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White AJ, Jollota SP, Hammer CG, Khan AU, DeWerd LA, Culberson WS. Thermoluminescent dosimeters (TLD-100) for absorbed dose measurements in alpha-emitting radionuclides. Appl Radiat Isot 2024; 208:111307. [PMID: 38564840 DOI: 10.1016/j.apradiso.2024.111307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 03/25/2024] [Accepted: 03/27/2024] [Indexed: 04/04/2024]
Abstract
Early works that used thermoluminescent dosimeters (TLDs) to measure absorbed dose from alpha particles reported relatively high variation (10%) between TLDs, which is undesirable for modern dosimetry applications. This work outlines a method to increase precision for absorbed dose measured using TLDs with alpha-emitting radionuclides by applying an alpha-specific chip factor (CF) that individually characterizes the TLD sensitivity to alpha particles. Variation between TLDs was reduced from 21.8% to 6.7% for the standard TLD chips and 7.9% to 3.3% for the thin TLD chips. It has been demonstrated by this work that TLD-100 can be calibrated to precisely measure the absorbed dose to water from alpha-emitting radionuclides.
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Affiliation(s)
- Andrew J White
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Ave, Madison, WI, 53705, USA.
| | - Sean P Jollota
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Ave, Madison, WI, 53705, USA
| | - Cliff G Hammer
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Ave, Madison, WI, 53705, USA
| | - Ahtesham U Khan
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Ave, Madison, WI, 53705, USA; Department of Radiation Oncology, Northwestern Memorial Hospital, 250 E. Huron St, Chicago, IL, 60611, USA
| | - Larry A DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Ave, Madison, WI, 53705, USA
| | - Wesley S Culberson
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Ave, Madison, WI, 53705, USA
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Khan AU, Jollota S, DeWerd LA. A diffusion-leakage model coupled with dose point kernels (DPK) for dosimetry of diffusing alpha-emitters radiation therapy (DaRT). Med Phys 2024; 51:3725-3733. [PMID: 38284426 DOI: 10.1002/mp.16960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 12/12/2023] [Accepted: 01/17/2024] [Indexed: 01/30/2024] Open
Abstract
BACKGROUND Diffusing alpha-emitters radiation therapy (DaRT) is a novel brachytherapy technique that leverages the diffusive flow of 224Ra progeny within the tumor volume over the course of the treatment. Cell killing is achieved by the emitted alpha particles that have a short range in tissue and high linear energy transfer. The current proposed absorbed dose calculation method for DaRT is based on a diffusion-leakage (DL) model that neglects absorbed dose from beta particles. PURPOSE This work aimed to couple the DL model with dose point kernels (DPKs) to account for dose from beta particles as well as to consider the non-local deposition of energy. METHODS The DaRT seed was modeled using COMSOL multiphysics and the DL model was implemented to extract the spatial information of the diffusing daughters. Using Monte-Carlo (MC) methods, DPKs were generated for 212Pb, 212Bi, and their progenies since they were considered to be the dominant beta emitters in the 224Ra radioactive decay chain. A convolution operation was performed between the integrated number densities of the diffusing daughters and DPKs to calculate the total absorbed dose over a 30-day treatment period. Both high-diffusion and low-diffusion cases were considered. RESULTS The calculated DPKs showed non-negligible energy deposition over several millimeters from the source location. An absorbed dose >10 Gy was deposited within a 1.8 mm radial distance for the low diffusion case and a 2.2 mm radial distance for the high diffusion case. When the DPK method was compared with the local energy deposition method that solely considered dose from alpha particles, differences above 1 Gy were found within 1.3 and 1.8 mm radial distances from the surface of the source for the low diffusion and high diffusion cases, respectively. CONCLUSIONS The proposed method enhances the accuracy of the dose calculation method used for the DaRT technique.
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Affiliation(s)
- Ahtesham Ullah Khan
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Sean Jollota
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Larry A DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
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Stern W, Alaei P, Berbeco R, DeWerd LA, Kamen J, MacKenzie C, Moros EG, Poirier Y, Potter CA, Schaue D, Patallo IS, Abend M, Swarts S, Trompier F. Recommendations for harmonized reporting of radiation Dosimetry by adoption of Compatibility in Irradiation Research Protocols Expert Roundtable (CIRPER). Int J Radiat Biol 2024:1-3. [PMID: 38568854 DOI: 10.1080/09553002.2024.2331130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 03/05/2024] [Indexed: 04/05/2024]
Affiliation(s)
- Warren Stern
- Nonproliferation and National Security Department, Brookhaven National Laboratory, Upton, NY, USA
| | - Parham Alaei
- Department of Radiation Oncology, University of Minnesota, Minneapolis, MN, USA
| | - Ross Berbeco
- Department of Radiation Oncology Brigham and Women's Hospital, Dana-Farber Cancer Institute, and Harvard Medical School, Boston, MA, USA
| | - Larry A DeWerd
- Medical Radiation Research Center, Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Jacob Kamen
- Department of Radiology, Mount Sinai Health System, New York, NY, USA
| | | | - Eduardo G Moros
- H. Lee Moffitt Cancer Center and Research Institute, Department of Oncological Sciences and Department of Physics, University of South Florida, Tampa, FL, USA
| | - Yannick Poirier
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MA, USA
| | | | - Dörthe Schaue
- Department of Radiation Oncology, David Geffen School of Medicine, University of California Los Angelos, Los Angeles, CA, USA
| | - Ileana Silvestre Patallo
- Medical Radiation Physics and Science Groups, National Physical Laboratory (NPL), Guilford, UK
- RadNet Standardization Dosimetry Group (Co-chair), Cancer Research UK (CRUK), London, UK
| | - Michael Abend
- Bundeswehr Institute of Radiobiology, Munich, Germany
| | - Steven Swarts
- Department of Radiation Oncology, University of Florida, Gainesville, FL, USA
| | - François Trompier
- Ionizing Radiation Dosimetry Laboratory (LDRI), Human Radiation Protection Unity, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Fontenay-aux-Rose, France
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Stern W, Alaei P, Berbeco R, DeWerd LA, Kamen J, MacKenzie C, Moros EG, Poirier Y, Potter CA, Schaue D, Patallo IS, Abend M, Swarts S, Trompier F. Achieving Consistent Reporting of Radiation Dosimetry by Adoption of Compatibility in Irradiation Research Protocols Expert Roundtable (CIRPER) Recommendations. Radiat Res 2024; 201:267-269. [PMID: 38205905 DOI: 10.1667/rade-23-00234.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 12/15/2023] [Indexed: 01/12/2024]
Affiliation(s)
- Warren Stern
- Nonproliferation and National Security Department, Brookhaven National Laboratory, Upton, New York
| | - Parham Alaei
- Department of Radiation Oncology, University of Minnesota, Minneapolis, Minnesota
| | - Ross Berbeco
- Department of Radiation Oncology Brigham and Women's Hospital, Dana-Farber Cancer Institute, and Harvard Medical School, Boston, Massachusetts
| | - Larry A DeWerd
- Medical Radiation Research Center, Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Jacob Kamen
- Department of Radiology, Mount Sinai Health System, New York, New York
| | | | - Eduardo G Moros
- H. Lee Moffitt Cancer Center and Research Institute, Department of Oncological Sciences and Department of Physics, University of South Florida, Tampa, Florida
| | - Yannick Poirier
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland
| | | | - Dörthe Schaue
- Department of Radiation Oncology, David Geffen School of Medicine, University of California Los Angeles, California
| | - Ileana Silvestre Patallo
- Medical Radiation Physics and Science Groups, National Physical Laboratory (NPL), Teddington, United Kingdom; RadNet Standardization Dosimetry Group (Co-chair), Cancer Research UK (CRUK), London, United Kingdom
| | - Michael Abend
- Bundeswehr Institute of Radiobiology, Munich, Germany
| | - Steven Swarts
- Department of Radiation Oncology, University of Florida, Gainesville, Florida
| | - François Trompier
- Ionizing Radiation Dosimetry Laboratory (LDRI), Human Radiation Protection Unity, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Fontenay-aux-Rose, France
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Ullah Khan A, DeWerd LA, Yadav P. Beam quality correction factors for ionization chambers in a 0.35 T magnetic resonance (MR)-linac - A Monte Carlo study. Phys Med 2024; 119:103314. [PMID: 38335742 DOI: 10.1016/j.ejmp.2024.103314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 01/29/2024] [Accepted: 02/04/2024] [Indexed: 02/12/2024] Open
Abstract
PURPOSE The purpose of this study was to directly calculate [Formula: see text] correction factors for four cylindrical ICs for a 0.35 T MR-linac using the Monte Carlo (MC) method. METHODS A previously-validated TOPAS/GEANT4 MC head model of the 0.35 T MR-linac was employed. The MR-compatible Exradin A12, A1SL, A26, and A28 cylindrical ICs were modeled considering the dead volume in the air cavity. The [Formula: see text] correction factor was determined for initial electron energies of 5-7 MeV. The correction factor was calculated for all four angular orientations in the lateral plane. The impact of the 0.35 T magnetic field on the IC response was also investigated. RESULTS The maximum beam quality dependence in the [Formula: see text] exhibited by the A12, A1SL, A26, and A28 ICs was 1.10 %, 2.17 %, 0.81 %, and 1.75 %, respectively, considering all angular orientations. The magnetic field dependence was < 1 % and the maximum [Formula: see text] correction was < 2 % when the detector was aligned along the direction of the magnetic field at 0° and 180° angles. The A12 IC over-responded up to 5.40 % for the orthogonal orientation. An asymmetry in the response of up to 8.30 % was noted for the A28 IC aligned at 90° and 270° angles. CONCLUSIONS A parallel orientation for the IC, with respect to the magnetic field, is recommended for reference dosimetry in MRgRT. Both over and under-response in the IC signal was noted for the orthogonal orientations, which is highly dependent on the cavity diameter, cavity length, and the dead volume.
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Affiliation(s)
- Ahtesham Ullah Khan
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Radiation Oncology, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
| | - Larry A DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Poonam Yadav
- Department of Radiation Oncology, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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Trompier F, DeWerd LA, Poirier Y, Dos Santos M, Sheng K, Kunugi KA, Winters TA, DiCarlo AL, Satyamitra M. Minimum reporting standards should be expected for preclinical radiobiology irradiators and dosimetry in the published literature. Int J Radiat Biol 2023; 100:1-6. [PMID: 37695653 PMCID: PMC10841746 DOI: 10.1080/09553002.2023.2250848] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 08/07/2023] [Accepted: 08/16/2023] [Indexed: 09/12/2023]
Abstract
The cornerstones of science advancement are rigor in performing scientific research, reproducibility of research findings and unbiased reporting of design and results of the experiments. For radiation research, this requires rigor in describing experimental details as well as the irradiation protocols for accurate, precise and reproducible dosimetry. Most institutions conducting radiation biology research in in vitro or animal models do not have describe experimental irradiation protocols in sufficient details to allow for balanced review of their publication nor for other investigators to replicate published experiments. The need to increase and improve dosimetry standards, traceability to National Institute of Standards and Technology (NIST) standard beamlines, and to provide dosimetry harmonization within the radiation biology community has been noted for over a decade both within the United States and France. To address this requirement subject matter experts have outlined minimum reporting standards that should be included in published literature for preclinical irradiators and dosimetry.
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Affiliation(s)
- François Trompier
- Ionizing Radiation Dosimetry Laboratory (LDRI), Human Radiation Protection Unity, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Fontenay-aux-Roses, France
| | - Larry A DeWerd
- Medical Radiation Research Center, Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Yannick Poirier
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Morgane Dos Santos
- Department of Radiobiology and Regenerative Medicine (SERAMED), Radiobiology of Accidental, Exposure Laboratory (LRAcc), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Fontenay-aux-Roses, France
| | - Ke Sheng
- Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, USA
| | - Keith A Kunugi
- Medical Radiation Research Center, Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Thomas A Winters
- Radiation and Nuclear Countermeasures Program (RNCP), Division of Allergy, Immunology and Transplantation (DAIT), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Rockville, MD, USA
| | - Andrea L DiCarlo
- Radiation and Nuclear Countermeasures Program (RNCP), Division of Allergy, Immunology and Transplantation (DAIT), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Rockville, MD, USA
| | - Merriline Satyamitra
- Radiation and Nuclear Countermeasures Program (RNCP), Division of Allergy, Immunology and Transplantation (DAIT), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Rockville, MD, USA
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Poirier Y, DeWerd LA, Trompier F, Santos MD, Sheng K, Kunugi K, Satyamitra MM, DiCarlo AL, Winters TA. Minimum Reporting Standards Should be Expected for Preclinical Radiobiology Irradiators and Dosimetry in the Published Literature. Radiat Res 2023; 200:217-222. [PMID: 37590483 PMCID: PMC10578361 DOI: 10.1667/rade-23-00119.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 07/25/2023] [Indexed: 08/19/2023]
Affiliation(s)
- Yannick Poirier
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Larry A. DeWerd
- Medical Radiation Research Center, Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - François Trompier
- Ionizing Radiation Dosimetry Laboratory (LDRI), Human Radiation Protection Unity, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Fontenay-aux-Rose, France
| | - Morgane Dos Santos
- Department of Radiobiology and Regenerative Medicine (SERAMED), Radiobiology of Accidental Exposure Laboratory (LRAcc), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Fontenay-aux-Roses, France
| | - Ke Sheng
- Department of Radiation Oncology, University of California San Francisco, San Francisco, California
| | - Keith Kunugi
- Medical Radiation Research Center, Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Merriline M. Satyamitra
- Radiation and Nuclear Countermeasures Program (RNCP), Division of Allergy, Immunology and Transplantation (DAIT), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Rockville, Maryland
| | - Andrea L. DiCarlo
- Radiation and Nuclear Countermeasures Program (RNCP), Division of Allergy, Immunology and Transplantation (DAIT), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Rockville, Maryland
| | - Thomas A. Winters
- Radiation and Nuclear Countermeasures Program (RNCP), Division of Allergy, Immunology and Transplantation (DAIT), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Rockville, Maryland
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Walter AE, DeWerd LA. Determination of an air kerma-rate correction factor for the S7600 Xoft Axxent Ⓡ source model. Brachytherapy 2023; 22:512-517. [PMID: 36966035 DOI: 10.1016/j.brachy.2023.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 02/09/2023] [Accepted: 02/10/2023] [Indexed: 03/27/2023]
Abstract
PURPOSE The purpose of this work was to provide guidance for the lack of an air-kerma rate standard for the S7600 Xoft Axxent® source by providing a correction factor to apply to the National Institute of Standards and Technology (NIST) traceable S7500 well chamber (WC) calibration coefficient before the development of an S7600 standard at NIST. METHODS AND MATERIALS The Attix free air chamber (FAC) at the University of Wisconsin Medical Radiation Research Center was used to measure the air-kerma rate at 50 cm for six S7500 and six S7600 sources. These same sources were then measured using five standard imaging HDR1000+ WCs. The measurements made with the FAC were used to calculate source-specific WC calibration coefficients for the S7500 and S7600 source. These results were compared to the NIST traceable calibration coefficients for the S7500 source. The average results for each WC were then averaged together, and a ratio of the S7600 to S7500 WC calibration coefficients was determined. RESULTS The average S7600 air-kerma rate measurement with the FAC was 7% lower than the average air-kerma rate measurements of the S7500 source. On average, the S7500 determined WC calibration coefficients agreed within ±1% of the NIST traceable S7500 values. The S7600 WC calibration coefficients were up to 16% less than the NIST traceable S7500 values. The final correction factor determined to be applied to the NIST traceable S7500 value was 0.8415 with an associated uncertainty of ±8.1% at k = 2. CONCLUSIONS This work provides a suggested correction factor for the S7600 Xoft Axxent source such that the sources can be accurately implemented in the clinical setting.
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Affiliation(s)
- Autumn E Walter
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, WI; Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin, Madison, WI.
| | - Larry A DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, WI
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Walter AE, Cosper PF, Nickel KP, Ramesh S, Khan AU, DeWerd LA, Kimple RJ. Biological Characterization of the Effects of Filtration on the Xoft Axxent® Electronic Brachytherapy Source for Cervical Cancer Applications. Radiat Res 2023; 199:429-438. [PMID: 37014873 PMCID: PMC10288372 DOI: 10.1667/rade-22-00112.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 03/10/2023] [Indexed: 04/05/2023]
Abstract
Low-energy X-ray sources that operate in the kilovoltage energy range have been shown to induce more cellular damage when compared to their megavoltage counterparts. However, low-energy X-ray sources are more susceptible to the effects of filtration on the beam spectrum. This work sought to characterize the biological effects of the Xoft Axxent® source, a low-energy therapeutic X-ray source, both with and without the titanium vaginal applicator in place. It was hypothesized that there would be an increase in relative biological effectiveness (RBE) of the Axxent® source compared to 60Co and that the source in the titanium vaginal applicator (SIA) would have decreased biological effects compared to the bare source (BS). This hypothesis was drawn from linear energy transfer (LET) simulations performed using the TOPAS Monte Carlo user code as well a reduction in dose rate of the SIA compared to the BS. A HeLa cell line was maintained and used to evaluate these effects. Clonogenic survival assays were performed to evaluate differences in the RBE between the BS and SIA using 60Co as the reference beam quality. Neutral comet assay was used to assess induction of DNA strand damage by each beam to estimate differences in RBE. Quantification of mitotic errors was used to evaluate differences in chromosomal instability (CIN) induced by the three beam qualities. The BS was responsible for the greatest quantity of cell death due to a greater number of DNA double strand breaks (DSB) and CIN observed in the cells. The differences observed in the BS and SIA surviving fractions and RBE values were consistent with the 13% difference in LET as well as the factor of 3.5 reduction in dose rate of the SIA. Results from the comet and CIN assays were consistent with these results as well. The use of the titanium applicator results in a reduction in the biological effects observed with these sources, but still provides an advantage over megavoltage beam qualities. © 2023 by Radiation Research Society.
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Affiliation(s)
- Autumn E. Walter
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Pippa F. Cosper
- Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
- University of Wisconsin, Carbone Cancer Center, Madison, WI
| | - Kwangok P. Nickel
- Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Shrey Ramesh
- Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Ahtesham U. Khan
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Larry A. DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
- University of Wisconsin, Carbone Cancer Center, Madison, WI
| | - Randall J. Kimple
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
- Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
- University of Wisconsin, Carbone Cancer Center, Madison, WI
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Walter AE, Khan AU, DeWerd LA. Measurement of the modified TG43 parameters for the bare S7600 Xoft Axxent source model. Brachytherapy 2023; 22:260-268. [PMID: 36623989 DOI: 10.1016/j.brachy.2022.11.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 11/16/2022] [Accepted: 11/22/2022] [Indexed: 01/09/2023]
Abstract
PURPOSE The purpose of this work is to provide measured data for the modified TG43 parameters [DeWerd et al.] for the newest, Galden-cooled S7600 Xoft Axxent source model. METHODS The measurement of radial dose distributions at distances of 1 cm to 4 cm from the source was performed using TLD100 microcubes, EBT3 film, and an Exradin A26 microionization chamber. The overall uncertainty and reproducibility of each dosimeter was evaluated for its use in determining the radial dose function and dose rate conversion coefficient. An acrylic phantom developed in house for previous works was used to measure the polar anisotropy function using TLD100 microcubes at distances of 1 cm, 2 cm, and 5 cm from the source. RESULTS The Exradin A26 chamber was deemed most suitable for measuring the radial dose function. Values determined had a maximum k = 1 uncertainty of 1.4%. The dose rate conversion coefficient measured with the chamber was found to be 9.33 ± 0.21cGy/hrμGy/min. TLD100 microcube measurements of the polar anisotropy had average uncertainties of 6%, 3%, and 2.5% at 1 cm, 2 cm, and 5 cm, respectively. CONCLUSIONS The modified TG43 parameters for the bare source were measured with reasonable uncertainty. The values determined will aid with the clinical implementation of the source for breast and endometrial cancer applications.
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Affiliation(s)
- Autumn E Walter
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, WI; Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin, Madison, WI.
| | - Ahtesham U Khan
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, WI
| | - Larry A DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, Madison, WI
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Ma Chair CM, Coffey CW, DeWerd LA, Liu C, Nath R, Seltzer SM, Seuntjens JP. Erratum: "AAPM protocol for 40-300 kV x-ray beam dosimetry in radiotherapy and radiobiology". Med Phys 2023. [PMID: 36735148 DOI: 10.1002/mp.16239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 01/19/2023] [Indexed: 02/04/2023] Open
Affiliation(s)
- C-M Ma Chair
- Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania, USA
| | - C W Coffey
- Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - L A DeWerd
- Medical Physics, University of Wisconsin, Madison, Wisconsin, USA
| | - C Liu
- Department of Radiation Oncology, University of Florida, Gainesville, Florida, USA
| | - R Nath
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - S M Seltzer
- Radiation Physics Division, National Institute of Standards and Technology, Gaithersburg, Maryland, USA
| | - J P Seuntjens
- Department of Medical Physics, Princess Margaret Cancer Centre, Toronto, ON, Canada
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Khan AU, Nelson NP, Culberson WS, DeWerd LA. On the perturbation effect and LET dependence of beam quality correction factors in carbon ion beams. Med Phys 2023; 50:1105-1120. [PMID: 36334024 DOI: 10.1002/mp.16089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 05/31/2022] [Accepted: 10/26/2022] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND In a recent study, we reported beam quality correction factors, fQ , in carbon ion beams using Monte Carlo (MC) methods for a cylindrical and a parallel-plate ionization chamber (IC). A non-negligible perturbation effect was observed; however, the magnitude of the perturbation correction due to the specific IC subcomponents was not included. Furthermore, the stopping power data presented in the International Commission on Radiation Units and Measurements (ICRU) report 73 were used, whereas the latest stopping power data have been reported in the ICRU report 90. PURPOSE The aim of this study was to extend our previous work by computing fQ correction factors using the ICRU 90 stopping power data and by reporting IC-specific perturbation correction factors. Possible energy or linear energy transfer (LET) dependence of the fQ correction factor was investigated by simulating both pristine beams and spread-out Bragg peaks (SOBPs). METHODS The TOol for PArticle Simulation (TOPAS)/GEANT4 MC code was used in this study. A 30 × 30 × 50 cm3 water phantom was simulated with a uniform 10 × 10 cm2 parallel beam incident on the surface. A Farmer-type cylindrical IC (Exradin A12) and two parallel-plate ICs (Exradin P11 and A11) were simulated in TOPAS using the manufacturer-provided geometrical drawings. The fQ correction factor was calculated in pristine carbon ion beams in the 150-450 MeV/u energy range at 2 cm depth and in the middle of the flat region of four SOBPs. The kQ correction factor was calculated by simulating the fQo correction factor in a 60 Co beam at 5 cm depth. The perturbation correction factors due to the presence of the individual IC subcomponents, such as the displacement effect in the air cavity, collecting electrode, chamber wall, and chamber stem, were calculated at 2 cm depth for monoenergetic beams only. Additionally, the mean dose-averaged and track-averaged LET was calculated at the depths at which the fQ was calculated. RESULTS The ICRU 90 fQ correction factors were reported. The pdis correction factor was found to be significant for the cylindrical IC with magnitudes up to 1.70%. The individual perturbation corrections for the parallel-plate ICs were <1.0% except for the A11 pcel correction at the lowest energy. The fQ correction for the P11 IC exhibited an energy dependence of >1.00% and displayed differences up to 0.87% between pristine beams and SOBPs. Conversely, the fQ for A11 and A12 displayed a minimal energy dependence of <0.50%. The energy dependence was found to manifest in the LET dependence for the P11 IC. A statistically significant LET dependence was found only for the P11 IC in pristine beams only with a magnitude of <1.10%. CONCLUSIONS The perturbation and kQ correction factor should be calculated for the specific IC to be used in carbon ion beam reference dosimetry as a function of beam quality.
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Affiliation(s)
- Ahtesham Ullah Khan
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Nicholas P Nelson
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Wesley S Culberson
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Larry A DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
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Walter AE, DeWerd LA. Feasibility of implementing a megavoltage ionization chamber calibration service at the secondary standards level. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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Khan AU, Simiele EA, Lotey R, DeWerd LA, Yadav P. An independent Monte Carlo-based IMRT QA tool for a 0.35 T MRI-guided linear accelerator. J Appl Clin Med Phys 2022; 24:e13820. [PMID: 36325743 PMCID: PMC9924112 DOI: 10.1002/acm2.13820] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 10/08/2022] [Accepted: 10/11/2022] [Indexed: 11/06/2022] Open
Abstract
PURPOSE To develop an independent log file-based intensity-modulated radiation therapy (IMRT) quality assurance (QA) tool for the 0.35 T magnetic resonance-linac (MR-linac) and investigate the ability of various IMRT plan complexity metrics to predict the QA results. Complexity metrics related to tissue heterogeneity were also introduced. METHODS The tool for particle simulation (TOPAS) Monte Carlo code was utilized with a previously validated linac head model. A cohort of 29 treatment plans was selected for IMRT QA using the developed QA tool and the vendor-supplied adaptive QA (AQA) tool. For 27 independent patient cases, various IMRT plan complexity metrics were calculated to assess the deliverability of these plans. A correlation between the gamma pass rates (GPRs) from the AQA results and calculated IMRT complexity metrics was determined using the Pearson correlation coefficients. Tissue heterogeneity complexity metrics were calculated based on the gradient of the Hounsfield units. RESULTS The median and interquartile range for the TOPAS GPRs (3%/3 mm criteria) were 97.24% and 3.75%, respectively, and were 99.54% and 0.36% for the AQA tool, respectively. The computational time for TOPAS ranged from 4 to 8 h to achieve a statistical uncertainty of <1.5%, whereas the AQA tool had an average calculation time of a few minutes. Of the 23 calculated IMRT plan complexity metrics, the AQA GPRs had correlations with 7 out of 23 of the calculated metrics. Strong correlations (|r| > 0.7) were found between the GPRs and the heterogeneity complexity metrics introduced in this work. CONCLUSIONS An independent MC and log file-based IMRT QA tool was successfully developed and can be clinically deployed for offline QA. The complexity metrics will supplement QA reports and provide information regarding plan complexity.
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Affiliation(s)
- Ahtesham Ullah Khan
- Department of Medical PhysicsSchool of Medicine and Public HealthUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
| | - Eric A. Simiele
- Department of Radiation OncologyRutgers Cancer Institute of New Jersey, Rutgers Robert Wood Johnson Medical SchoolNew BrunswickNew JerseyUSA
| | | | - Larry A. DeWerd
- Department of Medical PhysicsSchool of Medicine and Public HealthUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
| | - Poonam Yadav
- Department of Radiation OncologyNorthwestern Memorial HospitalNorthwestern University Feinberg School of MedicineChicagoIllinoisUSA
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King EJ, Viscariello NN, DeWerd LA. Development of Standard X-Ray Beams for Calibration of Radiobiology Cabinet and Conformal Irradiators. Radiat Res 2022; 197:113-121. [PMID: 34634111 DOI: 10.1667/rade-21-00121.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 09/23/2021] [Indexed: 11/03/2022]
Abstract
This work seeks to develop standard X-ray beams that are matched to radiobiology X-ray irradiators. The calibration of detectors used for dose determination of these irradiators is performed with a set of standard X rays that are more heavily filtered and/or lower energy, which leads to a higher uncertainty in the dose measurement. Models of the XRad320, SARRP, and the X-ray tube at the University of Wisconsin Medical Radiation Research Center (UWMRRC) were created using the BEAMnrc user code of the EGSnrc Monte Carlo code system. These models were validated against measurements, and the resultant modeled spectra were used to determine the amount of added filtration needed to match the X-ray beams at the UWMRRC to those of the XRad320 and SARRP. The depth profiles and half-value layer (HVL) simulations performed using BEAMnrc agreed to measurements within 3% and 3.6%, respectively. A primary measurement device, a free-air chamber, was developed to measure air kerma in the medium energy range of X rays. The resultant spectra of the matched beams had HVL's that matched the HVL's of the radiobiology irradiators well within the 3% criteria recommended by the International Atomic Energy Agency (IAEA) and the average energies agreed within 2.4%. In conclusion, three standard X-ray beams were developed at the UWMRRC with spectra that more closely match the spectra of the XRad320 and SARRP radiobiology irradiators, which will aid in a more accurate dose determination during calibration of these irradiators.
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Affiliation(s)
- Emily J King
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin
| | | | - Larry A DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin
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DeWerd LA, Khan AU, Jensen AR. On the length used for CT ionization chambers to determine CTDI. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac60b8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 03/24/2022] [Indexed: 11/12/2022]
Abstract
Abstract
Objective. Computed tomography dose index (CTDI) calculations based on measurements made with CT ionization chambers require characterization of two chamber properties: radiation sensitivity and effective length. The sensitivity of a CT ionization chamber is currently determined in some countries by calibration in an x-ray field that irradiates the entire chamber. Determination of the effective length is left to the user, and this value is frequently assumed to be equivalent to the nominal length—typically 100 mm—stated by the manufacturer. This assumption undermines the intention and usefulness of CTDI calculation. Thus, a slit-based calibration, N
KL, of the CT ionization chambers was proposed by collimating the x-ray beam to a well-defined aperture width. The aim of this work is to compare the two methods. Approach. Four different CT ionization chambers (Standard Imaging Exradin A101, Radcal 10x5-3CT, Victoreen 500-100, and Capintec PC-4P) are investigated in this work. Sensitivity profiles were measured for all four chambers and effective/rated chamber lengths were calculated. A novel Monte-Carlo based correction was proposed to account for the presence of the aperture. CTDI was calculated and compared for two calibration beams as well as for a commercial CT scanner using Exradin A101 and Radcal 10x5-3CT chambers. Main results. The nominal chamber length was found to deviate up to 21% compared to the effective length. Correction for the aperture depended on the aperture opening size. CTDI calculation results illustrate the potential 17% error in CTDI calculation that can be caused by assuming the effective chamber length is equivalent to the manufacturer’s stated nominal length. CTDI calculations with CT ionization chambers calibrated with an air-kerma length calibration method yield the smallest variation in the CTDI regardless of the chamber model. Significance. To avoid an erroneous CTDI, information regarding the chamber’s effective length must be included in the calibration or stated by the manufacturer. Alternatively, a slit-based calibration can be performed.
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Khan AU, Lotey R, DeWerd LA, Yadav P. A multi-institutional comparison of dosimetric data for a 0.35 T MR-linac. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac53df] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 02/10/2022] [Indexed: 11/11/2022]
Abstract
Abstract
Objective. A comparison of percent depth dose (PDD) curves, lateral beam profiles, output factors (OFs), multileaf collimator (MLC) leakage, and couch transmission factors was performed between ten institutes for a commercial 0.35 T MR-linac. Approach. The measured data was collected during acceptance testing of the MR-linac. The PDD curves were measured for the 3.32 × 3.32 cm2, 9.96 × 9.96 cm2, and 27.20 × 24.07 cm2 field sizes. The lateral beam profiles were acquired for a 27.20 × 24.07 cm2 field size using an ion chamber array and penumbra was defined as the distance between 80% of the maximum dose and 20% of the maximum dose after normalizing the profiles to the dose at the inflection points. The OFs were measured using solid-state dosimeters, whereas radiochromic films were utilized to measure radiation leakage through the MLC stacks. The relative couch transmission factors were measured for various gantry angles. The variation in the multi-institutional data was quantified using the percent standard deviation metric. Main results. Minimal variations (<1%) were found between the PDD data, except for the build-up region and the deeper regions of the PDD curve. The in-field region of the lateral beam profiles varied <1.5% between different institutions and a small variation (<0.7 mm) in penumbra was observed. A variation of <1% was observed in the OF data for field sizes above 1.66 × 1.66 cm2, whereas large variations were shown for small-field sizes. The average and maximum MLC leakage was calculated to be <0.3% and <0.6%, which was well below the international electrotechnical commission (IEC) leakage thresholds. The couch transmission was smallest for oblique beams and ranged from 0.83 to 0.87. Significance. The variation in the data was found to be relatively small and the different 0.35 T MR-linacs were concluded to have similar dosimetric characteristics.
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Walter AE, Hull JL, DeWerd LA. Comparison of air kerma rate between the S7500 and S7600 xoft axxent sources. Brachytherapy 2022; 21:354-361. [DOI: 10.1016/j.brachy.2021.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 12/03/2021] [Accepted: 12/05/2021] [Indexed: 11/02/2022]
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Ferris WS, DeWerd LA, Culberson WS. Fiducial visibility on planar images during motion-synchronized tomotherapy treatments. Biomed Phys Eng Express 2022; 8. [PMID: 35026743 DOI: 10.1088/2057-1976/ac4b3e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 01/13/2022] [Indexed: 11/11/2022]
Abstract
Objective. Synchrony®is a motion management system on the Radixact®that uses planar kV radiographs to locate the target during treatment. The purpose of this work is to quantify the visibility of fiducials on these radiographs.Approach. A custom acrylic slab was machined to hold 8 gold fiducials of various lengths, diameters, and orientations with respect to the imaging axis. The slab was placed on the couch at the imaging isocenter and planar radiographs were acquired perpendicular to the custom slab with varying thicknesses of acrylic on each side. Fiducial signal to noise ratio (SNR) and detected fiducial position error in millimeters were quantified.Main Results. The minimum output protocol (100 kVp, 0.8 mAs) was sufficient to detect all fiducials on both Radixact configurations when the thickness of the phantom was 20 cm. However, no fiducials for any protocol were detected when the phantom was 50 cm thick. The algorithm accurately detected fiducials on the image when the SNR was larger than 4. The MV beam was observed to cause RFI artifacts on the kV images and to decrease SNR by an average of 10%.Significance. This work provides the first data on fiducial visibility on kV radiographs from Radixact Synchrony treatments. The Synchrony fiducial detection algorithm was determined to be very accurate when sufficient SNR is achieved. However, a higher output protocol may need to be added for use with larger patients. This work provided groundwork for investigating visibility of fiducial-free solid targets in future studies and provided a direct comparison of fiducial visibility on the two Radixact configurations, which will allow for intercomparison of results between configurations.
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Affiliation(s)
- William S Ferris
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, United States of America
| | - Larry A DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, United States of America
| | - Wesley S Culberson
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, United States of America
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Khan AU, Simiele EA, DeWerd LA. Monte Carlo-derived ionization chamber correction factors in therapeutic carbon ion beams. Phys Med Biol 2021; 66. [PMID: 34464949 DOI: 10.1088/1361-6560/ac226c] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 08/31/2021] [Indexed: 11/12/2022]
Abstract
The accuracy of electromagnetic transport in the GEANT4 Monte Carlo (MC) code was investigated for carbon ion beams and ionization chamber (IC)-specific beam quality correction factors were calculated. This work implemented a Fano cavity test for carbon ion beams in the 100-450 MeV/u energy range to assess the accuracy of the default electromagnetic physics parameters. TheUrbanand theWentzel-VImultiple Coulomb scattering models were evaluated and the impact ofmaxStep,dRover,andfinal rangeparameters on the accuracy of the transport algorithm was investigated. The optimal production thresholds for an accurate calculation offQvalues, which is the product of the water-to-air stopping power ratio and the IC-specific perturbation correction factor, were also studied. ThefQcorrection factors were calculated for a cylindrical and a parallel-plate IC using carbon ions in the 150-450 MeV/u energy range. Modifying the default electromagnetic physics parameters resulted in a maximum deviation from theory of 0.3%. Therefore, the default EM parameters were used for the remainder of this work. ThefQfactors were found to converge for both ICs with decreasing production threshold distance below 5μm. ThefQvalues obtained in this work agreed with the TRS-398 stopping power ratios and other previously reported results within uncertainty. This study highlights an accurate MC-based technique to calculate the combined stopping power ratio and the perturbation correction factor for any IC in carbon ion beams.
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Affiliation(s)
- Ahtesham Ullah Khan
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, United States of America
| | - Eric A Simiele
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, United States of America
| | - Larry A DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, United States of America
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DeWerd LA, Kunugi K. Accurate Dosimetry for Radiobiology. Int J Radiat Oncol Biol Phys 2021; 111:e75-e81. [PMID: 34509551 DOI: 10.1016/j.ijrobp.2021.09.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/31/2021] [Accepted: 09/01/2021] [Indexed: 10/20/2022]
Abstract
PURPOSE Accurate radiation dose is required to ensure reproducibility in establishing the radiobiological effect in biological systems among institutions. The dose should be the most precise and accurate parameter of the entire process. The goal is a system to provide uniform radiation dose verification among institutions that is traceable to the National Institute of Standards and Technology (NIST) through an Accredited Dosimetry Calibration Laboratory. METHODS AND MATERIALS Radiobiological beams are not NIST traceable but can be approximated based on the radiograph's half value layer. Phantoms have been developed containing detectors to measure the dose from total body irradiation of mice and others. Ionization chambers calibrated to NIST-traceable beams are the best detectors for precise and accurate dose determinations. However, thermoluminescent dosimeters have been mostly used for this application for comparison between institutions. RESULTS A comparison of thermoluminescent dosimeters results among surveyed institutions showed a large variation in delivered dose. The range of radiograph doses that were measured deviated from the standard dose by 12% to 42%. The results have an uncertainty of 2.5% at 1 standard deviation. The surveyed radionuclide irradiators demonstrated a dose range variation of 1.6% to 13.5% from target dose. There is less variation among high energy (linacs) because a calibrated ionization chamber is generally used by personnel (eg, medical physicist) and the output is determined for radiation therapy applications as well. CONCLUSIONS Radiobiological dosimetry is lacking with respect to its precision and accuracy. The accuracy of radiograph calibrations for radiobiology can be estimated to be approximately 5%, because there are no NIST-traceable beams. However, among institutions, the variations can be up to 42%. Intercomparisons between institutions is important to have a clear understanding of the transference of dose between given studies.
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Affiliation(s)
- Larry A DeWerd
- Department of Medical Physics, Medical Radiation Research Center, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin.
| | - Keith Kunugi
- Department of Medical Physics, Medical Radiation Research Center, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin
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Lambeck J, Kennan W, DeWerd LA. Effect of well chamber altitude pressure corrections for cesium Blu 131 Cs and CivaDot 103 Pd brachytherapy sources. Med Phys 2021; 48:5584-5592. [PMID: 34460946 DOI: 10.1002/mp.15190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 08/18/2021] [Accepted: 08/19/2021] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Previous publications have described how the standard temperature and pressure correction will overcorrect measurements with a low-energy photon low-dose rate brachytherapy source at low ambient air pressures. To account for this effect, an additional correction factor is applied after the standard temperature and pressure correction. This additional correction is dependent on the source being measured and the chamber it is measured in. Well chamber corrections for two sources and findings regarding aspects that may affect the altitude response of the sources are presented. METHODS A purpose-built pressure vessel was constructed previously, which could achieve pressures ranging from 74.661 to 106.66 kPa (560-800 mmHg). Three Cesium Blu sources (131 Cs) from Isoray Inc. and three CivaDots (103 Pd) from CivaTech Oncology Inc. were tested over this pressure range in increments of 2.7 kPa (20 mmHg) in three HDR 1000 Plus chambers, and the Cesium Blu sources were also tested in two IVB 1000 chambers. Both chamber models are air communicating well-type ionization chambers produced by Standard Imaging Inc. Multiple runs of each source/chamber combination were completed, corrected with the standard temperature and pressure correction, normalized to the result at 101.325 kPa, and averaged with runs of the same combination. The chamber response was also simulated using MCNP6 to validate the experimental results. RESULTS Measurements of both sources in all chambers followed the expected power dependence on ambient pressure as seen in previous studies. The Cesium Blu source, however, demonstrated a significant difference in response in the HDR 1000 Plus chamber versus the IVB 1000 chamber. For an altitude correction factor of the form, PA = k1 (P)k 2 , new coefficients are proposed for both sources for pressure units of kPa and mmHg. The Monte Carlo calculated chamber response agreed with the experimental results within 2% for all sources and chambers at all pressures. CONCLUSIONS Altitude correction coefficients for two new low-energy photon low-dose rate brachytherapy sources are provided. The directional dependence of the CivaDot has no bearing on its dependence on pressure; however, the difference in construction materials from other 103 Pd sources leads to unique correction coefficients. The higher energy of the Cesium Blu source with respect to 103 Pd and 125 I sources yields a difference in correction factors depending on which model chamber is used for air-kerma strength calculations. Clinics must be careful to select the correct pair of coefficients for the chamber model they used.
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Affiliation(s)
- Jacob Lambeck
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin - Madison, Madison, Wisconsin, 53705, USA
| | - Wendy Kennan
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin - Madison, Madison, Wisconsin, 53705, USA
| | - Larry A DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin - Madison, Madison, Wisconsin, 53705, USA
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Petti PL, Rivard MJ, Alvarez PE, Bednarz G, Daniel Bourland J, DeWerd LA, Drzymala RE, Johansson J, Kunugi K, Ma L, Meltsner SG, Neyman G, Seuntjens JP, Shiu AS, Goetsch SJ. Recommendations on the practice of calibration, dosimetry, and quality assurance for gamma stereotactic radiosurgery: Report of AAPM Task Group 178. Med Phys 2021; 48:e733-e770. [DOI: 10.1002/mp.14831] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 02/21/2021] [Accepted: 02/24/2021] [Indexed: 12/25/2022] Open
Affiliation(s)
- Paula L. Petti
- Gamma Knife Center Washington Hospital Fremont CA 94538 USA
| | - Mark J. Rivard
- Department of Radiation Oncology Alpert Medical School of Brown University Providence RI 02903 USA
| | - Paola E. Alvarez
- Radiological Physics Center University of Texas MD Anderson Cancer Center Houston TX 77054 USA
| | - Greg Bednarz
- Department of Radiation Oncology University of Pittsburgh Medical Center Pittsburgh PA 15232 USA
| | - J. Daniel Bourland
- Department of Radiation Oncology Wake Forest University Winston‐Salem NC 27157 USA
| | - Larry A. DeWerd
- Accredited Dosimetry and Calibration Laboratory University of Wisconsin Madison WI 53705 USA
| | - Robert E. Drzymala
- Department of Radiation Oncology Washington University Saint Louis MO 63119 USA
| | | | - Keith Kunugi
- Accredited Dosimetry and Calibration Laboratory University of Wisconsin Madison WI 53705 USA
| | - Lijun Ma
- Department of Radiation Oncology University California–San Francisco San Francisco CA 94143 USA
| | - Sheridan G. Meltsner
- Department of Radiation Oncology Duke University Medical Center Durham NC 27713 USA
| | - Gennady Neyman
- Department of Radiation Oncology The Cleveland Clinic Cleveland OH 44195 USA
| | - Jan P. Seuntjens
- Department of Medical Physics McGill University Montreal QC H4A3J1 Canada
| | - Almon S. Shiu
- Department of Radiation Oncology University of Southern California Los Angeles CA 90033 USA
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Ferris WS, DeWerd LA, Bayouth JE, Culberson WS. Technical note: On the impact of the kV imaging configuration on doses from planar images during motion-synchronized treatments on Radixact®. J Appl Clin Med Phys 2021; 22:227-231. [PMID: 34309182 PMCID: PMC8425929 DOI: 10.1002/acm2.13371] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/30/2021] [Accepted: 07/12/2021] [Indexed: 11/12/2022] Open
Abstract
Kilovoltage radiographs are acquired during motion‐synchronized treatments on Radixact to localize the tumor during the treatment. Several previous publications have provided estimates of patient dose from these planar radiographs. However, a recent hardware update changed several aspects of the kV imaging system, including a new X‐ray tube, an extended source‐to‐axis distance (SAD), and a larger field size. This is denoted the extended configuration. The purpose of this work was to assess the impact of the configuration change on patient dose from these procedures. Point doses in water were measured using the TG‐61 protocol for tube potentials between 100 and 140 kVp for both the standard and extended configurations under the same water tank setup. Comparisons were made for equal mAs since the same protocols (kVp, mAs) will be used for both configurations. In comparison to the standard configuration, doses per mAs from the extended configuration were found to be ~66% less and falloff less steep due to the increased SAD. However, a larger volume of tissue is irradiated due to the larger field size. Beam quality for a given tube potential was the same as determined by half‐value layer measurements. Both kV configurations are available from the vendor, therefore, the values in this work can be used to compare values previously published in the literature for the standard configuration or to intercompare doses from these two system configurations.
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Affiliation(s)
- William S Ferris
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Larry A DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - John E Bayouth
- Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Wesley S Culberson
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
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Chinnadurai R, Bates PD, Kunugi KA, Nickel KP, DeWerd LA, Capitini CM, Galipeau J, Kimple RJ. Dichotomic Potency of IFNγ Licensed Allogeneic Mesenchymal Stromal Cells in Animal Models of Acute Radiation Syndrome and Graft Versus Host Disease. Front Immunol 2021; 12:708950. [PMID: 34386012 PMCID: PMC8352793 DOI: 10.3389/fimmu.2021.708950] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 07/01/2021] [Indexed: 12/19/2022] Open
Abstract
Mesenchymal stromal cells (MSCs) are being tested as a cell therapy in clinical trials for dozens of inflammatory disorders, with varying levels of efficacy reported. Suitable and robust preclinical animal models for testing the safety and efficacy of different types of MSC products before use in clinical trials are rare. We here introduce two highly robust animal models of immune pathology: 1) acute radiation syndrome (ARS) and 2) graft versus host disease (GvHD), in conjunction with studying the immunomodulatory effect of well-characterized Interferon gamma (IFNγ) primed bone marrow derived MSCs. The animal model of ARS is based on clinical grade dosimetry precision and bioluminescence imaging. We found that allogeneic MSCs exhibit lower persistence in naïve compared to irradiated animals, and that intraperitoneal infusion of IFNγ prelicensed allogeneic MSCs protected animals from radiation induced lethality by day 30. In direct comparison, we also investigated the effect of IFNγ prelicensed allogeneic MSCs in modulating acute GvHD in an animal model of MHC major mismatched bone marrow transplantation. Infusion of IFNγ prelicensed allogeneic MSCs failed to mitigate acute GvHD. Altogether our results demonstrate that infused IFNγ prelicensed allogeneic MSCs protect against lethality from ARS, but not GvHD, thus providing important insights on the dichotomy of IFNγ prelicensed allogenic MSCs in well characterized and robust animal models of acute tissue injury.
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Affiliation(s)
- Raghavan Chinnadurai
- Department of Biomedical Sciences, Mercer University School of Medicine, Savannah, GA, United States
| | - Paul D Bates
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Keith A Kunugi
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Kwangok P Nickel
- Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Larry A DeWerd
- Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Christian M Capitini
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States.,University of Wisconsin Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Jacques Galipeau
- University of Wisconsin Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States.,Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Randall J Kimple
- Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States.,University of Wisconsin Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
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Khan AU, Simiele EA, Lotey R, DeWerd LA, Yadav P. Development and evaluation of a GEANT4-based Monte Carlo Model of a 0.35 T MR-guided radiation therapy (MRgRT) linear accelerator. Med Phys 2021; 48:1967-1982. [PMID: 33555052 PMCID: PMC8251819 DOI: 10.1002/mp.14761] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 01/05/2021] [Accepted: 02/02/2021] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The aim of this work was to develop and benchmark a magnetic resonance (MR)-guided linear accelerator head model using the GEANT4 Monte Carlo (MC) code. The validated model was compared to the treatment planning system (TPS) and was also used to quantify the electron return effect (ERE) at a lung-water interface. METHODS The average energy, including the spread in the energy distribution, and the radial intensity distribution of the incident electron beam were iteratively optimized in order to match the simulated beam profiles and percent depth dose (PDD) data to measured data. The GEANT4 MC model was then compared to the TPS model using several photon beam tests including oblique beams, an off-axis aperture, and heterogeneous phantoms. The benchmarked MC model was utilized to compute output factors (OFs) with the 0.35 T magnetic field turned on and off. The ERE was quantified at a lung-water interface by simulating PDD curves with and without the magnetic field for 6.6 × 6.6 cm 2 and 2.5 × 2.5 cm 2 field sizes. A 2%/2 mm gamma criterion was used to compare the MC model with the TPS data throughout this study. RESULTS The final incident electron beam parameters were 6.0 MeV average energy with a 1.5 MeV full width at half maximum (FWHM) Gaussian energy spread and a 1.0 mm FWHM Gaussian radial intensity distribution. The MC-simulated OFs were found to be in agreement with the TPS-calculated and measured OFs, and no statistical difference was observed between the 0.35 T and 0.0 T OFs. Good agreement was observed between the TPS-calculated and MC-simulated data for the photon beam tests with gamma pass rates ranging from 96% to 100%. An increase of 4.3% in the ERE was observed for the 6.6 × 6.6 cm 2 field size relative to the 2.5 × 2.5 cm 2 field size. The ratio of the 0.35 T PDD to the 0.0 T PDD was found to be up to 1.098 near lung-water interfaces for the 6.6 × 6.6 cm 2 field size using the MC model. CONCLUSIONS A vendor-independent Monte Carlo model has been developed and benchmarked for a 0.35 T/6 MV MR-linac. Good agreement was obtained between the GEANT4 and TPS models except near heterogeneity interfaces.
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Affiliation(s)
- Ahtesham Ullah Khan
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, 53705, USA
| | - Eric A Simiele
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Rajiv Lotey
- ViewRay Inc, Oakwood Village, Ohio, 44146, USA
| | - Larry A DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, 53705, USA
| | - Poonam Yadav
- Department of Human Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
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Abstract
Background: Density-based dose point kernel (DPK) scaling accuracy was investigated in various homogeneous tissue media. Methods: Using GEometry ANd Tracking 4 Monte Carlo code, DPKs were generated for 5, 8 MeV monoenergetic α particles and 223Ra, 225Ac, and 227Th. Dose was scored in 1 μm thick concentric shells and DPKs were scaled based on the tissue's mass density and compared with the water DPK. Results: Scaled kernels agreed within ±5% except near the Bragg peaks, where they differed up to 25%. Conclusions: The authors conclude that kernel scaling based on mass density of the transport medium can be utilized accurately up to 5%, excluding Bragg peak regions.
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Affiliation(s)
- Ahtesham Ullah Khan
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Larry A DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
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Walter AE, Hansen JB, DeWerd LA. Evaluation of ionization chamber stability checks using various sources. Phys Med 2020; 80:327-334. [DOI: 10.1016/j.ejmp.2020.11.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 09/30/2020] [Accepted: 11/07/2020] [Indexed: 10/22/2022] Open
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Khan AU, Culberson WS, DeWerd LA. Characterizing a PTW microDiamond detector in kilovoltage radiation beams. Med Phys 2020; 47:4553-4562. [DOI: 10.1002/mp.14330] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 05/12/2020] [Accepted: 06/08/2020] [Indexed: 12/16/2022] Open
Affiliation(s)
- Ahtesham Ullah Khan
- Department of Medical Physics School of Medicine and Public Health University of Wisconsin‐Madison Madison Wisconsin53705USA
| | - Wesley S. Culberson
- Department of Medical Physics School of Medicine and Public Health University of Wisconsin‐Madison Madison Wisconsin53705USA
| | - Larry A. DeWerd
- Department of Medical Physics School of Medicine and Public Health University of Wisconsin‐Madison Madison Wisconsin53705USA
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30
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Smith BR, DeWerd LA, Culberson WS. On the stability of well‐type ionization chamber source strength calibration coefficients. Med Phys 2020; 47:4491-4501. [DOI: 10.1002/mp.14247] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/26/2020] [Accepted: 05/06/2020] [Indexed: 11/09/2022] Open
Affiliation(s)
- Blake R. Smith
- Department of Medical Physics School of Medicine and Public Health University of Wisconsin‐Madison Madison WI 53705 USA
| | - Larry A. DeWerd
- Department of Medical Physics School of Medicine and Public Health University of Wisconsin‐Madison Madison WI 53705 USA
| | - Wesley S. Culberson
- Department of Medical Physics School of Medicine and Public Health University of Wisconsin‐Madison Madison WI 53705 USA
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Desai VK, Labby ZE, DeWerd LA, Culberson WS. On the implementation of the plan‐class specific reference field using multidimensional clustering of plan features and alternative strategies for improved dosimetry in modulated clinical linear accelerator treatments. Med Phys 2020; 47:3621-3635. [DOI: 10.1002/mp.14207] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 04/14/2020] [Accepted: 04/20/2020] [Indexed: 11/08/2022] Open
Affiliation(s)
- Vimal K. Desai
- Department of Human Oncology School of Medicine and Public Health University of Wisconsin‐Madison Madison WI 53792 USA
| | - Zacariah E. Labby
- Department of Human Oncology School of Medicine and Public Health University of Wisconsin‐Madison Madison WI 53792 USA
| | - Larry A. DeWerd
- Department of Medical Physics School of Medicine and Public Health University of Wisconsin‐Madison Madison WI 53705 USA
| | - Wesley S. Culberson
- Department of Medical Physics School of Medicine and Public Health University of Wisconsin‐Madison Madison WI 53705 USA
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DiMaso LD, Miller JR, Lawless MJ, Bassetti MF, DeWerd LA, Huang J. Investigating split-filter dual-energy CT for improving liver tumor visibility for radiation therapy. J Appl Clin Med Phys 2020; 21:249-255. [PMID: 32410336 PMCID: PMC7484851 DOI: 10.1002/acm2.12904] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 01/20/2020] [Accepted: 04/16/2020] [Indexed: 11/17/2022] Open
Abstract
Purpose Accurate liver tumor delineation is crucial for radiation therapy, but liver tumor volumes are difficult to visualize with conventional single‐energy CT. This work investigates the use of split‐filter dual‐energy CT (DECT) for liver tumor visibility by quantifying contrast and contrast‐to‐noise ratio (CNR). Methods Split‐filter DECT contrast‐enhanced scans of 20 liver tumors including cholangiocarcinomas, hepatocellular carcinomas, and liver metastases were acquired. Analysis was performed on the arterial and venous phases of mixed 120 kVp‐equivalent images and VMIs at 57 keV and 40 keV gross target volume (GTV) contrast and CNR were calculated. Results For the arterial phase, liver GTV contrast was 12.1 ± 10.0 HU and 43.1 ± 32.3 HU (P < 0.001) for the mixed images and 40 keV VMIs. Image noise increased on average by 116% for the 40 keV VMIs compared to the mixed images. The average CNR did not change significantly (1.6 ± 1.5, 1.7 ± 1.4, 2.4 ± 1.7 for the mixed, 57 keV and 40 keV VMIs (P > 0.141)). For individual cases, however, CNR increases of up to 607% were measured for the 40 keV VMIs compared to the mixed image. Venous phase 40 keV VMIs demonstrated an average increase of 35.4 HU in GTV contrast and 121% increase in image noise. Average CNR values were also not statistically different, but for individual cases CNR increases of up to 554% were measured for the 40 keV VMIs compared to the mixed image. Conclusions Liver tumor contrast was significantly improved using split‐filter DECT 40 keV VMIs compared to mixed images. On average, there was no statistical difference in CNR between the mixed images and VMIs, but for individual cases, CNR was greatly increased for the 57 keV and 40 keV VMIs. Therefore, although not universally successful for our patient cohort, split‐filter DECT VMIs may provide substantial gains in tumor visibility of certain liver cases for radiation therapy treatment planning.
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Affiliation(s)
- Lianna D. DiMaso
- Department of Medical PhysicsUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Jessica R. Miller
- Department of Human OncologyUniversity of Wisconsin‐MadisonMadisonWIUSA
| | | | | | - Larry A. DeWerd
- Department of Medical PhysicsUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Jessie Huang
- Department of Human OncologyUniversity of Wisconsin‐MadisonMadisonWIUSA
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Fru LC, Jacques SL, Nickel KP, Varghese T, Kissick MW, DeWerd LA, Kimple RJ. Interstitial diffuse optical probe with spectral fitting to measure dynamic tumor hypoxia. Biomed Phys Eng Express 2020; 6. [PMID: 32095273 DOI: 10.1088/2057-1976/ab6e16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Understanding the dynamic nature of tumor hypoxia is vital for cancer therapy. The presence of oxygen within a tumor during radiation therapy increases the likelihood of local control. We used a novel interstitial diffuse optical probe to make real-time measurements of blood volume fraction and hemoglobin oxygen saturation within a tumor at a high temporal resolution. This device was initially characterized and benchmarked using a customized vessel designed to control hemoglobin oxygen saturation and blood volume in a solution of blood with different concentrations of an oxygen scavenger, tetrakis (hydroxymethyl) phosphonium chloride. The optical device was found to consistently monitor the changes in oxygen saturation and these changes correlated to the concentration of the oxygen scavenger added. In near-simultaneous measurements of blood volume and oxygen saturation in tumor-bearing mice, the changes in blood volume fraction and oxygen saturation measured with the interstitial diffuse optical probe were benchmarked against photoacoustic imaging system to track and compare temporal dynamics of oxygen saturation and blood volume in a patient-derived xenograft model of hypopharyngeal carcinoma. Positive correlations between our device and photoacoustic imaging in measuring blood volume and oxygen saturation were observed.
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Affiliation(s)
- Leonard Che Fru
- Department of Medical Physics, University of Wisconsin - Madison, Madison WI USA
| | - Steven L Jacques
- Department of Biomedical Engineering, Tufts School of Engineering, Medford MA USA
| | - Kwang P Nickel
- Department of Human Oncology, University of Wisconsin - Madison, Madison WI USA.,University of Wisconsin Carbone Cancer Center, Madison WI USA
| | - Tomy Varghese
- Department of Medical Physics, University of Wisconsin - Madison, Madison WI USA.,Department of Biomedical Engineering, University of Wisconsin - Madison, Madison WI USA
| | - Michael W Kissick
- Department of Medical Physics, University of Wisconsin - Madison, Madison WI USA
| | - Larry A DeWerd
- Department of Medical Physics, University of Wisconsin - Madison, Madison WI USA.,Radiation Calibration Laboratory, University of Wisconsin - Madison, Madison WI USA
| | - Randall J Kimple
- Department of Human Oncology, University of Wisconsin - Madison, Madison WI USA.,University of Wisconsin Carbone Cancer Center, Madison WI USA
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34
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Smith BR, Pankuch M, Hammer CG, DeWerd LA, Culberson WS. LET response variability of Gafchromic TM EBT3 film from a 60 Co calibration in clinical proton beam qualities. Med Phys 2019; 46:2716-2728. [PMID: 30740699 DOI: 10.1002/mp.13442] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 11/01/2019] [Accepted: 02/02/2019] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To establish a method of accurate dosimetry required to quantify the expected linear energy transfer (LET) quenching effect of EBT3 film used to benchmark the dose distribution for a given treatment field and specified measurement depth. In order to facilitate this technique, a full analysis of film calibration which considers LET variability at the plane of measurement and as a function of proton beam quality is demonstrated. Additionally, the corresponding uncertainty from the process was quantified for several measurement scenarios. MATERIALS AND METHODS The net change in optical density (OD) from a single version of Gafchromic TM EBT3 film was measured using an Epson flatbed scanner and NIST-traceable OD filters. Film OD response was characterized with respect to the known dose to water at the point of measurement for both a NIST-traceable 60 Co beam at the UWADCL and several clinical single-energy and spread-out Bragg peak (SOBP) proton beam qualities at the Northwestern Medicine Chicago Proton Center. Increasing proton LET environments were acquired by placing film at increasing depths of Gammex HE Solid Water® whose water-equivalent thickness was characterized prior to measurement. RESULTS A strong LET dependence was observed near the Bragg peak (BP) consistent with previous studies performed with earlier versions of EBT3 film. The influence of range straggling on the film's LET response appears to have a uniform effect toward the BP regardless of the nominal beam energy. Proximal to this depth, the film's response decreased with decreasing energy at the same dose-average LET. The opposite trend was observed for depths past the BP. Changes in the SOBP energy modulation showed a linear relationship between the film's relative response and dose-averaged LET. Relative effectiveness factors (RE) were observed to range between 2%-7% depending on the width of the SOBP and depth of the film. Using the field-specific calibration technique, a total k = 1 uncertainty in the absorbed dose to water was estimated to range from 4.68%-5.21%. CONCLUSION While EBT3 film's strong LET dependence is a common problem in proton beam dosimetry, this work has shown that the LET dependence can be taken into account by carefully considering the depth and energy modulation across the film using field-specific corrections. RE factors were determined with a combined k = 1 uncertainty of 3.57% for SOBP environments and between 3.17%-4.69% for uniform, monoenergetic fields proximal to the distal 80% of the BP.
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Affiliation(s)
- Blake R Smith
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Mark Pankuch
- Division of Medical Physics, Northwestern Medicine Chicago Proton Center, 4455 Weaver Parkway, Warrenville, IL, 60555, USA
| | - Clifford G Hammer
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Larry A DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Wesley S Culberson
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
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Hansen JB, Culberson WS, DeWerd LA. A convex windowless extrapolation chamber to measure surface dose rate from 106 Ru/ 106 Rh episcleral plaques. Med Phys 2019; 46:2430-2443. [PMID: 30873611 DOI: 10.1002/mp.13488] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 02/19/2019] [Accepted: 02/28/2019] [Indexed: 11/08/2022] Open
Abstract
PURPOSE A convex windowless extrapolation chamber was developed as a primary measurement device to determine surface dose rate from curved 106 Ru/106 Rh episcleral plaques. METHODS A convex extrapolation chamber without an entrance window was constructed for this work, and surface dose rate measurements were performed with two curved CCB-type 106 Ru/106 Rh plaques (S/N 2545 and 2596) manufactured by Eckert & Ziegler BEBIG. FARO ® Gage measurements were performed to verify the radius of curvature for the convex electrode and the concave plaque surface. Furthermore, the collecting electrode area was verified through capacitance measurements. Chamber correction factors for divergence and backscatter were generated using the EGSnrc cavity user code. For each source, surface dose rate was measured with the convex extrapolation chamber and compared with on-contact measurements made with curved un-laminated EBT3 film strips. A Monte Carlo correction was generated for radiochromic film measurements to account for volume averaging within the active layer and effects of phantom scatter. Additionally, extrapolation chamber results for each plaque were compared with scintillation detector measurements performed by the manufacturer. For the second source (S/N 2596), a comparison was also made with the Monte Carlo-corrected surface dose rate measured at the National Physical Laboratory (NPL) using cylindrical alanine pellets. Finally, source measurements were performed using conventional ionization chambers (Exradin A26, A1SL, and A20) within a custom fixture to investigate the transfer of extrapolation chamber surface dose rate to clinics. RESULTS For the first 106 Ru/106 Rh plaque (S/N 2545), average surface dose rate from the convex windowless extrapolation chamber was found to be 1.5% higher than the corresponding value from curved un-laminated EBT3 film measurements and 5.6% lower than the manufacturer value. For the second source (S/N 2596), the extrapolation chamber surface dose rate was 2.5% higher than the un-laminated EBT3 film result, 4.5% lower than the manufacturer value, and 3.9% higher compared to corrected alanine measurements made at NPL. Total uncertainty in the extrapolation chamber measurement was estimated to be approximately ± 7.0% (k = 2). For the plaque measurements made using conventional ionization chambers with a custom fixture, surface dose rate from the transfer technique was found to agree within 3.8% with the expected convex extrapolation chamber result for S/N 2596. CONCLUSIONS A convex windowless extrapolation chamber was developed as a primary measurement device for 106 Ru/106 Rh plaques. Through comparison with the extrapolation chamber, the accuracy of surface dose rate measurements from current dosimetry techniques was assessed and agreement was seen within 5.6%. Finally, it was found that conventional ionization chambers could be calibrated with a reference 106 Ru/106 Rh plaque in order to transfer the extrapolation chamber result for surface dose rate to clinics.
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Affiliation(s)
- Jon B Hansen
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Wesley S Culberson
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Larry A DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
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Hansen JB, Culberson WS, DeWerd LA. Surface dose rate from a flat 106Ru/106Rh episcleral plaque measured with a planar windowless extrapolation chamber and un-laminated EBT3 film. RADIAT MEAS 2019. [DOI: 10.1016/j.radmeas.2018.12.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Desai VK, Labby ZE, Hyun MA, DeWerd LA, Culberson WS. VMAT and IMRT plan‐specific correction factors for linac‐based ionization chamber dosimetry. Med Phys 2018; 46:913-924. [DOI: 10.1002/mp.13293] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 11/08/2018] [Accepted: 11/09/2018] [Indexed: 11/07/2022] Open
Affiliation(s)
- Vimal K. Desai
- Department of Medical Physics School of Medicine and Public Health University of Wisconsin‐Madison Madison WI 53705USA
| | - Zacariah E. Labby
- Department of Human Oncology School of Medicine and Public Health University of Wisconsin‐Madison Madison WI 53705 USA
| | - Megan A. Hyun
- Department of Radiation Oncology University of Nebraska Medical Center Omaha NE 68198 USA
| | - Larry A. DeWerd
- Department of Medical Physics School of Medicine and Public Health University of Wisconsin‐Madison Madison WI 53705USA
| | - Wesley S. Culberson
- Department of Medical Physics School of Medicine and Public Health University of Wisconsin‐Madison Madison WI 53705USA
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40
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Lawless MJ, Dimaso L, Palmer B, Micka J, Culberson WS, DeWerd LA. Monte Carlo and60Co‐based kilovoltage x‐ray dosimetry methods. Med Phys 2018; 45:5564-5576. [DOI: 10.1002/mp.13213] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 09/07/2018] [Accepted: 09/07/2018] [Indexed: 11/08/2022] Open
Affiliation(s)
- Michael J. Lawless
- Department of Human Oncology University of Wisconsin‐Madison Madison WI 53705USA
| | - Lianna Dimaso
- Department of Medical Physics University of Wisconsin‐Madison Madison WI 53705USA
| | - Benjamin Palmer
- Department of Medical Physics University of Wisconsin‐Madison Madison WI 53705USA
| | - John Micka
- Department of Medical Physics University of Wisconsin‐Madison Madison WI 53705USA
| | - Wesley S. Culberson
- Department of Medical Physics University of Wisconsin‐Madison Madison WI 53705USA
| | - Larry A. DeWerd
- Department of Medical Physics University of Wisconsin‐Madison Madison WI 53705USA
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Di Maso LD, Huang J, Bassetti MF, DeWerd LA, Miller JR. Investigating a novel split-filter dual-energy CT technique for improving pancreas tumor visibility for radiation therapy. J Appl Clin Med Phys 2018; 19:676-683. [PMID: 30117641 PMCID: PMC6123148 DOI: 10.1002/acm2.12435] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 07/17/2018] [Accepted: 07/21/2018] [Indexed: 12/17/2022] Open
Abstract
Purpose Tumor delineation using conventional CT images can be a challenge for pancreatic adenocarcinoma where contrast between the tumor and surrounding healthy tissue is low. This work investigates the ability of a split‐filter dual‐energy CT (DECT) system to improve pancreatic tumor contrast and contrast‐to‐noise ratio (CNR) for radiation therapy treatment planning. Materials and methods Multiphasic scans of 20 pancreatic tumors were acquired using a split‐filter DECT technique with iodinated contrast medium, OMNIPAQUETM. Analysis was performed on the pancreatic and portal venous phases for several types of DECT images. Pancreatic gross target volume (GTV) contrast and CNR were calculated and analyzed from mixed 120 kVp‐equivalent images and virtual monoenergetic images (VMI) at 57 and 40 keV. The role of iterative reconstruction on DECT images was also investigated. Paired t‐tests were used to assess the difference in GTV contrast and CNR among the different images. Results The VMIs at 40 keV had a 110% greater image noise compared to the mixed 120 kVp‐equivalent images (P < 0.0001). VMIs at 40 keV increased GTV contrast from 15.9 ± 19.9 HU to 93.7 ± 49.6 HU and CNR from 1.37 ± 2.05 to 3.86 ± 2.78 in comparison to the mixed 120 kVp‐equivalent images. The iterative reconstruction algorithm investigated decreased noise in the VMIs by about 20% and improved CNR by about 30%. Conclusions Pancreatic tumor contrast and CNR were significantly improved using VMIs reconstructed from the split‐filter DECT technique, and the use of iterative reconstruction further improved CNR. This gain in tumor contrast may lead to more accurate tumor delineation for radiation therapy treatment planning.
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Affiliation(s)
- Lianna D Di Maso
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, 53716, USA
| | - Jessie Huang
- Department of Human Oncology, University of Wisconsin-Madison, Madison, WI, 53716, USA
| | - Michael F Bassetti
- Department of Human Oncology, University of Wisconsin-Madison, Madison, WI, 53716, USA
| | - Larry A DeWerd
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, 53716, USA
| | - Jessica R Miller
- Department of Human Oncology, University of Wisconsin-Madison, Madison, WI, 53716, USA
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42
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Hansen JB, Culberson WS, DeWerd LA. Surface Dose Rate from a 106 Ru Episcleral Plaque Measured with a Convex Windowless Extrapolation Chamber and EBT3 Film. Brachytherapy 2018. [DOI: 10.1016/j.brachy.2018.04.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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43
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Simiele EA, DeWerd LA. Characterization of spectral and intensity changes with measurement geometry in various light guides used in scintillation dosimetry. Med Phys 2018; 45:3417-3428. [DOI: 10.1002/mp.12992] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 05/02/2018] [Accepted: 05/15/2018] [Indexed: 11/09/2022] Open
Affiliation(s)
- Eric A. Simiele
- Department of Medical Physics School of Medicine and Public Health University of Wisconsin–Madison Madison WI 53705USA
| | - Larry A. DeWerd
- Department of Medical Physics School of Medicine and Public Health University of Wisconsin–Madison Madison WI 53705USA
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44
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Aima M, DeWerd LA, Mitch MG, Hammer CG, Culberson WS. Dosimetric characterization of a new directional low-dose rate brachytherapy source. Med Phys 2018; 45:10.1002/mp.12994. [PMID: 29797517 PMCID: PMC6548702 DOI: 10.1002/mp.12994] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 03/27/2018] [Accepted: 04/04/2018] [Indexed: 12/28/2022] Open
Abstract
PURPOSE CivaTech Oncology Inc. (Durham, NC) has developed a novel low-dose rate (LDR) brachytherapy source called the CivaSheet.TM The source is a planar array of discrete elements ("CivaDots") which are directional in nature. The CivaDot geometry and design are considerably different than conventional LDR cylindrically symmetric sources. Thus, a thorough investigation is required to ascertain the dosimetric characteristics of the source. This work investigates the repeatability and reproducibility of a primary source strength standard for the CivaDot and characterizes the CivaDot dose distribution by performing in-phantom measurements and Monte Carlo (MC) simulations. Existing dosimetric formalisms were adapted to accommodate a directional source, and other distinguishing characteristics including the presence of gold shield x-ray fluorescence were addressed in this investigation. METHODS Primary air-kerma strength (SK ) measurements of the CivaDots were performed using two free-air chambers namely, the Variable-Aperture Free-Air Chamber (VAFAC) at the University of Wisconsin Medical Radiation Research Center (UWMRRC) and the National Institute of Standards and Technology (NIST) Wide-Angle Free-Air Chamber (WAFAC). An intercomparison of the two free-air chamber measurements was performed along with a comparison of the different assumed CivaDot energy spectra and associated correction factors. Dose distribution measurements of the source were performed in a custom polymethylmethacrylate (PMMA) phantom using GafchromicTM EBT3 film and thermoluminescent dosimeter (TLD) microcubes. Monte Carlo simulations of the source and the measurement setup were performed using MCNP6 radiation transport code. RESULTS The CivaDot SK was determined using the two free-air chambers for eight sources with an agreement of better than 1.1% for all sources. The NIST measured CivaDot energy spectrum intensity peaks were within 1.8% of the MC-predicted spectrum intensity peaks. The difference in the net source-specific correction factor determined for the CivaDot free-air chamber measurements for the NIST WAFAC and UW VAFAC was 0.7%. The dose-rate constant analog was determined to be 0.555 cGy h-1 U-1 . The average difference observed in the estimated CivaDot dose-rate constant analog using measurements and MCNP6-predicted value (0.558 cGy h-1 U-1 ) was 0.6% ± 2.3% for eight CivaDot sources using EBT3 film, and -2.6% ± 1.7% using TLD microcube measurements. The CivaDot two-dimensional dose-to-water distribution measured in phantom was compared to the corresponding MC predictions at six depths. The observed difference using a pixel-by-pixel subtraction map of the measured and the predicted dose-to-water distribution was generally within 2-3%, with maximum differences up to 5% of the dose prescribed at the depth of 1 cm. CONCLUSION Primary SK measurements of the CivaDot demonstrated good repeatability and reproducibility of the free-air chamber measurements. Measurements of the CivaDot dose distribution using the EBT3 film stack phantom and its subsequent comparison to Monte Carlo-predicted dose distributions were encouraging, given the overall uncertainties. This work will aid in the eventual realization of a clinically viable dosimetric framework for the CivaSheet based on the CivaDot dose distribution.
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Affiliation(s)
- Manik Aima
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Larry A. DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Michael G. Mitch
- National Institute of Standards and Technology, Gaithersburg, MD, 20899
| | - Clifford G. Hammer
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705
| | - Wesley S. Culberson
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705
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45
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Trichter S, Soares CG, Zaider M, DeWyngaert JK, DeWerd LA, Kleiman NJ. 15 years of
106
Ru eye plaque dosimetry at Memorial Sloan-Kettering Cancer Center and Weill Cornell Medical Center using radiochromic film in a Solid Water phantom. Biomed Phys Eng Express 2018. [DOI: 10.1088/2057-1976/aab674] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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46
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Rivard MJ, Ballester F, Butler WM, DeWerd LA, Ibbott GS, Meigooni AS, Melhus CS, Mitch MG, Nath R, Papagiannis P. Erratum: “Supplement 2 for the 2004 update of the AAPM Task Group No. 43 Report: Joint recommendations by the AAPM and GEC-ESTRO” [Med. Phys. Vol 44 (9), e297-e338 (2017)]. Med Phys 2018; 45:971-974. [DOI: 10.1002/mp.12728] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 11/20/2017] [Accepted: 11/30/2017] [Indexed: 12/23/2022] Open
Affiliation(s)
- Mark J. Rivard
- Department of Radiation Oncology; Tufts University School of Medicine; Boston MA 02111 USA
| | - Facundo Ballester
- Department of Atomic, Molecular and Nuclear Physics; University of Valencia; Burjassot 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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47
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Hansen JB, Culberson WS, DeWerd LA. Windowless extrapolation chamber measurement of surface dose rate from a 90 Sr/ 90 Y ophthalmic applicator. RADIAT MEAS 2018. [DOI: 10.1016/j.radmeas.2017.11.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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48
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Hammer CG, Rosen BS, Fagerstrom JM, Culberson WS, DeWerd LA. Experimental investigation of GafChromic®
EBT3 intrinsic energy dependence with kilovoltage x rays, 137
Cs, and 60
Co. Med Phys 2017; 45:448-459. [DOI: 10.1002/mp.12682] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 10/13/2017] [Accepted: 11/07/2017] [Indexed: 11/10/2022] Open
Affiliation(s)
- Cliff G. Hammer
- Department of Medical Physics; School of Medicine and Public Health; University of Wisconsin-Madison; Madison WI 53705 USA
| | - Benjamin Saul Rosen
- Department of Radiation Oncology; University of Michigan; Ann Arbor MI 48109 USA
| | | | - Wesley S. Culberson
- Department of Medical Physics; School of Medicine and Public Health; University of Wisconsin-Madison; Madison WI 53705 USA
| | - Larry A. DeWerd
- Department of Medical Physics; School of Medicine and Public Health; University of Wisconsin-Madison; Madison WI 53705 USA
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49
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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50
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Ellefson ST, Culberson WS, Bednarz BP, DeWerd LA, Bayouth JE. An analysis of the ArcCHECK-MR diode array's performance for ViewRay quality assurance. J Appl Clin Med Phys 2017; 18:161-171. [PMID: 28681448 PMCID: PMC5874930 DOI: 10.1002/acm2.12107] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 04/11/2017] [Accepted: 04/18/2017] [Indexed: 11/06/2022] Open
Abstract
The ArcCHECK-MR diode array utilizes a correction system with a virtual inclinometer to correct the angular response dependencies of the diodes. However, this correction system cannot be applied to measurements on the ViewRay MR-IGRT system due to the virtual inclinometer's incompatibility with the ViewRay's multiple simultaneous beams. Additionally, the ArcCHECK's current correction factors were determined without magnetic field effects taken into account. In the course of performing ViewRay IMRT quality assurance with the ArcCHECK, measurements were observed to be consistently higher than the ViewRay TPS predictions. The goals of this study were to quantify the observed discrepancies and test whether applying the current factors improves the ArcCHECK's accuracy for measurements on the ViewRay. Gamma and frequency analysis were performed on 19 ViewRay patient plans. Ion chamber measurements were performed at a subset of diode locations using a PMMA phantom with the same dimensions as the ArcCHECK. A new method for applying directionally dependent factors utilizing beam information from the ViewRay TPS was developed in order to analyze the current ArcCHECK correction factors. To test the current factors, nine ViewRay plans were altered to be delivered with only a single simultaneous beam and were measured with the ArcCHECK. The current correction factors were applied using both the new and current methods. The new method was also used to apply corrections to the original 19 ViewRay plans. It was found the ArcCHECK systematically reports doses higher than those actually delivered by the ViewRay. Application of the current correction factors by either method did not consistently improve measurement accuracy. As dose deposition and diode response have both been shown to change under the influence of a magnetic field, it can be concluded the current ArcCHECK correction factors are invalid and/or inadequate to correct measurements on the ViewRay system.
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Affiliation(s)
- Steven T Ellefson
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, AZ, USA
| | - Wesley S Culberson
- School of Medicine and Public Health, Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA
| | - Bryan P Bednarz
- School of Medicine and Public Health, Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA
| | - Larry A DeWerd
- School of Medicine and Public Health, Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA
| | - John E Bayouth
- School of Medicine and Public Health, Department of Human Oncology, University of Wisconsin-Madison, Madison, WI, USA
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