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Ibáñez P, Villa-Abaunza A, Udías JM. Impact on the estimated dose of different tissue assignment strategies during partial breast irradiations with INTRABEAM. Brachytherapy 2024; 23:470-477. [PMID: 38705803 DOI: 10.1016/j.brachy.2024.02.003] [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: 11/24/2023] [Revised: 01/19/2024] [Accepted: 02/12/2024] [Indexed: 05/07/2024]
Abstract
PURPOSE Partial breast irradiations with electronic brachytherapy or kilovoltage intraoperative radiotherapy devices such as Axxent or INTRABEAM are becoming more common every day. Breast is mainly composed of glandular and adipose tissues, which are not always clearly disentangled in planning breast CTs. In these cases, breast tissues are replaced with an average soft tissue, or even water. However, at kilovoltage energies, this may lead to large differences in the delivered dose, due to the dominance of photoelectric effect. Therefore, the aim of this work was to study the effect on the dose prescribed in breast with the INTRABEAM device using different soft tissue assignment strategies that would replace the adipose and glandular tissues that constitute the breast in cases where these tissues cannot be adequately distinguished in a CT scan. METHODS AND MATERIALS Dose was computed with a Monte Carlo code in five patients with a 3 cm diameter INTRABEAM spherical applicator. Tissues within the breast were assigned following six different strategies: one based on the TG-43 recommendations, representing the whole breast as water of unity density, another one also water-based but with CT derived density, and the other four also based on CT-derived densities, using a single tissue resulting from different mixes of glandular and adipose tissues. These were compared against the reference dose computed in an accurately segmented CT, following TG-186 recommendations. Relative differences and dose ratios between the reference and the other tissue assignment strategies were obtained in three regions of interest inside the breast. RESULTS AND CONCLUSIONS Dose planning in water-based tissues was found inaccurate for breast treatment with INTRABEAM, as it would incur in up to 30% under-prescription of dose. If accurate soft tissue assignments in the breast cannot be safely done, a single-tissue composition of 80% adipose and 20% glandular tissue, or even a 100% adipose tissue, would be recommended to avoid dose under-prescription.
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Affiliation(s)
- Paula Ibáñez
- Nuclear Physics Group and IPARCOS, Department of Structure of Matter, Thermal Physics and Electronics, CEI Moncloa, Universidad Complutense de Madrid, Madrid, Spain; Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain.
| | - Amaia Villa-Abaunza
- Nuclear Physics Group and IPARCOS, Department of Structure of Matter, Thermal Physics and Electronics, CEI Moncloa, Universidad Complutense de Madrid, Madrid, Spain
| | - José Manuel Udías
- Nuclear Physics Group and IPARCOS, Department of Structure of Matter, Thermal Physics and Electronics, CEI Moncloa, Universidad Complutense de Madrid, Madrid, Spain; Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain
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2
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Antunes PCG, Siqueira PDTD, Shorto JMB, Yoriyaz H. Heterogeneous physical phantom for I-125 dose measurements and dose-to-medium determination. Brachytherapy 2024; 23:73-84. [PMID: 38016863 DOI: 10.1016/j.brachy.2023.08.007] [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: 04/17/2023] [Revised: 07/30/2023] [Accepted: 08/30/2023] [Indexed: 11/30/2023]
Abstract
PURPOSE In this paper we present a further step in the implementation of a physical phantom designed to generate sets of "true" independent reference data as requested by TG-186, intending to address and mitigate the scarcity of experimental studies on brachytherapy (BT) validation in heterogeneous media. To achieve this, we incorporated well-known heterogeneous materials into the phantom in order to perform measurements of 125I dose distribution. The work aims to experimentally validate Monte Carlo (MC) calculations based on MBDCA and determine the conversion factors from LiF response to absorbed dose in different media, using cavity theory. METHODS AND MATERIALS The physical phantom was adjusted to incorporate tissue equivalent materials, such as: adipose tissue, bone, breast and lung with varying thickness. MC calculations were performed using MCNP6.2 code to calculate the absorbed dose in the LiF and the dose conversion factors (DCF). RESULTS The proposed heterogeneous phantom associated with the experimental procedure carried out in this work yielded accurate dose data that enabled the conversion of the LiF responses into absorbed dose to medium. The results showed a maximum uncertainty of 6.92 % (k = 1), which may be considered excellent for dosimetry with low-energy BT sources. CONCLUSIONS The presented heterogeneous phantom achieves the required precision in dose evaluations due to its easy reproducibility in the experimental setup. The obtained results support the dose conversion methodology for all evaluated media. The experimental validation of the DCF in different media holds great significance for clinical procedures, as it can be applied to other tissues, including water, which remains a widely utilized reference medium in clinical practice.
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Affiliation(s)
- Paula Cristina Guimarães Antunes
- Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP, Sao Paulo, Brazil; Institute of Physics, University of Sao Paulo, Sao Paulo, Brazil.
| | | | | | - Hélio Yoriyaz
- Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP, Sao Paulo, Brazil
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Beaulieu L, Ballester F, Granero D, Tedgren ÅC, Haworth A, Lowenstein JR, Ma Y, Mourtada F, Papagiannis P, Rivard MJ, Siebert FA, Sloboda RS, Smith RL, Thomson RM, Verhaegen F, Fonseca G, Vijande J. AAPM WGDCAB Report 372: A joint AAPM, ESTRO, ABG, and ABS report on commissioning of model-based dose calculation algorithms in brachytherapy. Med Phys 2023; 50:e946-e960. [PMID: 37427750 DOI: 10.1002/mp.16571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 02/16/2023] [Accepted: 04/24/2023] [Indexed: 07/11/2023] Open
Abstract
The introduction of model-based dose calculation algorithms (MBDCAs) in brachytherapy provides an opportunity for a more accurate dose calculation and opens the possibility for novel, innovative treatment modalities. The joint AAPM, ESTRO, and ABG Task Group 186 (TG-186) report provided guidance to early adopters. However, the commissioning aspect of these algorithms was described only in general terms with no quantitative goals. This report, from the Working Group on Model-Based Dose Calculation Algorithms in Brachytherapy, introduced a field-tested approach to MBDCA commissioning. It is based on a set of well-characterized test cases for which reference Monte Carlo (MC) and vendor-specific MBDCA dose distributions are available in a Digital Imaging and Communications in Medicine-Radiotherapy (DICOM-RT) format to the clinical users. The key elements of the TG-186 commissioning workflow are now described in detail, and quantitative goals are provided. This approach leverages the well-known Brachytherapy Source Registry jointly managed by the AAPM and the Imaging and Radiation Oncology Core (IROC) Houston Quality Assurance Center (with associated links at ESTRO) to provide open access to test cases as well as step-by-step user guides. While the current report is limited to the two most widely commercially available MBDCAs and only for 192 Ir-based afterloading brachytherapy at this time, this report establishes a general framework that can easily be extended to other brachytherapy MBDCAs and brachytherapy sources. The AAPM, ESTRO, ABG, and ABS recommend that clinical medical physicists implement the workflow presented in this report to validate both the basic and the advanced dose calculation features of their commercial MBDCAs. Recommendations are also given to vendors to integrate advanced analysis tools into their brachytherapy treatment planning system to facilitate extensive dose comparisons. The use of the test cases for research and educational purposes is further encouraged.
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Affiliation(s)
- Luc Beaulieu
- Service de Physique Médicale et Radioprotection et Axe Oncologie du Centre de Recherche du CHU de Québec, CHU de Québec-Université Laval, Québec, Québec, Canada
- Département de Physique, de Génie Physique et d'Optique et Centre de Recherche sur le Cancer, Université Laval, Québec, Québec, Canada
| | - Facundo Ballester
- Departamento de Física Atómica, Molecular y Nuclear, IRIMED, IIS-La Fe-Universitat de Valencia, Burjassot, Spain
| | - Domingo Granero
- Departamento de Física Atómica, Molecular y Nuclear, IRIMED, IIS-La Fe-Universitat de Valencia, Burjassot, Spain
| | - Åsa Carlsson Tedgren
- Department of Health, Medicine and Caring Sciences (HMV), Radiation Physics, Linköping University, Linköping, Sweden
- Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden
- Department of Oncology Pathology, Karolinska Institute, Stockholm, Sweden
| | | | - Jessica R Lowenstein
- Department of Radiation Physics, UT MD Anderson Cancer Center, Houston, Texas, USA
| | - Yunzhi Ma
- Service de Physique Médicale et Radioprotection et Axe Oncologie du Centre de Recherche du CHU de Québec, CHU de Québec-Université Laval, Québec, Québec, Canada
- Département de Physique, de Génie Physique et d'Optique et Centre de Recherche sur le Cancer, Université Laval, Québec, Québec, Canada
| | - Firas Mourtada
- Department of Radiation Oncology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Panagiotis Papagiannis
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Mark J Rivard
- Department of Radiation Oncology, Alpert Medical School of Brown University, Providence, Rhode Island, USA
| | - Frank-André Siebert
- Clinic of Radiotherapy, University Hospital of Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Ron S Sloboda
- Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
| | - Ryan L Smith
- Alfred Health Radiation Oncology, The Alfred Hospital, Melbourne, Victoria, Australia
| | - Rowan M Thomson
- Carleton Laboratory for Radiotherapy Physics, Department of Physics, Carleton University, Ottawa, Ontario, Canada
| | - Frank Verhaegen
- Department of Radiation Oncology (MAASTRO), GROW, School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Gabriel Fonseca
- Department of Radiation Oncology (MAASTRO), GROW, School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Javier Vijande
- Departamento de Física Atómica, Molecular y Nuclear, IRIMED, IIS-La Fe-Universitat de Valencia, Burjassot, Spain
- Instituto de Física Corpuscular, IFIC (UV-CSIC), Burjassot, Spain
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Poher A, Berumen F, Ma Y, Perl J, Beaulieu L. Validation of the TOPAS Monte Carlo toolkit for LDR brachytherapy simulations. Phys Med 2023; 107:102516. [PMID: 36804693 DOI: 10.1016/j.ejmp.2022.102516] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 11/07/2022] [Accepted: 12/27/2022] [Indexed: 02/18/2023] Open
Abstract
PURPOSE This work has the purpose of validating the Monte Carlo toolkit TOol for PArticle Simulation (TOPAS) for low-dose-rate (LDR) brachytherapy uses. METHODS AND MATERIALS Simulations of 12 LDR sources and 2 COMS eye plaques (10 mm and 20 mm in diameter) and comparisons with published reference data from the Carleton Laboratory for Radiotherapy Physics (CLRP), the TG-43 consensus data and the TG-129 consensus data were performed. Sources from the IROC Houston Source Registry were modeled. The OncoSeed 6711 and the SelectSeed 130.002 were also modeled for historical reasons. For each source, the dose rate constant, the radial dose function and the anisotropy functions at 0.5, 1 and 5 cm were extracted. For the eye plaques (loaded with 125I sources), dose distribution maps, dose profiles along the central axis and transverse axis were calculated. RESULTS Dose rate constants for 11 of the 12 sources are within 4% of the consensus data and within 2% of the CLRP data. The radial dose functions and anisotropy functions are mostly within 2% of the CLRP data. In average, 92% of all voxels are within 1% of the CLRP data for the eye plaques dose distributions. The dose profiles are within 0.5% (central axis) and 1% (transverse axis) of the reference data. CONCLUSION The TOPAS MC toolkit was validated for LDR brachytherapy applications. Single-seed and multi-seed results agree with the published reference data. TOPAS has several benefits such as a simplified approach to MC simulations and an accessible brachytherapy package including comprehensive learning resources.
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Affiliation(s)
- Audran Poher
- Service de physique médicale et de radioprotection, Centre Intégré de Cancérologie, CHU de Québec - Université Laval et Centre de recherche du CHU de Québec, Québec, Québec, Canada; Département de Physique, de Génie Physique et d'Optique et Centre de Recherche sur le Cancer, Université Laval, Québec Québec G1V 0A6, Canada.
| | - Francisco Berumen
- Service de physique médicale et de radioprotection, Centre Intégré de Cancérologie, CHU de Québec - Université Laval et Centre de recherche du CHU de Québec, Québec, Québec, Canada; Département de Physique, de Génie Physique et d'Optique et Centre de Recherche sur le Cancer, Université Laval, Québec Québec G1V 0A6, Canada
| | - Yunzhi Ma
- Service de physique médicale et de radioprotection, Centre Intégré de Cancérologie, CHU de Québec - Université Laval et Centre de recherche du CHU de Québec, Québec, Québec, Canada; Département de Physique, de Génie Physique et d'Optique et Centre de Recherche sur le Cancer, Université Laval, Québec Québec G1V 0A6, Canada
| | - Joseph Perl
- SLAC National Accelerator Laboratory, Menlo Park, CA, United States of America
| | - Luc Beaulieu
- Service de physique médicale et de radioprotection, Centre Intégré de Cancérologie, CHU de Québec - Université Laval et Centre de recherche du CHU de Québec, Québec, Québec, Canada; Département de Physique, de Génie Physique et d'Optique et Centre de Recherche sur le Cancer, Université Laval, Québec Québec G1V 0A6, Canada
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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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6
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Melhus CS, Simiele SJ, Aima M, Richardson S. Learning from the past: a century of accuracy, aspirations, and aspersions in brachytherapy. Br J Radiol 2022; 95:20220500. [PMID: 35969474 PMCID: PMC9733622 DOI: 10.1259/bjr.20220500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 07/19/2022] [Accepted: 07/25/2022] [Indexed: 11/05/2022] Open
Abstract
The oldest form of radiation therapy, brachytherapy, has been investigated and reported in the scientific and medical literature for well over a century. Known by many names over the years, radium-based, empirical practices evolved over decades to contemporary practice. This includes treatment at various dose rates using multiple radionuclides or even electrically generated photon sources. Predictions or prognostications of what may happen in the future enjoy a history that spans centuries, e.g. those by Nostradamus in the 1500s. In this review article, publications from several eras of past practice between the early 1900s and the late 2010s where the authors address the "future of brachytherapy" are presented, and for many of these publications, one can use the benefit of the intervening years to comment on the accuracy or the inaccuracies inherent in those publications. Finally, recently published papers are reviewed to examine current expectations for the future practice of brachytherapy.
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Affiliation(s)
- Christopher S Melhus
- Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts
| | - Samantha J Simiele
- Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Manik Aima
- Department of Radiation Oncology, Stanford University, Stanford, California, United States
| | - Susan Richardson
- Department of Radiation Oncology, Swedish Medical Center, Seattle, Washington, United States
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Dosimetry procedure to verify dose in High Dose Rate (HDR) brachytherapy treatment of cancer patients: A systematic review. Phys Med 2022; 96:70-80. [DOI: 10.1016/j.ejmp.2022.02.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 02/18/2022] [Accepted: 02/21/2022] [Indexed: 01/12/2023] Open
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Feng W, Rivard MJ, Carey EM, Hearn RA, Pai S, Nath R, Kim Y, Thomason CL, Boyce DE, Zhang H. Recommendations for intraoperative mesh brachytherapy: Report of AAPM Task Group No. 222. Med Phys 2021; 48:e969-e990. [PMID: 34431524 DOI: 10.1002/mp.15191] [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: 12/20/2020] [Revised: 08/17/2021] [Accepted: 08/17/2021] [Indexed: 11/11/2022] Open
Abstract
Mesh brachytherapy is a special type of a permanent brachytherapy implant: it uses low-energy radioactive seeds in an absorbable mesh that is sutured onto the tumor bed immediately after a surgical resection. This treatment offers low additional risk to the patient as the implant procedure is carried out as part of the tumor resection surgery. Mesh brachytherapy utilizes identification of the tumor bed through direct visual evaluation during surgery or medical imaging following surgery through radiographic imaging of radio-opaque markers within the sources located on the tumor bed. Thus, mesh brachytherapy is customizable for individual patients. Mesh brachytherapy is an intraoperative procedure involving mesh implantation and potentially real-time treatment planning while the patient is under general anesthesia. The procedure is multidisciplinary and requires the complex coordination of multiple medical specialties. The preimplant dosimetry calculation can be performed days beforehand or expediently in the operating room with the use of lookup tables. In this report, the guidelines of American Association of Physicists in Medicine (AAPM) are presented on the physics aspects of mesh brachytherapy. It describes the selection of radioactive sources, design and preparation of the mesh, preimplant treatment planning using a Task Group (TG) 43-based lookup table, and postimplant dosimetric evaluation using the TG-43 formalism or advanced algorithms. It introduces quality metrics for the mesh implant and presents an example of a risk analysis based on the AAPM TG-100 report. Recommendations include that the preimplant treatment plan be based upon the TG-43 dose calculation formalism with the point source approximation, and the postimplant dosimetric evaluation be performed by using either the TG-43 approach, or preferably the newer model-based algorithms (viz., TG-186 report) if available to account for effects of material heterogeneities. To comply with the written directive and regulations governing the medical use of radionuclides, this report recommends that the prescription and written directive be based upon the implanted source strength, not target-volume dose coverage. The dose delivered by mesh implants can vary and depends upon multiple factors, such as postsurgery recovery and distortions in the implant shape over time. For the sake of consistency necessary for outcome analysis, prescriptions based on the lookup table (with selection of the intended dose, depth, and treatment area) are recommended, but the use of more advanced techniques that can account for real situations, such as material heterogeneities, implant geometric perturbations, and changes in source orientations, is encouraged in the dosimetric evaluation. The clinical workflow, logistics, and precautions are also presented.
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Affiliation(s)
- Wenzheng Feng
- Department of Radiation Oncology, Saint Barnabas Medical Center, Livingston, New Jersey, USA
| | - Mark J Rivard
- Department of Radiation Oncology, Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA
| | | | - Robert A Hearn
- Department of Radiation Physics at Theragenics, Theragenics Corp., Buford, Georgia, USA
| | - Sujatha Pai
- Department of Radiation Oncology, Memorial Hermann Texas Medical Center, Houston, Texas, USA
| | - Ravinder Nath
- Department of Therapeutic Radiology, School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Yongbok Kim
- Department of Radiation Oncology, University of Arizona, Tucson, Arizona, USA
| | - Cynthia L Thomason
- Department of Radiation Oncology, Loyola University Medical Center, Maywood, Illinois, USA
| | | | - Hualin Zhang
- Department of Radiation Oncology, Northwestern University Feinberg School of Medicine, Northwestern Memorial Hospital, Chicago, Illinois, USA
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Berumen F, Ma Y, Ramos-Méndez J, Perl J, Beaulieu L. Validation of the TOPAS Monte Carlo toolkit for HDR brachytherapy simulations. Brachytherapy 2021; 20:911-921. [PMID: 33896732 DOI: 10.1016/j.brachy.2020.12.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 11/03/2020] [Accepted: 12/12/2020] [Indexed: 11/27/2022]
Abstract
PURPOSE The goal of this work is to validate the user-friendly Geant4-based Monte Carlo toolkit TOol for PArticle Simulation (TOPAS) for brachytherapy applications. METHODS AND MATERIALS Brachytherapy simulations performed with TOPAS were systematically compared with published TG-186 reference data. The photon emission energy spectrum, the air-kerma strength, and the dose-rate constant of the model-based dose calculation algorithm (MBDCA)-WG generic Ir-192 source were extracted. For dose calculations, a track-length estimator was implemented. The four Joint AAPM/ESTRO/ABG MBDCA-WG test cases were evaluated through histograms of the local and global dose difference volumes. A prostate, a palliative lung, and a breast case were simulated. For each case, the dose ratio map, the histogram of the global dose difference volume, and cumulative dose-volume histograms were calculated. RESULTS The air-kerma strength was (9.772 ± 0.001) × 10-8 U Bq-1 (within 0.3% of the reference value). The dose-rate constant was 1.1107 ± 0.0005 cGy h-1 U-1 (within 0.01% of the reference value). For all cases, at least 96.9% of voxels had a local dose difference within [-1%, 1%] and at least 99.9% of voxels had a global dose difference within [-0.1%, 0.1%]. The implemented track-length estimator scorer was more efficient than the default analog dose scorer by a factor of 237. For all clinical cases, at least 97.5% of voxels had a global dose difference within [-1%, 1%]. Dose-volume histograms were consistent with the reference data. CONCLUSIONS TOPAS was validated for high-dose-rate brachytherapy simulations following the TG-186 recommended approach for MBDCAs. Built on top of Geant4, TOPAS provides broad access to a state-of-the-art Monte Carlo code for brachytherapy simulations.
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Affiliation(s)
- Francisco Berumen
- Département de Radio-Oncologie et Axe oncologie du Centre de recherche du CHU de Québec, CHU de Québec, Québec, QC, Canada; Département de Physique, de Génie Physique et d'Optique et Centre de Recherche sur le Cancer, Université Laval, Québec, QC, Canada
| | - Yunzhi Ma
- Département de Radio-Oncologie et Axe oncologie du Centre de recherche du CHU de Québec, CHU de Québec, Québec, QC, Canada; Département de Physique, de Génie Physique et d'Optique et Centre de Recherche sur le Cancer, Université Laval, Québec, QC, Canada
| | - José Ramos-Méndez
- Department of Radiation Oncology, University of California San Francisco, San Francisco, CA
| | - Joseph Perl
- SLAC National Accelerator Laboratory, Menlo Park, CA
| | - Luc Beaulieu
- Département de Radio-Oncologie et Axe oncologie du Centre de recherche du CHU de Québec, CHU de Québec, Québec, QC, Canada; Département de Physique, de Génie Physique et d'Optique et Centre de Recherche sur le Cancer, Université Laval, Québec, QC, Canada.
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Evaluation of a collapsed-cone convolution algorithm for esophagus and surface mold 192Ir brachytherapy treatment planning. Brachytherapy 2020; 20:393-400. [PMID: 33071170 DOI: 10.1016/j.brachy.2020.09.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 09/08/2020] [Accepted: 09/10/2020] [Indexed: 11/20/2022]
Abstract
PURPOSE TG43 does not account for a lack of scatter and tissue and applicator heterogeneities. The advanced collapsed-cone engine (ACE) algorithm available for use in the Oncentra Brachy treatment planning system (Elekta AB, Stockholm, Sweden) can model these conditions more accurately and is evaluated for esophageal and surface mold brachytherapy treatments. METHODS AND MATERIALS ACE was commissioned for use then compared against TG43 for five esophageal and five surface mold treatment plans. Dosimetric differences between each algorithm were assessed using superimposed comparisons and dose-volume histogram statistics. RESULTS Esophagus (6 Gy per fraction): Compared with TG43, ACE demonstrated up to a 0.63% and 0.05 Gy reduction in planning target volume (PTV) V100% and PTV D98, respectively. Lung D2cc and bone D2cc deviated by up to 0.09 Gy and 0.03 Gy, respectively. Lung D0.1 cc and bone D0.1 cc both deviated by up to 0.12 Gy. Surface mold (4.5 Gy per fraction): Compared with TG43, ACE demonstrated up to a 12.5% and 0.18 Gy reduction in PTV V80% and PTV D98, respectively. Bone D2cc and D0.1 cc both reduced by up to 0.2 Gy when modeled with ACE. Increasing mold size laterally increased the dosimetric differences between TG43 and ACE. CONCLUSIONS TG43 generally overestimated dose delivered to the target volume and organs at risk for the sites investigated. Dosimetric differences observed for esophageal treatments were minimal; however, surface mold treatments would benefit from the increased dosimetric accuracy offered by ACE. Implementation should be considered for surface mold 192Ir treatment planning, but increased calculation time, additional contouring, and mass density assignment requirements should be scrutinized with regard to their potentially negative impact on current clinical practice.
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Kanani A, Owrangi AM, Mosleh-Shirazi MA. Comprehensive methodology for commissioning modern 3D-image-based treatment planning systems for high dose rate gynaecological brachytherapy: A review. Phys Med 2020; 77:21-29. [PMID: 32768917 DOI: 10.1016/j.ejmp.2020.07.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 07/19/2020] [Accepted: 07/28/2020] [Indexed: 12/12/2022] Open
Abstract
PURPOSE Correct commissioning of treatment planning systems (TPSs) is important for reducing treatment failure events. There is currently no comprehensive and robust methodology available for TPS commissioning in modern brachytherapy. This review aimed to develop a comprehensive template for commissioning modern 3D-image-based brachytherapy TPSs for high dose rate (HDR) gynaecological applications. METHODS The literature relevant to TPS commissioning, including both external beam radiation therapy (EBRT) and brachytherapy, as well as guidelines by the International Atomic Energy Agency (IAEA), the American Association of Physicists in Medicine (AAPM), and the European Society for Radiotherapy and Oncology (ESTRO) were searched, studied and appraised. The applied relevant EBRT TPS commissioning tests were applied to brachytherapy. The developed template aimed to cover all dosimetric and non-dosimetric issues. RESULTS The essential commissioning items could be categorized into six parts: geometry, dose calculation, plan evaluation tools, plan optimization, TPS output, and end-to-end verification. The final template consists of 43 items. This paper presents the purpose and role of each test, as well as tolerance limits, to facilitate the use of the template. CONCLUSION The information and recommendations available in a collection of publications over many years have been reviewed in order to develop a comprehensive template for commissioning complex modern 3D-image-based brachytherapy TPSs for HDR gynaecological applications. The up-to-date and concise information contained in the template can aid brachytherapy physicists during TPS commissioning as well as devising a regular quality assurance program and allocation of time and resources.
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Affiliation(s)
- Abolfazl Kanani
- Ionizing and Non-Ionizing Radiation Protection Research Center, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Amir M Owrangi
- Department of Radiation Oncology, UT Southwestern Medical Center, 2280 Inwood Rd, EC2.242, Dallas, TX 75235, USA
| | - Mohammad Amin Mosleh-Shirazi
- Ionizing and Non-Ionizing Radiation Protection Research Center, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran; Physics Unit, Department of Radio-oncology, School of Medicine, Shiraz University of Medical Sciences, Shiraz 71936-13311, Iran.
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Abstract
The purpose of this study was to review the limitations of dose calculation formalisms for photon-emitting brachytherapy sources based on the American Association of Physicists in Medicine (AAPM) Task Group No. 43 (TG-43) report and to provide recommendations to transition to model-based dose calculation algorithms. Additionally, an overview of these algorithms and approaches is presented. The influence of tissue and seed/applicator heterogeneities on brachytherapy dose distributions for breast, gynecologic, head and neck, rectum, and prostate cancers as well as eye plaques and electronic brachytherapy treatments were investigated by comparing dose calculations based on the TG-43 formalism and model-based dose calculation algorithms.
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A novel quality assurance system for eye plaque brachytherapy. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2019; 42:1109-1115. [PMID: 31728937 DOI: 10.1007/s13246-019-00808-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 10/16/2019] [Indexed: 10/25/2022]
Abstract
Eye Plaque brachytherapy pre-treatment quality assurance (QA) conducted clinically involves an activity verification of individual seeds via well chamber and does not include a physical measurement of dose-rate of the final assembly. A novel spectroscopic, dose-rate detection system, was evaluated for pre-treatment QA of eye plaque brachytherapy. The system includes a water phantom with sterility management. The system was calibrated using a known-activity I-125 seed, measured at 1 cm in water along the radial axis, compared to TG-43 U1 calculations and verified over a number of distances. A depth dose curve was acquired for a clinical, mixed activity eye plaque and two 'error' plaques. The probe was stepped from a water equivalent source to a detector distance (SDD) of 2.5 to 12 mm along the plaque central axis. The latter measurements aimed to characterise the sensitivity of the system. The calculated and measured single-seed dose-rates agreed to within 0.5 cGy/h from a SDD of 3 mm and above. The clinical plaque showed agreement between measured and treatment planning system (TPS) calculated dose-rates within 2%. Sensitivity testing resulted in a maximum deviation from TPS data of 18%, therefore was able to detect the presence of packing errors. The dose-rate detection system was successfully evaluated for verification of I-125 based eye plaques without compromising sterility, allowing for quick pre-treatment, dose-rate verification of patient-ready plaques. Its agreement with TPS data for the unmodified plaque and its deviation when introducing errors confirms the approach suggested is a viable QA tool.
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Robert C, Dumas I, Martinetti F, Chargari C, Haie-Meder C, Lefkopoulos D. Nouveaux algorithmes de calcul en curiethérapie pour les traitements par iridium 192. Cancer Radiother 2018; 22:319-325. [DOI: 10.1016/j.canrad.2017.11.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 11/15/2017] [Indexed: 10/16/2022]
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Verification of high-dose-rate brachytherapy treatment planning dose distribution using liquid-filled ionization chamber array. J Contemp Brachytherapy 2018; 10:142-154. [PMID: 29789763 PMCID: PMC5961529 DOI: 10.5114/jcb.2018.75599] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 03/23/2018] [Indexed: 11/23/2022] Open
Abstract
Purpose This study aims to investigate the dosimetric performance of a liquid-filled ionization chamber array in high-dose-rate (HDR) brachytherapy dosimetry. A comparative study was carried out with air-filled ionization chamber array and EBT3 Gafchromic films to demonstrate its suitability in brachytherapy. Material and methods The PTW OCTAVIUS detector 1000 SRS (IA 2.5-5 mm) is a liquid-filled ionization chamber array of area 11 x 11 cm2 and chamber spacing of 2.5-5 mm, whereas the PTW OCTAVIUS detector 729 (IA 10 mm) is an air vented ionization chamber array of area 27 x 27 cm2 and chamber spacing of 10 mm. EBT3 films were exposed to doses up to a maximum of 6 Gy and evaluated using multi-channel analysis. The detectors were evaluated using test plans to mimic a HDR intracavitary gynecological treatment. The plan was calculated and delivered with the applicator plane placed 20 mm from the detector plane. The acquired measurements were compared to the treatment plan. In addition to point dose measurement, profile/isodose, gamma analysis, and uncertainty analysis were performed. Detector sensitivity was evaluated by introducing simulated errors to the test plans. Results The mean point dose differences between measured and calculated plans were 0.2% ± 1.6%, 1.8% ± 1.0%, and 1.5% ± 0.81% for film, IA 10 mm, and IA 2.5-5 mm, respectively. The average percentage of passed gamma (global/local) values using 3%/3 mm criteria was above 99.8% for all three detectors on the original plan. For IA 2.5-5 mm, local gamma criteria of 2%/1 mm with a passing rate of at least 95% was found to be sensitive when simulated positional errors of 1 mm was introduced. Conclusion The dosimetric properties of IA 2.5-5 mm showed the applicability of liquid-filled ionization chamber array as a potential QA device for HDR brachytherapy treatment planning systems.
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Mann-Krzisnik D, Verhaegen F, Enger SA. The influence of tissue composition uncertainty on dose distributions in brachytherapy. Radiother Oncol 2018; 126:394-410. [PMID: 29428259 DOI: 10.1016/j.radonc.2018.01.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 12/31/2017] [Accepted: 01/05/2018] [Indexed: 11/26/2022]
Abstract
BACKGROUND AND PURPOSE Model-based dose calculation algorithms (MBDCAs) have evolved from serving as a research tool into clinical practice in brachytherapy. This study investigates primary sources of tissue elemental compositions used as input to MBDCAs and the impact of their variability on MBDCA-based dosimetry. MATERIALS AND METHODS Relevant studies were retrieved through PubMed. Minimum dose delivered to 90% of the target (D90), minimum dose delivered to the hottest specified volume for organs at risk (OAR) and mass energy-absorption coefficients (μen/ρ) generated by using EGSnrc "g" user-code were compared to assess the impact of compositional variability. RESULTS Elemental composition for hydrogen, carbon, oxygen and nitrogen are derived from the gross contents of fats, proteins and carbohydrates for any given tissue, the compositions of which are taken from literature dating back to 1940-1950. Heavier elements are derived from studies performed in the 1950-1960. Variability in elemental composition impacts greatly D90 for target tissues and doses to OAR for brachytherapy with low energy sources and less for 192Ir-based brachytherapy. Discrepancies in μen/ρ are also indicative of dose differences. CONCLUSIONS Updated elemental compositions are needed to optimize MBDCA-based dosimetry. Until then, tissue compositions based on gross simplifications in early studies will dominate the uncertainties in tissue heterogeneity.
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Affiliation(s)
| | - Frank Verhaegen
- Department of Radiation Oncology (MAASTRO), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre, The Netherlands
| | - Shirin A Enger
- Medical Physics Unit, McGill University, Montreal, Canada; Department of Oncology, McGill University, Montreal, Canada; Research Institute of the McGill University Health Centre, Montreal, Canada
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Zwierzchowski G, Bieleda G, Skowronek J. Quality Assurance Procedures based on Dosimetric, Gamma Analysis as a Fast Reliable Tool for Commissioning Brachytherapy Treatment Planning Systems. Radiol Oncol 2018; 51:469-474. [PMID: 29333127 PMCID: PMC5765325 DOI: 10.1515/raon-2017-0050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 10/10/2017] [Indexed: 11/15/2022] Open
Abstract
Background Fast and easily repeatable methods for commissioning procedures for brachytherapy (BT) treatment planning systems (TPS) are needed. Radiochromic film dosimetry with gamma analysis is widely used in external beam quality assurance (QA) procedures and planar film dosimetry is also increasingly used for verification of the dose distribution in BT applications. Using the gamma analysis method for comparing calculated and measured dose data could be used for commissioning procedures of the newly developed TG-186 and MBDCA calculation algorithms. The aim of this study was dosimetric verification of the calculation algorithm used in TPS when the CT/MRI ring applicator is used. Materials and methods Ring applicators with 26 and 30 mm diameters and a 60 mm intra-uterine tube with 60° angle were used for verification. Gafchromic® EBT films were used as dosimetric media. Dose grids, corresponding to each plane (dosimetric film location), were exported from the TPS as a raw data. Gafchromic® films were digitized after irradiation. gamma analysis of the data were performed using the OMNI Pro I’mRT® system, as recommended by the AAPM TG-119 rapport criterion for gamma analysis of 3%, 3 mm and a level of 95%. Results For the 26 mm and 30 mm rings, the average gamma ranged, respectively, from 0.1 to 0.44 and from 0.1 to 0.27. In both cases, 99% of the measured points corresponded with the calculated data. Conclusions This analysis showed excellent agreement between the dose distribution calculated with the TPS and the doses measured by Gafchromic films. This finding confirms the viability of using film dosimetry in BT.
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Affiliation(s)
- Grzegorz Zwierzchowski
- Poznan University of Medical Sciences, Faculty of Health Sciences, Poznana, Poland.,Greater Poland Cancer Centre, Medical Physics Department, Poznan, Poland
| | - Grzegorz Bieleda
- Poznan University of Medical Sciences, Faculty of Health Sciences, Poznana, Poland.,Greater Poland Cancer Centre, Medical Physics Department, Poznan, Poland
| | - Janusz Skowronek
- Poznan University of Medical Sciences, Faculty of Health Sciences, Poznana, Poland.,Greater Poland Cancer Centre, Brachytherapy Department, Poznan, Poland
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Tien CJ, Astrahan MA, Kim JM, Materin M, Chen Z, Nath R, Liu W. Incorporating patient-specific CT-based ophthalmic anatomy in modeling iodine-125 eye plaque brachytherapy dose distributions. Brachytherapy 2017; 16:1057-1064. [DOI: 10.1016/j.brachy.2017.06.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 06/30/2017] [Accepted: 06/30/2017] [Indexed: 12/18/2022]
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Jacob D, Lamberto M, DeSouza Lawrence L, Mourtada F. Clinical transition to model-based dose calculation algorithm: A retrospective analysis of high-dose-rate tandem and ring brachytherapy of the cervix. Brachytherapy 2017; 16:624-629. [DOI: 10.1016/j.brachy.2017.02.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 02/23/2017] [Accepted: 02/23/2017] [Indexed: 10/19/2022]
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Rivard MJ. A directional 103Pd brachytherapy device: Dosimetric characterization and practical aspects for clinical use. Brachytherapy 2016; 16:421-432. [PMID: 28039011 DOI: 10.1016/j.brachy.2016.11.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 11/10/2016] [Accepted: 11/29/2016] [Indexed: 02/08/2023]
Abstract
PURPOSE A brachytherapy (BT) device has been developed with shielding to provide directional BT for preferentially irradiating malignancies while sparing healthy tissues. The CivaSheet is a flexible low-dose-rate BT device containing CivaDots with 103Pd shielded by a thin Au disk. This is the first report of a clinical dosimetric characterization of the CivaSheet device. METHODS AND MATERIALS Radiation dose distributions near a CivaDot were estimated using the MCNP6 radiation transport code. CivaSheet arrays were also modeled to evaluate the dose superposition principle for treatment planning. The resultant data were commissioned in a treatment planning system (TPS) (VariSeed 9.0), and the accuracy of the dose superposition principle was evaluated for summing individual elements comprising a planar CivaSheet. RESULTS The dose-rate constant (0.579 cGy/h/U) was lower than for 103Pd seeds due to Au L-shell x-rays increasing the air-kerma strength. Radial dose function values at 0.1, 0.5, 2, 5, and 10 cm were 1.884, 1.344, 0.558, 0.088, and 0.0046, respectively. The two-dimensional anisotropy function exhibited dramatic reduction between the forward (0°) and rearward (180°) directions by a factor of 276 at r = 0.1 cm, 24 at r = 1 cm, and 5.3 at r = 10 cm. This effect diminished due to increasingly scattered radiation. The largest gradient in the two-dimensional anisotropy function was in contact with the device at 92° due to the Au disk shielding. TPS commissioning and dose superposition accuracies were typically within 2%. CONCLUSIONS Simulations of the CivaDot yielded comprehensive dosimetry parameters that were entered into a TPS and deemed acceptable for clinical use. Dosimetry measurements of the CivaSheet are also of interest to the BT community.
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Affiliation(s)
- Mark J Rivard
- Department of Radiation Oncology, Tufts University School of Medicine, Boston, MA.
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Giménez-Alventosa V, Antunes PCG, Vijande J, Ballester F, Pérez-Calatayud J, Andreo P. Collision-kerma conversion between dose-to-tissue and dose-to-water by photon energy-fluence corrections in low-energy brachytherapy. Phys Med Biol 2016; 62:146-164. [PMID: 27991455 DOI: 10.1088/1361-6560/aa4f6a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The AAPM TG-43 brachytherapy dosimetry formalism, introduced in 1995, has become a standard for brachytherapy dosimetry worldwide; it implicitly assumes that charged-particle equilibrium (CPE) exists for the determination of absorbed dose to water at different locations, except in the vicinity of the source capsule. Subsequent dosimetry developments, based on Monte Carlo calculations or analytical solutions of transport equations, do not rely on the CPE assumption and determine directly the dose to different tissues. At the time of relating dose to tissue and dose to water, or vice versa, it is usually assumed that the photon fluence in water and in tissues are practically identical, so that the absorbed dose in the two media can be related by their ratio of mass energy-absorption coefficients. In this work, an efficient way to correlate absorbed dose to water and absorbed dose to tissue in brachytherapy calculations at clinically relevant distances for low-energy photon emitting seeds is proposed. A correction is introduced that is based on the ratio of the water-to-tissue photon energy-fluences. State-of-the art Monte Carlo calculations are used to score photon fluence differential in energy in water and in various human tissues (muscle, adipose and bone), which in all cases include a realistic modelling of low-energy brachytherapy sources in order to benchmark the formalism proposed. The energy-fluence based corrections given in this work are able to correlate absorbed dose to tissue and absorbed dose to water with an accuracy better than 0.5% in the most critical cases (e.g. bone tissue).
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Affiliation(s)
- Vicent Giménez-Alventosa
- Department of Atomic, Molecular, and Nuclear Physics, University of Valencia, E46100 Burjassot, Spain
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Branco ISL, Antunes PCG, Fonseca GP, Yoriyaz H. Monte Carlo studies on water and LiF cavity properties for dose-reporting quantities when using x-ray and brachytherapy sources. Phys Med Biol 2016; 61:8890-8907. [DOI: 10.1088/1361-6560/61/24/8890] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Film based verification of calculation algorithms used for brachytherapy planning-getting ready for upcoming challenges of MBDCA. J Contemp Brachytherapy 2016; 8:326-35. [PMID: 27648087 PMCID: PMC5018527 DOI: 10.5114/jcb.2016.61828] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 07/29/2016] [Indexed: 11/17/2022] Open
Abstract
Purpose Well-known defect of TG-43 based algorithms used in brachytherapy is a lack of information about interaction cross-sections, which are determined not only by electron density but also by atomic number. TG-186 recommendations with using of MBDCA (model-based dose calculation algorithm), accurate tissues segmentation, and the structure's elemental composition continue to create difficulties in brachytherapy dosimetry. For the clinical use of new algorithms, it is necessary to introduce reliable and repeatable methods of treatment planning systems (TPS) verification. The aim of this study is the verification of calculation algorithm used in TPS for shielded vaginal applicators as well as developing verification procedures for current and further use, based on the film dosimetry method. Material and methods Calibration data was collected by separately irradiating 14 sheets of Gafchromic® EBT films with the doses from 0.25 Gy to 8.0 Gy using HDR 192Ir source. Standard vaginal cylinders of three diameters were used in the water phantom. Measurements were performed without any shields and with three shields combination. Gamma analyses were performed using the VeriSoft® package. Results Calibration curve was determined as third-degree polynomial type. For all used diameters of unshielded cylinder and for all shields combinations, Gamma analysis were performed and showed that over 90% of analyzed points meets Gamma criteria (3%, 3 mm). Conclusions Gamma analysis showed good agreement between dose distributions calculated using TPS and measured by Gafchromic films, thus showing the viability of using film dosimetry in brachytherapy.
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Ma Y, Lacroix F, Lavallée MC, Beaulieu L. Validation of the Oncentra Brachy Advanced Collapsed cone Engine for a commercial (192)Ir source using heterogeneous geometries. Brachytherapy 2015; 14:939-52. [PMID: 26403533 DOI: 10.1016/j.brachy.2015.08.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 07/27/2015] [Accepted: 08/09/2015] [Indexed: 01/29/2023]
Abstract
PURPOSE To validate the Advanced Collapsed cone Engine (ACE) dose calculation engine of Oncentra Brachy (OcB) treatment planning system using an (192)Ir source. METHODS AND MATERIALS Two levels of validation were performed, conformant to the model-based dose calculation algorithm commissioning guidelines of American Association of Physicists in Medicine TG-186 report. Level 1 uses all-water phantoms, and the validation is against TG-43 methodology. Level 2 uses real-patient cases, and the validation is against Monte Carlo (MC) simulations. For each case, the ACE and TG-43 calculations were performed in the OcB treatment planning system. ALGEBRA MC system was used to perform MC simulations. RESULTS In Level 1, the ray effect depends on both accuracy mode and the number of dwell positions. The volume fraction with dose error ≥2% quickly reduces from 23% (13%) for a single dwell to 3% (2%) for eight dwell positions in the standard (high) accuracy mode. In Level 2, the 10% and higher isodose lines were observed overlapping between ACE (both standard and high-resolution modes) and MC. Major clinical indices (V100, V150, V200, D90, D50, and D2cc) were investigated and validated by MC. For example, among the Level 2 cases, the maximum deviation in V100 of ACE from MC is 2.75% but up to ~10% for TG-43. Similarly, the maximum deviation in D90 is 0.14 Gy between ACE and MC but up to 0.24 Gy for TG-43. CONCLUSION ACE demonstrated good agreement with MC in most clinically relevant regions in the cases tested. Departure from MC is significant for specific situations but limited to low-dose (<10% isodose) regions.
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Affiliation(s)
- Yunzhi Ma
- Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec, Canada; Département de radio-oncologie et CRCHU de Québec, CHU de Québec, Québec, Canada.
| | - Fréderic Lacroix
- Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec, Canada
| | - Marie-Claude Lavallée
- Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec, Canada
| | - Luc Beaulieu
- Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec, Canada; Département de radio-oncologie et CRCHU de Québec, CHU de Québec, Québec, Canada
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Fonseca GP, Tedgren ÅC, Reniers B, Nilsson J, Persson M, Yoriyaz H, Verhaegen F. Dose specification for192Ir high dose rate brachytherapy in terms of dose-to-water-in-medium and dose-to-medium-in-medium. Phys Med Biol 2015; 60:4565-79. [DOI: 10.1088/0031-9155/60/11/4565] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Multi-axis dose accumulation of noninvasive image-guided breast brachytherapy through biomechanical modeling of tissue deformation using the finite element method. J Contemp Brachytherapy 2015; 7:55-71. [PMID: 25829938 PMCID: PMC4371066 DOI: 10.5114/jcb.2015.49355] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 01/29/2015] [Accepted: 02/01/2015] [Indexed: 01/08/2023] Open
Abstract
PURPOSE Noninvasive image-guided breast brachytherapy delivers conformal HDR (192)Ir brachytherapy treatments with the breast compressed, and treated in the cranial-caudal and medial-lateral directions. This technique subjects breast tissue to extreme deformations not observed for other disease sites. Given that, commercially-available software for deformable image registration cannot accurately co-register image sets obtained in these two states, a finite element analysis based on a biomechanical model was developed to deform dose distributions for each compression circumstance for dose summation. MATERIAL AND METHODS The model assumed the breast was under planar stress with values of 30 kPa for Young's modulus and 0.3 for Poisson's ratio. Dose distributions from round and skin-dose optimized applicators in cranial-caudal and medial-lateral compressions were deformed using 0.1 cm planar resolution. Dose distributions, skin doses, and dose-volume histograms were generated. Results were examined as a function of breast thickness, applicator size, target size, and offset distance from the center. RESULTS Over the range of examined thicknesses, target size increased several millimeters as compression thickness decreased. This trend increased with increasing offset distances. Applicator size minimally affected target coverage, until applicator size was less than the compressed target size. In all cases, with an applicator larger or equal to the compressed target size, > 90% of the target covered by > 90% of the prescription dose. In all cases, dose coverage became less uniform as offset distance increased and average dose increased. This effect was more pronounced for smaller target-applicator combinations. CONCLUSIONS The model exhibited skin dose trends that matched MC-generated benchmarking results within 2% and clinical observations over a similar range of breast thicknesses and target sizes. The model provided quantitative insight on dosimetric treatment variables over a range of clinical circumstances. These findings highlight the need for careful target localization and accurate identification of compression thickness and target offset.
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Zwierzchowski G. In regard to: “Dosimetric verification of a high dose rate brachytherapy treatment planning system in homogeneous and heterogeneous media”. Phys Med 2014; 30:865-6. [DOI: 10.1016/j.ejmp.2014.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 10/06/2014] [Accepted: 10/08/2014] [Indexed: 10/24/2022] Open
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Collins Fekete CA, Plamondon M, Martin AG, Vigneault É, Verhaegen F, Beaulieu L. Quantifying the effect of seed orientation in postplanning dosimetry of low-dose-rate prostate brachytherapy. Med Phys 2014; 41:101704. [DOI: 10.1118/1.4895012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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Camgöz B, Kumru MN. A Monte Carlo evaluation for effects of probable dimensional uncertainties of low dose rate brachytherapy seeds on dose. Rep Pract Oncol Radiother 2014; 19:301-9. [PMID: 25184054 DOI: 10.1016/j.rpor.2014.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 09/17/2013] [Accepted: 01/07/2014] [Indexed: 10/25/2022] Open
Abstract
The aim of this study is to determine effects of size deviations of brachytherapy seeds on two dimensional dose distributions around the seed. Although many uncertainties are well known, the uncertainties which stem from geometric features of radiation sources are weakly considered and predicted. Neither TG-43 report which is not completely in common consensus, nor individual scientific MC and experimental studies include sufficient data for geometric uncertainties. Sizes of seed and its components can vary in a manufacturing deviation. This causes geometrical uncertainties, too. In this study, three seeds which have different geometrical properties were modeled using EGSnrc-Code Packages. Seeds were designed with all their details using the geometry package. 5% deviations of seed sizes were assumed. Modified seeds were derived from original seed by changing sizes by 5%. Normalizations of doses which were calculated from three kinds of brachytherapy seed and their derivations were found to be about 3%-20%. It was shown that manufacturing differences of brachytherapy seed cause considerable changes in dose distribution.
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Affiliation(s)
- Berkay Camgöz
- Ege University, Institute of Nuclear Sciences, 35100 Bornova, Izmir, Turkey
| | - Mehmet N Kumru
- Ege University, Institute of Nuclear Sciences, 35100 Bornova, Izmir, Turkey
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Abstract
Dosimetric audit is required for the improvement of patient safety in radiotherapy and to aid optimization of treatment. The reassurance that treatment is being delivered in line with accepted standards, that delivered doses are as prescribed and that quality improvement is enabled is as essential for brachytherapy as it is for the more commonly audited external beam radiotherapy. Dose measurement in brachytherapy is challenging owing to steep dose gradients and small scales, especially in the context of an audit. Several different approaches have been taken for audit measurement to date: thimble and well-type ionization chambers, thermoluminescent detectors, optically stimulated luminescence detectors, radiochromic film and alanine. In this work, we review all of the dosimetric brachytherapy audits that have been conducted in recent years, look at current audits in progress and propose required directions for brachytherapy dosimetric audit in the future. The concern over accurate source strength measurement may be essentially resolved with modern equipment and calibration methods, but brachytherapy is a rapidly developing field and dosimetric audit must keep pace.
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Affiliation(s)
- A L Palmer
- Department of Physics, Faculty of Engineering and Physical Science, University of Surrey, UK
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31
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Chibani O, C-M Ma C. HDRMC, an accelerated Monte Carlo dose calculator for high dose rate brachytherapy with CT-compatible applicators. Med Phys 2014; 41:051712. [DOI: 10.1118/1.4873318] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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ACPSEM brachytherapy working group recommendations for quality assurance in brachytherapy. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2013; 36:387-96. [DOI: 10.1007/s13246-013-0228-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Zourari K, Pantelis E, Moutsatsos A, Sakelliou L, Georgiou E, Karaiskos P, Papagiannis P. Dosimetric accuracy of a deterministic radiation transport based (192)Ir brachytherapy treatment planning system. Part III. Comparison to Monte Carlo simulation in voxelized anatomical computational models. Med Phys 2013; 40:011712. [PMID: 23298082 DOI: 10.1118/1.4770275] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To compare TG43-based and Acuros deterministic radiation transport-based calculations of the BrachyVision treatment planning system (TPS) with corresponding Monte Carlo (MC) simulation results in heterogeneous patient geometries, in order to validate Acuros and quantify the accuracy improvement it marks relative to TG43. METHODS Dosimetric comparisons in the form of isodose lines, percentage dose difference maps, and dose volume histogram results were performed for two voxelized mathematical models resembling an esophageal and a breast brachytherapy patient, as well as an actual breast brachytherapy patient model. The mathematical models were converted to digital imaging and communications in medicine (DICOM) image series for input to the TPS. The MCNP5 v.1.40 general-purpose simulation code input files for each model were prepared using information derived from the corresponding DICOM RT exports from the TPS. RESULTS Comparisons of MC and TG43 results in all models showed significant differences, as reported previously in the literature and expected from the inability of the TG43 based algorithm to account for heterogeneities and model specific scatter conditions. A close agreement was observed between MC and Acuros results in all models except for a limited number of points that lay in the penumbra of perfectly shaped structures in the esophageal model, or at distances very close to the catheters in all models. CONCLUSIONS Acuros marks a significant dosimetry improvement relative to TG43. The assessment of the clinical significance of this accuracy improvement requires further work. Mathematical patient equivalent models and models prepared from actual patient CT series are useful complementary tools in the methodology outlined in this series of works for the benchmarking of any advanced dose calculation algorithm beyond TG43.
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Affiliation(s)
- K Zourari
- Medical School, University of Athens, Athens, Greece.
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Mikell JK, Klopp AH, Price M, Mourtada F. Commissioning of a grid-based Boltzmann solver for cervical cancer brachytherapy treatment planning with shielded colpostats. Brachytherapy 2013; 12:645-53. [PMID: 23891341 DOI: 10.1016/j.brachy.2013.04.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 04/02/2013] [Accepted: 04/05/2013] [Indexed: 10/26/2022]
Abstract
PURPOSE We sought to commission a gynecologic shielded colpostat analytic model provided from a treatment planning system (TPS) library. We have reported retrospectively the dosimetric impact of this applicator model in a cohort of patients. METHODS AND MATERIALS A commercial TPS with a grid-based Boltzmann solver (GBBS) was commissioned for (192)Ir high-dose-rate (HDR) brachytherapy for cervical cancer with stainless steel-shielded colpostats. Verification of the colpostat analytic model was verified using a radiograph and vendor schematics. MCNPX v2.6 Monte Carlo simulations were performed to compare dose distributions around the applicator in water with the TPS GBBS dose predictions. Retrospectively, the dosimetric impact was assessed over 24 cervical cancer patients' HDR plans. RESULTS Applicator (TPS ID #AL13122005) shield dimensions were within 0.4 mm of the independent shield dimensions verification. GBBS profiles in planes bisecting the cap around the applicator agreed with Monte Carlo simulations within 2% at most locations; differing screw representations resulted in differences of up to 9%. For the retrospective study, the GBBS doses differed from TG-43 as follows (mean value ± standard deviation [min, max]): International Commission on Radiation units [ICRU]rectum (-8.4 ± 2.5% [-14.1, -4.1%]), ICRUbladder (-7.2 ± 3.6% [-15.7, -2.1%]), D2cc-rectum (-6.2 ± 2.6% [-11.9, -0.8%]), D2cc-sigmoid (-5.6 ± 2.6% [-9.3, -2.0%]), and D2cc-bladder (-3.4 ± 1.9% [-7.2, -1.1%]). CONCLUSIONS As brachytherapy TPSs implement advanced model-based dose calculations, the analytic applicator models stored in TPSs should be independently validated before clinical use. For this cohort, clinically meaningful differences (>5%) from TG-43 were observed. Accurate dosimetric modeling of shielded applicators may help to refine organ toxicity studies.
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Affiliation(s)
- Justin K Mikell
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX; Department of Radiation Physics, The University of Texas MD Anderson Cancer, Houston, TX
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Tedgren ÅC, Carlsson GA. Specification of absorbed dose to water using model-based dose calculation algorithms for treatment planning in brachytherapy. Phys Med Biol 2013; 58:2561-79. [PMID: 23528349 DOI: 10.1088/0031-9155/58/8/2561] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Model-based dose calculation algorithms (MBDCAs), recently introduced in treatment planning systems (TPS) for brachytherapy, calculate tissue absorbed doses. In the TPS framework, doses have hereto been reported as dose to water and water may still be preferred as a dose specification medium. Dose to tissue medium Dmed then needs to be converted into dose to water in tissue Dw,med. Methods to calculate absorbed dose to differently sized water compartments/cavities inside tissue, infinitesimal (used for definition of absorbed dose), small, large or intermediate, are reviewed. Burlin theory is applied to estimate photon energies at which cavity sizes in the range 1 nm-10 mm can be considered small or large. Photon and electron energy spectra are calculated at 1 cm distance from the central axis in cylindrical phantoms of bone, muscle and adipose tissue for 20, 50, 300 keV photons and photons from (125)I, (169)Yb and (192)Ir sources; ratios of mass-collision-stopping powers and mass energy absorption coefficients are calculated as applicable to convert Dmed into Dw,med for small and large cavities. Results show that 1-10 nm sized cavities are small at all investigated photon energies; 100 µm cavities are large only at photon energies <20 keV. A choice of an appropriate conversion coefficient Dw, med/Dmed is discussed in terms of the cavity size in relation to the size of important cellular targets. Free radicals from DNA bound water of nanometre dimensions contribute to DNA damage and cell killing and may be the most important water compartment in cells implying use of ratios of mass-collision-stopping powers for converting Dmed into Dw,med.
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Affiliation(s)
- Åsa Carlsson Tedgren
- Radiation Physics, Department of Medical and Health Sciences, Linköping University and Center of Medical Image Science and Visualization, SE-581 85 Linköping, Sweden.
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36
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Uniyal S, Sharma S, Naithani U. Dosimetric verification of a high dose rate brachytherapy treatment planning system in homogeneous and heterogeneous media. Phys Med 2013; 29:171-7. [DOI: 10.1016/j.ejmp.2012.01.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 12/02/2011] [Accepted: 01/17/2012] [Indexed: 10/28/2022] Open
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Chiu-Tsao ST, Astrahan MA, Finger PT, Followill DS, Meigooni AS, Melhus CS, Mourtada F, Napolitano ME, Nath R, Rivard MJ, Rogers DWO, Thomson RM. Dosimetry of (125)I and (103)Pd COMS eye plaques for intraocular tumors: report of Task Group 129 by the AAPM and ABS. Med Phys 2012; 39:6161-84. [PMID: 23039655 DOI: 10.1118/1.4749933] [Citation(s) in RCA: 146] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Dosimetry of eye plaques for ocular tumors presents unique challenges in brachytherapy. The challenges in accurate dosimetry are in part related to the steep dose gradient in the tumor and critical structures that are within millimeters of radioactive sources. In most clinical applications, calculations of dose distributions around eye plaques assume a homogenous water medium and full scatter conditions. Recent Monte Carlo (MC)-based eye-plaque dosimetry simulations have demonstrated that the perturbation effects of heterogeneous materials in eye plaques, including the gold-alloy backing and Silastic insert, can be calculated with reasonable accuracy. Even additional levels of complexity introduced through the use of gold foil "seed-guides" and custom-designed plaques can be calculated accurately using modern MC techniques. Simulations accounting for the aforementioned complexities indicate dose discrepancies exceeding a factor of ten to selected critical structures compared to conventional dose calculations. Task Group 129 was formed to review the literature; re-examine the current dosimetry calculation formalism; and make recommendations for eye-plaque dosimetry, including evaluation of brachytherapy source dosimetry parameters and heterogeneity correction factors. A literature review identified modern assessments of dose calculations for Collaborative Ocular Melanoma Study (COMS) design plaques, including MC analyses and an intercomparison of treatment planning systems (TPS) detailing differences between homogeneous and heterogeneous plaque calculations using the American Association of Physicists in Medicine (AAPM) TG-43U1 brachytherapy dosimetry formalism and MC techniques. This review identified that a commonly used prescription dose of 85 Gy at 5 mm depth in homogeneous medium delivers about 75 Gy and 69 Gy at the same 5 mm depth for specific (125)I and (103)Pd sources, respectively, when accounting for COMS plaque heterogeneities. Thus, the adoption of heterogeneous dose calculation methods in clinical practice would result in dose differences >10% and warrant a careful evaluation of the corresponding changes in prescription doses. Doses to normal ocular structures vary with choice of radionuclide, plaque location, and prescription depth, such that further dosimetric evaluations of the adoption of MC-based dosimetry methods are needed. The AAPM and American Brachytherapy Society (ABS) recommend that clinical medical physicists should make concurrent estimates of heterogeneity-corrected delivered dose using the information in this report's tables to prepare for brachytherapy TPS that can account for material heterogeneities and for a transition to heterogeneity-corrected prescriptive goals. It is recommended that brachytherapy TPS vendors include material heterogeneity corrections in their systems and take steps to integrate planned plaque localization and image guidance. In the interim, before the availability of commercial MC-based brachytherapy TPS, it is recommended that clinical medical physicists use the line-source approximation in homogeneous water medium and the 2D AAPM TG-43U1 dosimetry formalism and brachytherapy source dosimetry parameter datasets for treatment planning calculations. Furthermore, this report includes quality management program recommendations for eye-plaque brachytherapy.
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Beaulieu L, Carlsson Tedgren A, Carrier JF, Davis SD, Mourtada F, Rivard MJ, Thomson RM, Verhaegen F, Wareing TA, Williamson JF. Report of the Task Group 186 on model-based dose calculation methods in brachytherapy beyond the TG-43 formalism: Current status and recommendations for clinical implementation. Med Phys 2012; 39:6208-36. [PMID: 23039658 DOI: 10.1118/1.4747264] [Citation(s) in RCA: 345] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Luc Beaulieu
- Département de Radio-Oncologie, Centre hospitalier universitaire de Québec, Québec, Québec G1R 2J6, Canada.
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39
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Enger SA, Ahnesjö A, Verhaegen F, Beaulieu L. Dose to tissue medium or water cavities as surrogate for the dose to cell nuclei at brachytherapy photon energies. Phys Med Biol 2012; 57:4489-500. [DOI: 10.1088/0031-9155/57/14/4489] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Palmer A, Bradley D, Nisbet A. Physics-aspects of dose accuracy in high dose rate (HDR) brachytherapy: source dosimetry, treatment planning, equipment performance and in vivo verification techniques. J Contemp Brachytherapy 2012; 4:81-91. [PMID: 23349649 PMCID: PMC3552629 DOI: 10.5114/jcb.2012.29364] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2012] [Revised: 04/14/2012] [Accepted: 05/05/2012] [Indexed: 11/17/2022] Open
Abstract
This study provides a review of recent publications on the physics-aspects of dosimetric accuracy in high dose rate (HDR) brachytherapy. The discussion of accuracy is primarily concerned with uncertainties, but methods to improve dose conformation to the prescribed intended dose distribution are also noted. The main aim of the paper is to review current practical techniques and methods employed for HDR brachytherapy dosimetry. This includes work on the determination of dose rate fields around brachytherapy sources, the capability of treatment planning systems, the performance of treatment units and methods to verify dose delivery. This work highlights the determinants of accuracy in HDR dosimetry and treatment delivery and presents a selection of papers, focusing on articles from the last five years, to reflect active areas of research and development. Apart from Monte Carlo modelling of source dosimetry, there is no clear consensus on the optimum techniques to be used to assure dosimetric accuracy through all the processes involved in HDR brachytherapy treatment. With the exception of the ESTRO mailed dosimetry service, there is little dosimetric audit activity reported in the literature, when compared with external beam radiotherapy verification.
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Affiliation(s)
- Antony Palmer
- Department of Physics, Faculty of Engineering and Physical Science, University of Surrey, United Kingdom
- Medical Physics Department, Queen Alexandra Hospital, Portsmouth Hospitals NHS Trust, Portsmouth, United Kingdom
| | - David Bradley
- Department of Physics, Faculty of Engineering and Physical Science, University of Surrey, United Kingdom
| | - Andrew Nisbet
- Department of Physics, Faculty of Engineering and Physical Science, University of Surrey, United Kingdom
- Medical Physics Department, Royal Surrey County Hospital NHS Foundation Trust, Guildford, United Kingdom
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Perez-Calatayud J, Ballester F, Das RK, Dewerd LA, Ibbott GS, Meigooni AS, Ouhib Z, Rivard MJ, Sloboda RS, Williamson JF. Dose calculation for photon-emitting brachytherapy sources with average energy higher than 50 keV: Report of the AAPM and ESTRO. Med Phys 2012; 39:2904-29. [PMID: 22559663 DOI: 10.1118/1.3703892] [Citation(s) in RCA: 196] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Affiliation(s)
- Jose Perez-Calatayud
- Radiotherapy Department, La Fe Polytechnic and University Hospital, Valencia, Spain
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Mikell JK, Klopp AH, Gonzalez GMN, Kisling KD, Price MJ, Berner PA, Eifel PJ, Mourtada F. Impact of heterogeneity-based dose calculation using a deterministic grid-based Boltzmann equation solver for intracavitary brachytherapy. Int J Radiat Oncol Biol Phys 2012; 83:e417-22. [PMID: 22436788 DOI: 10.1016/j.ijrobp.2011.12.074] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Accepted: 12/18/2011] [Indexed: 11/30/2022]
Abstract
PURPOSE To investigate the dosimetric impact of the heterogeneity dose calculation Acuros (Transpire Inc., Gig Harbor, WA), a grid-based Boltzmann equation solver (GBBS), for brachytherapy in a cohort of cervical cancer patients. METHODS AND MATERIALS The impact of heterogeneities was retrospectively assessed in treatment plans for 26 patients who had previously received (192)Ir intracavitary brachytherapy for cervical cancer with computed tomography (CT)/magnetic resonance-compatible tandems and unshielded colpostats. The GBBS models sources, patient boundaries, applicators, and tissue heterogeneities. Multiple GBBS calculations were performed with and without solid model applicator, with and without overriding the patient contour to 1 g/cm(3) muscle, and with and without overriding contrast materials to muscle or 2.25 g/cm(3) bone. Impact of source and boundary modeling, applicator, tissue heterogeneities, and sensitivity of CT-to-material mapping of contrast were derived from the multiple calculations. American Association of Physicists in Medicine Task Group 43 (TG-43) guidelines and the GBBS were compared for the following clinical dosimetric parameters: Manchester points A and B, International Commission on Radiation Units and Measurements (ICRU) report 38 rectal and bladder points, three and nine o'clock, and (D2cm3) to the bladder, rectum, and sigmoid. RESULTS Points A and B, D(2) cm(3) bladder, ICRU bladder, and three and nine o'clock were within 5% of TG-43 for all GBBS calculations. The source and boundary and applicator account for most of the differences between the GBBS and TG-43 guidelines. The D(2cm3) rectum (n = 3), D(2cm3) sigmoid (n = 1), and ICRU rectum (n = 6) had differences of >5% from TG-43 for the worst case incorrect mapping of contrast to bone. Clinical dosimetric parameters were within 5% of TG-43 when rectal and balloon contrast were mapped to bone and radiopaque packing was not overridden. CONCLUSIONS The GBBS has minimal impact on clinical parameters for this cohort of patients with unshielded applicators. The incorrect mapping of rectal and balloon contrast does not have a significant impact on clinical parameters. Rectal parameters may be sensitive to the mapping of radiopaque packing.
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Affiliation(s)
- Justin K Mikell
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
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43
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Hyer DE, Sheybani A, Jacobson GM, Kim Y. The dosimetric impact of heterogeneity corrections in high-dose-rate ¹⁹²Ir brachytherapy for cervical cancer: Investigation of both conventional Point-A and volume-optimized plans. Brachytherapy 2012; 11:515-20. [PMID: 22386723 DOI: 10.1016/j.brachy.2012.01.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 12/19/2011] [Accepted: 01/16/2012] [Indexed: 11/18/2022]
Abstract
PURPOSE To evaluate the dosimetric impact of heterogeneity corrections on both conventional and volume-optimized high-dose-rate (HDR) ¹⁹²Ir brachytherapy tandem-and-ovoid treatment plans. METHODS AND MATERIALS Both conventional and volume-optimized treatment plans were retrospectively created using eight unique CT data sets. In the volume-optimized plans, the clinical target volume (CTV) and organs-at-risk (rectum, bladder, and sigmoid) were contoured on the CT data sets by a single physician. For each plan, dose calculations representing homogeneous water medium were performed using the Task Group (TG-43) formalism and dose calculations with heterogeneity corrections were performed using a commercially available treatment planning system. RESULTS For the conventional plans, the change in dose between TG-43 and heterogeneity-corrected calculations was assessed for the following points: Point-A (left and right) and International Commission on Radiation Units and Measurements (ICRU) 38 defined rectum and bladder points. It was found that the dose to the ICRU bladder decreased the most (-2.2±0.9%), whereas ICRU rectum (-1.7±0.8%), Point-A right (-1.1±0.4%), and Point-A left (-1.0±0.3%) also showed decreases with heterogeneity-corrected calculations. For the volume-optimized plans, the change in dose between TG-43 and heterogeneity-corrected calculations was assessed for the following dose-volume histogram parameters: D(90) of the CTV and D(2cc) of the rectum, bladder, and sigmoid. It was found that D(90) of the CTV decreased by -1.9±0.7% and D(2cc) decreased by -2.6±1.4%, -1.0±0.4%, and -2.0±0.6% for the rectum, bladder and sigmoid, respectively, with heterogeneity-corrected calculations. CONCLUSIONS Heterogeneity corrections on high-dose rate plans were found to have only a small dosimetric impact over TG-43-based dose calculations for both conventional Point-A and volume-optimized plans.
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Affiliation(s)
- Daniel E Hyer
- Department of Radiation Oncology, University of Iowa, Iowa City, IA, USA
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44
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Yang Y, Rivard MJ. Evaluation of brachytherapy lung implant dose distributions from photon-emitting sources due to tissue heterogeneities. Med Phys 2012; 38:5857-62. [PMID: 22047349 DOI: 10.1118/1.3641872] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
PURPOSE Photon-emitting brachytherapy sources are used for permanent implantation to treat lung cancer. However, the current brachytherapy dose calculation formalism assumes a homogeneous water medium without considering the influence of radiation scatter or tissue heterogeneities. The purpose of this study was to determine the dosimetric effects of tissue heterogeneities for permanent lung brachytherapy. METHODS The MCNP5 v1.40 radiation transport code was used for Monte Carlo (MC) simulations. Point sources with energies of 0.02, 0.03, 0.05, 0.1, 0.2, and 0.4 MeV were simulated to cover the range of pertinent brachytherapy energies and to glean dosimetric trends independent of specific radionuclide emissions. Source positions from postimplant CT scans of five patient implants were used for source coordinates, with dose normalized to 200 Gy at the center of each implant. With the presence of fibrosis (around the implant), cortical bone, lung, and healthy tissues, dose distributions and (PTV)DVH were calculated using the MCNP ∗FMESH4 tally and the NIST mass-energy absorption coefficients. This process was repeated upon replacing all tissues with water. For all photon energies, 10(9) histories were simulated to achieve statistical errors (k = 1) typically of 1%. RESULTS The mean PTV doses calculated using tissue heterogeneities for all five patients changed (compared to dose to water) by only a few percent over the examined photon energy range, as did PTV dose at the implant center. The (PTV)V(100) values were 81.2%, 90.0% (as normalized), 94.3%, 93.9%, 92.7%, and 92.2% for 0.02, 0.03, 0.05, 0.1, 0.2, and 0.4 MeV source photons, respectively. Relative to water, the maximum bone doses were higher by factors of 3.7, 5.1, 5.2, 2.4, 1.2, and 1.0 The maximum lung doses were about 0.98, 0.94, 0.91, 0.94, 0.97, and 0.99. Relative to water, the maximum healthy tissue doses at the mediastinal position were higher by factors of 9.8, 2.2, 1.3, 1.1, 1.1, and 1.1. However, the maximum doses to these healthy tissues were only 3.1, 7.2, 11.3, 10.9, 9.0, and 8.1 Gy while maximum bone doses were 66, 177, 236, 106, 49, and 39 Gy, respectively. Similarly, maximum lung doses were 55, 66, 73, 74, 73, and 73 Gy, respectively. CONCLUSIONS The current brachytherapy dose calculation formalism overestimates PTV dose and significantly underestimates doses to bone and healthy tissue. Further investigation using specific brachytherapy source models and patient-based CT datasets as MC input may indicate whether the observed trends can be generalized for low-energy lung brachytherapy dosimetry.
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Affiliation(s)
- Yun Yang
- Tufts University School of Medicine, Boston, MA 02111, USA
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Deufel C, Furutani KM, Thomson RM, Antolak JA. Mathematical solutions of the TG-43 geometry function for curved line, ring, disk, sphere, dome and annulus sources, and applications for quality assurance. Phys Med Biol 2011; 56:5429-44. [DOI: 10.1088/0031-9155/56/16/022] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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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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Rivard MJ, Chiu-Tsao ST, Finger PT, Meigooni AS, Melhus CS, Mourtada F, Napolitano ME, Rogers DWO, Thomson RM, Nath R. Comparison of dose calculation methods for brachytherapy of intraocular tumors. Med Phys 2011; 38:306-16. [PMID: 21361199 DOI: 10.1118/1.3523614] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To investigate dosimetric differences among several clinical treatment planning systems (TPS) and Monte Carlo (MC) codes for brachytherapy of intraocular tumors using 125I or 103Pd plaques, and to evaluate the impact on the prescription dose of the adoption of MC codes and certain versions of a TPS (Plaque Simulator with optional modules). METHODS Three clinical brachytherapy TPS capable of intraocular brachytherapy treatment planning and two MC codes were compared. The TPS investigated were Pinnacle v8.0dp1, BrachyVision v8.1, and Plaque Simulator v5.3.9, all of which use the AAPM TG-43 formalism in water. The Plaque Simulator software can also handle some correction factors from MC simulations. The MC codes used are MCNP5 v1.40 and BrachyDose/EGSnrc. Using these TPS and MC codes, three types of calculations were performed: homogeneous medium with point sources (for the TPS only, using the 1D TG-43 dose calculation formalism); homogeneous medium with line sources (TPS with 2D TG-43 dose calculation formalism and MC codes); and plaque heterogeneity-corrected line sources (Plaque Simulator with modified 2D TG-43 dose calculation formalism and MC codes). Comparisons were made of doses calculated at points-of-interest on the plaque central-axis and at off-axis points of clinical interest within a standardized model of the right eye. RESULTS For the homogeneous water medium case, agreement was within approximately 2% for the point- and line-source models when comparing between TPS and between TPS and MC codes, respectively. For the heterogeneous medium case, dose differences (as calculated using the MC codes and Plaque Simulator) differ by up to 37% on the central-axis in comparison to the homogeneous water calculations. A prescription dose of 85 Gy at 5 mm depth based on calculations in a homogeneous medium delivers 76 Gy and 67 Gy for specific 125I and 103Pd sources, respectively, when accounting for COMS-plaque heterogeneities. For off-axis points-of-interest, dose differences approached factors of 7 and 12 at some positions for 125I and 103Pd, respectively. There was good agreement (approximately 3%) among MC codes and Plaque Simulator results when appropriate parameters calculated using MC codes were input into Plaque Simulator. Plaque Simulator and MC users are perhaps at risk of overdosing patients up to 20% if heterogeneity corrections are used and the prescribed dose is not modified appropriately. CONCLUSIONS Agreement within 2% was observed among conventional brachytherapy TPS and MC codes for intraocular brachytherapy dose calculations in a homogeneous water environment. In general, the magnitude of dose errors incurred by ignoring the effect of the plaque backing and Silastic insert (i.e., by using the TG-43 approach) increased with distance from the plaque's central-axis. Considering the presence of material heterogeneities in a typical eye plaque, the best method in this study for dose calculations is a verified MC simulation.
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Affiliation(s)
- Mark J Rivard
- Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
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Yang Y, Melhus CS, Sioshansi S, Rivard MJ. Treatment planning of a skin-sparing conical breast brachytherapy applicator using conventional brachytherapy software. Med Phys 2011; 38:1519-25. [PMID: 21520863 PMCID: PMC3060933 DOI: 10.1118/1.3552921] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 01/06/2011] [Accepted: 01/15/2011] [Indexed: 11/07/2022] Open
Abstract
PURPOSE AccuBoost is a noninvasive image-guided technique for the delivery of partial breast irradiation to the tumor bed and currently serves as an alternate to conventional electron beam boost. To irradiate the target volume while providing dose sparing to the skin, the round applicator design was augmented through the addition of an internally truncated conical shield and the reduction of the source to skin distance. METHODS Brachytherapy dose distributions for two types of conical applicators were simulated and estimated using Monte Carlo (MC) methods for radiation transport and a conventional treatment planning system (TPS). MC-derived and TPS-generated dose volume histograms (DVHs) and dose distribution data were compared for both the conical and round applicators for benchmarking purposes. RESULTS Agreement using the gamma-index test was > or = 99.95% for distance to agreement and dose accuracy criteria of 2 mm and 2%, respectively. After observing good agreement, TPS DVHs and dose distributions for the conical and round applicators were obtained and compared. Brachytherapy dose distributions generated using Pinnacle for ten CT data sets showed that the parallel-opposed beams of the conical applicators provided similar PTV coverage to the round applicators and reduced the maximum dose to skin, chest wall, and lung by up to 27%, 42%, and 43%, respectively. CONCLUSIONS Brachytherapy dose distributions for the conical applicators have been generated using MC methods and entered into the Pinnacle TPS via the Tufts technique. Treatment planning metrics for the conical AccuBoost applicators were significantly improved in comparison to those for conventional electron beam breast boost.
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Affiliation(s)
- Yun Yang
- Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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DeWerd LA, Ibbott GS, Meigooni AS, Mitch MG, Rivard MJ, Stump KE, Thomadsen BR, Venselaar JLM. A dosimetric uncertainty analysis for photon-emitting brachytherapy sources: report of AAPM Task Group No. 138 and GEC-ESTRO. Med Phys 2011; 38:782-801. [PMID: 21452716 PMCID: PMC3033879 DOI: 10.1118/1.3533720] [Citation(s) in RCA: 180] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Revised: 12/06/2010] [Accepted: 12/14/2010] [Indexed: 11/07/2022] Open
Abstract
This report addresses uncertainties pertaining to brachytherapy single-source dosimetry preceding clinical use. The International Organization for Standardization (ISO) Guide to the Expression of Uncertainty in Measurement (GUM) and the National Institute of Standards and Technology (NIST) Technical Note 1297 are taken as reference standards for uncertainty formalism. Uncertainties in using detectors to measure or utilizing Monte Carlo methods to estimate brachytherapy dose distributions are provided with discussion of the components intrinsic to the overall dosimetric assessment. Uncertainties provided are based on published observations and cited when available. The uncertainty propagation from the primary calibration standard through transfer to the clinic for air-kerma strength is covered first. Uncertainties in each of the brachytherapy dosimetry parameters of the TG-43 formalism are then explored, ending with transfer to the clinic and recommended approaches. Dosimetric uncertainties during treatment delivery are considered briefly but are not included in the detailed analysis. For low- and high-energy brachytherapy sources of low dose rate and high dose rate, a combined dosimetric uncertainty <5% (k=1) is estimated, which is consistent with prior literature estimates. Recommendations are provided for clinical medical physicists, dosimetry investigators, and source and treatment planning system manufacturers. These recommendations include the use of the GUM and NIST reports, a requirement of constancy of manufacturer source design, dosimetry investigator guidelines, provision of the lowest uncertainty for patient treatment dosimetry, and the establishment of an action level based on dosimetric uncertainty. These recommendations reflect the guidance of the American Association of Physicists in Medicine (AAPM) and the Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) for their members and may also be used as guidance to manufacturers and regulatory agencies in developing good manufacturing practices for sources used in routine clinical treatments.
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Affiliation(s)
- Larry A DeWerd
- Department of Medical Physics and Accredited Dosimetry Calibration Laboratory, University of Wisconsin, Madison, Wisconsin 53706, USA
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Mikell JK, Mourtada F. Dosimetric impact of an I192r brachytherapy source cable length modeled using a grid-based Boltzmann transport equation solver. Med Phys 2010; 37:4733-43. [DOI: 10.1118/1.3478278] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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