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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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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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Sharifzadeh M, Chiniforoush TA, Sadeghi M. Design and optimizing a novel ocular plaque brachytherapy with dual-core of 103Pd and 106Ru. Phys Med 2021; 91:99-104. [PMID: 34742099 DOI: 10.1016/j.ejmp.2021.10.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 09/24/2021] [Accepted: 10/05/2021] [Indexed: 10/19/2022] Open
Abstract
In recent decades, eye plaques of brachytherapy have been extensively used as primary treatment as well as a complementary treatment for ocular cancer. The purpose of this study is the development of the eye plaque brachytherapy throughout a new design of eye plaque by combining the COMS plaque and the CCB BEBIG plaque loaded by IRA1-103Pd and 106Ru, respectively. A new dual-core plaque with a diameter of 20 mm was designed in the way that the BEBIG plaque with a diameter of 20 mm loaded by 106Ru plate is attached to the COMS plaque with a diameter of 20 mm loaded by 24 of IRA1-103Pd seeds. Dose calculations for the new plaque were performed by using the MCNP5 code. Dose calculations of dual-core plaque including 103Pd seeds (gamma) and 106Ru plate (beta) were separately done for the sake of MCNP constraints in gamma and beta particle transfer simultaneously. The new dual-core plaque delivers a much higher dose rate to the tumor compared with every single plaque, while the dose rate reached to healthy tissues is slightly higher than each plaque separately. Of course, this is acceptable because the treatment time reduces and subsequently the error in radiation therapy reduces.
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Affiliation(s)
- Mohsen Sharifzadeh
- Radiation Application Research School, Nuclear Science and Technology Research Institute (NSTRI), Tehran, Iran
| | - Tayebeh A Chiniforoush
- Department of Medical Radiation Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Mahdi Sadeghi
- Medical Physics Department, School of Medicine, Iran University of Medical Sciences, P.O. Box: 14155-6183 Tehran, Iran.
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Taheri ME, Poorbaygi H, Hadadi A, Sheibani S. Dosimetry investigation of a prototype of 169Yb seed brachytherapy for use in circular stapler. Phys Eng Sci Med 2021; 44:525-534. [PMID: 33970439 DOI: 10.1007/s13246-021-01004-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 04/23/2021] [Indexed: 11/28/2022]
Abstract
This study aims to investigate dosimetry parameters for the new design of 169Yb seed in the form of a surgical staple for circular staplers commonly used in the abdominal incision and the esophageal and gastric surgery, which facilitates the precise placement. This seed includes a titanium tube with the inner diameter and outer diameter 0.68 mm and 2.2 mm, respectively, and length of 0.8 mm. Both sides of the tube are closed by titanium wires with the thickness of 0.65 mm by the laser. Natural ytterbium oxide is used after the thermal neutron activation; it is necessary for cooling time of 40 days. The dosimetry parameters were calculated based on the TG-43U1 using Monte Carlo MCNP5 code. The experimental dosimetry was performed by EBT3 radiochromic film to determine 2D dosimetry at near distance of the source and validate the MC code. The dose rate constant of MC calculation was obtained at 1.39cGyh-1U-1 ± 4% with the difference of 5% compared to another study. The dose distribution was symmetrical along the Z-axis and Y-axis (around the seed) and there was a uniform activity inside the tube. The distinction of dose rate was not noticeable at the 90 and 270 degrees on the Z-axis, which indicated a slight effect on staple legs in the matter of delivery dose. However, to understand dose distribution and introduce this source in a pre-clinical study, 3D dosimetry as well as further studying the heterogeneous function is required.
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Affiliation(s)
- Mostafa E Taheri
- Department of Medical Radiation Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Hosein Poorbaygi
- Radiation Application Research School, Nuclear Science and Technology Research Institute, Tehran, Iran.
| | - Asghar Hadadi
- Department of Medical Radiation Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Shahab Sheibani
- Radiation Application Research School, Nuclear Science and Technology Research Institute, Tehran, Iran
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Safigholi H, Chamberland MJP, Taylor REP, Allen CH, Martinov MP, Rogers DWO, Thomson RM. Update of the CLRP TG‐43 parameter database for low‐energy brachytherapy sources. Med Phys 2020; 47:4656-4669. [DOI: 10.1002/mp.14249] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 06/08/2020] [Accepted: 05/05/2020] [Indexed: 12/23/2022] Open
Affiliation(s)
- Habib Safigholi
- Carleton Laboratory for Radiotherapy Physics (CLRP) Department of Physics Carleton University Ottawa ON K1S 5B6 Canada
| | - Marc J. P. Chamberland
- Carleton Laboratory for Radiotherapy Physics (CLRP) Department of Physics Carleton University Ottawa ON K1S 5B6 Canada
| | - Randle E. P. Taylor
- Carleton Laboratory for Radiotherapy Physics (CLRP) Department of Physics Carleton University Ottawa ON K1S 5B6 Canada
| | - Christian H. Allen
- Carleton Laboratory for Radiotherapy Physics (CLRP) Department of Physics Carleton University Ottawa ON K1S 5B6 Canada
| | - Martin P. Martinov
- Carleton Laboratory for Radiotherapy Physics (CLRP) Department of Physics Carleton University Ottawa ON K1S 5B6 Canada
| | - D. W. O. Rogers
- Carleton Laboratory for Radiotherapy Physics (CLRP) Department of Physics Carleton University Ottawa ON K1S 5B6 Canada
| | - Rowan M. Thomson
- Carleton Laboratory for Radiotherapy Physics (CLRP) Department of Physics Carleton University Ottawa ON K1S 5B6 Canada
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Kry SF, Alvarez P, Cygler JE, DeWerd LA, Howell RM, Meeks S, O'Daniel J, Reft C, Sawakuchi G, Yukihara EG, Mihailidis D. AAPM TG 191: Clinical use of luminescent dosimeters: TLDs and OSLDs. Med Phys 2019; 47:e19-e51. [DOI: 10.1002/mp.13839] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 08/27/2019] [Accepted: 08/28/2019] [Indexed: 12/20/2022] Open
Affiliation(s)
- Stephen F. Kry
- The University of Texas MD Anderson Cancer Center Houston TX USA
| | - Paola Alvarez
- The University of Texas MD Anderson Cancer Center Houston TX USA
| | | | | | | | - Sanford Meeks
- University of Florida Health Cancer Center Orlando FL USA
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Rivard MJ, Ballester F, Butler WM, DeWerd LA, Ibbott GS, Meigooni AS, Melhus CS, Mitch MG, Nath R, Papagiannis P. Supplement 2 for the 2004 update of the AAPM Task Group No. 43 Report: Joint recommendations by the AAPM and GEC-ESTRO. Med Phys 2017. [DOI: 10.1002/mp.12430] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Mark J. Rivard
- Department of Radiation Oncology; Tufts University School of Medicine; Boston MA 02111 USA
| | - Facundo Ballester
- Unidad Mixta de Investigación en Radiofísica e Instrumentación Nuclear en Medicina (IRIMED); Instituto de Investigación Sanitaria La Fe (IIS-La Fe)-Universitat de Valéncia; Bujassot 46100 Spain
| | - Wayne M. Butler
- Schiffler Cancer Center; Wheeling Hospital; Wheeling WV 26003 USA
| | - Larry A. DeWerd
- Accredited Dosimetry and Calibration Laboratory; University of Wisconsin; Madison WI 53706 USA
| | - Geoffrey S. Ibbott
- Department of Radiation Physics; M.D. Anderson Cancer Center; Houston TX 77030 USA
| | - Ali S. Meigooni
- Comprehensive Cancer Centers of Nevada; Las Vegas NV 89169 USA
| | - Christopher S. Melhus
- Department of Radiation Oncology; Tufts University School of Medicine; Boston MA 02111 USA
| | - Michael G. Mitch
- Radiation Physics Division; National Institute of Standards and Technology; Gaithersburg MD 20899 USA
| | - Ravinder Nath
- Department of Therapeutic Radiology; Yale University School of Medicine; New Haven CT 06510 USA
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Brivio D, Nguyen PL, Sajo E, Ngwa W, Zygmanski P. A Monte Carlo study of I-125 prostate brachytherapy with gold nanoparticles: dose enhancement with simultaneous rectal dose sparing via radiation shielding. Phys Med Biol 2017; 62:1935-1948. [PMID: 28140338 DOI: 10.1088/1361-6560/aa5bc7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We investigate via Monte Carlo simulations a new 125I brachytherapy treatment technique for high-risk prostate cancer patients via injection of Au nanoparticle (AuNP) directly into the prostate. The purpose of using the nanoparticles is to increase the therapeutic index via two synergistic effects: enhanced energy deposition within the prostate and simultaneous shielding of organs at risk from radiation escaping from the prostate. Both uniform and non-uniform concentrations of AuNP are studied. The latter are modeled considering the possibility of AuNP diffusion after the injection using brachy needles. We study two extreme cases of coaxial AuNP concentrations: centered on brachy needles and centered half-way between them. Assuming uniform distribution of 30 mg g-1 of AuNP within the prostate, we obtain a dose enhancement larger than a factor of 2 to the prostate. Non-uniform concentration of AuNP ranging from 10 mg g-1 and 66 mg g-1 were studied. The higher the concentration in a given region of the prostate the greater is the enhancement therein. We obtain the highest dose enhancement when the brachytherapy needles are coincident with AuNP injection needles but, at the same time, the regions in the tail are colder (average dose ratio of 0.7). The best enhancement uniformity is obtained with the seeds in the tail of the AuNP distribution. In both uniform and non-uniform cases the urethra and rectum receive less than 1/3 dose compared to an analog treatment without AuNP. Remarkably, employing AuNP not only significantly increases dose to the target but also decreases dose to the neighboring rectum and even urethra, which is embedded within the prostate. These are mutually interdependent effects as more enhancement leads to more shielding and vice-versa. Caution must be paid since cold spot or hot spots may be created if the AuNP concentration versus seed position is not properly distributed respect to the seed locations.
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Affiliation(s)
- D Brivio
- Brigham and Women's Hospital, Boston, MA, United States of America. Dana Farber Cancer Institute, Boston, MA, United States of America. Harvard Medical School, Boston, MA, United States of America
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Chamberland MJP, Taylor REP, Rogers DWO, Thomson RM. egs_brachy: a versatile and fast Monte Carlo code for brachytherapy. Phys Med Biol 2016; 61:8214-8231. [DOI: 10.1088/0031-9155/61/23/8214] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Malin MJ, Palmer BR, DeWerd LA. Absolute measurement of LDR brachytherapy source emitted power: Instrument design and initial measurements. Med Phys 2016; 43:796-806. [PMID: 26843242 DOI: 10.1118/1.4939666] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Energy-based source strength metrics may find use with model-based dose calculation algorithms, but no instruments exist that can measure the energy emitted from low-dose rate (LDR) sources. This work developed a calorimetric technique for measuring the power emitted from encapsulated low-dose rate, photon-emitting brachytherapy sources. This quantity is called emitted power (EP). The measurement methodology, instrument design and performance, and EP measurements made with the calorimeter are presented in this work. METHODS A calorimeter operating with a liquid helium thermal sink was developed to measure EP from LDR brachytherapy sources. The calorimeter employed an electrical substitution technique to determine the power emitted from the source. The calorimeter's performance and thermal system were characterized. EP measurements were made using four (125)I sources with air-kerma strengths ranging from 2.3 to 5.6 U and corresponding EPs of 0.39-0.79 μW, respectively. Three Best Medical 2301 sources and one Oncura 6711 source were measured. EP was also computed by converting measured air-kerma strengths to EPs through Monte Carlo-derived conversion factors. The measured EP and derived EPs were compared to determine the accuracy of the calorimeter measurement technique. RESULTS The calorimeter had a noise floor of 1-3 nW and a repeatability of 30-60 nW. The calorimeter was stable to within 5 nW over a 12 h measurement window. All measured values agreed with derived EPs to within 10%, with three of the four sources agreeing to within 4%. Calorimeter measurements had uncertainties ranging from 2.6% to 4.5% at the k = 1 level. The values of the derived EPs had uncertainties ranging from 2.9% to 3.6% at the k = 1 level. CONCLUSIONS A calorimeter capable of measuring the EP from LDR sources has been developed and validated for (125)I sources with EPs between 0.43 and 0.79 μW.
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Affiliation(s)
- Martha J Malin
- Department of Medical Physics, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin 53705
| | - Benjamin R Palmer
- Department of Medical Physics, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin 53705
| | - Larry A DeWerd
- Department of Medical Physics, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin 53705
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Rodriguez M, Rogers DWO. Effect of improved TLD dosimetry on the determination of dose rate constants for (125)I and (103)Pd brachytherapy seeds. Med Phys 2015; 41:114301. [PMID: 25370677 DOI: 10.1118/1.4895003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
PURPOSE To more accurately account for the relative intrinsic energy dependence and relative absorbed-dose energy dependence of TLDs when used to measure dose rate constants (DRCs) for (125)I and (103)Pd brachytherapy seeds, to thereby establish revised "measured values" for all seeds and compare the revised values with Monte Carlo and consensus values. METHODS The relative absorbed-dose energy dependence, f(rel), for TLDs and the phantom correction, Pphant, are calculated for (125)I and (103)Pd seeds using the EGSnrc BrachyDose and DOSXYZnrc codes. The original energy dependence and phantom corrections applied to DRC measurements are replaced by calculated (f(rel))(-1) and Pphant values for 24 different seed models. By comparing the modified measured DRCs to the MC values, an appropriate relative intrinsic energy dependence, kbq (rel), is determined. The new Pphant values and relative absorbed-dose sensitivities, SAD (rel), calculated as the product of (f(rel))(-1) and (kbq (rel))(-1), are used to individually revise the measured DRCs for comparison with Monte Carlo calculated values and TG-43U1 or TG-43U1S1 consensus values. RESULTS In general, f(rel) is sensitive to the energy spectra and models of the brachytherapy seeds. Values may vary up to 8.4% among (125)I and (103)Pd seed models and common TLD shapes. Pphant values depend primarily on the isotope used. Deduced (kbq (rel))(-1) values are 1.074 ± 0.015 and 1.084 ± 0.026 for (125)I and (103)Pd seeds, respectively. For (1 mm)(3) chips, this implies an overall absorbed-dose sensitivity relative to (60)Co or 6 MV calibrations of 1.51 ± 1% and 1.47 ± 2% for (125)I and (103)Pd seeds, respectively, as opposed to the widely used value of 1.41. Values of Pphant calculated here have much lower statistical uncertainties than literature values, but systematic uncertainties from density and composition uncertainties are significant. Using these revised values with the literature's DRC measurements, the average discrepancies between revised measured values and Monte Carlo values are 1.2% and 0.2% for (125)I and (103)Pd seeds, respectively, compared to average discrepancies for the original measured values of 4.8%. On average, the revised measured values are 4.3% and 5.9% lower than the original measured values for (103)Pd and (125)I seeds, respectively. The average of revised DRCs and Monte Carlo values is 3.8% and 2.8% lower for (125)I and (103)Pd seeds, respectively, than the consensus values in TG-43U1 or TG-43U1S1. CONCLUSIONS This work shows that f(rel) is TLD shape and seed model dependent suggesting a need to update the generalized energy response dependence, i.e., relative absorbed-dose sensitivity, measured 25 years ago and applied often to DRC measurements of (125)I and (103)Pd brachytherapy seeds. The intrinsic energy dependence for LiF TLDs deduced here is consistent with previous dosimetry studies and emphasizes the need to revise the DRC consensus values reported by TG-43U1 or TG-43U1S1.
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Affiliation(s)
- M Rodriguez
- Carleton Laboratory for Radiotherapy Physics, Carleton University, Ottawa, Ontario K1S 5B6, Canada and Princess Margaret Hospital, Toronto, Ontario M5G 2M9, Canada
| | - D W O Rogers
- Carleton Laboratory for Radiotherapy Physics, Carleton University, Ottawa, Ontario K1S 5B6, Canada
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Malin MJ, Bartol LJ, DeWerd LA. Impact of the differential fluence distribution of brachytherapy sources on the spectroscopic dose-rate constant. Med Phys 2015; 42:2379-88. [PMID: 25979033 DOI: 10.1118/1.4918325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To investigate why dose-rate constants for (125)I and (103)Pd seeds computed using the spectroscopic technique, Λ spec, differ from those computed with standard Monte Carlo (MC) techniques. A potential cause of these discrepancies is the spectroscopic technique's use of approximations of the true fluence distribution leaving the source, φ full. In particular, the fluence distribution used in the spectroscopic technique, φ spec, approximates the spatial, angular, and energy distributions of φ full. This work quantified the extent to which each of these approximations affects the accuracy of Λ spec. Additionally, this study investigated how the simplified water-only model used in the spectroscopic technique impacts the accuracy of Λ spec. METHODS Dose-rate constants as described in the AAPM TG-43U1 report, Λ full, were computed with MC simulations using the full source geometry for each of 14 different (125)I and 6 different (103)Pd source models. In addition, the spectrum emitted along the perpendicular bisector of each source was simulated in vacuum using the full source model and used to compute Λ spec. Λ spec was compared to Λ full to verify the discrepancy reported by Rodriguez and Rogers. Using MC simulations, a phase space of the fluence leaving the encapsulation of each full source model was created. The spatial and angular distributions of φ full were extracted from the phase spaces and were qualitatively compared to those used by φ spec. Additionally, each phase space was modified to reflect one of the approximated distributions (spatial, angular, or energy) used by φ spec. The dose-rate constant resulting from using approximated distribution i, Λ approx,i, was computed using the modified phase space and compared to Λ full. For each source, this process was repeated for each approximation in order to determine which approximations used in the spectroscopic technique affect the accuracy of Λ spec. RESULTS For all sources studied, the angular and spatial distributions of φ full were more complex than the distributions used in φ spec. Differences between Λ spec and Λ full ranged from -0.6% to +6.4%, confirming the discrepancies found by Rodriguez and Rogers. The largest contribution to the discrepancy was the assumption of isotropic emission in φ spec, which caused differences in Λ of up to +5.3% relative to Λ full. Use of the approximated spatial and energy distributions caused smaller average discrepancies in Λ of -0.4% and +0.1%, respectively. The water-only model introduced an average discrepancy in Λ of -0.4%. CONCLUSIONS The approximations used in φ spec caused discrepancies between Λ approx,i and Λ full of up to 7.8%. With the exception of the energy distribution, the approximations used in φ spec contributed to this discrepancy for all source models studied. To improve the accuracy of Λ spec, the spatial and angular distributions of φ full could be measured, with the measurements replacing the approximated distributions. The methodology used in this work could be used to determine the resolution that such measurements would require by computing the dose-rate constants from phase spaces modified to reflect φ full binned at different spatial and angular resolutions.
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Affiliation(s)
- Martha J Malin
- Department of Medical Physics, University of Wisconsin - Madison, Madison, Wisconsin 53705
| | - Laura J Bartol
- Department of Medical Physics, University of Wisconsin - Madison, Madison, Wisconsin 53705
| | - Larry A DeWerd
- Department of Medical Physics, University of Wisconsin - Madison, Madison, Wisconsin 53705
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Reed JL, Rasmussen BE, Davis SD, Micka JA, Culberson WS, DeWerd LA. Determination of the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters for125I and103Pd brachytherapy sources relative to60Co. Med Phys 2014; 41:122103. [DOI: 10.1118/1.4901300] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Experimental determination of the Task Group-43 dosimetric parameters of the new I25.S17plus 125I brachytherapy source. Brachytherapy 2014; 13:618-26. [DOI: 10.1016/j.brachy.2014.07.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 07/02/2014] [Accepted: 07/02/2014] [Indexed: 11/24/2022]
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Investigation of interseed attenuation and tissue composition effects in 125I seed implant prostate brachytherapy. Brachytherapy 2014; 13:603-10. [DOI: 10.1016/j.brachy.2014.04.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 03/03/2014] [Accepted: 04/11/2014] [Indexed: 11/24/2022]
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Aryal P, Molloy JA, Rivard MJ. A modern Monte Carlo investigation of the TG-43 dosimetry parameters for an 125I seed already having AAPM consensus data. Med Phys 2014; 41:021702. [PMID: 24506593 DOI: 10.1118/1.4860135] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To investigate potential causes for differences in TG-43 brachytherapy dosimetry parameters in the existent literature for the model IAI-125A(125)I seed and to propose new standard dosimetry parameters. METHODS The MCNP5 code was used for Monte Carlo (MC) simulations. Sensitivity of dose distributions, and subsequently TG-43 dosimetry parameters, was explored to reproduce historical methods upon which American Association of Physicists in Medicine (AAPM) consensus data are based. Twelve simulation conditions varying(125)I coating thickness, coating mass density, photon interaction cross-section library, and photon emission spectrum were examined. RESULTS Varying(125)I coating thickness, coating mass density, photon cross-section library, and photon emission spectrum for the model IAI-125A seed changed the dose-rate constant by up to 0.9%, about 1%, about 3%, and 3%, respectively, in comparison to the proposed standard value of 0.922 cGy h(-1) U(-1). The dose-rate constant values by Solberg et al. ["Dosimetric parameters of three new solid core (125)I brachytherapy sources," J. Appl. Clin. Med. Phys. 3, 119-134 (2002)], Meigooni et al. ["Experimental and theoretical determination of dosimetric characteristics of IsoAid ADVANTAGE™ (125)I brachytherapy source," Med. Phys. 29, 2152-2158 (2002)], and Taylor and Rogers ["An EGSnrc Monte Carlo-calculated database of TG-43 parameters," Med. Phys. 35, 4228-4241 (2008)] for the model IAI-125A seed and Kennedy et al. ["Experimental and Monte Carlo determination of the TG-43 dosimetric parameters for the model 9011 THINSeed™ brachytherapy source," Med. Phys. 37, 1681-1688 (2010)] for the model 6711 seed were +4.3% (0.962 cGy h(-1) U(-1)), +6.2% (0.98 cGy h(-1) U(-1)), +0.3% (0.925 cGy h(-1) U(-1)), and -0.2% (0.921 cGy h(-1) U(-1)), respectively, in comparison to the proposed standard value. Differences in the radial dose functions between the current study and both Solberg et al. and Meigooni et al. were <10% for r ≤ 5 cm, and increased for r > 5 cm with a maximum difference of 29% at r = 9 cm. In comparison to Taylor and Rogers, these differences were lower (maximum of 2% at r = 9 cm). For the similarly designed model 6711 (125)I seed, differences did not exceed 0.5% for 0.5 ≤ r ≤ 10 cm. Radial dose function values varied by 1% as coating thickness and coating density were changed. Varying the cross-section library and source spectrum altered the radial dose function by 25% and 12%, respectively, but these differences occurred at r = 10 cm where the dose rates were very low. The 2D anisotropy function results were most similar to those of Solberg et al. and most different to those of Meigooni et al. The observed order of simulation condition variables from most to least important for influencing the 2D anisotropy function was spectrum, coating thickness, coating density, and cross-section library. CONCLUSIONS Several MC radiation transport codes are available for calculation of the TG-43 dosimetry parameters for brachytherapy seeds. The physics models in these codes and their related cross-section libraries have been updated and improved since publication of the 2007 AAPM TG-43U1S1 report. Results using modern data indicated statistically significant differences in these dosimetry parameters in comparison to data recommended in the TG-43U1S1 report. Therefore, it seems that professional societies such as the AAPM should consider reevaluating the consensus data for this and others seeds and establishing a process of regular evaluations in which consensus data are based upon methods that remain state-of-the-art.
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Affiliation(s)
- Prakash Aryal
- Department of Radiation Medicine, University of Kentucky, Lexington, Kentucky 40536
| | - Janelle A Molloy
- Department of Radiation Medicine, University of Kentucky, Lexington, Kentucky 40536
| | - Mark J Rivard
- Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111
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Chiu-Tsao ST, Napoli JJ, Davis SD, Hanley J, Rivard MJ. Dosimetry for 131Cs and 125I seeds in solid water phantom using radiochromic EBT film. Appl Radiat Isot 2014; 92:102-14. [PMID: 25038559 DOI: 10.1016/j.apradiso.2014.06.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 06/23/2014] [Indexed: 12/31/2022]
Abstract
PURPOSE To measure the 2D dose distributions with submillimeter resolution for (131)Cs (model CS-1 Rev2) and (125)I (model 6711) seeds in a Solid Water phantom using radiochromic EBT film for radial distances from 0.06cm to 5cm. To determine the TG-43 dosimetry parameters in water by applying Solid Water to liquid water correction factors generated from Monte Carlo simulations. METHODS Each film piece was positioned horizontally above and in close contact with a (131)Cs or (125)I seed oriented horizontally in a machined groove at the center of a Solid Water phantom, one film at a time. A total of 74 and 50 films were exposed to the (131)Cs and (125)I seeds, respectively. Different film sizes were utilized to gather data in different distance ranges. The exposure time varied according to the seed air-kerma strength and film size in order to deliver doses in the range covered by the film calibration curve. Small films were exposed for shorter times to assess the near field, while larger films were exposed for longer times in order to assess the far field. For calibration, films were exposed to either 40kV (M40) or 50kV (M50) x-rays in air at 100.0cm SSD with doses ranging from 0.2Gy to 40Gy. All experimental, calibration and background films were scanned at a 0.02cmpixel resolution using a CCD camera-based microdensitometer with a green light source. Data acquisition and scanner uniformity correction were achieved with Microd3 software. Data analysis was performed using ImageJ, FV, IDL and Excel software packages. 2D dose distributions were based on the calibration curve established for 50kV x-rays. The Solid Water to liquid water medium correction was calculated using the MCNP5 Monte Carlo code. Subsequently, the TG-43 dosimetry parameters in liquid water medium were determined. RESULTS Values for the dose-rate constants using EBT film were 1.069±0.036 and 0.923±0.031cGyU(-1)h(-1) for (131)Cs and (125)I seed, respectively. The corresponding values determined using the Monte Carlo method were 1.053±0.014 and 0.924±0.016cGyU(-1)h(-1) for (131)Cs and (125)I seed, respectively. The radial dose functions obtained with EBT film measurements and Monte Carlo simulations were plotted for radial distances up to 5cm, and agreed within the uncertainty of the two methods. The 2D anisotropy functions obtained with both methods also agreed within their uncertainties. CONCLUSION EBT film dosimetry in a Solid Water phantom is a viable method for measuring (131)Cs (model CS-1 Rev2) and (125)I (model 6711) brachytherapy seed dose distributions with submillimeter resolution. With the Solid Water to liquid water correction factors generated from Monte Carlo simulations, the measured TG-43 dosimetry parameters in liquid water for these two seed models were found to be in good agreement with those in the literature.
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Affiliation(s)
| | - John J Napoli
- John Theurer Cancer Center at Hackensack University Medical Center, Hackensack, NJ 07601, USA
| | - Stephen D Davis
- Medical Physics, McGill University Health Centre, Montreal, QC, Canada H3G 1A4
| | - Joseph Hanley
- Princeton Radiation Oncology Center, Monroe, NJ 08831, USA
| | - Mark J Rivard
- Department of Radiation Oncology, Tufts University School of Medicine, Boston, MA 02111, USA
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Reed JL, Rivard MJ, Micka JA, Culberson WS, DeWerd LA. Experimental and Monte Carlo dosimetric characterization of a 1 cm (103)Pd brachytherapy source. Brachytherapy 2014; 13:657-67. [PMID: 24880585 DOI: 10.1016/j.brachy.2014.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 03/06/2014] [Accepted: 04/08/2014] [Indexed: 11/16/2022]
Abstract
PURPOSE To determine the in-air azimuthal anisotropy and in-water dose distribution for the 1 cm length of a new elongated (103)Pd brachytherapy source through both experimental measurements and Monte Carlo (MC) simulations. Measured and MC-calculated dose distributions were used to determine the American Association of Physicists in Medicine Task Group No. 43 (TG-43) dosimetry parameters for this source. METHODS AND MATERIALS The in-air azimuthal anisotropy of the source was measured with a NaI scintillation detector and was simulated with the MCNP5 radiation transport code. Measured and MC results were normalized to their respective mean values and then compared. The source dose distribution was determined from measurements with LiF:Mg,Ti thermoluminescent dosimeter (TLD) microcubes and MC simulations. TG-43 dosimetry parameters for the source, including the dose-rate constant, Λ, two-dimensional anisotropy function, F(r, θ), and line-source radial dose function, gL(r), were determined from the TLD measurements and MC simulations. RESULTS NaI scintillation detector measurements and MC simulations of the in-air azimuthal anisotropy of the source showed that ≥95% of the normalized values for each source were within 1.2% of the mean value. TLD measurements and MC simulations of Λ, F(r, θ), and gL(r) agreed to within the associated uncertainties. CONCLUSIONS This new (103)Pd source exhibits a high level of azimuthal symmetry as indicated by the measured and MC-calculated results for the in-air azimuthal anisotropy. TG-43 dosimetry parameters for the source were determined through TLD measurements and MC simulations.
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Affiliation(s)
- Joshua L Reed
- Department of Medical Physics, University of Wisconsin-Madison, UW Medical Radiation Research Center, Madison, WI.
| | - Mark J Rivard
- Department of Radiation Oncology, Tufts University School of Medicine, Boston, MA
| | - John A Micka
- Department of Medical Physics, University of Wisconsin-Madison, UW Medical Radiation Research Center, Madison, WI
| | - Wesley S Culberson
- Department of Medical Physics, University of Wisconsin-Madison, UW Medical Radiation Research Center, Madison, WI
| | - Larry A DeWerd
- Department of Medical Physics, University of Wisconsin-Madison, UW Medical Radiation Research Center, Madison, WI
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Tanaka K, Tateoka K, Asanuma O, Kamo KI, Sato K, Takeda H, Takagi M, Hareyama M, Takada J. A dosimetry method for low dose rate brachytherapy by EGS5 combined with regression to reflect source strength shortage. JOURNAL OF RADIATION RESEARCH 2014; 55:608-612. [PMID: 24449715 PMCID: PMC4014170 DOI: 10.1093/jrr/rrt147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 11/29/2013] [Accepted: 11/29/2013] [Indexed: 06/03/2023]
Abstract
The post-implantation dosimetry for brachytherapy using Monte Carlo calculation by EGS5 code combined with the source strength regression was investigated with respect to its validity. In this method, the source strength for the EGS5 calculation was adjusted with the regression, so that the calculation would reproduce the dose monitored with the glass rod dosimeters (GRDs) on a water phantom. The experiments were performed, simulating the case where one of two (125)I sources of Oncoseed 6711 was lacking strength by 4-48%. As a result, the calculation without regression was in agreement with the GRD measurement within 26-62%. In this case, the shortage in strength of a source was neglected. By the regression, in order to reflect the strength shortage, the agreement was improved up to 17-24%. This agreement was also comparable with accuracy of the dose calculation for single source geometry reported previously. These results suggest the validity of the dosimetry method proposed in this study.
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Affiliation(s)
- Kenichi Tanaka
- Department of Medicine, Graduate School of Sapporo Medical University, South 1, West 17, Chuo-ward, Sapporo, Hokkaido 060-8556, Japan
| | - Kunihiko Tateoka
- Department of Medicine, Graduate School of Sapporo Medical University, South 1, West 17, Chuo-ward, Sapporo, Hokkaido 060-8556, Japan
| | - Osamu Asanuma
- Division of Radiology and Nuclear Medicine, Sapporo Medical University Hospital, South 1, West 17, Chuo-ward, Sapporo, Hokkaido 060-8556, Japan
| | - Ken-ichi Kamo
- Department of Medicine, Graduate School of Sapporo Medical University, South 1, West 17, Chuo-ward, Sapporo, Hokkaido 060-8556, Japan
| | - Kaori Sato
- Division of Radiology and Nuclear Medicine, Sapporo Medical University Hospital, South 1, West 17, Chuo-ward, Sapporo, Hokkaido 060-8556, Japan
| | - Hiromitsu Takeda
- Division of Radiology and Nuclear Medicine, Sapporo Medical University Hospital, South 1, West 17, Chuo-ward, Sapporo, Hokkaido 060-8556, Japan
| | - Masaru Takagi
- Hyogo Ion Beam Medical Center, 1-2-1, Kouto, Shingu, Tatsuno, Hyogo 679-5165, Japan
| | - Masato Hareyama
- Teishin-kai Radiation Therapy Institute, 1–6, North 44, East 8, Higashi-ward, Sapporo, Hokkaido 007-0844, Japan
| | - Jun Takada
- Department of Medicine, Graduate School of Sapporo Medical University, South 1, West 17, Chuo-ward, Sapporo, Hokkaido 060-8556, Japan
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21
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Fulkerson RK, Micka JA, DeWerd LA. Dosimetric characterization and output verification for conical brachytherapy surface applicators. Part II. High dose rate 192Ir sources. Med Phys 2014; 41:022104. [PMID: 24506636 PMCID: PMC3987768 DOI: 10.1118/1.4862506] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 11/20/2013] [Accepted: 12/09/2013] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Historically, treatment of malignant surface lesions has been achieved with linear accelerator based electron beams or superficial x-ray beams. Recent developments in the field of brachytherapy now allow for the treatment of surface lesions with specialized conical applicators placed directly on the lesion. Applicators are available for use with high dose rate (HDR)(192)Ir sources, as well as electronic brachytherapy sources. Part I of this paper discussed the applicators used with electronic brachytherapy sources. Part II will discuss those used with HDR (192)Ir sources. Although the use of these applicators has gained in popularity, the dosimetric characteristics have not been independently verified. Additionally, there is no recognized method of output verification for quality assurance procedures with applicators like these. METHODS This work aims to create a cohesive method of output verification that can be used to determine the dose at the treatment surface as part of a quality assurance/commissioning process for surface applicators used with HDR electronic brachytherapy sources (Part I) and(192)Ir sources (Part II). Air-kerma rate measurements for the (192)Ir sources were completed with several models of small-volume ionization chambers to obtain an air-kerma rate at the treatment surface for each applicator. Correction factors were calculated using MCNP5 and EGSnrc Monte Carlo codes in order to determine an applicator-specific absorbed dose to water at the treatment surface from the measured air-kerma rate. Additionally, relative dose measurements of the surface dose distributions and characteristic depth dose curves were completed in-phantom. RESULTS Theoretical dose distributions and depth dose curves were generated for each applicator and agreed well with the measured values. A method of output verification was created that allows users to determine the applicator-specific dose to water at the treatment surface based on a measured air-kerma rate. CONCLUSIONS The novel output verification methods described in this work will reduce uncertainties in dose delivery for treatments with these kinds of surface applicators, ultimately improving patient care.
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Affiliation(s)
- Regina K Fulkerson
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - John A Micka
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Larry A DeWerd
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705
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Fulkerson RK, Micka JA, DeWerd LA. Dosimetric characterization and output verification for conical brachytherapy surface applicators. Part I. Electronic brachytherapy source. Med Phys 2014; 41:022103. [PMID: 24506635 PMCID: PMC3987645 DOI: 10.1118/1.4862505] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 11/20/2013] [Accepted: 12/16/2013] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Historically, treatment of malignant surface lesions has been achieved with linear accelerator based electron beams or superficial x-ray beams. Recent developments in the field of brachytherapy now allow for the treatment of surface lesions with specialized conical applicators placed directly on the lesion. Applicators are available for use with high dose rate (HDR)(192)Ir sources, as well as electronic brachytherapy sources. Part I of this paper will discuss the applicators used with electronic brachytherapy sources; Part II will discuss those used with HDR (192)Ir sources. Although the use of these applicators has gained in popularity, the dosimetric characteristics including depth dose and surface dose distributions have not been independently verified. Additionally, there is no recognized method of output verification for quality assurance procedures with applicators like these. Existing dosimetry protocols available from the AAPM bookend the cross-over characteristics of a traditional brachytherapy source (as described by Task Group 43) being implemented as a low-energy superficial x-ray beam (as described by Task Group 61) as observed with the surface applicators of interest. METHODS This work aims to create a cohesive method of output verification that can be used to determine the dose at the treatment surface as part of a quality assurance/commissioning process for surface applicators used with HDR electronic brachytherapy sources (Part I) and(192)Ir sources (Part II). Air-kerma rate measurements for the electronic brachytherapy sources were completed with an Attix Free-Air Chamber, as well as several models of small-volume ionization chambers to obtain an air-kerma rate at the treatment surface for each applicator. Correction factors were calculated using MCNP5 and EGSnrc Monte Carlo codes in order to determine an applicator-specific absorbed dose to water at the treatment surface from the measured air-kerma rate. Additionally, relative dose measurements of the surface dose distributions and characteristic depth dose curves were completed in-phantom. RESULTS Theoretical dose distributions and depth dose curves were generated for each applicator and agreed well with the measured values. A method of output verification was created that allows users to determine the applicator-specific dose to water at the treatment surface based on a measured air-kerma rate. CONCLUSIONS The novel output verification methods described in this work will reduce uncertainties in dose delivery for treatments with these kinds of surface applicators, ultimately improving patient care.
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Affiliation(s)
- Regina K Fulkerson
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - John A Micka
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Larry A DeWerd
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705
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New (125)I brachytherapy source IsoSeed I25.S17plus: Monte Carlo dosimetry simulation and comparison to sources of similar design. J Contemp Brachytherapy 2013; 5:240-9. [PMID: 24474975 PMCID: PMC3899641 DOI: 10.5114/jcb.2013.39631] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2013] [Revised: 12/03/2013] [Accepted: 12/31/2013] [Indexed: 11/17/2022] Open
Abstract
Purpose To determine the relative dose rate distribution around the new 125I brachytherapy source IsoSeed I25.S17plus and report results in a form suitable for clinical use. Results for the new source are also compared to corresponding results for other commercially available 125I sources of similar design. Material and methods Monte Carlo simulations were performed using the MCNP5 v.1.6 general purpose code. The model of the new source was prepared from information provided by the manufacturer and verified by imaging a sample of ten non-radioactive sources. Corresponding simulations were also performed for the 6711 125I brachytherapy source, using updated geometric information presented recently in the literature. The uncertainty of the dose distribution around the new source, as well as the dosimetric quantities derived from it according to the Task Group 43 formalism, were determined from the standard error of the mean of simulations for a sample of fifty source models. These source models were prepared by randomly selecting values of geometric parameters from uniform distributions defined by manufacturer stated tolerances. Results and Conclusions Results are presented in the form of the quantities defined in the update of the Task Group 43 report, as well as a relative dose rate table in Cartesian coordinates. The dose rate distribution of the new source is comparable to that of sources of similar design (IsoSeed I25.S17, Oncoseed 6711, SelectSeed 130.002, Advantage IAI-125A, I-Seed AgX100, Thinseed 9011). Noticeable differences were observed only for the IsoSeed I25.S06 and Best 2301 sources.
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Novel high resolution 125I brachytherapy source dosimetry using Ge-doped optical fibres. Radiat Phys Chem Oxf Engl 1993 2013. [DOI: 10.1016/j.radphyschem.2013.06.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Mason J, Al-Qaisieh B, Bownes P, Henry A, Thwaites D. Monte Carlo investigation of I-125 interseed attenuation for standard and thinner seeds in prostate brachytherapy with phantom validation using a MOSFET. Med Phys 2013; 40:031717. [PMID: 23464312 DOI: 10.1118/1.4793256] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE In permanent seed implant prostate brachytherapy the actual dose delivered to the patient may be less than that calculated by TG-43U1 due to interseed attenuation (ISA) and differences between prostate tissue composition and water. In this study the magnitude of the ISA effect is assessed in a phantom and in clinical prostate postimplant cases. Results are compared for seed models 6711 and 9011 with 0.8 and 0.5 mm diameters, respectively. METHODS A polymethyl methacrylate (PMMA) phantom was designed to perform ISA measurements in a simple eight-seed arrangement and at the center of an implant of 36 seeds. Monte Carlo (MC) simulation and experimental measurements using a MOSFET dosimeter were used to measure dose rate and the ISA effect. MC simulations of 15 CT-based postimplant prostate treatment plans were performed to compare the clinical impact of ISA on dose to prostate, urethra, rectum, and the volume enclosed by the 100% isodose, for 6711 and 9011 seed models. RESULTS In the phantom, ISA reduced the dose rate at the MOSFET position by 8.6%-18.3% (6711) and 7.8%-16.7% (9011) depending on the measurement configuration. MOSFET measured dose rates agreed with MC simulation predictions within the MOSFET measurement uncertainty, which ranged from 5.5% to 7.2% depending on the measurement configuration (k = 1, for the mean of four measurements). For 15 clinical implants, the mean ISA effect for 6711 was to reduce prostate D90 by 4.2 Gy (3%), prostate V100 by 0.5 cc (1.4%), urethra D10 by 11.3 Gy (4.4%), rectal D2cc by 5.5 Gy (4.6%), and the 100% isodose volume by 2.3 cc. For the 9011 seed the mean ISA effect reduced prostate D90 by 2.2 Gy (1.6%), prostate V100 by 0.3 cc (0.7%), urethra D10 by 8.0 Gy (3.2%), rectal D2cc by 3.1 Gy (2.7%), and the 100% isodose volume by 1.2 cc. Differences between the MC simulation and TG-43U1 consensus data for the 6711 seed model had a similar impact, reducing mean prostate D90 by 6 Gy (4.2%) and V100 by 0.6 cc (1.8%). CONCLUSIONS ISA causes the delivered dose in prostate seed implant brachytherapy to be lower than the dose calculated by TG-43U1. MC simulation of phantom seed arrangements show that dose at a point can be reduced by up to 18% and this has been validated using a MOSFET dosimeter. Clinical simulations show that ISA reduces DVH parameter values, but the reduction is less for thinner seeds.
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Affiliation(s)
- J Mason
- Department of Medical Physics and Engineering, St. James's Institute of Oncology, St. James's University Hospital, Leeds, UK.
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Sylvester J, Grimm P, Naidoo D, Bilik J, Miller A, Wong J. First report on the use of a thinner 125I radioactive seed within 20-gauge needles for permanent radioactive seed prostate brachytherapy: Evaluation of postimplant dosimetry and acute toxicity. Brachytherapy 2013; 12:375-81. [DOI: 10.1016/j.brachy.2012.07.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 06/26/2012] [Accepted: 07/16/2012] [Indexed: 11/28/2022]
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The phylogeny of permanent prostate brachytherapy. J Contemp Brachytherapy 2013; 5:89-92. [PMID: 23878553 PMCID: PMC3708145 DOI: 10.5114/jcb.2013.35562] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 05/04/2013] [Accepted: 06/25/2013] [Indexed: 11/17/2022] Open
Abstract
Permanent prostate brachytherapy has been practiced for more than a century. This review examines the influence of earlier procedures on the modern transperineal ultrasound-directed technique. A literature review was conducted to examine the origin of current clinical practice. The dimensions of the modern brachytherapy seed, the prescription dose, and implant/teletherapy sequencing are vestigial features, which may be suboptimal in the current era of low-energy photon-emitting radionuclides and computerized dose calculations. Although the modern transperineal permanent prostate implant procedure has proven to be safe and effective, it should undergo continuous re-evaluation and evolution to ensure that its potential is maximized.
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Zhang H, Beyer D. Dosimetric comparison between model 9011 and 6711 sources in prostate implants. Med Dosim 2013; 38:199-203. [DOI: 10.1016/j.meddos.2013.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 11/13/2012] [Accepted: 01/07/2013] [Indexed: 10/27/2022]
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Roberts G, Al-Qaisieh B, Bownes P. Evaluation of the visibility of a new thinner 125I radioactive source for permanent prostate brachytherapy. Brachytherapy 2012; 11:460-7. [DOI: 10.1016/j.brachy.2012.01.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Revised: 01/12/2012] [Accepted: 01/12/2012] [Indexed: 11/26/2022]
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Mosleh-Shirazi MA, Hadad K, Faghihi R, Baradaran-Ghahfarokhi M, Naghshnezhad Z, Meigooni AS. EchoSeed Model 6733 Iodine-125 brachytherapy source: improved dosimetric characterization using the MCNP5 Monte Carlo code. Med Phys 2012; 39:4653-9. [PMID: 22894389 DOI: 10.1118/1.4736418] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
This study primarily aimed to obtain the dosimetric characteristics of the Model 6733 (125)I seed (EchoSeed) with improved precision and accuracy using a more up-to-date Monte-Carlo code and data (MCNP5) compared to previously published results, including an uncertainty analysis. Its secondary aim was to compare the results obtained using the MCNP5, MCNP4c2, and PTRAN codes for simulation of this low-energy photon-emitting source. The EchoSeed geometry and chemical compositions together with a published (125)I spectrum were used to perform dosimetric characterization of this source as per the updated AAPM TG-43 protocol. These simulations were performed in liquid water material in order to obtain the clinically applicable dosimetric parameters for this source model. Dose rate constants in liquid water, derived from MCNP4c2 and MCNP5 simulations, were found to be 0.993 cGyh(-1) U(-1) (±1.73%) and 0.965 cGyh(-1) U(-1) (±1.68%), respectively. Overall, the MCNP5 derived radial dose and 2D anisotropy functions results were generally closer to the measured data (within ±4%) than MCNP4c and the published data for PTRAN code (Version 7.43), while the opposite was seen for dose rate constant. The generally improved MCNP5 Monte Carlo simulation may be attributed to a more recent and accurate cross-section library. However, some of the data points in the results obtained from the above-mentioned Monte Carlo codes showed no statistically significant differences. Derived dosimetric characteristics in liquid water are provided for clinical applications of this source model.
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Affiliation(s)
- M A Mosleh-Shirazi
- Center for Research in Medical Physics and Biomedical Engineering and Physics Unit, Radiotherapy Department, Shiraz University of Medical Sciences, Shiraz 71936-13311, Iran.
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Duan Y, Zhang M, Wang G, Du L. Experimental determination of dosimetry parameters for Sinko (125)I seed source using a modified polystyrene phantom. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2012; 35:291-6. [PMID: 22766686 DOI: 10.1007/s13246-012-0152-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 06/19/2012] [Indexed: 10/28/2022]
Abstract
Successful treatment for permanent implant brachytherapy is based on accurate measurement of dosimetry parameters for the seed sources. Literature describes the application of various types of phantom to determine the AAPM TG-43 dosimetry parameters for permanent implant seeds. Previously we created a new type of phantom used to measure the dosimetry parameters of a high dose-rate (192)Ir source. In this study, we modified the phantom to suit to a common type of (125)I seed source (Sinko BT-125-1). The dose-rate constant, radial dose function and anisotropy function of this source were measured in detail and compared with the published values of other similar in-design (125)I seed sources. The experimental results exhibit fairly small measurement uncertainties and good self-consistency. The modified phantom is demonstrated on the measurement of dosimetry parameters for the Sinko BT-125-1 (125)I seed, however, it could easily be used for similar measurements of other permanent implantation seed sources.
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Affiliation(s)
- Yuting Duan
- Liaocheng People's Hospital, Liaocheng, China
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Paixão L, Facure A, Santos AMM, dos Santos AM, Grynberg SE. Monte Carlo study of a new I-125 brachytherapy prototype seed with a ceramic radionuclide carrier and radiographic marker. J Appl Clin Med Phys 2012; 13:3741. [PMID: 22584172 PMCID: PMC5716570 DOI: 10.1120/jacmp.v13i3.3741] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 01/12/2012] [Accepted: 01/09/2012] [Indexed: 11/23/2022] Open
Abstract
In prostate cancer treatment, there is an increasing interest in the permanent radioactive seeds implant technique. Currently, in Brazil, the seeds are imported with high prices, which prohibit their use in public hospitals. A ceramic matrix that can be used as a radioisotope carrier and radiographic marker was developed at our institution. The ceramic matrix is distinguished by the characteristic of maintaining the radioactive material uniformly distributed in its surface. In this work, Monte Carlo simulations were performed in order to assess the dose distributions generated by this prototype seed model, with the ceramic matrix encapsulated in titanium, in the same way as the commercial 6711 seed. The obtained data was assessed, as described in the TG-43U1 report by the American Association of Physicists in Medicine, for two seed models: (1) the most used model 6711 source - for validation and comparison, and (2) for the prototype model with the ceramic matrix. The dosimetric parameters dose rate constant, Λ, radial dose function, gL(r), and anisotropy function, F(r,θ), were derived from simulations by the Monte Carlo method using the MCNP5 code. A Λ 0.992 (± 2.33%) cGyh-1U-1 was found for the prototype model. In comparison with the 6711 model, a lower dose fall-off on transverse axis was found, as well as a lower dose anisotropy for the radius r = 0.25 cm. In general, for all distances, the prototype seed model presents a slightly larger anisotropy between 0° ≤ Θ < 50° and anisotropy similar to the 6711 model for Θ ≥ 50°. The dosimetric characteristics of the prototype model presented in this study suggest that its use is feasible. Because of the model's characteristics, seeds of lower specific activity iodine might be necessary which, on the other hand, would help to reduce costs. However, it has to be emphasized that the proposed source is a prototype, and the required (AAPM prerequisites) experimental study and tolerance manufacturer values are pending for future studies.
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Affiliation(s)
- Lucas Paixão
- Comissão Nacional de Energia Nuclear, Belo Horizonte/MG, Brazil
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Robertson AKH, Basran PS, Thomas SD, Wells D. CT, MR, and ultrasound image artifacts from prostate brachytherapy seed implants: The impact of seed size. Med Phys 2012; 39:2061-8. [DOI: 10.1118/1.3694669] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Tanaka K, Tateoka K, Asanuma O, Kamo KI, Bengua G, Sato K, Ueda T, Takeda H, Takagi M, Hareyama M, Takada J. A dosimetry study of the Oncoseed 6711 using glass rod dosimeters and EGS5 Monte Carlo code in a geometry lacking radiation equilibrium scatter conditions. Med Phys 2011; 38:3069-76. [PMID: 21815380 DOI: 10.1118/1.3590370] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The aim of this study was to develop a dose calculation method which is applicable to the interseed attenuation and the geometry lacking the equilibrium radiation scatter conditions in brachytherapy. METHODS The dose obtained from measurement with a radiophotoluminescent glass rod dosimeter (GRD) was compared to the dose calculated with the Monte Carlo (MC) code "EGS5," using the 125I source structure detailed in by Kennedy et al. The GRDs were irradiated with 125I Oncoseed 6711 in a human head phantom. The phantom was a cylinder made of 2 mm thick PMMA with a diameter of 18 cm and length of 16 cm. Some of the GRD positions were so close to the phantom surface that the backscatter margin was less than 5 cm, insufficient for photons. RESULTS The EGS5 simulations were found to reproduce the relative dose distributions as measured with the GRDs to within 25% uncertainty in the geometry lacking the equilibrium radiation scatter conditions. The absolute value of the GRD measurement agreed with the American Association of Physicist in Medicine Task Group No 43 Updated Protocol (AAPM-TG43U1) formalism to within 3% of the reference point (r = 1 cm, theta = 90 degrees), where the TG43U1 is especially reliable because of the abundant data accumulation in composing the formalism. The factor to normalize the measured or calculated dose to the TG43U1 estimate at the reference point was evaluated to be 0.97 for the GRD measurement and 1.8 for the MC calculation, which uses the integration of the apparent activity with the time as the amount of disintegration during the irradiation. Also, F(r,theta) and g(r) estimated by this calculation method were consistent with those proposed in the TG43U1. CONCLUSIONS The results of this investigation support the validity of both the MC calculation method and GRD measurement in this study as well as the TG-43U1 formalism. Also, this calculation is applicable to interseed attenuation and the geometry lacking the equilibrium radiation scatter.
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Affiliation(s)
- Kenichi Tanaka
- Department of Medicine, Graduate School of Sapporo Medical University, Nishi 17, Minami 1 Jo, Chuo-ku, Sapporo 060-8556, Japan.
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