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Kuhlmann ML, Pojtinger S. Implementation of a new EGSnrc particle source class for computed tomography: validation and uncertainty quantification. Phys Med Biol 2024; 69:095021. [PMID: 38537305 DOI: 10.1088/1361-6560/ad3886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 03/26/2024] [Indexed: 04/25/2024]
Abstract
Objective. Personalized dose monitoring and risk management are of increasing significance with the growing number of computer tomography (CT) examinations. These require high-quality Monte Carlo (MC) simulations that are of the utmost importance for the new developments in personalized CT dosimetry. This work aims to extend the MC framework EGSnrc source code with a new particle source. This, in turn, allows CT-scanner-specific dose and image calculations for any CT scanner. The novel method can be used with all modern EGSnrc user codes, particularly for the simulation of the effective dose based on DICOM images and the calculation of CT images.Approach. The new particle source can be used with input data derived by the user. The input data can be generated by the user based on a previously developed method for the experimental characterization of any CT scanner (doi.org/10.1016/j.ejmp.2015.09.006). Furthermore, the new particle source was benchmarked by air kerma measurements in an ionization chamber at a clinical CT scanner. For this, the simulated angular distribution and attenuation characteristics were compared to measurements to verify the source output free in air. In a second validation step, simulations of air kerma in a homogenous cylindrical and an anthropomorphic thorax phantom were performed and validated against experimentally determined results. A detailed uncertainty evaluation of the simulated air kerma values was developed.Main results. We successfully implemented a new particle source class for the simulation of realistic CT scans. This method can be adapted to any CT scanner. For the attenuation characteristics, there was a maximal deviation of 6.86% between the measurement and the simulation. The mean deviation for all tube voltages was 2.36% (σ= 1.6%). For the phantom measurements and simulations, all the values agreed within 5.0%. The uncertainty evaluation resulted in an uncertainty of 5.5% (k=1).
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Affiliation(s)
- Marie-Luise Kuhlmann
- Dosimetry for Radiation Therapy and Diagnostic Radiology, Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, D-38116, Germany
- Technische Universität Dortmund, Dortmund, D-44227, Germany
| | - Stefan Pojtinger
- Dosimetry for Radiation Therapy and Diagnostic Radiology, Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, D-38116, Germany
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Jansen JT, Shrimpton PC, Edyvean S. CT scanner-specific organ dose coefficients generated by Monte Carlo calculation for the ICRP adult male and female reference computational phantoms. Phys Med Biol 2022; 67. [PMID: 36317285 DOI: 10.1088/1361-6560/ac9e3d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 10/27/2022] [Indexed: 11/17/2022]
Abstract
Objective.Provide analyses of new organ dose coefficients (hereafter also referred to as normalized doses) for CT that have been developed to update the widely-utilized collection of data published 30 years ago in NRPB-SR250.Approach.In order to reflect changes in technology, and also ICRP recommendations concerning use of the computational phantoms adult male (AM) and adult female (AF), 102 series of new Monte Carlo simulations have been performed covering the range of operating conditions for 12 contemporary models of CT scanner from 4 manufacturers. Normalized doses (relative to free air on axis) have been determined for 39 organs, and for every 8 mm or 4.84 mm slab of AM and AF, respectively.Main results.Analyses of results confirm the significant influence (by up to a few tens of percent), on values of normalized organ (or contributions to effective dose (E103,phan)), for whole body exposure arising from selection of tube voltage and beam shaping filter. Use of partial (when available) rather than a Full fan beam reduced both organ and effective dose by up to 7%. Normalized doses to AF were larger than corresponding figures for AM by up to 30% for organs and by 10% forE103,phan. Additional simulations for whole body exposure have also demonstrated that: practical simplifications in the main modelling (point source, single slice thickness, neglect of patient couch and immobility of phantom arms) have sufficiently small (<5%) effect onE103,phan; mis-centring of the phantom away from the axis of rotation by 5 mm (in any direction) leads to changes in normalized organ dose andE103,phanby up to 20% and 6%, respectively; and angular tube current modulation can result in reductions by up to 35% and <15% in normalized organ dose andE103,phan, respectively, for 100% cosine variation.Significance.These analyses help advance understanding of the influence of operational scanner settings on organ dose coefficients for contemporary CT, in support of improved patient protection. The results will allow the future development of a new dose estimation tool.
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Affiliation(s)
- Jan Tm Jansen
- Radiation, Chemical and Environmental Hazards, United Kingdom Health Security Agency, Chilton, Didcot, Oxfordshire, OX11 0RQ, United Kingdom
| | - Paul C Shrimpton
- Radiation, Chemical and Environmental Hazards, United Kingdom Health Security Agency, Chilton, Didcot, Oxfordshire, OX11 0RQ, United Kingdom.,Retired, United Kingdom
| | - Sue Edyvean
- Radiation, Chemical and Environmental Hazards, United Kingdom Health Security Agency, Chilton, Didcot, Oxfordshire, OX11 0RQ, United Kingdom
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Boschini A, Riccardi L, Monte FD, Zandonà R, Paiusco M. [OA213] Implementation and in-phantom testing of a free Monte Carlo software for CT dose calculation. Phys Med 2018. [DOI: 10.1016/j.ejmp.2018.06.285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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Hassan AI, Skalej M, Schlattl H, Hoeschen C. Determination and verification of the x-ray spectrum of a CT scanner. J Med Imaging (Bellingham) 2018; 5:013506. [PMID: 29430476 DOI: 10.1117/1.jmi.5.1.013506] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 01/10/2018] [Indexed: 11/14/2022] Open
Abstract
The accuracy of Monte Carlo (MC) simulations in estimating the computed tomography radiation dose is highly dependent on the proprietary x-ray source information. To address this, this study develops a method to precisely estimate the x-ray spectrum and bowtie (BT) filter thickness of the x-ray source based on physical measurements and calculations. The static x-ray source of the CT localizer radiograph was assessed to measure the total filtration at the isocenter for the x-ray spectrum characterization and the BT profile (air-kerma values as a function of fan angle). With these values, the utilized BT filter in the localizer radiograph was assessed by integrating the measured air kerma in a full 360-deg cycle. The consistency observed between the integrated BT filter profiles and the directly measured profiles pointed to the similarity in the utilized BT filter in terms of thickness and material between the static and rotating x-ray geometries. Subsequently, the measured air kerma was used to calculate the BT filter thickness and was verified using MC simulations by comparing the calculated and measured air-kerma values, where a very good agreement was observed. This would allow a more accurate computed tomography simulation and facilitate the estimation of the dose delivered to the patients.
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Affiliation(s)
- Ahmad Ibrahim Hassan
- Otto von Guericke Universität Magdeburg, Universitätsklinikum Magdeburg A.ö.R., Institut für Neuroradiologie, Magdeburg, Deutschland, Germany.,Otto von Guericke Universität, Institut für Medizintechnik, Fakultät für Elektrotechnik und Informationstechnik Universitätsplatz, Magdeburg, Deutschland, Germany
| | - Martin Skalej
- Otto von Guericke Universität Magdeburg, Universitätsklinikum Magdeburg A.ö.R., Institut für Neuroradiologie, Magdeburg, Deutschland, Germany
| | - Helmut Schlattl
- Institute of Radiation Protection, Helmholtz Zentrum München-German Research Center for Environmental Health, Neuherberg, Deutschland, Germany
| | - Christoph Hoeschen
- Otto von Guericke Universität, Institut für Medizintechnik, Fakultät für Elektrotechnik und Informationstechnik Universitätsplatz, Magdeburg, Deutschland, Germany
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Bohrer E, Schäfer S, Mäder U, Noël PB, Krombach GA, Fiebich M. Optimizing radiation exposure for CT localizer radiographs. Z Med Phys 2017; 27:145-158. [DOI: 10.1016/j.zemedi.2016.09.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 09/16/2016] [Accepted: 09/16/2016] [Indexed: 10/20/2022]
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Neubauer J, Benndorf M, Reidelbach C, Krauß T, Lampert F, Zajonc H, Kotter E, Langer M, Fiebich M, Goerke SM. Comparison of Diagnostic Accuracy of Radiation Dose-Equivalent Radiography, Multidetector Computed Tomography and Cone Beam Computed Tomography for Fractures of Adult Cadaveric Wrists. PLoS One 2016; 11:e0164859. [PMID: 27788215 PMCID: PMC5082876 DOI: 10.1371/journal.pone.0164859] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 10/03/2016] [Indexed: 11/18/2022] Open
Abstract
PURPOSE To compare the diagnostic accuracy of radiography, to radiography equivalent dose multidetector computed tomography (RED-MDCT) and to radiography equivalent dose cone beam computed tomography (RED-CBCT) for wrist fractures. METHODS As study subjects we obtained 10 cadaveric human hands from body donors. Distal radius, distal ulna and carpal bones (n = 100) were artificially fractured in random order in a controlled experimental setting. We performed radiation dose equivalent radiography (settings as in standard clinical care), RED-MDCT in a 320 row MDCT with single shot mode and RED-CBCT in a device dedicated to musculoskeletal imaging. Three raters independently evaluated the resulting images for fractures and the level of confidence for each finding. Gold standard was evaluated by consensus reading of a high-dose MDCT. RESULTS Pooled sensitivity was higher in RED-MDCT with 0.89 and RED-MDCT with 0.81 compared to radiography with 0.54 (P = < .004). No significant differences were detected concerning the modalities' specificities (with values between P = .98). Raters' confidence was higher in RED-MDCT and RED-CBCT compared to radiography (P < .001). CONCLUSION The diagnostic accuracy of RED-MDCT and RED-CBCT for wrist fractures proved to be similar and in some parts even higher compared to radiography. Readers are more confident in their reporting with the cross sectional modalities. Dose equivalent cross sectional computed tomography of the wrist could replace plain radiography for fracture diagnosis in the long run.
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Affiliation(s)
- Jakob Neubauer
- Department of Radiology, University Medical Center Freiburg, Freiburg, Germany
- * E-mail:
| | - Matthias Benndorf
- Department of Radiology, University Medical Center Freiburg, Freiburg, Germany
| | - Carolin Reidelbach
- Department of Radiology, University Medical Center Freiburg, Freiburg, Germany
| | - Tobias Krauß
- Department of Radiology, University Medical Center Freiburg, Freiburg, Germany
| | - Florian Lampert
- Department of Plastic and Hand Surgery, University Medical Center Freiburg, Freiburg, Germany
| | - Horst Zajonc
- Department of Plastic and Hand Surgery, University Medical Center Freiburg, Freiburg, Germany
| | - Elmar Kotter
- Department of Radiology, University Medical Center Freiburg, Freiburg, Germany
| | - Mathias Langer
- Department of Radiology, University Medical Center Freiburg, Freiburg, Germany
| | - Martin Fiebich
- Department of Medical Physics and Radiation Protection, University of Applied Sciences Gießen, Gießen, Germany
| | - Sebastian M. Goerke
- Department of Radiology, Ortenau Klinikum Offenburg-Gengenbach, Offenburg, Germany
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Sechopoulos I, Ali ESM, Badal A, Badano A, Boone JM, Kyprianou IS, Mainegra-Hing E, McMillan KL, McNitt-Gray MF, Rogers DWO, Samei E, Turner AC. Monte Carlo reference data sets for imaging research: Executive summary of the report of AAPM Research Committee Task Group 195. Med Phys 2016; 42:5679-91. [PMID: 26429242 DOI: 10.1118/1.4928676] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The use of Monte Carlo simulations in diagnostic medical imaging research is widespread due to its flexibility and ability to estimate quantities that are challenging to measure empirically. However, any new Monte Carlo simulation code needs to be validated before it can be used reliably. The type and degree of validation required depends on the goals of the research project, but, typically, such validation involves either comparison of simulation results to physical measurements or to previously published results obtained with established Monte Carlo codes. The former is complicated due to nuances of experimental conditions and uncertainty, while the latter is challenging due to typical graphical presentation and lack of simulation details in previous publications. In addition, entering the field of Monte Carlo simulations in general involves a steep learning curve. It is not a simple task to learn how to program and interpret a Monte Carlo simulation, even when using one of the publicly available code packages. This Task Group report provides a common reference for benchmarking Monte Carlo simulations across a range of Monte Carlo codes and simulation scenarios. In the report, all simulation conditions are provided for six different Monte Carlo simulation cases that involve common x-ray based imaging research areas. The results obtained for the six cases using four publicly available Monte Carlo software packages are included in tabular form. In addition to a full description of all simulation conditions and results, a discussion and comparison of results among the Monte Carlo packages and the lessons learned during the compilation of these results are included. This abridged version of the report includes only an introductory description of the six cases and a brief example of the results of one of the cases. This work provides an investigator the necessary information to benchmark his/her Monte Carlo simulation software against the reference cases included here before performing his/her own novel research. In addition, an investigator entering the field of Monte Carlo simulations can use these descriptions and results as a self-teaching tool to ensure that he/she is able to perform a specific simulation correctly. Finally, educators can assign these cases as learning projects as part of course objectives or training programs.
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Affiliation(s)
- Ioannis Sechopoulos
- Department of Radiology and Imaging Sciences, Emory University, Atlanta, Georgia 30322
| | - Elsayed S M Ali
- Carleton Laboratory for Radiotherapy Physics, Department of Physics, Carleton University, Ottawa, Ontario K1S 5B6, Canada
| | - Andreu Badal
- Food and Drug Administration, Silver Spring, Maryland 20993-0002
| | - Aldo Badano
- Food and Drug Administration, Silver Spring, Maryland 20993-0002
| | - John M Boone
- Departments of Radiology and Biomedical Engineering, University of California, Davis, California 95817
| | | | | | - Kyle L McMillan
- Department of Biomedical Physics and Department of Radiology, University of California, Los Angeles, California 90024
| | - Michael F McNitt-Gray
- Department of Biomedical Physics and Department of Radiology, University of California, Los Angeles, California 90024
| | - D W O Rogers
- Carleton Laboratory for Radiotherapy Physics, Department of Physics, Carleton University, Ottawa, Ontario K1A 0R6, Canada
| | - Ehsan Samei
- Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University, Durham, North Carolina 27705
| | - Adam C Turner
- Department of Biomedical Physics and Department of Radiology, University of California, Los Angeles, California 90024
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