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Mishra S, Selvam TP, Sahoo S, Saxena SK, Kumar Y, Sapra BK. Monte Carlo-based dosimetry of proposed bi-radionuclide ( 125I and 106Ru/ 106Rh) eye plaque: A feasibility study. Med Phys 2024. [PMID: 38935327 DOI: 10.1002/mp.17257] [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: 11/07/2023] [Revised: 05/16/2024] [Accepted: 06/03/2024] [Indexed: 06/28/2024] Open
Abstract
BACKGROUND Combining the sharp dose fall off feature of beta-emitting 106Ru/106Rh radionuclide with larger penetration depth feature of photon-emitting125I radionuclide in a bi-radionuclide plaque, prescribed dose to the tumor apex can be delivered while maintaining the tumor dose uniformity and sparing the organs at risk. The potential advantages of bi-radionuclide plaque could be of interest in context of ocular brachytherapy. PURPOSE The aim of the study is to evaluate the dosimetric advantages of a proposed bi-radionuclide plaque for two different designs, consisting of indigenous 125I seeds and 106Ru/106Rh plaque, using Monte Carlo technique. The study also explores the influence of other commercial 125I seed models and presence or absence of silastic/acrylic seed carrier on the calculated dose distributions. The study further included the calculation of depth dose distributions for the bi-radionuclide eye plaque for which experimental data are available. METHODS The proposed bi-radionuclide plaque consists of a 1.2-mm-thick silver (Ag) spherical shell with radius of curvature of 12.5 mm, 20 µm-thick-106Ru/106Rh encapsulated between 0.2 mm Ag disk, and a 0.1-mm-thick Ag window, and water-equivalent gel containing 12 symmetrically arranged 125I seeds. Two bi-radionuclide plaque models investigated in the present study are designated as Design I and Design II. In Design I, 125I seeds are placed on the top of the plaque, while in Design II 106Ru/106Rh source is positioned on the top of the plaque. In Monte Carlo calculations, the plaque is positioned in a spherical water phantom of 30 cm diameter. RESULTS The proposed bi-radionuclide eye plaque demonstrated superior dose distributions as compared to 125I or 106Ru plaque for tumor thicknesses ranges from 5 to 10 mm. Amongst the designs, dose at a given voxel for Design I is higher as compared to the corresponding voxel dose for Design II. This difference is attributed to the higher degree of attenuation of 125I photons in Ag as compared to beta particles. Influence of different 125I seed models on the normalized lateral dose profiles of Design I (in the absence of carrier) is negligible and within 5% on the central axis depth dose distribution as compared to the corresponding values of the plaque that has indigenous 125I seeds. In the presence of a silastic/acrylic seed carrier, the normalized central axis dose distributions of Design I are smaller by 3%-12% as compared to the corresponding values in the absence of a seed carrier. For the published bi-radionuclide plaque model, good agreement is observed between the Monte Carlo-calculated and published measured depth dose distributions for clinically relevant depths. CONCLUSION Regardless of the type of 125I seed model utilized and whether silastic/acrylic seed carrier is present or not, Design I bi-radionuclide plaque offers superior dose distributions in terms of tumor dose uniformity, rapid dose fall off and lesser dose to nearby critical organs at risk over the Design II plaque. This shows that Design I bi-radionuclide plaque could be a promising alternative to 125I plaque for treatment of tumor sizes in the range 5 to 10 mm.
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Affiliation(s)
- Subhalaxmi Mishra
- Radiological Physics and Advisory Division, Health, Safety & Environment Group, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
| | - T Palani Selvam
- Radiological Physics and Advisory Division, Health, Safety & Environment Group, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai, Maharashtra, India
| | - Sridhar Sahoo
- Radiological Physics and Advisory Division, Health, Safety & Environment Group, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
| | - Sanjay Kumar Saxena
- Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
| | - Yogendra Kumar
- Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
| | - Balvinder K Sapra
- Radiological Physics and Advisory Division, Health, Safety & Environment Group, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai, Maharashtra, India
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Mishra S, Mishra B, Selvam TP, Deshpande S, Pathan MS, Kumar R. Monte Carlo Study on Dose Distributions Around 192Ir, 169Yb, and 125I Brachytherapy Sources Using EGSnrc-based egs_brachy User-code. J Med Phys 2022; 47:270-278. [PMID: 36684701 PMCID: PMC9847004 DOI: 10.4103/jmp.jmp_16_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 05/01/2022] [Accepted: 05/13/2022] [Indexed: 11/10/2022] Open
Abstract
Introduction As per the recommendations of the American Association of Physicists in Medicine Task Group 43, Monte Carlo (MC) investigators should reproduce previously published dose distributions whenever new features of the code are explored. The purpose of the present study is to benchmark the TG-43 dosimetric parameters calculated using the new MC user-code egs_brachy of EGSnrc code system for three different radionuclides 192Ir, 169Yb, and 125I which represent high-, intermediate-, and low-energy sources, respectively. Materials and Methods Brachytherapy sources investigated in this study are high-dose rate (HDR) 192Ir VariSource (Model VS2000), 169Yb HDR (Model 4140), and 125I -low-dose-rate (LDR) (Model OcuProsta). The TG-43 dosimetric parameters such as air-kerma strength, S k, dose rate constant, Λ, radial dose function, g(r) and anisotropy function, F(r,θ) and two-dimensional (2D) absorbed dose rate data (along-away table) are calculated in a cylindrical water phantom of mass density 0.998 g/cm3 using the MC code egs_brachy. Dimensions of phantom considered for 192Ir VS2000 and 169Yb sources are 80 cm diameter ×80 cm height, whereas for 125I OcuProsta source, 30 cm diameter ×30 cm height cylindrical water phantom is considered for MC calculations. Results The dosimetric parameters calculated using egs_brachy are compared against the values published in the literature. The calculated values of dose rate constants from this study agree with the published values within statistical uncertainties for all investigated sources. Good agreement is found between the egs_brachy calculated radial dose functions, g(r), anisotropy functions, and 2D dose rate data with the published values (within 2%) for the same phantom dimensions. For 192Ir VS2000 source, difference of about 28% is observed in g(r) value at 18 cm from the source which is due to differences in the phantom dimensions. Conclusion The study validates TG-43 dose parameters calculated using egs_brachy for 192Ir, 169Yb, and 125I brachytherapy sources with the values published in the literature.
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Affiliation(s)
- Subhalaxmi Mishra
- Division of Radiological Physics and Advisory, Health Safety and Environment Group, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
| | - Bibekananda Mishra
- Division of Radiological Safety, Atomic Energy Regulatory Board, Mumbai, Maharashtra, India
| | - T. Palani Selvam
- Division of Radiological Physics and Advisory, Health Safety and Environment Group, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
- Homi Bhabha National Institute, Mumbai, Maharashtra, India
| | - Sudesh Deshpande
- Department of Radiation Oncology, P. D. Hinduja National Hospital and MRC, Mumbai, Maharashtra, India
| | - Munir Shabbir Pathan
- Division of Radiological Physics and Advisory, Health Safety and Environment Group, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
| | - Rajesh Kumar
- Division of Radiological Physics and Advisory, Health Safety and Environment Group, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
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Saminathan S, Maheshraja K, Ganesh KM. Validation of American Association of Physicists in Medicine TG 43 Dosimetry Data in Commercial Treatment Planning System. J Med Phys 2021; 46:197-203. [PMID: 34703104 PMCID: PMC8491312 DOI: 10.4103/jmp.jmp_20_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 06/22/2021] [Accepted: 06/29/2021] [Indexed: 11/18/2022] Open
Abstract
AIMS This study aimed to validate the dosimetric data of low-energy photon-emitting low-dose rate (LE-LDR) brachytherapy seed sources in commercial treatment planning system (TPS). MATERIALS AND METHODS The LE-LDR seed sources dosimetric data were published in the American Association of Physicists in Medicine (AAPM) Task Group reports TG-43 (1995), TG-43U1 (2004), TG-43U1S1 (2007), and TG-43U1S2. The Bhabha Atomic Research centre (BARC) 125I Ocu-Prosta seed dosimetry data are also available in the literature. The commercially available TPSs are using both two-dimensional (cylindrically symmetric line-source) and one-dimensional (1D) (point source) dose-calculation formalisms. TPS used in this study uses only 1D dose-calculation formalism for permanent implant dosimetry. The point-dose calculation, dose summation, isodose representation, and dose-volume histogram quality assurance tests were performed in this study. The point-source dose-calculation tests were performed for all the available sources in the literature. The others tests were performed for the I-125 BARC Ocu-Prosta seeds. The TPS-calculated doses were validated using manual calculation. RESULTS AND DISCUSSION In point-source calculation test, the TPS-calculated point-dose values are within ±2% agreement with manually calculated dose for all the seeds studied. The agreement between the TPS and manually calculated dose is 0.5% for the dose summation test. The isodose line pass through the grid points at an equal distance was verified visually on the computer screen for seed used clinically. In dose-volume histogram test, the TPS-determined volume was compared with the real volume. CONCLUSION Misinterpretation of the TPS test and/or misunderstanding of the TG-43 dose-calculation formalism may cause large errors. It is very important to validate the TPS using literature provided dosimetric data. The dosimetric data of BARC 125I Ocu-Prosta Seed are validated with other AAPM TG-43-recommended seeds. The dose calculation of Best® NOMOS permanent implant TPS is accurate for all permanent implant seeds studied.
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Affiliation(s)
- Sathiyan Saminathan
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India
| | - K. Maheshraja
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India
| | - K. M. Ganesh
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India
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Shah PK, Selvaraj U, Narendran V, Guhan P, Saxena SK, Dash A. Indigenous (125)I brachytherapy source for the management of intraocular melanomas in India. Cancer Biother Radiopharm 2013; 28:21-8. [PMID: 23301846 DOI: 10.1089/cbr.2011.1123] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Episcleral plaque brachytherapy using (125)I seed is a viable option for the management of intraocular cancer with minimal invasiveness and surgical complications. This article describes the fabrication of (125)I seeds and initial experience on their use for the management of intraocular choroidal melanomas. The process of (125)I seed fabrication includes immobilization of (125)I into palladium-coated silver wires, its encapsulation in titanium capsules using Nd: YAG laser and quality control to assure safety. Plaque preparation consists of the assignment of seeds to slots on the plaque to achieve a desired dose rate distribution. The clinical study reported here includes the retrospective review of 9 eyes of 9 patients who underwent ophthalmic brachytherapy between May 2008 and June 2011. The average apical diameter before brachytherapy was 7.6 mm and the average largest basal diameter was 12.1 mm, which reduced to 3.3 and 7.2 mm, respectively, after the procedure at an average follow-up of 24 months. Patients in our studies experienced good local tumor control. The results of this study represent a significant step forward in the management of intraocular tumors in India.
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Uniyal SC, Naithani UC, Sharma SD. Evaluation of Gafchromic EBT2 film for the measurement of anisotropy function for high-dose-rate (192)Ir brachytherapy source with respect to thermoluminescent dosimetry. Rep Pract Oncol Radiother 2010; 16:14-20. [PMID: 24376951 DOI: 10.1016/j.rpor.2010.11.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 10/10/2010] [Accepted: 11/09/2010] [Indexed: 11/17/2022] Open
Abstract
AIM The aim of this work was to assess the suitability of the use of a Gafchromic EBT2 film for the measurement of anisotropy function for microSelectron HDR (192)Ir (classic) source with a comparative dosimetry method using a Gafchromic EBT2 film and thermoluminescence dosimeters (TLDs). BACKGROUND Sealed linear radiation sources are commonly used for high dose rate (HDR) brachytherapy treatments. Due to self-absorption and oblique filtration of radiation in the source capsule material, an inherent anisotropy is present in the dose distribution around the source which can be described by a measurable two-dimensional anisotropy function, F(r, θ). MATERIALS AND METHODS Measurements were carried out in a specially designed and locally fabricated PMMA phantom with provisions to accommodate miniature LiF TLD rods and EBT2 film dosimeters at identical radial distances with respect to the (192)Ir source. RESULTS The data of anisotropy function generated by the use of the Gafchromic EBT2 film method are in agreement with their TLD measured values within 4%. The produced data are also consistent with their experimental and Monte Carlo calculated results for this source available in the literature. CONCLUSION Gafchromic EBT2 film was found to be a feasible dosimeter in determining anisotropy in the dose distribution of (192)Ir source. It offers high resolution and is a viable alternative to TLD dosimetry at discrete points. The method described in this paper is useful for comparing the performances of detectors and can be applied for other brachytherapy sources as well.
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Affiliation(s)
- Satish C Uniyal
- Department of Radiology, Himalayan Institute of Medical Sciences, Jolly Grant, Dehradun 248140, India
| | - Umesh C Naithani
- Department of Physics, H N B Garhwal Central University, Campus Pauri, Pauri (Garhwal), Uttarakhand 246001, India
| | - Sunil D Sharma
- Radiological Physics & Advisory Division, Bhabha Atomic Research Centre, CT & CRS Building, Anushaktinagar, Mumbai 400094, India
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Saxena SK, Sharma S, Dash A, Venkatesh M. Development of a new design 125I-brachytherapy seed for its application in the treatment of eye and prostate cancer. Appl Radiat Isot 2009; 67:1421-5. [DOI: 10.1016/j.apradiso.2009.02.040] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Sahoo S, Palani Selvam T. An EGSnrc investigation of the air-kerma strength, dose rate constant, and radial dose function of 125I brachytherapy sources. Radiol Phys Technol 2009; 2:198-204. [DOI: 10.1007/s12194-009-0066-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Revised: 06/11/2009] [Accepted: 06/11/2009] [Indexed: 11/30/2022]
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Saxena SK, Sharma SD, Kumar Y, Muthe KP, Dash A, Venkatesh M. Development of a spherical (125)i-brachytherapy seed for its application in the treatment of eye and prostate cancer. Cancer Biother Radiopharm 2008; 23:807-18. [PMID: 19111051 DOI: 10.1089/cbr.2008.0511] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Palladium-coated silver beads of 0.5 mm (phi) were used to adsorb (125)I, encapsulated inside a titanium capsule by an Nd:YAG laser, for use as a brachytherapy source. Experimental conditions, such as feed activity, carrier concentration, and reaction time, were optimized for the maximum adsorption of (125)I. Uniform distribution of radioactivity on the source core was ascertained by the autoradiography technique. Leachability of (125)I was found to be <0.01%. The dose-rate constant of the new source was estimated to be 1.045 cGyh(-1)U(-1). This newly developed source could be an alternative to other (125)I sources.
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