller field sizes (4.5 x 4.5 cm), the results obtained with EBT were comparable with results of EDR2 films
Cros, Maria; Joemai, Raoul M. S.; Geleijns, Jacob; Molina, Diego; Salvadó, Marçal
2017-08-01
This study aims to develop and test software for assessing and reporting doses for standard patients undergoing computed tomography (CT) examinations in a 320 detector-row cone-beam scanner. The software, called SimDoseCT, is based on the Monte Carlo (MC) simulation code, which was developed to calculate organ doses and effective doses in ICRP anthropomorphic adult reference computational phantoms for acquisitions with the Aquilion ONE CT scanner (Toshiba). MC simulation was validated by comparing CTDI measurements within standard CT dose phantoms with results from simulation under the same conditions. SimDoseCT consists of a graphical user interface connected to a MySQL database, which contains the look-up-tables that were generated with MC simulations for volumetric acquisitions at different scan positions along the phantom using any tube voltage, bow tie filter, focal spot and nine different beam widths. Two different methods were developed to estimate organ doses and effective doses from acquisitions using other available beam widths in the scanner. A correction factor was used to estimate doses in helical acquisitions. Hence, the user can select any available protocol in the Aquilion ONE scanner for a standard adult male or female and obtain the dose results through the software interface. Agreement within 9% between CTDI measurements and simulations allowed the validation of the MC program. Additionally, the algorithm for dose reporting in SimDoseCT was validated by comparing dose results from this tool with those obtained from MC simulations for three volumetric acquisitions (head, thorax and abdomen). The comparison was repeated using eight different collimations and also for another collimation in a helical abdomen examination. The results showed differences of 0.1 mSv or less for absolute dose in most organs and also in the effective dose calculation. The software provides a suitable tool for dose assessment in standard adult patients undergoing CT
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Saito, K.; Petoussi, N.; Zankl, M.; Veit, R.; Jacob, P.; Drexler, G.
1990-01-01
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)
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Petitguillaume, A.; Broggio, D.; Franck, D.; Desbree, A.; Bernardini, M.; Labriolle Vaylet, C. de
2014-01-01
For targeted radionuclide therapies, treatment planning usually consists of the administration of standard activities without accounting for the patient-specific activity distribution, pharmacokinetics and dosimetry to organs at risk. The OEDIPE software is a user-friendly interface which has an automation level suitable for performing personalized Monte Carlo 3D dosimetry for diagnostic and therapeutic radionuclide administrations. Mean absorbed doses to regions of interest (ROIs), isodose curves superimposed on a personalized anatomical model of the patient and dose-volume histograms can be extracted from the absorbed dose 3D distribution. Moreover, to account for the differences in radiosensitivity between tumoral and healthy tissues, additional functionalities have been implemented to calculate the 3D distribution of the biologically effective dose (BED), mean BEDs to ROIs, isoBED curves and BED-volume histograms along with the Equivalent Uniform Biologically Effective Dose (EUD) to ROIs. Finally, optimization tools are available for treatment planning optimization using either the absorbed dose or BED distributions. These tools enable one to calculate the maximal injectable activity which meets tolerance criteria to organs at risk for a chosen fractionation protocol. This paper describes the functionalities available in the latest version of the OEDIPE software to perform personalized Monte Carlo dosimetry and treatment planning optimization in targeted radionuclide therapies. (authors)
Hunt, J G; da Silva, F C A; Mauricio, C L P; dos Santos, D S
2004-01-01
The Monte Carlo program 'Visual Monte Carlo-dose calculation' (VMC-dc) uses a voxel phantom to simulate the body organs and tissues, transports photons through this phantom and reports the absorbed dose received by each organ and tissue relevant to the calculation of effective dose as defined in ICRP Publication 60. This paper shows the validation of VMC-dc by comparison with EGSnrc and with a physical phantom containing TLDs. The validation of VMC-dc by comparison with EGSnrc was made for a collimated beam of 0.662 MeV photons irradiating a cube of water. For the validation by comparison with the physical phantom, the case considered was a whole body irradiation with a point 137Cs source placed at a distance of 1 m from the thorax of an Alderson-RANDO phantom. The validation results show good agreement for the doses obtained using VMC-dc and EGSnrc calculations, and from VMC-dc and TLD measurements. The program VMC-dc was then applied to the calculation of doses due to immersion in water containing gamma emitters. The dose conversion coefficients for water immersion are compared with their equivalents in the literature.
International Nuclear Information System (INIS)
Hunt, J. G.; Da Silva, F. C. A.; Mauricio, C. L. P.; Dos Santos, D. S.
2004-01-01
The Monte Carlo program 'Visual Monte Carlo-dose calculation' (VMC-dc) uses a voxel phantom to simulate the body organs and tissues, transports photons through this phantom and reports the absorbed dose received by each organ and tissue relevant to the calculation of effective dose as defined in ICRP Publication 60. This paper shows the validation of VMC-dc by comparison with EGSnrc and with a physical phantom containing TLDs. The validation of VMC-dc by comparison with EGSnrc was made for a collimated beam of 0.662 MeV photons irradiating a cube of water. For the validation by comparison with the physical phantom, the case considered was a whole body irradiation with a point 137 Cs source placed at a distance of 1 m from the thorax of an Alderson-RANDO phantom. The validation results show good agreement for the doses obtained using VMC-dc and EGSnrc calculations, and from VMC-dc and TLD measurements. The program VMC-dc was then applied to the calculation of doses due to immersion in water containing gamma emitters. The dose conversion coefficients for water immersion are compared with their equivalents in the literature. (authors)
Chow, James C L; Leung, Michael K K; Islam, Mohammad K; Norrlinger, Bernhard D; Jaffray, David A
2008-01-01
The aim of this study is to evaluate the impact of the patient dose due to the kilovoltage cone beam computed tomography (kV-CBCT) in a prostate intensity-modulated radiation therapy (IMRT). The dose distributions for the five prostate IMRTs were calculated using the Pinnacle treatment planning system. To calculate the patient dose from CBCT, phase-space beams of a CBCT head based on the ELEKTA x-ray volume imaging system were generated using the Monte Carlo BEAMnr code for 100, 120, 130, and 140 kVp energies. An in-house graphical user interface called DOSCTP (DOSXYZnrc-based) developed using MATLAB was used to calculate the dose distributions due to a 360 degrees photon arc from the CBCT beam with the same patient CT image sets as used in Pinnacle. The two calculated dose distributions were added together by setting the CBCT doses equal to 1%, 1.5%, 2%, and 2.5% of the prescription dose of the prostate IMRT. The prostate plan and the summed dose distributions were then processed in the CERR platform to determine the dose-volume histograms (DVHs) of the regions of interest. Moreover, dose profiles along the x- and y-axes crossing the isocenter with and without addition of the CBCT dose were determined. It was found that the added doses due to CBCT are most significant at the femur heads. Higher doses were found at the bones for a relatively low energy CBCT beam such as 100 kVp. Apart from the bones, the CBCT dose was observed to be most concentrated on the anterior and posterior side of the patient anatomy. Analysis of the DVHs for the prostate and other critical tissues showed that they vary only slightly with the added CBCT dose at different beam energies. On the other hand, the changes of the DVHs for the femur heads due to the CBCT dose and beam energy were more significant than those of rectal and bladder wall. By analyzing the vertical and horizontal dose profiles crossing the femur heads and isocenter, with and without the CBCT dose equal to 2% of the
International Nuclear Information System (INIS)
Chow, James C. L.; Leung, Michael K. K.; Islam, Mohammad K.; Norrlinger, Bernhard D.; Jaffray, David A.
2008-01-01
The aim of this study is to evaluate the impact of the patient dose due to the kilovoltage cone beam computed tomography (kV-CBCT) in a prostate intensity-modulated radiation therapy (IMRT). The dose distributions for the five prostate IMRTs were calculated using the Pinnacle3 treatment planning system. To calculate the patient dose from CBCT, phase-space beams of a CBCT head based on the ELEKTA x-ray volume imaging system were generated using the Monte Carlo BEAMnrc code for 100, 120, 130, and 140 kVp energies. An in-house graphical user interface called DOSCTP (DOSXYZnrc-based) developed using MATLAB was used to calculate the dose distributions due to a 360 deg. photon arc from the CBCT beam with the same patient CT image sets as used in Pinnacle3. The two calculated dose distributions were added together by setting the CBCT doses equal to 1%, 1.5%, 2%, and 2.5% of the prescription dose of the prostate IMRT. The prostate plan and the summed dose distributions were then processed in the CERR platform to determine the dose-volume histograms (DVHs) of the regions of interest. Moreover, dose profiles along the x- and y-axes crossing the isocenter with and without addition of the CBCT dose were determined. It was found that the added doses due to CBCT are most significant at the femur heads. Higher doses were found at the bones for a relatively low energy CBCT beam such as 100 kVp. Apart from the bones, the CBCT dose was observed to be most concentrated on the anterior and posterior side of the patient anatomy. Analysis of the DVHs for the prostate and other critical tissues showed that they vary only slightly with the added CBCT dose at different beam energies. On the other hand, the changes of the DVHs for the femur heads due to the CBCT dose and beam energy were more significant than those of rectal and bladder wall. By analyzing the vertical and horizontal dose profiles crossing the femur heads and isocenter, with and without the CBCT dose equal to 2% of the
International Nuclear Information System (INIS)
Pan, Yuxi; Qiu, Rui; Ge, Chaoyong; Xie, Wenzhang; Li, Junli; Gao, Linfeng; Zheng, Junzheng
2014-01-01
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)
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Haus, A.G.; Marks, J.E.
1974-01-01
In patient radiation therapy, it is important to know that the diseased area is included in the treatment field and that normal anatomy is properly shielded or excluded. Since 1969, a film technique developed for imaging of the complete patient radiation exposure has been applied for treatment verification and for the detection and evaluation of localization errors that may occur during treatment. The technique basically consists of placing a film under the patient during the entire radiation exposure. This film should have proper sensitivity and contrast in the exit dose exposure range encountered in radiotherapy. In this communication, we describe how various exit doses fit the characteristic curve of the film; examples of films exposed to various exit doses; the technique for using the film to determine the spatial distribution of the absorbed exit dose; and types of errors commonly detected. Results are presented illustrating that, as the frequency of use of this film technique is increased, localization error is reduced significantly
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Tsai, Hui-Yu; Lai, Pei-Ling; Li, Yang-Ying; Tyan, Yeu-Sheng
2011-01-01
Less invasive imaging-guided vascular interventions with fluoroscopy and digital subtraction angiography have recently become widespread and have been successfully used for treating various diseases. However, interventional fluoroscopy procedures may present deterministic and stochastic radiation risks. The International Commission on Radiological Protection (ICRP) and the Food and Drug Administration have requested identifying procedures that may involve patient doses greater than the recommended thresholds. In this study, radiochromic dosimetric media, known as self-developing films, and measurement-based Monte Carlo simulations were used to establish an interventional radiology dosing system for individual patients undergoing interventional transcatheter arterial embolization. The peak skin dose, evaluated from the entrance surface dose distribution, was 21% less than the cumulated dose reported from the console. A 3D dose map incorporated into CT images was established. The organ doses and effective doses for individual patients were evaluated using this dosing system. This system could be applied very well to other fluoroscopic or interventional procedures for patient dose management.
Monte Carlo Treatment Planning for Advanced Radiotherapy
DEFF Research Database (Denmark)
Cronholm, Rickard
This Ph.d. project describes the development of a workflow for Monte Carlo Treatment Planning for clinical radiotherapy plans. The workflow may be utilized to perform an independent dose verification of treatment plans. Modern radiotherapy treatment delivery is often conducted by dynamically...... modulating the intensity of the field during the irradiation. The workflow described has the potential to fully model the dynamic delivery, including gantry rotation during irradiation, of modern radiotherapy. Three corner stones of Monte Carlo Treatment Planning are identified: Building, commissioning...... and validation of a Monte Carlo model of a medical linear accelerator (i), converting a CT scan of a patient to a Monte Carlo compliant phantom (ii) and translating the treatment plan parameters (including beam energy, angles of incidence, collimator settings etc) to a Monte Carlo input file (iii). A protocol...
International Nuclear Information System (INIS)
Kawai, D; Takahashi, R; Kamima, T; Baba, H; Yamamoto, T; Kubo, Y; Ishibashi, S; Higuchi, Y; Takahashi, H; Tachibana, H
2015-01-01
Purpose: The accuracy of dose distribution depends on treatment planning system especially in heterogeneity-region. The tolerance level (TL) of the secondary check using the independent dose verification may be variable in lung SBRT plans. We conducted a multi-institutional study to evaluate the tolerance level of lung SBRT plans shown in the AAPM TG114. Methods: Five institutes in Japan participated in this study. All of the institutes used a same independent dose verification software program (Simple MU Analysis: SMU, Triangle Product, Ishikawa, JP), which is Clarkson-based and CT images were used to compute radiological path length. Analytical Anisotropic Algorithm (AAA), Pencil Beam Convolution with modified Batho-method (PBC-B) and Adaptive Convolve (AC) were used for lung SBRT planning. A measurement using an ion-chamber was performed in a heterogeneous phantom to compare doses from the three different algorithms and the SMU to the measured dose. In addition to it, a retrospective analysis using clinical lung SBRT plans (547 beams from 77 patients) was conducted to evaluate the confidence limit (CL, Average±2SD) in dose between the three algorithms and the SMU. Results: Compared to the measurement, the AAA showed the larger systematic dose error of 2.9±3.2% than PBC-B and AC. The Clarkson-based SMU showed larger error of 5.8±3.8%. The CLs for clinical plans were 7.7±6.0 % (AAA), 5.3±3.3 % (AC), 5.7±3.4 % (PBC -B), respectively. Conclusion: The TLs from the CLs were evaluated. A Clarkson-based system shows a large systematic variation because of inhomogeneous correction. The AAA showed a significant variation. Thus, we must consider the difference of inhomogeneous correction as well as the dependence of dose calculation engine
International Nuclear Information System (INIS)
Qi Zhenyu; Deng Xiaowu; Huang Shaomin; Lu Jie; Lerch, Michael; Cutajar, Dean; Rosenfeld, Anatoly
2007-01-01
The feasibility of a recently designed metal-oxide-semiconductor field effect transistor (MOSFET) dosimetry system for dose verification of high dose rate (HDR) brachytherapy treatment planning was investigated. MOSFET detectors were calibrated with a 0.6 cm 3 NE-2571 Farmer-type ionization chamber in water. Key characteristics of the MOSFET detectors, such as the energy dependence, that will affect phantom measurements with HDR 192 Ir sources were measured. The MOSFET detector was then applied to verify the dosimetric accuracy of HDR brachytherapy treatments in a custom-made water phantom. Three MOSFET detectors were calibrated independently, with the calibration factors ranging from 0.187 to 0.215 cGy/mV. A distance dependent energy response was observed, significant within 2 cm from the source. The new MOSFET detector has a good reproducibility ( 2 =1). It was observed that the MOSFET detectors had a linear response to dose until the threshold voltage reached approximately 24 V for 192 Ir source measurements. Further comparison of phantom measurements using MOSFET detectors with dose calculations by a commercial treatment planning system for computed tomography-based brachytherapy treatment plans showed that the mean relative deviation was 2.2±0.2% for dose points 1 cm away from the source and 2.0±0.1% for dose points located 2 cm away. The percentage deviations between the measured doses and the planned doses were below 5% for all the measurements. The MOSFET detector, with its advantages of small physical size and ease of use, is a reliable tool for quality assurance of HDR brachytherapy. The phantom verification method described here is universal and can be applied to other HDR brachytherapy treatments
Energy Technology Data Exchange (ETDEWEB)
Kawai, D [Kanagawa Cancer Center, Yokohama, Kanagawa-prefecture (Japan); Takahashi, R; Kamima, T [The Cancer Institute Hospital of JFCR, Koutou-ku, Tokyo (Japan); Baba, H [The National Cancer Center Hospital East, Kashiwa-city, Chiba prefecture (Japan); Yamamoto, T; Kubo, Y [Otemae Hospital, Chuou-ku, Osaka-city (Japan); Ishibashi, S; Higuchi, Y [Sasebo City General Hospital, Sasebo, Nagasaki (Japan); Takahashi, H [St Lukes International Hospital, Chuou-ku, Tokyo (Japan); Tachibana, H [National Cancer Center Hospital East, Kashiwa, Chiba (Japan)
2015-06-15
Purpose: The accuracy of dose distribution depends on treatment planning system especially in heterogeneity-region. The tolerance level (TL) of the secondary check using the independent dose verification may be variable in lung SBRT plans. We conducted a multi-institutional study to evaluate the tolerance level of lung SBRT plans shown in the AAPM TG114. Methods: Five institutes in Japan participated in this study. All of the institutes used a same independent dose verification software program (Simple MU Analysis: SMU, Triangle Product, Ishikawa, JP), which is Clarkson-based and CT images were used to compute radiological path length. Analytical Anisotropic Algorithm (AAA), Pencil Beam Convolution with modified Batho-method (PBC-B) and Adaptive Convolve (AC) were used for lung SBRT planning. A measurement using an ion-chamber was performed in a heterogeneous phantom to compare doses from the three different algorithms and the SMU to the measured dose. In addition to it, a retrospective analysis using clinical lung SBRT plans (547 beams from 77 patients) was conducted to evaluate the confidence limit (CL, Average±2SD) in dose between the three algorithms and the SMU. Results: Compared to the measurement, the AAA showed the larger systematic dose error of 2.9±3.2% than PBC-B and AC. The Clarkson-based SMU showed larger error of 5.8±3.8%. The CLs for clinical plans were 7.7±6.0 % (AAA), 5.3±3.3 % (AC), 5.7±3.4 % (PBC -B), respectively. Conclusion: The TLs from the CLs were evaluated. A Clarkson-based system shows a large systematic variation because of inhomogeneous correction. The AAA showed a significant variation. Thus, we must consider the difference of inhomogeneous correction as well as the dependence of dose calculation engine.
International Nuclear Information System (INIS)
Long, Daniel J.; Lee, Choonsik; Tien, Christopher; Fisher, Ryan; Hoerner, Matthew R.; Hintenlang, David; Bolch, Wesley E.
2013-01-01
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
Energy Technology Data Exchange (ETDEWEB)
Zankl, M. [GSF - Forschungszentrum fuer Umwelt und Gesundheit Neuherberg GmbH, Oberschleissheim (Germany). Inst. fuer Strahlenschutz; Drexler, G. [GSF - Forschungszentrum fuer Umwelt und Gesundheit Neuherberg GmbH, Oberschleissheim (Germany). Inst. fuer Strahlenschutz; Petoussi-Henss, N. [GSF - Forschungszentrum fuer Umwelt und Gesundheit Neuherberg GmbH, Oberschleissheim (Germany). Inst. fuer Strahlenschutz; Saito, K. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan)
1997-03-01
This report presents a tabulation of organ and tissue equivalent dose as well as effective dose conversion coefficients, normalised to air kerma free in air, for occupational exposures and environmental exposures of the public to external photon radiation. For occupational exposures, whole-body irradiation with idealised geometries, i.e. broad parallel beams and fully isotropic radiation incidence, is considered. The directions of incidence for the parallel beams are anterior-posterior, posterior-anterior, left lateral, right lateral and a full 360 rotation around the body`s longitudinal axis. The influence of beam divergence on the body doses is also considered as well as the dependence of effective dose on the angle of radiation incidence. Regarding exposure of the public to environmental sources, three source geometries are considered: exposure from a radioactive cloud, from ground contamination and from the natural radionuclides distributed homogeneously in the ground. The precise angular and energy distributions of the gamma rays incident on the human body were taken into account. The organ dose conversion coefficients given in this catalogue were calculated using a Monte Carlo code simulating the photon transport in mathematical models of an adult male and an adult female, respectively. Conversion coefficients are given for the equivalent dose of 23 organs and tissues as well as for effective dose and the equivalent dose of the so-called `remainder`. The organ equivalent dose conversion coefficients are given separately for the adult male and female models and - as arithmetic mean of the conversion coefficients of both - for an average adult. Fitted data of the coefficients are presented in tables; the primary raw data as resulting from the Monte Carlo calculation are shown in figures together with the fitted data. (orig.)
International Nuclear Information System (INIS)
Zankl, M.
1997-03-01
This report presents a tabulation of organ and tissue equivalent dose as well as effective dose conversion coefficients, normalised to air kerma free in air, for occupational exposures and environmental exposures of the public to external photon radiation. For occupational exposures, whole-body irradiation with idealised geometries, i.e. broad parallel beams and fully isotropic radiation incidence, is considered. The directions of incidence for the parallel beams are anterior-posterior, posterior-anterior, left lateral, right lateral and a full 360 rotation around the body's longitudinal axis. The influence of beam divergence on the body doses is also considered as well as the dependence of effective dose on the angle of radiation incidence. Regarding exposure of the public to environmental sources, three source geometries are considered: exposure from a radioactive cloud, from ground contamination and from the natural radionuclides distributed homogeneously in the ground. The precise angular and energy distributions of the gamma rays incident on the human body were taken into account. The organ dose conversion coefficients given in this catalogue were calculated using a Monte Carlo code simulating the photon transport in mathematical models of an adult male and an adult female, respectively. Conversion coefficients are given for the equivalent dose of 23 organs and tissues as well as for effective dose and the equivalent dose of the so-called 'remainder'. The organ equivalent dose conversion coefficients are given separately for the adult male and female models and - as arithmetic mean of the conversion coefficients of both - for an average adult. Fitted data of the coefficients are presented in tables; the primary raw data as resulting from the Monte Carlo calculation are shown in figures together with the fitted data. (orig.)
Adapted Prescription Dose for Monte Carlo Algorithm in Lung SBRT: Clinical Outcome on 205 Patients.
Directory of Open Access Journals (Sweden)
Jean-Emmanuel Bibault
Full Text Available SBRT is the standard of care for inoperable patients with early-stage lung cancer without lymph node involvement. Excellent local control rates have been reported in a large number of series. However, prescription doses and calculation algorithms vary to a great extent between studies, even if most teams prescribe to the D95 of the PTV. Type A algorithms are known to produce dosimetric discrepancies in heterogeneous tissues such as lungs. This study was performed to present a Monte Carlo (MC prescription dose for NSCLC adapted to lesion size and location and compare the clinical outcomes of two cohorts of patients treated with a standard prescription dose calculated by a type A algorithm or the proposed MC protocol.Patients were treated from January 2011 to April 2013 with a type B algorithm (MC prescription with 54 Gy in three fractions for peripheral lesions with a diameter under 30 mm, 60 Gy in 3 fractions for lesions with a diameter over 30 mm, and 55 Gy in five fractions for central lesions. Clinical outcome was compared to a series of 121 patients treated with a type A algorithm (TA with three fractions of 20 Gy for peripheral lesions and 60 Gy in five fractions for central lesions prescribed to the PTV D95 until January 2011. All treatment plans were recalculated with both algorithms for this study. Spearman's rank correlation coefficient was calculated for GTV and PTV. Local control, overall survival and toxicity were compared between the two groups.205 patients with 214 lesions were included in the study. Among these, 93 lesions were treated with MC and 121 were treated with TA. Overall survival rates were 86% and 94% at one and two years, respectively. Local control rates were 79% and 93% at one and two years respectively. There was no significant difference between the two groups for overall survival (p = 0.785 or local control (p = 0.934. Fifty-six patients (27% developed grade I lung fibrosis without clinical consequences. GTV size
International Nuclear Information System (INIS)
Rodrigues, Leonardo; Braz, Delson; Goncalves Magalhaes, Luis Alexandre
2015-01-01
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
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Poppe, Bjoern; Djouguela, Armand; Blechschmidt, Arne; Willborn, Kay; Ruehmann, Antje; Harder, Dietrich
2007-01-01
The spatial resolution of 2D detector arrays equipped with ionization chambers or diodes, used for the dose verification of IMRT treatment plans, is limited by the size of the single detector and the centre-to-centre distance between the detectors. Optimization criteria with regard to these parameters have been developed by combining concepts of dosimetry and pattern analysis. The 2D-ARRAY Type 10024 (PTW-Freiburg, Germany), single-chamber cross section 5 x 5 mm 2 , centre-to-centre distance between chambers in each row and column 10 mm, served as an example. Additional frames of given dose distributions can be taken by shifting the whole array parallel or perpendicular to the MLC leaves by, e.g., 5 mm. The size of the single detector is characterized by its lateral response function, a trapezoid with 5 mm top width and 9 mm base width. Therefore, values measured with the 2D array are regarded as sample values from the convolution product of the accelerator generated dose distribution and this lateral response function. Consequently, the dose verification, e.g., by means of the gamma index, is performed by comparing the measured values of the 2D array with the values of the convolution product of the treatment planning system (TPS) calculated dose distribution and the single-detector lateral response function. Sufficiently small misalignments of the measured dose distributions in comparison with the calculated ones can be detected since the lateral response function is symmetric with respect to the centre of the chamber, and the change of dose gradients due to the convolution is sufficiently small. The sampling step width of the 2D array should provide a set of sample values representative of the sampled distribution, which is achieved if the highest spatial frequency contained in this function does not exceed the 'Nyquist frequency', one half of the sampling frequency. Since the convolution products of IMRT-typical dose distributions and the single
Measurement of dose rates and Monte Carlo analysis of neutrons in a spent-fuel shipping vessel
International Nuclear Information System (INIS)
Ueki, K.; Namito, Y.; Fuse, T.
1986-01-01
On-board experiments were carried out in a spent-fuel shipping vessel, the Pacific Swan, in which 13 casks of TN-12A and Excellox 3 were loaded in five holds, and neutron and gamma-ray dose rates were measured on the hatch covers of the holds. Before shipping those casks, dose rates were also measured on the cask surfaces, one by one, to eliminate radiation from other casks. The Monte Carlo coupling technique was employed successfully to analyze the measured neutron dose rate distributions in the spent-fuel shipping vessel. Through this study, the Monte Carlo coupling code system, MORSE-CG/CASK-VESSEL, on which the MORSE-CG code was based, was established. The agreement between the measured and the calculated neutron dose rates on the TN-12A cask surface was quite satisfactory. The calculated neutron dose rates agreed with the measured values within a factor of 1.5 on the hold 3 hatch cover and within a factor of 2 on the hold 5 hatch cover in which the concrete shield was fixed in the Pacific Swan
International Nuclear Information System (INIS)
Zankl, M.; Panzer, W.; Drexler, G.
1991-11-01
Computed tomography (CT) is a technique which offers a high diagnostic capability; however, the dose to the patient is high compared to conventional radiography. This report provides a catalogue of organ doses resulting from CT examinations. The organ doses were calculated for the type of CT scanners most commonly used in the FRG and for three different radiation qualities. For the dose calculations, the patients were represented by the adult mathematical phantoms Adam and Eva. The radiation transport in the body was simulated using a Monte Carlo method. The doses were calculated as conversion factors of mean organ doses per air kerma free in air on the axis of rotation. Mean organ dose conversion factors are given per organ and per single CT slice of 1 cm width. The mean dose to an organ resulting from a particular CT examination can be estimated by summing up the contribution to the organ dose from each relevant slice. In order to facilitate the selection of the appropriate slices, a table is given which relates the mathematical phantoms' coordinates to certain anatomical landmarks in the human body. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Schwarz, G; Hoffman, F O
1980-01-01
An evaluation of the imprecision in dose predictions has been performed using current dose assessment models and present knowledge of the variability or uncertainty in model parameter values. The propagation of parameter uncertainties is demonstrated using a Monte Carlo technique for elemental /sup 131/I transported via the pasture-cow-milk-child pathway. The results indicate that when site-specific information is not available the imprecision inherent in the predictions for this pathway is potentially large. Generally, the 99th percentile in thyroid dose for children was predicted to be approximately an order of magnitude greater than the median value. The potential consequences of the imprecision in dose for radiation protection purposes are discussed.
International Nuclear Information System (INIS)
Williams, G.; Zankl, M.; Drexler, G.
1984-12-01
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 cm 2 and 14 x 14 cm 2 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 cm 2 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.)
International Nuclear Information System (INIS)
Menser, Bernd; Manke, Dirk; Mentrup, Detlef; Neitzel, Ulrich
2016-01-01
In paediatric radiography, according to the as low as reasonably achievable (ALARA) principle, the imaging task should be performed with the lowest possible radiation dose. This paper describes a Monte-Carlo simulation framework for dose optimisation of imaging parameters in digital paediatric radiography. Patient models with high spatial resolution and organ segmentation enable the simultaneous evaluation of image quality and patient dose on the same simulated radiographic examination. The accuracy of the image simulation is analysed by comparing simulated and acquired images of technical phantoms. As a first application example, the framework is applied to optimise tube voltage and pre-filtration in newborn chest radiography. At equal patient dose, the highest CNR is obtained with low-kV settings in combination with copper filtration. (authors)
International Nuclear Information System (INIS)
Blake, Samuel J.; McNamara, Aimee L.; Deshpande, Shrikant; Holloway, Lois; Greer, Peter B.; Kuncic, Zdenka; Vial, Philip
2013-01-01
100 monitor units. Over this range, the prototype and standard EPID central axis responses agreed to within 1.6%. Images taken with the prototype EPID were noisier than those taken with the standard EPID, with fractional uncertainties of 0.2% and 0.05% within the central 1 cm 2 , respectively. For all dosimetry measurements, the prototype EPID exhibited a near water-equivalent response whereas the standard EPID did not. The CNR and spatial resolution of images taken with the standard EPID were greater than those taken with the prototype EPID.Conclusions: A prototype EPID employing an array of PS fibers has been developed and the first experimental measurements are reported. The prototype EPID demonstrated a much morewater-equivalent dose response than the standard EPID. While the imaging performance of the standard EPID was superior to that of the prototype, the prototype EPID has many design characteristics that may be optimized to improve imaging performance. This investigation demonstrates the feasibility of a new detector design for simultaneous imaging and dosimetry treatment verification in radiotherapy
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)
Mostafa, Laoues; Rachid, Khelifi; Ahmed, Sidi Moussa
2016-08-01
Eye applicators with 90Sr/90Y and 106Ru/106Rh beta-ray sources are generally used in brachytherapy for the treatment of eye diseases as uveal melanoma. Whenever, radiation is used in treatment, dosimetry is essential. However, knowledge of the exact dose distribution is a critical decision-making to the outcome of the treatment. 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 aim of this work consisted in using the Monte Carlo GATE platform to calculate the 3D dose distribution on a mathematical model of the human eye according to international recommendations. Mathematical models were developed for four ophthalmic applicators, two HDR 90Sr applicators SIA.20 and SIA.6, and two LDR 106Ru applicators, a concave CCB model and a flat CCB model. In present work, considering a heterogeneous eye phantom and the chosen tumor, obtained results with the use of GATE for mean doses distributions in a phantom and according to international recommendations show a discrepancy with respect to those specified by the manufacturers. The QC of dosimetric parameters shows that contrarily to the other applicators, the SIA.20 applicator is consistent with recommendations. The GATE platform show that the SIA.20 applicator present better results, namely the dose delivered to critical structures were lower compared to those obtained for the other applicators, and the SIA.6 applicator, simulated with MCNPX generates higher lens doses than those generated by GATE. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
TU-F-CAMPUS-T-05: A Cloud-Based Monte Carlo Dose Calculation for Electron Cutout Factors
Energy Technology Data Exchange (ETDEWEB)
Mitchell, T; Bush, K [Stanford School of Medicine, Stanford, CA (United States)
2015-06-15
Purpose: For electron cutouts of smaller sizes, it is necessary to verify electron cutout factors due to perturbations in electron scattering. Often, this requires a physical measurement using a small ion chamber, diode, or film. The purpose of this study is to develop a fast Monte Carlo based dose calculation framework that requires only a smart phone photograph of the cutout and specification of the SSD and energy to determine the electron cutout factor, with the ultimate goal of making this cloud-based calculation widely available to the medical physics community. Methods: The algorithm uses a pattern recognition technique to identify the corners of the cutout in the photograph as shown in Figure 1. It then corrects for variations in perspective, scaling, and translation of the photograph introduced by the user’s positioning of the camera. Blob detection is used to identify the portions of the cutout which comprise the aperture and the portions which are cutout material. This information is then used define physical densities of the voxels used in the Monte Carlo dose calculation algorithm as shown in Figure 2, and select a particle source from a pre-computed library of phase-spaces scored above the cutout. The electron cutout factor is obtained by taking a ratio of the maximum dose delivered with the cutout in place to the dose delivered under calibration/reference conditions. Results: The algorithm has been shown to successfully identify all necessary features of the electron cutout to perform the calculation. Subsequent testing will be performed to compare the Monte Carlo results with a physical measurement. Conclusion: A simple, cloud-based method of calculating electron cutout factors could eliminate the need for physical measurements and substantially reduce the time required to properly assure accurate dose delivery.
Directory of Open Access Journals (Sweden)
Nahideh Gharehaghaji
2018-01-01
Conclusion: Our study showed that the dose reduction with small fields in the lung was very high. Thus, inaccurate prediction of absorbed dose inside the lung and also lung/soft-tissue interfaces with small photon beams may lead to critical consequences for treatment outcome.
International Nuclear Information System (INIS)
Odano, N.; Miura, T.; Yamaji, A.
1996-01-01
Measurement of activation reaction rates was carried out for fast neutrons penetrating through graphite and water from the core of JRR-4 research reactor of JAERI, with paying attention to the energy above 10 MeV. Analysis of the experiment was made using a vectorized continuous energy Monte Carlo code MVP to verify the code. The analysis shows good agreements between the measurement and calculation and the MVP code has been confirmed its validity for the fast neutron transport calculations above 10 MeV in fission neutron field. (author)
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.
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...
TU-F-18A-03: Improving Tissue Segmentation for Monte Carlo Dose Calculation Using DECT Data
International Nuclear Information System (INIS)
Di, Salvio A; Bedwani, S; Carrier, J
2014-01-01
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
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.
Dewaraja, Yuni K; Ljungberg, Michael; Majumdar, Amitava; Bose, Abhijit; Koral, Kenneth F
2002-02-01
This paper reports the implementation of the SIMIND Monte Carlo code on an IBM SP2 distributed memory parallel computer. Basic aspects of running Monte Carlo particle transport calculations on parallel architectures are described. Our parallelization is based on equally partitioning photons among the processors and uses the Message Passing Interface (MPI) library for interprocessor communication and the Scalable Parallel Random Number Generator (SPRNG) to generate uncorrelated random number streams. These parallelization techniques are also applicable to other distributed memory architectures. A linear increase in computing speed with the number of processors is demonstrated for up to 32 processors. This speed-up is especially significant in Single Photon Emission Computed Tomography (SPECT) simulations involving higher energy photon emitters, where explicit modeling of the phantom and collimator is required. For (131)I, the accuracy of the parallel code is demonstrated by comparing simulated and experimental SPECT images from a heart/thorax phantom. Clinically realistic SPECT simulations using the voxel-man phantom are carried out to assess scatter and attenuation correction.
Energy Technology Data Exchange (ETDEWEB)
Guberina, Nika; Suntharalingam, Saravanabavaan; Nassenstein, Kai; Forsting, Michael; Theysohn, Jens; Wetter, Axel; Ringelstein, Adrian [University Hospital Essen, Institute of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany)
2016-10-15
The aim of this study was to verify the results of a dose monitoring software tool based on Monte Carlo Simulation (MCS) in assessment of eye lens doses for cranial CT scans. In cooperation with the Federal Office for Radiation Protection (Neuherberg, Germany), phantom measurements were performed with thermoluminescence dosimeters (TLD LiF:Mg,Ti) using cranial CT protocols: (I) CT angiography; (II) unenhanced, cranial CT scans with gantry angulation at a single and (III) without gantry angulation at a dual source CT scanner. Eye lens doses calculated by the dose monitoring tool based on MCS and assessed with TLDs were compared. Eye lens doses are summarized as follows: (I) CT angiography (a) MCS 7 mSv, (b) TLD 5 mSv; (II) unenhanced, cranial CT scan with gantry angulation, (c) MCS 45 mSv, (d) TLD 5 mSv; (III) unenhanced, cranial CT scan without gantry angulation (e) MCS 38 mSv, (f) TLD 35 mSv. Intermodality comparison shows an inaccurate calculation of eye lens doses in unenhanced cranial CT protocols at the single source CT scanner due to the disregard of gantry angulation. On the contrary, the dose monitoring tool showed an accurate calculation of eye lens doses at the dual source CT scanner without gantry angulation and for CT angiography examinations. The dose monitoring software tool based on MCS gave accurate estimates of eye lens doses in cranial CT protocols. However, knowledge of protocol and software specific influences is crucial for correct assessment of eye lens doses in routine clinical use. (orig.)
International Nuclear Information System (INIS)
Guberina, Nika; Suntharalingam, Saravanabavaan; Nassenstein, Kai; Forsting, Michael; Theysohn, Jens; Wetter, Axel; Ringelstein, Adrian
2016-01-01
The aim of this study was to verify the results of a dose monitoring software tool based on Monte Carlo Simulation (MCS) in assessment of eye lens doses for cranial CT scans. In cooperation with the Federal Office for Radiation Protection (Neuherberg, Germany), phantom measurements were performed with thermoluminescence dosimeters (TLD LiF:Mg,Ti) using cranial CT protocols: (I) CT angiography; (II) unenhanced, cranial CT scans with gantry angulation at a single and (III) without gantry angulation at a dual source CT scanner. Eye lens doses calculated by the dose monitoring tool based on MCS and assessed with TLDs were compared. Eye lens doses are summarized as follows: (I) CT angiography (a) MCS 7 mSv, (b) TLD 5 mSv; (II) unenhanced, cranial CT scan with gantry angulation, (c) MCS 45 mSv, (d) TLD 5 mSv; (III) unenhanced, cranial CT scan without gantry angulation (e) MCS 38 mSv, (f) TLD 35 mSv. Intermodality comparison shows an inaccurate calculation of eye lens doses in unenhanced cranial CT protocols at the single source CT scanner due to the disregard of gantry angulation. On the contrary, the dose monitoring tool showed an accurate calculation of eye lens doses at the dual source CT scanner without gantry angulation and for CT angiography examinations. The dose monitoring software tool based on MCS gave accurate estimates of eye lens doses in cranial CT protocols. However, knowledge of protocol and software specific influences is crucial for correct assessment of eye lens doses in routine clinical use. (orig.)
International Nuclear Information System (INIS)
Rojas C, E.L.; Al-Dweri, F.M.O.; Lallena R, A.M.
2005-01-01
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)
A novel method for sub-arc VMAT dose delivery verification based on portal dosimetry with an EPID.
Cools, Ruud A M; Dirkx, Maarten L P; Heijmen, Ben J M
2017-11-01
The EPID-based sub-arc verification of VMAT dose delivery requires synchronization of the acquired electronic portal images (EPIs) with the VMAT delivery, that is, establishment of the start- and stop-MU of the acquired images. To realize this, published synchronization methods propose the use of logging features of the linac or dedicated hardware solutions. In this study, we developed a novel, software-based synchronization method that only uses information inherently available in the acquired images. The EPIs are continuously acquired during pretreatment VMAT delivery and converted into Portal Dose Images (PDIs). Sub-arcs of approximately 10 MU are then defined by combining groups of sequentially acquired PDIs. The start- and stop-MUs of measured sub-arcs are established in a synchronization procedure, using only dosimetric information in measured and predicted PDIs. Sub-arc verification of a VMAT dose delivery is based on comparison of measured sub-arc PDIs with synchronized, predicted sub-arc PDIs, using γ-analyses. To assess the accuracy of this new method, measured and predicted PDIs were compared for 20 clinically applied VMAT prostate cancer plans. The sensitivity of the method for detection of delivery errors was investigated using VMAT deliveries with intentionally inserted, small perturbations (25 error scenarios; leaf gap deviations ≤ 1.5 mm, leaf motion stops during ≤ 15 MU, linac output error ≤ 2%). For the 20 plans, the average failed pixel rates (FPR) for full-arc and sub-arc dose QA were 0.36% ± 0.26% (1 SD) and 0.64% ± 0.88%, based on 2%/2 mm and 3%/3 mm γ-analyses, respectively. Small systematic perturbations of up to 1% output error and 1 mm leaf offset were detected using full-arc QA. Sub-arc QA was able to detect positioning errors in three leaves only during approximately 20 MU and small dose delivery errors during approximately 40 MU. In an ROC analysis, the area under the curve (AUC) for the combined full-arc/sub-arc approach was
International Nuclear Information System (INIS)
Champion, C.; Zanotti-Fregonara, P.; Hindie, E; Hindie, E.
2008-01-01
Monte Carlo simulation can be particularly suitable for modeling the microscopic distribution of energy received by normal tissues or cancer cells and for evaluating the relative merits of different radiopharmaceuticals. We used a new code, CELLDOSE, to assess electron dose for isolated spheres with radii varying from 2,500 μm down to 0.05 μm, in which 131 I is homogeneously distributed. Methods: All electron emissions of 131 I were considered,including the whole β - 131 I spectrum, 108 internal conversion electrons, and 21 Auger electrons. The Monte Carlo track-structure code used follows all electrons down to an energy threshold E-cutoff 7.4 eV. Results: Calculated S values were in good agreement with published analytic methods, lying in between reported results for all experimental points. Our S values were also close to other published data using a Monte Carlo code. Contrary to the latter published results, our results show that dose distribution inside spheres is not homogeneous, with the dose at the outmost layer being approximately half that at the center. The fraction of electron energy retained within the spheres decreased with decreasing radius (r): 87.1 % for r 2,500 μm, 8.73% for r 50 μm, and 1.18% for r 5 μm. Thus, a radioiodine concentration that delivers a dose of 100 Gy to a micro-metastasis of 2,500 μm radius would deliver 10 Gy in a cluster of 50 μm and only 1.4 Gy in an isolated cell. The specific contribution from Auger electrons varied from 0.25% for the largest sphere up to 76.8% for the smallest sphere. Conclusion: The dose to a tumor cell will depend on its position in a metastasis. For the treatment of very small metastases, 131 I may not be the isotope of choice. When trying to kill isolated cells or a small cluster of cells with 131 I, it is important to get the iodine as close as possible to the nucleus to get the enhancement factor from Auger electrons. The Monte Carlo code CELLDOSE can be used to assess the electron map deposit
International Nuclear Information System (INIS)
Sutherland, J. G. H.; Thomson, R. M.; Rogers, D. W. O.
2011-01-01
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
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
Sikora, M; Dohm, O; Alber, M
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(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(2) to 16 x 21 cm(2) was achieved. An IMRT plan film verification
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.
Energy Technology Data Exchange (ETDEWEB)
Schuch, Franciely F.; Nicolucci, Patricia, E-mail: franschuch@yahoo.com.br [Universidade de Sao Paulo (USP), Ribeiraoo Preto, SP (Brazil)
2017-11-01
The interest in optically stimulated luminescence (OSL) dosimetry materials is growing due to its potential use in quality control in Radiotherapy. The use of these dosimeters for in vivo dosimetry, however, may influence the dose to the skin and deeper tissues in the patient. The goal of this study is to evaluate the influence of the OSL Al{sub 2}O{sub 3} material in dose deposited in the skin and deep in Radiotherapy. Monte Carlo simulation is used to evaluate this purpose when OSL dosimeters of Al{sub 2}O{sub 3} are positioned on the skin surface of the patient. Percentage depth dose curves for clinical beams of 6 and 10 MV were simulated with and without the presence of the dosimeter on the surface of a water phantom. The results showed a decrease of doses in regions close to the surface of the skin. In the build-up region, the maximum decreases of dose produced by the presence of the dosimeters were 52,5% and 47,5% for the 6 and 10 MV beams, respectively. After the build-up region, there are not significant changes in the doses for any of the used beams. The differences of doses found are due to the influence of the dosimetric material on the relative fluence of electrons near the end surface of the dosimeter. Thus, the results showed that the presence of the dosimetric material on the surface interferes on the skin dose. However, these dosimeters do not cause dose variations in depths of clinical interest, allowing its application in routine in vivo dosimetry in Radiotherapy. (author)
Energy Technology Data Exchange (ETDEWEB)
Lou, K [U.T M.D. Anderson Cancer Center, Houston, TX (United States); Rice University, Houston, TX (United States); Mirkovic, D; Sun, X; Zhu, X; Poenisch, F; Grosshans, D; Shao, Y [U.T M.D. Anderson Cancer Center, Houston, TX (United States); Clark, J [Rice University, Houston, TX (United States)
2014-06-01
Purpose: To study the feasibility of intra-fraction proton beam-range verification with PET imaging. Methods: Two phantoms homogeneous cylindrical PMMA phantoms (290 mm axial length, 38 mm and 200 mm diameter respectively) were studied using PET imaging: a small phantom using a mouse-sized PET (61 mm diameter field of view (FOV)) and a larger phantom using a human brain-sized PET (300 mm FOV). Monte Carlo (MC) simulations (MCNPX and GATE) were used to simulate 179.2 MeV proton pencil beams irradiating the two phantoms and be imaged by the two PET systems. A total of 50 simulations were conducted to generate 50 positron activity distributions and correspondingly 50 measured activity-ranges. The accuracy and precision of these activity-ranges were calculated under different conditions (including count statistics and other factors, such as crystal cross-section). Separate from the MC simulations, an activity distribution measured from a simulated PET image was modeled as a noiseless positron activity distribution corrupted by Poisson counting noise. The results from these two approaches were compared to assess the impact of count statistics on the accuracy and precision of activity-range calculations. Results: MC Simulations show that the accuracy and precision of an activity-range are dominated by the number (N) of coincidence events of the reconstructed image. They are improved in a manner that is inversely proportional to 1/sqrt(N), which can be understood from the statistical modeling. MC simulations also indicate that the coincidence events acquired within the first 60 seconds with 10{sup 9} protons (small phantom) and 10{sup 10} protons (large phantom) are sufficient to achieve both sub-millimeter accuracy and precision. Conclusion: Under the current MC simulation conditions, the initial study indicates that the accuracy and precision of beam-range verification are dominated by count statistics, and intra-fraction PET image-based beam-range verification is
The Monte Carlo SRNA-VOX code for 3D proton dose distribution in voxelized geometry using CT data
International Nuclear Information System (INIS)
Ilic, Radovan D; Spasic-Jokic, Vesna; Belicev, Petar; Dragovic, Milos
2005-01-01
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
Monte Carlo evaluation of hand and finger doses due to exposure to 18F in PET procedures
International Nuclear Information System (INIS)
Pessanha, Paula R.; Queiroz Filho, Pedro P.; Santos, Denison S.; Mauricio, Claudia L.P.
2011-01-01
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 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)
International Nuclear Information System (INIS)
Milian, F. M.; Attili, A.; Russo, G; Marchetto, F.; Cirio, R.; Bourhaleb, F.
2013-01-01
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)
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
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Quispe H, B.; Pena V, J. D.; Waldo B, G.; Leon M, M.; Ceron R, P.; Vallejo H, A.; Sosa A, M. [Universidad de Guanajuato, Campus Leon, Division de Ciencias e Ingenierias, Loma del Bosque 103, Lomas del Campestre, 37150 Leon, Guanajuato (Mexico); Vega C, H. R., E-mail: b.quispehuillcara@ugto.mx [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98060 Zacatecas, Zac. (Mexico)
2017-10-15
Computed tomography is a diagnostic imaging method that deposits higher doses than other radio diagnosis methods. The knowledge of the spectrum of X-rays is important, since is in direct function with the dose absorbed by the patient. In this work we estimated the spectrum of X-rays, produced during the interaction of monoenergetic electrons of 130 KeV with Tungsten white, in order to determine their energetic characteristics at 50 cm from the focal point. The study was done using Monte Carlo methods with the code MCNP5 where the X-ray tube of a Siemens SOMATOM Perspective tomograph of the General Regional Hospital of Leon, Mexico was modeled. In the calculations, 3 x 10{sup 8} stories were used and a relative uncertainty of less than 0.1% was obtained. Also, a neck manikin with thyroid, thorax and head that included the eye, the table and gantry with 70 cm opening of the tomography was modeled. The X-ray spectrum calculated with a cut thickness of 10 mm limited by Pb collimators was used as the source term. The radiological service routine scanning protocol was used for chest computed tomography; the step-by-step or instant trigger method was simulated by moving the manikin coordinates for each cut and 360 degree continuous rotation movement. 36 positions of the X-ray tube were used in steps of 10 degrees. The radiation dispersed in the thorax deposits a dose of 2.063 mGy in crystalline and 252 mGy in thyroid. (Author)
International Nuclear Information System (INIS)
Khan, A.A.; Tallentire, A.; Dwyer, J.
1977-01-01
Values of the γ-radiation resistance parameters (k and n of the 'multi-hit' expression) for Bacillus pumilus E601 spores and Serratia marcescens cells have been determined and the constancy of values for a given test condition demonstrated. These organisms, differing by a factor of about 50 in k value, have been included in a laboratory test system for use in verification of a model describing the dependence of the proportion of contaminated items in a population of items on radiation dose. The proportions of contaminated units of the test system at various γ-radiation doses have been measured for different initial numbers and types of organisms present in units either singly or together. Using the model, the probabilities of contaminated units for corresponding sets of conditions have been evaluated together with associated variances. Measured proportions and predicted probabilities agree well, showing that the model holds in a laboratory contrived situation. (author)
Chan, EuJin; Lydon, Jenny; Kron, Tomas
2015-03-07
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.
International Nuclear Information System (INIS)
Drexler, G.; Panzer, W.; Widenmann, L.; Williams, G.; Zankl, M.
1984-03-01
This report gives tables of conversion factors for the calculation of organ doses from technical parameters of typical radiographic techniques. These conversion factors were calculated using a male and a female mathematical human phantom and an efficient Monte Carlo programme that determines the mean organ doses from the energy deposited in each organ. Each diagnostic X-ray examination is studied using three X-ray spectra resulting from three different high tension values. The conversion factors per unit entrance air dose in free air are given for sixteen organs and for the entrance and exit surface skin doses. The tables are actually valid only for the given parameters such as phantom dimensions, source-to-skin distance, projection and X-ray quality. This, of course, gives rise to some uncertainty when dealing with the individual technique and patient. The uncertainty in organ dose of adult patients, however, should not be very large, if the calculation is based on a similar geometry, and before all, on the actually administered entrance air dose in the selected high tension range according to the patient parameters. (orig.)
International Nuclear Information System (INIS)
Jansen, J. T. M.; Shrimpton, P. C.; Zankl, M.
2009-01-01
This paper discusses the simulation of contemporary computed tomography (CT) scanners using Monte Carlo calculation methods to derive normalized organ doses, which enable hospital physicists to estimate typical organ and effective doses for CT examinations. The hardware used in a small PC-cluster at the Health Protection Agency (HPA) for these calculations is described. Investigations concerning optimization of software, including the radiation transport codes MCNP5 and MCNPX, and the Intel and PGI FORTRAN compilers, are presented in relation to results and calculation speed. Differences in approach for modelling the X-ray source are described and their influences are analysed. Comparisons with previously published calculations at HPA from the early 1990's proved satisfactory for the purposes of quality assurance and are presented in terms of organ dose ratios for whole body exposure and differences in organ location. Influences on normalized effective dose are discussed in relation to choice of cross section library, CT scanner technology (contemporary multi slice versus single slice), definition for effective dose (1990 and 2007 versions) and anthropomorphic phantom (mathematical and voxel). The results illustrate the practical need for the updated scanner-specific dose coefficients presently being calculated at HPA, in order to facilitate improved dosimetry for contemporary CT practice. (authors)
International Nuclear Information System (INIS)
Oliver, P; Thomson, R
2015-01-01
Purpose: To investigate how doses to cellular (microscopic) targets depend on cell morphology, and how cellular doses relate to doses to bulk tissues and water for 20 to 370 keV photon sources using Monte Carlo (MC) simulations. Methods: Simulation geometries involve cell clusters, single cells, and single nuclear cavities embedded in various healthy and cancerous bulk tissue phantoms. A variety of nucleus and cytoplasm elemental compositions are investigated. Cell and nucleus radii range from 5 to 10 microns and 2 to 9 microns, respectively. Doses to water and bulk tissue cavities are compared to nucleus and cytoplasm doses. Results: Variations in cell dose with simulation geometry are most pronounced for lower energy sources. Nuclear doses are sensitive to the surrounding geometry: the nuclear dose in a multicell model differs from the dose to a cavity of nuclear medium in an otherwise homogeneous bulk tissue phantom by more than 7% at 20 keV. Nuclear doses vary with cell size by up to 20% at 20 keV, with 10% differences persisting up to 90 keV. Bulk tissue and water cavity doses differ from cellular doses by up to 16%. MC results are compared to cavity theory predictions; large and small cavity theories qualitatively predict nuclear doses for energies below and above 50 keV, respectively. Burlin’s (1969) intermediate cavity theory best predicts MC results with an average discrepancy of 4%. Conclusion: Cellular doses vary as a function of source energy, subcellular compartment size, elemental composition, and tissue morphology. Neither water nor bulk tissue is an appropriate surrogate for subcellular targets in radiation dosimetry. The influence of microscopic inhomogeneities in the surrounding environment on the nuclear dose and the importance of the nucleus as a target for radiation-induced cell death emphasizes the potential importance of cellular dosimetry for understanding radiation effects. Funded by the Natural Sciences and Engineering Research Council
Rodrigues, Anna; Sawkey, Daren; Yin, Fang-Fang; Wu, Qiuwen
2015-05-01
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. 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(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 R100, R50, Rp, and Rp+ for standard and extended source-to-surface distances (SSD), as well as cone and cut-out output factors. 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. We have presented a Monte Carlo simulation framework for electron beam dose calculations for Varian TrueBeam Linacs. Electron beam energies of 6 to 20 MeV for open and collimated
International Nuclear Information System (INIS)
Zhao, J; Hu, W; Xing, Y; Wu, X; Li, Y
2016-01-01
Purpose: All plan verification systems for particle therapy are designed to do plan verification before treatment. However, the actual dose distributions during patient treatment are not known. This study develops an online 2D dose verification tool to check the daily dose delivery accuracy. Methods: A Siemens particle treatment system with a modulated scanning spot beam is used in our center. In order to do online dose verification, we made a program to reconstruct the delivered 2D dose distributions based on the daily treatment log files and depth dose distributions. In the log files we can get the focus size, position and particle number for each spot. A gamma analysis is used to compare the reconstructed dose distributions with the dose distributions from the TPS to assess the daily dose delivery accuracy. To verify the dose reconstruction algorithm, we compared the reconstructed dose distributions to dose distributions measured using PTW 729XDR ion chamber matrix for 13 real patient plans. Then we analyzed 100 treatment beams (58 carbon and 42 proton) for prostate, lung, ACC, NPC and chordoma patients. Results: For algorithm verification, the gamma passing rate was 97.95% for the 3%/3mm and 92.36% for the 2%/2mm criteria. For patient treatment analysis,the results were 97.7%±1.1% and 91.7%±2.5% for carbon and 89.9%±4.8% and 79.7%±7.7% for proton using 3%/3mm and 2%/2mm criteria, respectively. The reason for the lower passing rate for the proton beam is that the focus size deviations were larger than for the carbon beam. The average focus size deviations were −14.27% and −6.73% for proton and −5.26% and −0.93% for carbon in the x and y direction respectively. Conclusion: The verification software meets our requirements to check for daily dose delivery discrepancies. Such tools can enhance the current treatment plan and delivery verification processes and improve safety of clinical treatments.
Energy Technology Data Exchange (ETDEWEB)
Zhao, J; Hu, W [Fudan University Shanghai Cancer Center, Shanghai, Shanghai (China); Xing, Y [Fudan univercity shanghai proton and heavy ion center, Shanghai (China); Wu, X [Fudan university shanghai proton and heavy ion center, Shanghai, shagnhai (China); Li, Y [Department of Medical physics at Shanghai Proton and Heavy Ion Center, Shanghai, Shanghai (China)
2016-06-15
Purpose: All plan verification systems for particle therapy are designed to do plan verification before treatment. However, the actual dose distributions during patient treatment are not known. This study develops an online 2D dose verification tool to check the daily dose delivery accuracy. Methods: A Siemens particle treatment system with a modulated scanning spot beam is used in our center. In order to do online dose verification, we made a program to reconstruct the delivered 2D dose distributions based on the daily treatment log files and depth dose distributions. In the log files we can get the focus size, position and particle number for each spot. A gamma analysis is used to compare the reconstructed dose distributions with the dose distributions from the TPS to assess the daily dose delivery accuracy. To verify the dose reconstruction algorithm, we compared the reconstructed dose distributions to dose distributions measured using PTW 729XDR ion chamber matrix for 13 real patient plans. Then we analyzed 100 treatment beams (58 carbon and 42 proton) for prostate, lung, ACC, NPC and chordoma patients. Results: For algorithm verification, the gamma passing rate was 97.95% for the 3%/3mm and 92.36% for the 2%/2mm criteria. For patient treatment analysis,the results were 97.7%±1.1% and 91.7%±2.5% for carbon and 89.9%±4.8% and 79.7%±7.7% for proton using 3%/3mm and 2%/2mm criteria, respectively. The reason for the lower passing rate for the proton beam is that the focus size deviations were larger than for the carbon beam. The average focus size deviations were −14.27% and −6.73% for proton and −5.26% and −0.93% for carbon in the x and y direction respectively. Conclusion: The verification software meets our requirements to check for daily dose delivery discrepancies. Such tools can enhance the current treatment plan and delivery verification processes and improve safety of clinical treatments.
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.)
SU-E-T-286: Dose Verification of Spot-Scanning Proton Beam Using GafChromic EBT3 Film
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Chen, C; Tang, S; Mah, D [ProCure Proton Therapy Center, Somerset, NJ (United States); Chan, M [Memorial Sloan-Kettering Cancer Center, Basking Ridge, NJ (United States)
2015-06-15
Purpose: Dose verification of spot-scanning proton pencil beam is performed via planar dose measurements at several depths using an ionization-chamber array, requiring repeat irradiations of each field for each depth. Here we investigate film dosimetry which has two advantages: higher resolution and efficiency from one-shot irradiation for multiple depths. Methods: Film calibration was performed using an EBT3 film at 20-cm depth of Plastic Water (CIRS, Norfolk, VA) exposed by a 10-level step wedge on a Proteus Plus proton system (IBA, Belgium). The calibration doses ranged from 25–250 cGy(RBE) for proton energies of 170–200 MeV. A uniform 1000 cm{sup 3} dose cube and a clinical prostate combined with seminal-vesicle and pelvic-nodes plan were used for this study. All treatment plans were generated in the RayStation (RaySearch Lab, Sweden). The planar doses at different depths for both cases were measured with film using triple-channel dosimetry and the MatriXX PT (IBA Dosimetry, Germany). The Gamma passing rates, dose-difference maps, and profiles of 2D planar doses measured with EBT3 film and MatriXX, versus treatment planning system (TPS) calculations were analyzed and compared using the FilmQA Pro (Ashland Inc., Bridgewater, NJ). Results: The EBT3 film measurement results matched well with the TPS calculation data with an average passing rate >95% for 2%/2mm and are comparable with the MatriXX measurements (0.7%, 1.8%, 3.8% mean differences corresponding to 3%/3mm, 3%/2mm, 2%/2mm, respectively). Overall passing rates for EBT3 films appear higher than those with MatriXX detectors. Conclusion: The energy dependence of the film response could be minimized by calibration using proton beam with mixed energies. The greater efficiency of the dose verification using GafChromic EBT3 results in a potential cost trade-off between room capacity and film cost. EBT3 film may offer distinct advantages in highly intensity-modulated fields due to its higher resolution
International Nuclear Information System (INIS)
Asenso, Y.A.
2015-07-01
.55 % respectively. That of the physical and internal grid alignment yielded a maximum discrepancy of 2.67 ± 0.01 mm at position 6A on the template. The probe retraction test produced no discrepancies in the “clicks” and corresponding distances. Meanwhile the depth of penetration and axial and lateral resolution test at the time performing the tests were no available standard measurements for comparison. The dose verification test consisted of three tests, the calibration point test, the source strength verification and the TPS dose verification. The calibration point test indicated that distance for maximum ionization chamber sensitivity is 3cm, so seeds can be calibrated at this point. The source strength verification were within the tolerances recommended by ICRU report 38 (ICRU, 1985). The average source strength measured was 0.651450 U ± 0.001052 U deviating from the manufacturer value of 0.64989 U by 0.242 % ± 0. 164 %. The TPS dose verification test produced results with significant errors which occurred due to post irradiation development of film with time but the doses obtained by both TPS and film followed the same pattern. The outcome of the performance evaluations indicate that for patient work, the ultrasound system and prostate brachytherapy system can provide the mechanism for accurate positioning of the brachytherapy seeds facilitating reliable identification of the target volume for accurate effective treatment. (au)
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Nagao, Y. E-mail: nagao@jmtr.oarai.jaeri.go.jp; Nakamichi, K.; Tsuchiya, M.; Ishitsuka, E.; Kawamura, H
2000-11-01
To evaluate exactly the total amount of tritium production in tritium breeding materials during in-pile test with JMTR, the 'tritium monitor' has been produced and evaluation of total tritium generation was done by using 'tritium monitor' in preliminary in-pile mock-up, and verification of procedure concerning tritium production evaluation was conducted by using Monte Carlo code MCNP and nuclear cross section library of FSXLIBJ3R2. Li-Al alloy (Li 3.4 wt.%, 95.5% enrichment of {sup 6}Li) was selected as tritium monitor material for the evaluation on the total amount of tritium production in high {sup 6}Li enriched materials. From the results of preliminary experiment, calculated amounts of total tritium production at each 'tritium monitor', which was installed in the preliminary in-pile mock-up, were about 50-290% higher than the measured values. Concerning tritium measurement, increase of measurement error in tritium leak form measuring system to measure small amount of tritium (0.2-0.7 mCi in tritium monitor) was found in the results of present experiment. The tendency for overestimation of calculated thermal neutron flux in the range of 1-6x10{sup 13} n cm{sup -2} per s was found in JMTR and the reason may be due to the beryllium cross section data base in JENDL3.2.
International Nuclear Information System (INIS)
Nagao, Y.; Nakamichi, K.; Tsuchiya, M.; Ishitsuka, E.; Kawamura, H.
2000-01-01
To evaluate exactly the total amount of tritium production in tritium breeding materials during in-pile test with JMTR, the 'tritium monitor' has been produced and evaluation of total tritium generation was done by using 'tritium monitor' in preliminary in-pile mock-up, and verification of procedure concerning tritium production evaluation was conducted by using Monte Carlo code MCNP and nuclear cross section library of FSXLIBJ3R2. Li-Al alloy (Li 3.4 wt.%, 95.5% enrichment of 6 Li) was selected as tritium monitor material for the evaluation on the total amount of tritium production in high 6 Li enriched materials. From the results of preliminary experiment, calculated amounts of total tritium production at each 'tritium monitor', which was installed in the preliminary in-pile mock-up, were about 50-290% higher than the measured values. Concerning tritium measurement, increase of measurement error in tritium leak form measuring system to measure small amount of tritium (0.2-0.7 mCi in tritium monitor) was found in the results of present experiment. The tendency for overestimation of calculated thermal neutron flux in the range of 1-6x10 13 n cm -2 per s was found in JMTR and the reason may be due to the beryllium cross section data base in JENDL3.2
Energy Technology Data Exchange (ETDEWEB)
Qi Zhenyu; Deng Xiaowu; Cao Xinping; Huang Shaomin; Lerch, Michael; Rosenfeld, Anatoly [State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou 510060 (China) and Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia); State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou 510060 (China); Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia)
2012-11-15
Purpose: A real-time in vivo dosimetric verification method using metal-oxide-semiconductor field effect transistor (MOSFET) dosimeters has been developed for patient dosimetry in high-dose rate (HDR) intracavitary brachytherapy of nasopharyngeal carcinoma (NPC). Methods: The necessary calibration and correction factors for MOSFET measurements in {sup 192}Iridium source were determined in a water phantom. With the detector placed inside a custom-made nasopharyngeal applicator, the actual dose delivered to the tumor was measured in vivo and compared to the calculated values using a commercial brachytherapy planning system. Results: Five MOSFETs were independently calibrated with the HDR source, yielding calibration factors of 0.48 {+-} 0.007 cGy/mV. The maximum sensitivity variation was no more than 7% in the clinically relevant distance range of 1-5 cm from the source. A total of 70 in vivo measurements in 11 NPC patients demonstrated good agreement with the treatment planning. The mean differences between the planned and the actually delivered dose within a single treatment fraction were -0.1%{+-} 3.8% and -0.1%{+-} 3.7%, respectively, for right and left side assessments. The maximum dose deviation was less than 8.5%. Conclusions: In vivo measurement using the real-time MOSFET dosimetry system is possible to evaluate the actual dose to the tumor received by the patient during a treatment fraction and thus can offer another line of security to detect and prevent large errors.
Fix, Michael K; Cygler, Joanna; Frei, Daniel; Volken, Werner; Neuenschwander, Hans; Born, Ernst J; Manser, Peter
2013-05-07
The electron Monte Carlo (eMC) dose calculation algorithm available in the Eclipse treatment planning system (Varian Medical Systems) is based on the macro MC method and uses a beam model applicable to Varian linear accelerators. This leads to limitations in accuracy if eMC is applied to non-Varian machines. In this work eMC is generalized to also allow accurate dose calculations for electron beams from Elekta and Siemens accelerators. First, changes made in the previous study to use eMC for low electron beam energies of Varian accelerators are applied. Then, a generalized beam model is developed using a main electron source and a main photon source representing electrons and photons from the scattering foil, respectively, an edge source of electrons, a transmission source of photons and a line source of electrons and photons representing the particles from the scrapers or inserts and head scatter radiation. Regarding the macro MC dose calculation algorithm, the transport code of the secondary particles is improved. The macro MC dose calculations are validated with corresponding dose calculations using EGSnrc in homogeneous and inhomogeneous phantoms. The validation of the generalized eMC is carried out by comparing calculated and measured dose distributions in water for Varian, Elekta and Siemens machines for a variety of beam energies, applicator sizes and SSDs. The comparisons are performed in units of cGy per MU. Overall, a general agreement between calculated and measured dose distributions for all machine types and all combinations of parameters investigated is found to be within 2% or 2 mm. The results of the dose comparisons suggest that the generalized eMC is now suitable to calculate dose distributions for Varian, Elekta and Siemens linear accelerators with sufficient accuracy in the range of the investigated combinations of beam energies, applicator sizes and SSDs.
Kang, Sei-Kwon; Yoon, Jai-Woong; Hwang, Taejin; Park, Soah; Cheong, Kwang-Ho; Han, Tae Jin; Kim, Haeyoung; Lee, Me-Yeon; Kim, Kyoung Ju; Bae, Hoonsik
2015-01-01
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. Copyright © 2015 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.
Directory of Open Access Journals (Sweden)
Firoozabadi M. M.
2017-03-01
Full Text Available Background: In neutron interaction with matter and reduction of neutron energy due to multiple scatterings to the thermal energy range, increasing the probability of thermal neutron capture by neutron captures makes dose enhancement in the tumors loaded with these materials. Objective: The purpose of this study is to evaluate dose distribution in the presence of 10B, 157Gd and 33S neutron capturers and to determine the effect of these materials on dose enhancement rate for 252Cf brachytherapy source. Methods: Neutron-ray flux and energy spectra, neutron and gamma dose rates and dose enhancement factor (DEF are determined in the absence and presence of 10B, 157Gd and 33S using Monte Carlo simulation. Results: The difference in the thermal neutron flux rate in the presence of 10B and 157Gd is significant, while the flux changes in the fast and epithermal energy ranges are insensible. The dose enhancement factor has increased with increasing distance from the source and reached its maximum amount equal to 258.3 and 476.1 cGy/h/µg for 157Gd and 10B, respectively at about 8 cm distance from the source center. DEF for 33S is equal to one. Conclusion: Results show that the magnitude of dose augmentation in tumors containing 10B and 157Gd in brachytherapy with 252Cf source will depend not only on the capture product dose level, but also on the tumor distance from the source. 33S makes dose enhancement under specific conditions that these conditions depend on the neutron energy spectra of source, the 33S concentration in tumor and tumor distance from the source.
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.
International Nuclear Information System (INIS)
Young-khi, Lim; Byoung-il, Lee; Jeong-in, Kim
2008-01-01
Full text: In the field of medical diagnosis or treatments using radiations, lead vests or aprons are widely used to protect the patients or workers from unwanted irradiation. Also, in nuclear power plants, it is recommended that the workers should wear a lead vest to reduce the dose for working in high radiation area. Generally, personal dosimeters were used to estimate the doses of workers but these cannot give the absolute values. So, measured values should be modified by comparing the reference conditions with conversion factors. Many trials to estimate the doses of workers with lead shield using two or more dosimeters at different locations were done but these had limitations. Through this study the personal dose with/without a lead vest and the effectiveness were evaluated by Monte Carlo methods. A lead vest which had been used at several nuclear sites was modelled with MIRD-V and typical Korean voxel phantom using MCNP-5 transport code. Organ doses were calculated in AP, PA, RLAT, LLAT irradiation geometry for several parallel photon beams. Also irradiation experiments were carried out using real typical Korean phantom with the lead vest and the results were compared with those calculated by simulations. In most cases, the lead vest decreases the organ doses about 30%. For low energy, the lead vest is very effective to reduce the dose but it is not so good for high energy photon shielding. For thyroids, the doses to high energy photons increased by 5% on the contrary. This study may be applied to the better design of personal shielding and dose estimation procedures for practical use. (author)
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Faught, A [UT MD Anderson Cancer Center, Houston, TX (United States); University of Texas Health Science Center Houston, Graduate School of Biomedical Sciences, Houston, TX (United States); Davidson, S [University of Texas Medical Branch of Galveston, Galveston, TX (United States); Kry, S; Ibbott, G; Followill, D [UT MD Anderson Cancer Center, Houston, TX (United States); Fontenot, J [Mary Bird Perkins Cancer Center, Baton Rouge, LA (United States); Etzel, C [Consortium of Rheumatology Researchers of North America (CORRONA), Inc., Southborough, MA (United States)
2014-06-01
Purpose: To develop a comprehensive end-to-end test for Varian's TrueBeam linear accelerator for head and neck IMRT using a custom phantom designed to utilize multiple dosimetry devices. Purpose: To commission a multiple-source Monte Carlo model of Elekta linear accelerator beams of nominal energies 6MV and 10MV. Methods: A three source, Monte Carlo model of Elekta 6 and 10MV therapeutic x-ray beams was developed. Energy spectra of two photon sources corresponding to primary photons created in the target and scattered photons originating in the linear accelerator head were determined by an optimization process that fit the relative fluence of 0.25 MeV energy bins to the product of Fatigue-Life and Fermi functions to match calculated percent depth dose (PDD) data with that measured in a water tank for a 10x10cm2 field. Off-axis effects were modeled by a 3rd degree polynomial used to describe the off-axis half-value layer as a function of off-axis angle and fitting the off-axis fluence to a piecewise linear function to match calculated dose profiles with measured dose profiles for a 40×40cm2 field. The model was validated by comparing calculated PDDs and dose profiles for field sizes ranging from 3×3cm2 to 30×30cm2 to those obtained from measurements. A benchmarking study compared calculated data to measurements for IMRT plans delivered to anthropomorphic phantoms. Results: Along the central axis of the beam 99.6% and 99.7% of all data passed the 2%/2mm gamma criterion for 6 and 10MV models, respectively. Dose profiles at depths of dmax, through 25cm agreed with measured data for 99.4% and 99.6% of data tested for 6 and 10MV models, respectively. A comparison of calculated dose to film measurement in a head and neck phantom showed an average of 85.3% and 90.5% of pixels passing a 3%/2mm gamma criterion for 6 and 10MV models respectively. Conclusion: A Monte Carlo multiple-source model for Elekta 6 and 10MV therapeutic x-ray beams has been developed as a
Monte Carlo simulations of the dose from imaging with GE eXplore 120 micro-CT using GATE
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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
A method for online verification of adapted fields using an independent dose monitor
International Nuclear Information System (INIS)
Chang Jina; Norrlinger, Bernhard D.; Heaton, Robert K.; Jaffray, David A.; Cho, Young-Bin; Islam, Mohammad K.; Mahon, Robert
2013-01-01
Purpose: Clinical implementation of online adaptive radiotherapy requires generation of modified fields and a method of dosimetric verification in a short time. We present a method of treatment field modification to account for patient setup error, and an online method of verification using an independent monitoring system.Methods: The fields are modified by translating each multileaf collimator (MLC) defined aperture in the direction of the patient setup error, and magnifying to account for distance variation to the marked isocentre. A modified version of a previously reported online beam monitoring system, the integral quality monitoring (IQM) system, was investigated for validation of adapted fields. The system consists of a large area ion-chamber with a spatial gradient in electrode separation to provide a spatially sensitive signal for each beam segment, mounted below the MLC, and a calculation algorithm to predict the signal. IMRT plans of ten prostate patients have been modified in response to six randomly chosen setup errors in three orthogonal directions.Results: A total of approximately 49 beams for the modified fields were verified by the IQM system, of which 97% of measured IQM signal agree with the predicted value to within 2%.Conclusions: The modified IQM system was found to be suitable for online verification of adapted treatment fields
International Nuclear Information System (INIS)
Silva, Aneli Oliveira da
2010-01-01
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 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 indicate
Yung, Lai Chin; Fei, Cheong Choke; Mandeep, Jit Singh; Amin, Nowshad; Lai, Khin Wee
2015-11-01
The leadframe fabrication process normally involves additional thin-metal layer plating on the bulk copper substrate surface for wire bonding purposes. Silver, tin, and copper flakes are commonly adopted as plating materials. It is critical to assess the density of the plated metal layer, and in particular to look for porosity or voids underneath the layer, which may reduce the reliability during high-temperature stress. A fast, reliable inspection technique is needed to assess the porosity or void weakness. To this end, the characteristics of x-rays generated from bulk samples were examined using an energy-dispersive x-ray (EDX) detector to examine the porosity percentage. Monte Carlo modeling was integrated with Castaing's formula to verify the integrity of the experimental data. Samples with different porosity percentages were considered to test the correlation between the intensity of the collected x-ray signal and the material density. To further verify the integrity of the model, conventional cross-sectional samples were also taken to observe the porosity percentage using Image J software measurement. A breakthrough in bulk substrate assessment was achieved by applying EDX for the first time to nonelemental analysis. The experimental data showed that the EDX features were not only useful for elemental analysis, but also applicable to thin-film metal layer thickness measurement and bulk material density determination. A detailed experiment was conducted using EDX to assess the plating metal layer and bulk material porosity.
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Oborn, B. M., E-mail: brad.oborn@gmail.com [Illawarra Cancer Care Centre (ICCC), Wollongong, NSW 2500, Australia and Centre for Medical Radiation Physics (CMRP), University of Wollongong, Wollongong, NSW 2500 (Australia); Ge, Y. [Sydney Medical School, University of Sydney, NSW 2006 (Australia); Hardcastle, N. [Northern Sydney Cancer Centre, Royal North Shore Hospital, Sydney, NSW 2065 (Australia); Metcalfe, P. E. [Centre for Medical Radiation Physics (CMRP), University of Wollongong, Wollongong NSW 2500, Australia and Ingham Institute for Applied Medical Research, Liverpool, NSW 2170 (Australia); Keall, P. J. [Sydney Medical School, University of Sydney, NSW 2006, Australia and Ingham Institute for Applied Medical Research, Liverpool, NSW 2170 (Australia)
2016-01-15
Purpose: To report on significant dose enhancement effects caused by magnetic fields aligned parallel to 6 MV photon beam radiotherapy of small lung tumors. Findings are applicable to future inline MRI-guided radiotherapy systems. Methods: A total of eight clinical lung tumor cases were recalculated using Monte Carlo methods, and external magnetic fields of 0.5, 1.0, and 3 T were included to observe the impact on dose to the planning target volume (PTV) and gross tumor volume (GTV). Three plans were 6 MV 3D-CRT plans while 6 were 6 MV IMRT. The GTV’s ranged from 0.8 to 16 cm{sup 3}, while the PTV’s ranged from 1 to 59 cm{sup 3}. In addition, the dose changes in a 30 cm diameter cylindrical water phantom were investigated for small beams. The central 20 cm of this phantom contained either water or lung density insert. Results: For single beams, an inline magnetic field of 1 T has a small impact in lung dose distributions by reducing the lateral scatter of secondary electrons, resulting in a small dose increase along the beam. Superposition of multiple small beams leads to significant dose enhancements. Clinically, this process occurs in the lung tissue typically surrounding the GTV, resulting in increases to the D{sub 98%} (PTV). Two isolated tumors with very small PTVs (3 and 6 cm{sup 3}) showed increases in D{sub 98%} of 23% and 22%. Larger PTVs of 13, 26, and 59 cm{sup 3} had increases of 9%, 6%, and 4%, describing a natural fall-off in enhancement with increasing PTV size. However, three PTVs bounded to the lung wall showed no significant increase, due to lack of dose enhancement in the denser PTV volume. In general, at 0.5 T, the GTV mean dose enhancement is around 60% lower than that at 1 T, while at 3 T, it is 5%–60% higher than 1 T. Conclusions: Monte Carlo methods have described significant and predictable dose enhancement effects in small lung tumor plans for 6 MV radiotherapy when an external inline magnetic field is included. Results of this study
Ishizawa, Yoshiki; Dobashi, Suguru; Kadoya, Noriyuki; Ito, Kengo; Chiba, Takahito; Takayama, Yoshiki; Sato, Kiyokazu; Takeda, Ken
2018-05-17
An accurate source model of a medical linear accelerator is essential for Monte Carlo (MC) dose calculations. This study aims to propose an analytical photon source model based on particle transport in parameterized accelerator structures, focusing on a more realistic determination of linac photon spectra compared to existing approaches. We designed the primary and secondary photon sources based on the photons attenuated and scattered by a parameterized flattening filter. The primary photons were derived by attenuating bremsstrahlung photons based on the path length in the filter. Conversely, the secondary photons were derived from the decrement of the primary photons in the attenuation process. This design facilitates these sources to share the free parameters of the filter shape and be related to each other through the photon interaction in the filter. We introduced two other parameters of the primary photon source to describe the particle fluence in penumbral regions. All the parameters are optimized based on calculated dose curves in water using the pencil-beam-based algorithm. To verify the modeling accuracy, we compared the proposed model with the phase space data (PSD) of the Varian TrueBeam 6 and 15 MV accelerators in terms of the beam characteristics and the dose distributions. The EGS5 Monte Carlo code was used to calculate the dose distributions associated with the optimized model and reference PSD in a homogeneous water phantom and a heterogeneous lung phantom. We calculated the percentage of points passing 1D and 2D gamma analysis with 1%/1 mm criteria for the dose curves and lateral dose distributions, respectively. The optimized model accurately reproduced the spectral curves of the reference PSD both on- and off-axis. The depth dose and lateral dose profiles of the optimized model also showed good agreement with those of the reference PSD. The passing rates of the 1D gamma analysis with 1%/1 mm criteria between the model and PSD were 100% for 4
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Del Nero, Renata Aline; Yoriyaz, Hélio [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Nakandakari, Marcos Vinicius Nakaoka, E-mail: hyoriyaz@ipen.br, E-mail: marcos.sake@gmail.com [Hospital Beneficência Portuguesa de São Paulo, SP (Brazil)
2017-07-01
The Monte Carlo method for radiation transport data has been adapted for medical physics application. More specifically, it has received more attention in clinical treatment planning with the development of more efficient computer simulation techniques. In linear accelerator modeling by the Monte Carlo method, the phase space data file (phsp) is used a lot. However, to obtain precision in the results, it is necessary detailed information about the accelerator's head and commonly the supplier does not provide all the necessary data. An alternative to the phsp is the Virtual Source Model (VSM). This alternative approach presents many advantages for the clinical Monte Carlo application. This is the most efficient method for particle generation and can provide an accuracy similar when the phsp is used. This research propose a VSM simulation with the use of a Virtual Flattening Filter (VFF) for profiles and percent deep doses calculation. Two different sizes of open fields (40 x 40 cm² and 40√2 x 40√2 cm²) were used and two different source to surface distance (SSD) were applied: the standard 100 cm and custom SSD of 370 cm, which is applied in radiotherapy treatments of total body irradiation. The data generated by the simulation was analyzed and compared with experimental data to validate the VSM. This current model is easy to build and test. (author)
Anderson, Danielle; Siegbahn, E. Albert; Fallone, B. Gino; Serduc, Raphael; Warkentin, Brad
2012-05-01
This work evaluates four dose-volume metrics applied to microbeam radiation therapy (MRT) using simulated dosimetric data as input. We seek to improve upon the most frequently used MRT metric, the peak-to-valley dose ratio (PVDR), by analyzing MRT dose distributions from a more volumetric perspective. Monte Carlo simulations were used to calculate dose distributions in three cubic head phantoms: a 2 cm mouse head, an 8 cm cat head and a 16 cm dog head. The dose distribution was calculated for a 4 × 4 mm2 microbeam array in each phantom, as well as a 16 × 16 mm2 array in the 8 cm cat head, and a 32 × 32 mm2 array in the 16 cm dog head. Microbeam widths of 25, 50 and 75 µm and center-to-center spacings of 100, 200 and 400 µm were considered. The metrics calculated for each simulation were the conventional PVDR, the peak-to-mean valley dose ratio (PMVDR), the mean dose and the percentage volume below a threshold dose. The PVDR ranged between 3 and 230 for the 2 cm mouse phantom, and between 2 and 186 for the 16 cm dog phantom depending on geometry. The corresponding ranges for the PMVDR were much smaller, being 2-49 (mouse) and 2-46 (dog), and showed a slightly weaker dependence on phantom size and array size. The ratio of the PMVDR to the PVDR varied from 0.21 to 0.79 for the different collimation configurations, indicating a difference between the geometric dependence on outcome that would be predicted by these two metrics. For unidirectional irradiation, the mean lesion dose was 102%, 79% and 42% of the mean skin dose for the 2 cm mouse, 8 cm cat and 16 cm dog head phantoms, respectively. However, the mean lesion dose recovered to 83% of the mean skin dose in the 16 cm dog phantom in intersecting cross-firing regions. The percentage volume below a 10% dose threshold was highly dependent on geometry, with ranges for the different collimation configurations of 2-87% and 33-96% for the 2 cm mouse and 16 cm dog heads, respectively. The results of this study
International Nuclear Information System (INIS)
Anderson, Danielle; Fallone, B Gino; Warkentin, Brad; Siegbahn, E Albert; Serduc, Raphael
2012-01-01
This work evaluates four dose-volume metrics applied to microbeam radiation therapy (MRT) using simulated dosimetric data as input. We seek to improve upon the most frequently used MRT metric, the peak-