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Antunes PCG, Siqueira PDTD, Shorto JBM, Yoriyaz H. A versatile physical phantom design and construction for I-125 dose measurements and dose-to-medium determination. Brachytherapy 2023; 22:80-92. [PMID: 36396567 DOI: 10.1016/j.brachy.2022.10.005] [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: 06/29/2022] [Revised: 09/15/2022] [Accepted: 10/09/2022] [Indexed: 11/16/2022]
Abstract
PURPOSE In this paper we present a phantom designed to provide conditions to generate set of "true" independent reference data as requested by TG-186, and mitigating the scarcity of experimental studies on brachytherapy validation. It was used to perform accurate experimental measurements of dose of 125I brachytherapy seeds using LiF dosimeters, with the objective of experimentally validating Monte Carlo (MC) calculations with model-based dose calculation algorithm (MBDCA). In addition, this work intends to evaluate a methodology to convert the experimental values from LiF into dose in the medium. METHODS AND MATERIALS The proposed PMMA physical phantom features cavities to insert a LiF dosimeter and a 125I seed, adjusted in different configurations with variable thickness. Monte Carlo calculations performed with MCNP6.2 code were used to score the absorbed dose in the LiF and the dose conversion parameters. A sensitivity analysis was done to verify the source of possible uncertainties and quantify their impact on the results. RESULTS The proposed phantom and experimental procedure developed in this work provided precise dose data within 5.68% uncertainty (k = 1). The achieved precision made it possible to convert the LiF responses into absorbed dose to medium and to validate the dose conversion factor methodology. CONCLUSIONS The proposed phantom is simple both in design and as in its composition, thus achieving the demanded precision in dose evaluations due to its easy reproducibility of experimental setup. The results derived from the phantom measurements support the dose conversion methodology. The phantom and the experimental procedure developed here can be applied for other materials and radiation sources.
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Affiliation(s)
| | | | | | - Hélio Yoriyaz
- Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP, São Paulo, Brazil
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Shaikh MY, Tanny S. Dosimetric comparison of the INTRABEAM and Axxent for intraoperative breast radiotherapy. Brachytherapy 2020; 19:234-240. [DOI: 10.1016/j.brachy.2019.11.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 11/18/2019] [Accepted: 11/19/2019] [Indexed: 01/28/2023]
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Badali DS, Plateau GR, Ellenor CW, Ku CY, Vatahov P, Esterline J, Wilfley BP, Mitchell CR, Fishman K, Funk T. Characterization of an x-ray source with a partitioned diamond-tungsten target for electronic brachytherapy with 3D beam directionality. ACTA ACUST UNITED AC 2019; 64:245007. [DOI: 10.1088/1361-6560/ab5130] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Devic S, Liang L, Tomic N, Bekerat H, Morcos M, Popovic M, Watson P, Aldelaijan S, Seuntjens J. Dose measurements nearby low energy electronic brachytherapy sources using radiochromic film. Phys Med 2019; 64:40-44. [DOI: 10.1016/j.ejmp.2019.05.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 05/24/2019] [Accepted: 05/25/2019] [Indexed: 11/25/2022] Open
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Martin E, Sowards K, Wang B. Investigation of a source model for a new electronic brachytherapy tandem by film measurement. J Appl Clin Med Phys 2018; 19:640-650. [PMID: 30105891 PMCID: PMC6123150 DOI: 10.1002/acm2.12440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 06/01/2018] [Accepted: 07/16/2018] [Indexed: 12/26/2022] Open
Abstract
PURPOSE To investigate the accuracy of a vendor-supplied source model for a new Xoft Axxent 0-degree titanium tandem by film measurement. METHODS We measured the anisotropy factors at varying distances and angles from the tandem in water using radiochromic film (Gafchromic EBT3) and an Epson Perfection v750 desktop flatbed scanner (US Epson, Long Beach, CA). A 0-degree tandem was placed vertically in a water phantom. Four pieces of film, each at varying depths, were positioned orthogonal to the longitudinal axis of the tandem for azimuthal anisotropy measurements. Polar anisotropy measurements were taken with the film aligned parallel to the tandem. An absolute dose calibration for the film was verified with a PTW 34013 Soft X-Ray Chamber. The film measurements were analyzed using different color channels. The measured polar anisotropy for varying source positions was compared to the vendor's data. Azimuthal anisotropy was measured as a function of the radius and angle, and normalized to the mean value over all angles at the specified radius. RESULTS The azimuthal anisotropy of the tandem and source was found to be consistent for different positions along the tandem's longitudinal axis and at varying distances from the tandem. Absolute dose using a calibrated parallel plate chamber showed agreement to within 2% of expected TPS values. The custom tandem, which has a thicker tip than the wall, was attenuating the 50 kV photons more than expected, at the angles where the photons had more wall material to traverse. This discrepancy was verified at different distances from the tandem and with different measurement techniques. As distance increased, anisotropy values had better agreement. CONCLUSIONS We quantified the agreement between the measured and provided anisotropy factors for a new Xoft Axxent 0-degree titanium tandem. Radiochromic film response at low kV energy was also investigated. Our results showed that vendor-supplied TG-43 values were appropriate for clinical use at majority of the angles. A rigorous quality assurance method for new electronic brachytherapy sources and applicators, along with complete knowledge of all dosimetric measuring tools, should be implemented for all parts of the verification and commissioning process.
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Affiliation(s)
- Elijah Martin
- Department of Radiation OncologyUniversity of LouisvilleLouisvilleKYUSA
| | - Keith Sowards
- Department of Radiation OncologyUniversity of LouisvilleLouisvilleKYUSA
| | - Brian Wang
- Department of Radiation OncologyUniversity of LouisvilleLouisvilleKYUSA
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Abstract
Literature was reviewed to assess the physical aspects governing the present and emerging technologies used in intraoperative radiation therapy (IORT). Three major technologies were identified: treatment with electrons, treatment with external generators of kV X-rays and electronic brachytherapy. Although also used in IORT, literature on brachytherapy with radioactive sources is not systematically reviewed since an extensive own body of specialized literature and reviews exists in this field. A comparison with radioactive sources is made in the use of balloon catheters for partial breast irradiation where these are applied in almost an identical applicator technique as used with kV X-ray sources. The physical constraints of adaption of the dose distribution to the extended target in breast IORT are compared. Concerning further physical issues, the literature on radiation protection, commissioning, calibration, quality assurance (QA) and in-vivo dosimetry of the three technologies was reviewed. Several issues were found in the calibration and the use of dosimetry detectors and phantoms for low energy X-rays which require further investigation. The uncertainties in the different steps of dose determination were estimated, leading to an estimated total uncertainty of around 10-15% for IORT procedures. The dose inhomogeneity caused by the prescription of electrons at 90% and by the steep dose gradient of kV X-rays causes additional deviations from prescription dose which must be considered in the assessment of dose response in IORT.
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Affiliation(s)
- Frank W Hensley
- Department of Radiation Oncology, University Hospital of Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
- , Present address: Birkenweg 35, 69221, Dossenheim, Germany.
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Hernández Quintanar LF, López Silva FY, Fabila Bustos DA, Serrano Navarro J, de La Rosa Vázquez JM, Brodin PN, Guha C, Tomé WA, Stolik Isakina S. In Vitro Photoirradiation System for Simultaneous Irradiation with Different Light Doses at a Fixed Temperature. Photomed Laser Surg 2016; 34:108-15. [PMID: 26890993 DOI: 10.1089/pho.2015.4030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
OBJECTIVE In this work an irradiance and temperature controlled in-vitro system for conducting investigations in PDT and phototherapy is presented. BACKGROUND DATA The development of new light sources has caused a considerable increase in research and application of several photodynamic (PDT) therapeutic methods, as well as other light-based therapeutic techniques. However, further work is needed to fully understand and elucidate the mechanisms as well as to increase the effectiveness of PDT. Nowadays, there are no commercial systems to perform automated light exposure experiments with cultured cells. Also, there are very few reports of similar photoirradiation systems. MATERIALS AND METHODS The system is composed of 24 independent light-emitting diodes that can be used to irradiate separate wells in a microwell plate. The system includes a module to measure changes in temperature within each irradiated well without contact. The light sources are placed on a plate that can easily be changed in order to irradiate at different wavelengths. The performance of the system is fully controlled with a computer, and all the experimental data are properly recorded. RESULTS The design, construction, operation, and a full characterization of the system are presented. CONCLUSIONS A novel fully automated photoirradiation system has been developed. The system allows the design of the experiments in this area with precise dosimetry, temperature, and irradiation regime controls reducing manipulation of the samples and saving time.
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Affiliation(s)
- Luis F Hernández Quintanar
- 1 Laboratorio de Biofotónica. Escuela Superior de Ingeniería Mecánica y Eléctrica del Instituto Politécnico Nacional , Madero, México
| | - Fulgencio Y López Silva
- 1 Laboratorio de Biofotónica. Escuela Superior de Ingeniería Mecánica y Eléctrica del Instituto Politécnico Nacional , Madero, México
| | - Diego A Fabila Bustos
- 1 Laboratorio de Biofotónica. Escuela Superior de Ingeniería Mecánica y Eléctrica del Instituto Politécnico Nacional , Madero, México
| | - Joel Serrano Navarro
- 1 Laboratorio de Biofotónica. Escuela Superior de Ingeniería Mecánica y Eléctrica del Instituto Politécnico Nacional , Madero, México
| | - José M de La Rosa Vázquez
- 1 Laboratorio de Biofotónica. Escuela Superior de Ingeniería Mecánica y Eléctrica del Instituto Politécnico Nacional , Madero, México
| | - Patrik N Brodin
- 2 Institute for Onco-Physics , Albert Einstein College of Medicine, Bronx, New York
| | - Chandan Guha
- 2 Institute for Onco-Physics , Albert Einstein College of Medicine, Bronx, New York
| | - Wolfgang A Tomé
- 2 Institute for Onco-Physics , Albert Einstein College of Medicine, Bronx, New York
| | - Suren Stolik Isakina
- 1 Laboratorio de Biofotónica. Escuela Superior de Ingeniería Mecánica y Eléctrica del Instituto Politécnico Nacional , Madero, México
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White SA, Reniers B, de Jong EEC, Rusch T, Verhaegen F. A comparison of the relative biological effectiveness of low energy electronic brachytherapy sources in breast tissue: a Monte Carlo study. Phys Med Biol 2015; 61:383-99. [DOI: 10.1088/0031-9155/61/1/383] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Eaton DJ. Electronic brachytherapy--current status and future directions. Br J Radiol 2015; 88:20150002. [PMID: 25748070 PMCID: PMC4628482 DOI: 10.1259/bjr.20150002] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 02/28/2015] [Accepted: 03/05/2015] [Indexed: 12/17/2022] Open
Abstract
In the past decade, electronic brachytherapy (EB) has emerged as an attractive modality for the treatment of skin lesions and intraoperative partial breast irradiation, as well as finding wider applications in intracavitary and interstitial sites. These miniature X-ray sources, which operate at low kilovoltage energies (<100 kV), have reduced shielding requirements and inherent portability, therefore can be used outside the traditional realms of the radiotherapy department. However, steep dose gradients and increased sensitivity to inhomogeneities challenge accurate dosimetry. Secondly, ease of use does not mitigate the need for close involvement by medical physics experts and consultant oncologists. Finally, further studies are needed to relate the more heterogeneous dose distributions to clinical outcomes. With these provisos, the practical convenience of EB strongly suggests that it will become an established option for selected patients, not only in radiotherapy departments but also in a range of operating theatres and clinics around the world.
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Affiliation(s)
- D J Eaton
- NCRI Radiotherapy Trials Quality Assurance Group, Mount Vernon Hospital, London, UK
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Sarrut D, Bardiès M, Boussion N, Freud N, Jan S, Létang JM, Loudos G, Maigne L, Marcatili S, Mauxion T, Papadimitroulas P, Perrot Y, Pietrzyk U, Robert C, Schaart DR, Visvikis D, Buvat I. A review of the use and potential of the GATE Monte Carlo simulation code for radiation therapy and dosimetry applications. Med Phys 2015; 41:064301. [PMID: 24877844 DOI: 10.1118/1.4871617] [Citation(s) in RCA: 238] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
In this paper, the authors' review the applicability of the open-source GATE Monte Carlo simulation platform based on the GEANT4 toolkit for radiation therapy and dosimetry applications. The many applications of GATE for state-of-the-art radiotherapy simulations are described including external beam radiotherapy, brachytherapy, intraoperative radiotherapy, hadrontherapy, molecular radiotherapy, and in vivo dose monitoring. Investigations that have been performed using GEANT4 only are also mentioned to illustrate the potential of GATE. The very practical feature of GATE making it easy to model both a treatment and an imaging acquisition within the same framework is emphasized. The computational times associated with several applications are provided to illustrate the practical feasibility of the simulations using current computing facilities.
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Affiliation(s)
- David Sarrut
- Université de Lyon, CREATIS; CNRS UMR5220; Inserm U1044; INSA-Lyon; Université Lyon 1; Centre Léon Bérard, France
| | - Manuel Bardiès
- Inserm, UMR1037 CRCT, F-31000 Toulouse, France and Université Toulouse III-Paul Sabatier, UMR1037 CRCT, F-31000 Toulouse, France
| | | | - Nicolas Freud
- Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Centre Léon Bérard, 69008 Lyon, France
| | | | - Jean-Michel Létang
- Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Centre Léon Bérard, 69008 Lyon, France
| | - George Loudos
- Department of Medical Instruments Technology, Technological Educational Institute of Athens, Athens 12210, Greece
| | - Lydia Maigne
- UMR 6533 CNRS/IN2P3, Université Blaise Pascal, 63171 Aubière, France
| | - Sara Marcatili
- Inserm, UMR1037 CRCT, F-31000 Toulouse, France and Université Toulouse III-Paul Sabatier, UMR1037 CRCT, F-31000 Toulouse, France
| | - Thibault Mauxion
- Inserm, UMR1037 CRCT, F-31000 Toulouse, France and Université Toulouse III-Paul Sabatier, UMR1037 CRCT, F-31000 Toulouse, France
| | - Panagiotis Papadimitroulas
- Department of Biomedical Engineering, Technological Educational Institute of Athens, 12210, Athens, Greece
| | - Yann Perrot
- UMR 6533 CNRS/IN2P3, Université Blaise Pascal, 63171 Aubière, France
| | - Uwe Pietrzyk
- Institut für Neurowissenschaften und Medizin, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany and Fachbereich für Mathematik und Naturwissenschaften, Bergische Universität Wuppertal, 42097 Wuppertal, Germany
| | - Charlotte Robert
- IMNC, UMR 8165 CNRS, Universités Paris 7 et Paris 11, Orsay 91406, France
| | - Dennis R Schaart
- Delft University of Technology, Faculty of Applied Sciences, Radiation Science and Technology Department, Delft Mekelweg 15, 2629 JB Delft, The Netherlands
| | | | - Irène Buvat
- IMNC, UMR 8165 CNRS, Universités Paris 7 et Paris 11, 91406 Orsay, France and CEA/DSV/I2BM/SHFJ, 91400 Orsay, France
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Fonseca GP, Landry G, White S, D'Amours M, Yoriyaz H, Beaulieu L, Reniers B, Verhaegen F. The use of tetrahedral mesh geometries in Monte Carlo simulation of applicator based brachytherapy dose distributions. Phys Med Biol 2014; 59:5921-35. [PMID: 25210788 DOI: 10.1088/0031-9155/59/19/5921] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
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.
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Affiliation(s)
- Gabriel Paiva Fonseca
- Instituto de Pesquisas Energéticas e Nucleares-IPEN-CNEN/SP, São Paulo, Brazil. Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, the Netherlands
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White SA, Landry G, Fonseca GP, Holt R, Rusch T, Beaulieu L, Verhaegen F, Reniers B. Comparison of TG-43 and TG-186 in breast irradiation using a low energy electronic brachytherapy source. Med Phys 2014; 41:061701. [DOI: 10.1118/1.4873319] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Dosimetric characteristics of a new unit for electronic skin brachytherapy. J Contemp Brachytherapy 2014; 6:45-53. [PMID: 24790622 PMCID: PMC4003426 DOI: 10.5114/jcb.2014.40770] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 01/15/2014] [Accepted: 03/28/2014] [Indexed: 12/19/2022] Open
Abstract
Purpose Brachytherapy with radioactive high dose rate (HDR) 192Ir source is applied to small skin cancer lesions, using surface applicators, i.e. Leipzig or Valencia type. New developments in the field of radiotherapy for skin cancer include electronic brachytherapy. This technique involves the placement of an HDR X-ray source close to the skin, therefore combining the benefits of brachytherapy with the reduced shielding requirements and targeted energy of low energy X-rays. Recently, the Esteya® Electronic Brachytherapy System (Esteya EBS, Elekta AB-Nucletron, Stockholm, Sweden) has been developed specifically for HDR brachytherapy treatment of surface lesions. The system provides radionuclide free HDR brachytherapy by means of a small 69.5 kV X-ray source. The purpose of this study is to obtain the dosimetric characterization required for clinical implementation, providing the detailed methodology to perform the commissioning. Material and methods Flatness, symmetry and penumbra, percentage of depth dose (PDD), kV stability, HVL, output, spectrum, linearity, and leakage have been evaluated for a set of applicators (from 10 mm to 30 mm in diameter). Results Flatness and symmetry resulted better than 5% with around 1 mm of penumbra. The depth dose gradient is about 7%/mm. A kV value of 68.4 ± 1.0 kV (k = 1) was obtained, in good agreement with manufacturer data (69.5 kV). HVL was 1.85 mm Al. Dose rate for a typical 6 Gy to 7 Gy prescription resulted about 3.3 Gy/min and the leakage value was < 100 µGy/min. Conclusions The new Esteya® Electronic Brachytherapy System presents excellent flatness and penumbra as with the Valencia applicator case, combined with an improved PDD, allowing treatment of lesions of up to a depth of 5 mm in combination with reduced treatment duration. The Esteya unit allows HDR brachytherapy superficial treatment within a minimally shielded environment due its low energy.
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White SA, Landry G, van Gils F, Verhaegen F, Reniers B. Influence of trace elements in human tissue in low-energy photon brachytherapy dosimetry. Phys Med Biol 2012; 57:3585-96. [DOI: 10.1088/0031-9155/57/11/3585] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Safigholi H, Faghihi R, Jashni SK, Meigooni AS. Characteristics of miniature electronic brachytherapy x-ray sources based on TG-43U1 formalism using Monte Carlo simulation techniques. Med Phys 2012; 39:1971-9. [DOI: 10.1118/1.3693046] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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D’Amours M, Pouliot J, Dagnault A, Verhaegen F, Beaulieu L. Patient-Specific Monte Carlo-Based Dose-Kernel Approach for Inverse Planning in Afterloading Brachytherapy. Int J Radiat Oncol Biol Phys 2011; 81:1582-9. [DOI: 10.1016/j.ijrobp.2010.09.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Revised: 09/03/2010] [Accepted: 09/21/2010] [Indexed: 11/27/2022]
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Rava P, Dvorak T, Markelewicz RJ, Hiatt JR, Sternick ES, MacAusland SG, Huber K, Wazer DE, Hepel JT. A comparison of the biological effective dose of 50-kV electronic brachytherapy with (192)Ir high-dose-rate brachytherapy for vaginal cuff irradiation. Brachytherapy 2011; 11:402-7. [PMID: 21996539 DOI: 10.1016/j.brachy.2011.08.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 07/28/2011] [Accepted: 08/17/2011] [Indexed: 10/16/2022]
Abstract
PURPOSE Advantages for electronic brachytherapy (EBT) of the vaginal cuff include decreased physical dose to the bladder and rectum. Here we compare (192)Ir with EBT using biological effective dose (BED) to account for the different radiobiological effectiveness (RBE) predicted for low-energy x-rays. METHODS AND MATERIALS Fifteen data sets from five consecutive postoperative endometrial cancer patients treated with EBT were analyzed. Treatment planning was performed using PLATO software. The dose was prescribed as 21Gy in three fractions to a depth of 0.5cm. Physical dose, BED(3), and BED(10) were evaluated for the mucosa, bladder, and rectum. An RBE value of 1.5 was used for BED calculations. RESULTS Mucosal physical dose is 28.4% greater with EBT (36.6 vs. 28.5Gy, p<0.05). However, the BED(10) is increased by 79.1% (55.6 vs. 99.6Gy, p<0.05) and the BED(3) by 71.5% (118.8 vs. 203.7Gy, p<0.05). The physical dose (dose to 50% volume of the organ) to the bladder (9.3 vs. 6.6Gy, p<0.05) and rectum (7.2 vs. 4.2Gy, p<0.05) are reduced with EBT. BED(3) to the rectum and bladder are also reduced but to a lesser extent (13 vs. 8.3Gy, p<0.05; 18.9 vs. 14.7Gy, p=0.06, respectively). CONCLUSIONS BED takes into account the higher RBE of low-energy photons generated with EBT and provides a more accurate estimate of the biological effect. When using EBT, physical dose may underestimate the biological effect on the vaginal mucosa and overestimate the benefit for the bladder and rectum. Dose adjustment for EBT based on BED should be considered.
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Affiliation(s)
- Paul Rava
- Department of Radiation Oncology, Tufts Medical Center, Boston, MA 02111, USA.
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Landry G, Reniers B, Pignol JP, Beaulieu L, Verhaegen F. The difference of scoring dose to water or tissues in Monte Carlo dose calculations for low energy brachytherapy photon sources. Med Phys 2011; 38:1526-33. [PMID: 21520864 DOI: 10.1118/1.3549760] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE 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. METHODS Two types of dose calculations are performed with the GEANT4 MC code. (1) For several human tissues, dose profiles are obtained in spherical geometries centered on four types of low energy brachytherapy sources: 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). RESULTS (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, CONCLUSIONS Given the small variation with distance, using conversion factors based on the emitted photon spectrum (or its mean energy) of a given source introduces minimal error. The large differences observed between scoring schemes underline the need for guidelines on choice of media for dose reporting. Providing such guidelines is beyond the scope of this work.
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Affiliation(s)
- Guillaume Landry
- Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN, The Netherlands
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Shi C, Guo B, Cheng CY, Esquivel C, Eng T, Papanikolaou N. Three dimensional intensity modulated brachytherapy (IMBT): dosimetry algorithm and inverse treatment planning. Med Phys 2010; 37:3725-37. [PMID: 20831080 DOI: 10.1118/1.3456598] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The feasibility of intensity modulated brachytherapy (IMBT) to improve dose conformity for irregularly shaped targets has been previously investigated by researchers by means of using partially shielded sources. However, partial shielding does not fully explore the potential of IMBT. The goal of this study is to introduce the concept of three dimensional (3D) intensity modulated brachytherapy and solve two fundamental issues regarding the application of 3D IMBT treatment planning: The dose calculation algorithm and the inverse treatment planning method. METHODS A 3D IMBT treatment planning system prototype was developed using the MATLAB platform. This system consists of three major components: (1) A comprehensive IMBT source calibration method with dosimetric inputs from Monte Carlo (EGSnrc) simulations; (2) a "modified TG-43" (mTG-43) dose calculation formalism for IMBT dosimetry; and (3) a physical constraint based inverse IMBT treatment planning platform utilizing a simulated annealing optimization algorithm. The model S700 Axxent electronic brachytherapy source developed by Xoft, Inc. (Fremont, CA), was simulated in this application. Ten intracavitary accelerated partial breast irradiation (APBI) cases were studied. For each case, an "isotropic plan" with only optimized source dwell time and a fully optimized IMBT plan were generated and compared to the original plan in various dosimetric aspects, such as the plan quality, planning, and delivery time. The issue of the mechanical complexity of the IMBT applicator is not addressed in this study. RESULTS IMBT approaches showed superior plan quality compared to the original plans and tht isotropic plans to different extents in all studied cases. An extremely difficult case with a small breast and a small distance to the ribs and skin, the IMBT plan minimized the high dose volume V200 by 16.1% and 4.8%, respectively, compared to the original and the isotropic plans. The conformity index for the target was increased by 0.13 and 0.04, respectively. The maximum dose to the skin was reduced by 56 and 28 cGy, respectively, per fraction. Also, the maximum dose to the ribs was reduced by 104 and 96 cGy, respectively, per fraction. The mean dose to the ipsilateral and contralateral breasts and lungs were also slightly reduced by the IMBT plan. The limitations of IMBT are the longer planning and delivery time. The IMBT plan took around 2 h to optimize, while the isotropic plan optimization could reach the global minimum within 5 min. The delivery time for the IMBT plan is typically four to six times longer than the corresponding isotropic plan. CONCLUSIONS In this study, a dosimetry method for IMBT sources was proposed and an inverse treatment planning system prototype for IMBT was developed. The improvement of plan quality by 3D IMBT was demonstrated using ten APBI case studies. Faster computers and higher output of the source can further reduce plan optimization and delivery time, respectively.
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Affiliation(s)
- Chengyu Shi
- Cancer Therapy and Research Center, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229, USA.
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Landry G, Reniers B, Murrer L, Lutgens L, Bloemen-Van Gurp E, Pignol JP, Keller B, Beaulieu L, Verhaegen F. Sensitivity of low energy brachytherapy Monte Carlo dose calculations to uncertainties in human tissue composition. Med Phys 2010; 37:5188-98. [DOI: 10.1118/1.3477161] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Afsharpour H, Pignol JP, Keller B, Carrier JF, Reniers B, Verhaegen F, Beaulieu L. Influence of breast composition and interseed attenuation in dose calculations for post-implant assessment of permanent breast103Pd seed implant. Phys Med Biol 2010; 55:4547-61. [DOI: 10.1088/0031-9155/55/16/s09] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Heo S, Ihsan A, Yoo S, Ali G, Cho S. Stable Field Emitters for a Miniature X-ray Tube Using Carbon Nanotube Drop Drying on a Flat Metal Tip. NANOSCALE RESEARCH LETTERS 2010; 5:720-724. [PMID: 20672136 PMCID: PMC2893921 DOI: 10.1007/s11671-010-9537-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 01/08/2010] [Indexed: 05/29/2023]
Abstract
Stable carbon nanotube (CNT) field emitters for a vacuum-sealed miniature X-ray tube have been fabricated. The field emitters with a uniform CNT coating are prepared by a simple drop drying of a CNT mixture solution that is composed of chemically modified multi-walled CNTs, silver nanoparticles, and isopropyl alcohol on flat tungsten tips. A highly thermal- and electrical-conductive silver layer strongly attaches CNTs to the tungsten tips. Consequently, the field emitters exhibit good electron emission stability: continuous electron emission of around 100 μA at 2.3 V/μm has stably lasted over 40 h even at non-high vacuum ambient (~10-3 Pa).
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Affiliation(s)
- Sunghwan Heo
- Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong, Yuseong, Daejeon, 305-701, Republic of Korea.
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A novel device for intravaginal electronic brachytherapy. Int J Radiat Oncol Biol Phys 2009; 74:1298-305. [PMID: 19545794 DOI: 10.1016/j.ijrobp.2009.01.082] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 01/27/2009] [Accepted: 01/27/2009] [Indexed: 11/20/2022]
Abstract
PURPOSE Postoperative intravaginal brachytherapy for endometrial carcinoma is usually performed with (192)Ir high-dose rate (HDR) afterloading. A potential alternative is treatment with a broadband 50kV X-ray point source, the advantage being its low energy and the consequential steep dose gradient. The aim of this study was to create and evaluate a homogeneous cylindrical energy deposition around a newly designed vaginal applicator. METHODS AND MATERIALS To create constant isodose layers along the cylindrical plastic vaginal applicator, the source (INTRABEAM system) was moved in steps of 17-19.5 mm outward from the tip of the applicator. Irradiation for a predetermined time was performed at each position. The axial shift was established by a stepping mechanism that was mounted on a table support. The total dose/dose distribution was determined using film dosimetry (Gafchromic EBT) in a "solid water" phantom. The films were evaluated with Mathematica 5.2 and OmniPro-I'mRT 1.6. The results (dose D0/D5/D10 in 0/5/10 mm tissue depth) were compared with an (192)Ir HDR afterloading plan for multiple sampling points around the applicator. RESULTS Three different dose distributions with lengths of 3.9-7.3 cm were created. The irradiation time based on the delivery of 5/7 Gy to a 5 mm tissue depth was 19/26 min to 27/38 min. D0/D5/D10 was 150%/100%/67% for electronic brachytherapy and 140%/100%/74% for the afterloading technique. The deviation for repeated measurements in the phantom was <7%. CONCLUSIONS It is possible to create a homogeneous cylindrical dose distribution, similar to (192)Ir HDR afterloading, through the superimposition of multiple spherical dose distributions by stepping a kilovolt point source.
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Reniers B, Liu D, Rusch T, Verhaegen F. Calculation of relative biological effectiveness of a low-energy electronic brachytherapy source. Phys Med Biol 2008; 53:7125-35. [PMID: 19033642 DOI: 10.1088/0031-9155/53/24/008] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Low-energy x-rays are known to have a higher relative biological effectiveness (RBE) than higher energy photons such as the gamma rays from 192Ir and 60Co. In this work the initial yield of single- and double-strand DNA breaks (SSB and DSB) and the RBE was estimated for a novel electronic brachytherapy source (EBS), emitting 40-50 kVp photons. An EGSnrc Monte Carlo model of the source was used in combination with the 'Monte Carlo damage simulation' program (Semenenko and Stewart 2004 Radiat. Res. 161 451-57; 2006 Phys. Med. Biol. 51 1693-706). The results indicate a substantially reduced SSB yield and increased DSB yield for the EBS compared to 60Co or 192Ir, leading to an enhanced RBE by 40-50%. The RBE estimate for the low-energy x-ray EBS was found to be very similar to the low-energy gamma ray brachytherapy isotope 125I. Biological damage was estimated in several human tissues: muscle, breast, calcified breast and cortical bone. SSB and DSB yields were similar in all media, except in bone. These findings should be taken into account if the EBS is intended to replace brachytherapy with the commonly used 192Ir isotope.
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Affiliation(s)
- Brigitte Reniers
- Medical Physics Department, McGill University, Montreal General Hospital, 1650 Cedar Avenue, Montreal, Québec, H3G 1A4, Canada
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