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Muir B, Davis S, Dhanesar S, Hillman Y, Iakovenko V, Kim GGY, Alves VGL, Lei Y, Lowenstein J, Renaud J, Sarfehnia A, Siebers J, Tantôt L. AAPM WGTG51 Report 385: Addendum to the AAPM's TG-51 protocol for clinical reference dosimetry of high-energy electron beams. Med Phys 2024. [PMID: 38980220 DOI: 10.1002/mp.17277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 03/29/2024] [Accepted: 06/14/2024] [Indexed: 07/10/2024] Open
Abstract
An Addendum to the AAPM's TG-51 protocol for the determination of absorbed dose to water is presented for electron beams with energies between 4 MeV and 22 MeV (1.70 cm ≤ R 50 ≤ 8.70 cm $1.70\nobreakspace {\rm cm} \le R_{\text{50}} \le 8.70\nobreakspace {\rm cm}$ ). This updated formalism allows simplified calibration procedures, including the use of calibrated cylindrical ionization chambers in all electron beams without the use of a gradient correction. Newk Q $k_{Q}$ data are provided for electron beams based on Monte Carlo simulations. Implementation guidance is provided. Components of the uncertainty budget in determining absorbed dose to water at the reference depth are discussed. Specifications for a reference-class chamber in electron beams include chamber stability, settling, ion recombination behavior, and polarity dependence. Progress in electron beam reference dosimetry is reviewed. Although this report introduces some major changes (e.g., gradient corrections are implicitly included in the electron beam quality conversion factors), they serve to simplify the calibration procedure. Results for absorbed dose per linac monitor unit are expected to be up to approximately 2 % higher using this Addendum compared to using the original TG-51 protocol.
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Affiliation(s)
- Bryan Muir
- Metrology Research Centre, National Research Council of Canada, Ottawa, Ontario, Canada
| | - Stephen Davis
- Department of Radiation Oncology, Miami Cancer Institute, Miami, Florida, USA
| | - Sandeep Dhanesar
- Department of Radiation Oncology, Houston Methodist Hospital, Houston, Texa, USA
| | - Yair Hillman
- Department of Radiation Oncology, Sharett Institute of Oncology, Hadassah Medical Center, Hebrew University of Jerusalem, Jerusalem, Israel
| | | | - Grace Gwe-Ya Kim
- Department of Radiation Medicine and Applied Sciences, UC San Diego School of Medicine, San Diego, California, USA
| | | | - Yu Lei
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Jessica Lowenstein
- Department of Radiation Physics, UT M.D. Anderson Cancer Center, Houston, Texa, USA
| | - James Renaud
- Metrology Research Centre, National Research Council of Canada, Ottawa, Ontario, Canada
| | - Arman Sarfehnia
- Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada
- Department of Medical Physics, Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
| | - Jeffrey Siebers
- Department of Radiation Oncology, University of Virginia, Charlottesville, Virginia, USA
| | - Laurent Tantôt
- Département de radio-oncologie, CIUSSS de l'Est-de-l'Île-de-Montréal - Hôpital Maisonneuve-Rosemont, Montreal, Quebec, Canada
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Hill LW, Jack D. A slope method for the determination of electron energy for quality assurance. J Appl Clin Med Phys 2024; 25:e14369. [PMID: 38685586 PMCID: PMC11244682 DOI: 10.1002/acm2.14369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 03/25/2024] [Accepted: 04/02/2024] [Indexed: 05/02/2024] Open
Abstract
BACKGROUND Particle accelerators, manufactured for delivering patient radiation treatment, require numerous and frequent quality assurance measures. One of those is the periodic check for electron energy stability. The American Association of Physicists in Medicine has established requirements for this procedure. The current recommendation is to perform a ratio of two ionization points, one at Dmax and another at a point approximately to the 50% depth, compared to a baseline as a relative check. PURPOSE This ratio method is a sensitive measurement and sometimes produces results that are difficult to interpret or relate to acceptable tolerances. We sought to find a simple method that gives more stable results, which can be interpreted and related to energy changes. METHOD We propose a method that takes two measurements on the descending portion of the shifted percent depth ionization (PDI) curves to calculate the slope, tangent to the I50 point, the point at which the ionization falls to 50% of its maximum value. We then used the slope measurement, compared to an established baseline, to relate energy. RESULTS After collecting data over a 3-year period, we saw that standard deviations for the slope method have much less variability than the traditional ratio method. We were also able to correlate the slope results to ionization scans performed in water and found they were in better agreement than the traditional ratio method. CONCLUSION The slope method does not require precise positioning since the slope remains relatively constant over the descending portion of the curve. Our data show that this results in an easier interpretative test of electron energy stability and delivers reliable feedback for quality assurance.
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Affiliation(s)
- Larry W Hill
- Department of Radiation Therapy, Genesis Care/21st Century Oncology, Fort Walton Beach, Florida, USA
| | - David Jack
- Department of Radiation Therapy, Genesis Care/21st Century Oncology, Fort Walton Beach, Florida, USA
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Garibaldi C, Beddar S, Bizzocchi N, Tobias Böhlen T, Iliaskou C, Moeckli R, Psoroulas S, Subiel A, Taylor PA, Van den Heuvel F, Vanreusel V, Verellen D. Minimum and optimal requirements for a safe clinical implementation of ultra-high dose rate radiotherapy: A focus on patient's safety and radiation protection. Radiother Oncol 2024; 196:110291. [PMID: 38648991 DOI: 10.1016/j.radonc.2024.110291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 03/28/2024] [Accepted: 04/16/2024] [Indexed: 04/25/2024]
Affiliation(s)
- Cristina Garibaldi
- IEO, Unit of Radiation Research, European Institute of Oncology IRCCS, 20141 Milan, Italy.
| | - Sam Beddar
- The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Nicola Bizzocchi
- Center for Proton Therapy, Paul Scherrer Institut, Villigen, Switzerland
| | - Till Tobias Böhlen
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Charoula Iliaskou
- Division of Medical Physics, Department of Radiation Oncology, University Medical Center Freiburg, 79106, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
| | - Raphaël Moeckli
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Serena Psoroulas
- Center for Proton Therapy, Paul Scherrer Institut, Villigen, Switzerland
| | - Anna Subiel
- National Physical Laboratory, Medical Radiation Science, Teddington, UK
| | - Paige A Taylor
- The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Frank Van den Heuvel
- Zuidwest Radiotherapeutisch Institute, Vlissingen, the Netherlands; Dept of Oncology, University of Oxford, Oxford, UK
| | - Verdi Vanreusel
- Iridium Netwerk, Antwerp University (Centre for Oncological Research, CORE), Antwerpen, Belgium; SCK CEN (Research in Dosimetric Applications), Mol, Belgium
| | - Dirk Verellen
- Iridium Netwerk, Antwerp University (Centre for Oncological Research, CORE), Antwerpen, Belgium
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Taneja S, Barbee DL, Cohen RF, Malin M. Implementation of a Stereoscopic Camera System for Clinical Electron Simulation and Treatment Planning. Pract Radiat Oncol 2024; 14:e291-e300. [PMID: 38325547 DOI: 10.1016/j.prro.2024.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 12/14/2023] [Accepted: 01/08/2024] [Indexed: 02/09/2024]
Abstract
PURPOSE A 3-dimensinal (3D) stereoscopic camera system developed by .decimal was commissioned and implemented into the clinic to improve the efficiency of clinical electron simulations. Capabilities of the camera allowed simulations to be moved from the treatment vault into any room with a flat surface that could accommodate patient positioning devices, eliminating the need for clinical patient setup timeslots on the treatment machine. This work describes the process used for these simulations and compares the treatment parameters determined by the system to those used in delivery. METHODS AND MATERIALS The Decimal3D scanner workflow consisted of: scanning the patient surface; contouring the treatment area; determining gantry, couch, collimator, and source-to-surface distance (SSD) parameters for en face entry of the beam with sufficient clearance at the machine; and ordering custom electron cutouts when needed. Transparencies showing the projection of in-house library cutouts at various clinical SSDs were created to assist in choosing an appropriate library cutout. Data from 73 treatment sites were analyzed to evaluate the accuracy of the scanner-determined beam parameters for each treatment delivery. RESULTS Clinical electron simulations for 73 treatment sites, predominately keloids, were transitioned out of the linear accelerator (LINAC) vault using the new workflow. For all patients, gantry, collimator, and couch parameters, along with SSD and cone size, were determined using the Decimal3D scanner with 57% of simulations using library cutouts. Tolerance tables for patient setup were updated to allow differences of 10, 20, and 5° for gantry, collimator, and couch, respectively. Approximately 7% of fractions (N = 181 total fractions) were set up outside of the tolerance table based on physician direction during treatment. This reflects physician preference to adjust the LINAC rather than patient position during treatment setup. No scanner-derived plan was untreatable because of cutout shape inaccuracy or clearance issues. CONCLUSIONS Clinical electron simulations were successfully transitioned out of the LINAC vault using the Decimal3D scanner without loss of setup accuracy, as measured through machine parameter determination and electron cutout shape.
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Affiliation(s)
- Sameer Taneja
- Department of Radiation Oncology, New York University Langone Medical Center, New York, New York.
| | - David L Barbee
- Department of Radiation Oncology, New York University Langone Medical Center, New York, New York
| | - Richard F Cohen
- Department of Radiation Oncology, New York University Langone Medical Center, New York, New York
| | - Martha Malin
- Department of Radiation Oncology, New York University Langone Medical Center, New York, New York
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Ono N. [Investigation of the Usefulness of Monte Carlo Simulation in Electron Beam Therapy Using Body Surface Lead Cutout]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2024; 80:175-187. [PMID: 38030241 DOI: 10.6009/jjrt.2024-1404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2023]
Abstract
PURPOSE The purpose of this study was to understand the PDD and OAR during electron beam therapy using lead cutout on the body surface. METHODS The Monte Carlo code PHITS version 3.24 was used to simulate PDD and OAR. The simulation results were compared with actual measurements using a silicon diode detector to evaluate the validity of the simulation results. RESULTS The simulated PDD and OAR parameters of the linac agreed with the measured values within 2 mm. When the lead cutout on the body surface was used, all parameters except for R100 agreed with the measured values within 2 mm. The cutout sizes of the broad-beam square irradiation fields were 3 cm for 6 MeV, 5 cm for 12 MeV, and 8 cm for 18 MeV when the lead cutout on the body surface was used. CONCLUSION The Monte Carlo simulation was useful for understanding the PDD and OAR of the lead cutout irradiation fields, which are difficult to measure.
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Affiliation(s)
- Naohito Ono
- Department of Radiology, Juntendo University Shizuoka Hospital
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Miles D, Sforza D, Wong J, Rezaee M. Dosimetric characterization of a rotating anode x-ray tube for FLASH radiotherapy research. Med Phys 2024; 51:1474-1483. [PMID: 37458068 PMCID: PMC10792113 DOI: 10.1002/mp.16609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 05/16/2023] [Accepted: 06/20/2023] [Indexed: 07/18/2023] Open
Abstract
PURPOSE Most current research toward ultra-high dose rate (FLASH) radiation is conducted with advanced proton and electron accelerators, which are of limited accessibility to basic laboratory research. An economical alternative to charged particle accelerators is to employ high-capacity rotating anode x-ray tubes to produce kilovoltage x-rays at FLASH dose rates at short source-to-surface distances (SSD). This work describes a comprehensive dosimetric evaluation of a rotating anode x-ray tube for potential application in laboratory FLASH study. METHODS AND MATERIALS A commercially available high-capacity fluoroscopy x-ray tube with 75 kW input power was implemented as a potential FLASH irradiator. Radiochromic EBT3 film and thermoluminescent dosimeters (TLDs) were used to investigate the effects of SSD and field size on dose rates and depth-dose characteristics in kV-compatible solid water phantoms. Custom 3D printed accessories were developed to enable reproducible phantom setup at very short SSD. Open and collimated radiation fields were assessed. RESULTS Despite the lower x-ray energy and short SSD used, FLASH dose rates above 40 Gy/s were achieved for targets up to 10-mm depth in solid water. Maximum surface dose rates of 96 Gy/s were measured in the open field at 47 mm SSD. A non-uniform high-to-low dose gradient was observed in the planar dose distribution, characteristic of anode heel effects. With added collimation, beams up to 10-mm diameter with reasonable uniformity can be produced. Typical 80%-20% penumbra in the collimated x-ray FLASH beams were less than 1 mm at 5-mm depth in phantom. Ramp-up times at the maximum input current were less than 1 ms. CONCLUSION Our dosimetric characterization demonstrates that rotating anode x-ray tube technology is capable of producing radiation beams in support of preclinical FLASH radiobiology research.
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Affiliation(s)
- Devin Miles
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, 21231 MD, USA
| | - Daniel Sforza
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, 21231 MD, USA
| | - John Wong
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, 21231 MD, USA
| | - Mohammad Rezaee
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, 21231 MD, USA
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Oguchi H. [5. Standard Dosimetry of Absorbed Dose to Water in External Beam Radiotherapy for Electron Beams -Focusing on Appendix]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2024; 80:104-111. [PMID: 38246632 DOI: 10.6009/jjrt.2024-2301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
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8
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Dosimetric characteristics of the LIAC intraoperative radiotherapy beams: Assessment of sensitivity to measurement errors at the commissioning phase. Radiat Phys Chem Oxf Engl 1993 2023. [DOI: 10.1016/j.radphyschem.2022.110737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Zaini MM, Fagerstrom JM, Marshall EI, Hedrick KM, Zaks D, Tran H, Fitzgerald TM. Therapeutic radiation beam output and energy variation across clinics, technologies, and time. J Appl Clin Med Phys 2023:e13945. [PMID: 36848039 DOI: 10.1002/acm2.13945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 01/24/2023] [Accepted: 02/09/2023] [Indexed: 03/01/2023] Open
Abstract
Over the past several decades, a medical physics service group covering 35 clinical sites has provided routine monthly output and energy quality assurance for over 75 linear accelerators. Based on the geographical spread of these clinics and the large number of physicists involved in data acquisition, a systematic calibration procedure was established to ensure uniformity. A consistent measurement geometry and data collection technique is used across all machines for every calendar month, using a standardized set of acrylic slabs. Charge readings in acrylic phantoms are linked to AAPM's TG-51 formalism via a parameter denoted kacrylic , used to convert raw charge readings to machine output values. Statistical analyses of energy ratios and kacrylic values are presented. Employing the kacrylic concept with a uniform measurement geometry of similar acrylic blocks was found to be a reproducible and simple way of referencing a calibration completed in water under reference conditions and comparing to other machines, with the ability to alert physicists of outliers.
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Affiliation(s)
| | | | | | | | - Daniel Zaks
- Northwest Medical Physics Center, Lynnwood, Washington, USA
| | - Hung Tran
- Northwest Medical Physics Center, Lynnwood, Washington, USA
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Varian Clinac 2100 linear accelerator simulation employing PRIMO phase space model. Radiat Phys Chem Oxf Engl 1993 2023. [DOI: 10.1016/j.radphyschem.2023.110859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
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11
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Kurokawa C. [3. Physics for Electron Beam Therapy]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2023; 79:1194-1199. [PMID: 37866904 DOI: 10.6009/jjrt.2023-2264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Affiliation(s)
- Chie Kurokawa
- Department of Radiological Technology, Faculty of Health Science, Juntendo University
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Miao T, Zhang R, Jermyn M, Bruza P, Zhu T, Pogue BW, Gladstone DJ, Williams BB. Computational dose visualization & comparison in total skin electron treatment suggests superior coverage by the rotational versus the Stanford technique. J Med Imaging Radiat Sci 2022; 53:612-622. [PMID: 36045017 PMCID: PMC10152509 DOI: 10.1016/j.jmir.2022.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 07/16/2022] [Accepted: 08/11/2022] [Indexed: 12/24/2022]
Abstract
INTRODUCTION/BACKGROUND The goal of Total Skin Electron Therapy (TSET) is to achieve a uniform surface dose, although assessment of this is never really done and typically limited points are sampled. A computational treatment simulation approach was developed to estimate dose distributions over the body surface, to compare uniformity of (i) the 6 pose Stanford technique and (ii) the rotational technique. METHODS The relative angular dose distributions from electron beam irradiation was calculated by Monte Carlo simulation for cylinders with a range of diameters, approximating body part curvatures. These were used to project dose onto a 3D body model of the TSET patient's skin surfaces. Computer animation methods were used to accumulate the dose values, for display and analysis of the homogeneity of coverage. RESULTS The rotational technique provided more uniform coverage than the Stanford technique. Anomalies of under dose were observed in lateral abdominal regions, above the shoulders and in the perineum. The Stanford technique had larger areas of low dose laterally. In the rotational technique, 90% of the patient's skin was within ±10% of the prescribed dose, while this percentage decreased to 60% or 85% for the Stanford technique, varying with patient body mass. Interestingly, the highest discrepancy was most apparent in high body mass patients, which can be attributed to the loss of tangent dose at low angles of curvature. DISCUSSION/CONCLUSION This simulation and visualization approach is a practical means to analyze TSET dose, requiring only optical surface body topography scans. Under- and over-exposed body regions can be found, and irradiation could be customized to each patient. Dose Area Histogram (DAH) distribution analysis showed the rotational technique to have better uniformity, with most areas within 10% of the umbilicus value. Future use of this approach to analyze dose coverage is possible as a routine planning tool.
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Affiliation(s)
- Tianshun Miao
- Thayer School of Engineering, Dartmouth College, Hanover NH, 03755, USA
| | - Rongxiao Zhang
- Thayer School of Engineering, Dartmouth College, Hanover NH, 03755, USA; Department of Medicine, Radiation Oncology, Norris Cotton Cancer Center, Dartmouth Hitchcock Medical Center, Lebanon, NH 03766, USA
| | - Michael Jermyn
- Thayer School of Engineering, Dartmouth College, Hanover NH, 03755, USA; DoseOptics, LLC, Lebanon NH 03755 USA
| | - Petr Bruza
- Thayer School of Engineering, Dartmouth College, Hanover NH, 03755, USA; DoseOptics, LLC, Lebanon NH 03755 USA
| | - Timothy Zhu
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia PA, 19104 USA
| | - Brian W Pogue
- Thayer School of Engineering, Dartmouth College, Hanover NH, 03755, USA; DoseOptics, LLC, Lebanon NH 03755 USA; Department of Medical Physics, University of Wisconsin-Madison, Wisconsin WI 53705 USA.
| | - David J Gladstone
- Thayer School of Engineering, Dartmouth College, Hanover NH, 03755, USA; Department of Medicine, Radiation Oncology, Norris Cotton Cancer Center, Dartmouth Hitchcock Medical Center, Lebanon, NH 03766, USA
| | - Benjamin B Williams
- Thayer School of Engineering, Dartmouth College, Hanover NH, 03755, USA; Department of Medicine, Radiation Oncology, Norris Cotton Cancer Center, Dartmouth Hitchcock Medical Center, Lebanon, NH 03766, USA
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Tavallaie M, Hariri Tabrizi S, Heidarloo N. Implementation of pencil beam redefinition algorithm (PBRA) for intraoperative electron radiation therapy (IOERT) treatment planning. Phys Med 2022; 104:32-42. [PMID: 36356502 DOI: 10.1016/j.ejmp.2022.10.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 09/01/2022] [Accepted: 10/22/2022] [Indexed: 11/11/2022] Open
Abstract
PURPOSE Similar to other radiation therapy techniques, intraoperative electron radiation therapy (IOERT) can benefit from an online treatment planning system (TPS). Among all the analytical electron dose calculation algorithms, pencil beam redefinition algorithm (PBRA) has shown an acceptable accuracy in inhomogeneities. The input dataset for PBRA includes electron planar fluence, mean direction and root mean square (RMS) spread about the mean direction which had been introduced based on the conventional linear accelerator geometry in former studies. Herein, three methods for implementing PBRA for IOERT system are presented. METHODS The initialization parameters were identified using Monte Carlo (MC) simulation of a dedicated IOERT system equipped with a cylindrical 10 cm applicator, irradiating a water phantom. Phase space distribution of electrons was recorded on a plane below the applicator. The input dataset was extracted for 2 × 2 mm2 pixels and energy bin width of 1 MeV. RESULTS PBRA was implemented with three initialization methods and compared to MC. The 3D gamma analysis of the algorithm with the Formula method, which was in best agreement with MC in a simple water phantom, showed passing rates of more than 99 % for all nominal energies and it was 97.1 % for 8 MeV in the presence of protecting disk and irregular surface. Implementing PBRA on CUDA C++ resulted in 5 s run time for 8 MeV nominal energy in a water phantom. CONCLUSIONS The agreement between PBRA dose calculation and MC is promising for the development of an intraoperative TPS for IOERT.
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Affiliation(s)
- Mina Tavallaie
- Department of Medical Radiation Engineering, Shahid Beheshti University, Tehran, Iran.
| | - Sanaz Hariri Tabrizi
- Department of Medical Radiation Engineering, Shahid Beheshti University, Tehran, Iran.
| | - Nematollah Heidarloo
- Department of Medical Radiation Engineering, Shahid Beheshti University, Tehran, Iran
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Muir B, Culberson W, Davis S, Kim GGY, Lee SW, Lowenstein J, Renaud J, Sarfehnia A, Siebers J, Tantôt L, Tolani N. AAPM WGTG51 Report 374: Guidance for TG-51 reference dosimetry. Med Phys 2022; 49:6739-6764. [PMID: 36000424 DOI: 10.1002/mp.15949] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 07/21/2022] [Accepted: 07/27/2022] [Indexed: 12/13/2022] Open
Abstract
Practical guidelines that are not explicit in the TG-51 protocol and its Addendum for photon beam dosimetry are presented for the implementation of the TG-51 protocol for reference dosimetry of external high-energy photon and electron beams. These guidelines pertain to: (i) measurement of depth-ionization curves required to obtain beam quality specifiers for the selection of beam quality conversion factors, (ii) considerations for the dosimetry system and specifications of a reference-class ionization chamber, (iii) commissioning a dosimetry system and frequency of measurements, (iv) positioning/aligning the water tank and ionization chamber for depth ionization and reference dose measurements, (v) requirements for ancillary equipment needed to measure charge (triaxial cables and electrometers) and to correct for environmental conditions, and (vi) translation from dose at the reference depth to that at the depth required by the treatment planning system. Procedures are identified to achieve the most accurate results (errors up to 8% have been observed) and, where applicable, a commonly used simplified procedure is described and the impact on reference dosimetry measurements is discussed so that the medical physicist can be informed on where to allocate resources.
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Affiliation(s)
- Bryan Muir
- Metrology Research Centre, National Research Council of Canada, Ottawa, Ontario, Canada
| | - Wesley Culberson
- Department of Medical Physics, University of Wisconsin - Madison, Madison, Wisconsin, United States
| | - Stephen Davis
- Radiation Oncology, Miami Cancer Institute, Miami, Florida, United States
| | - Grace Gwe-Ya Kim
- Department of Radiation Medicine and Applied Sciences, UC San Diego School of Medicine, La Jolla, California, United States
| | - Sung-Woo Lee
- Department of Radiation Oncology, University of Maryland School of Medicine, Columbia, Maryland, United States
| | - Jessica Lowenstein
- Department of Radiation Physics, UT M.D. Anderson Cancer Center, Houston, Texas, United States
| | - James Renaud
- Metrology Research Centre, National Research Council of Canada, Ottawa, Ontario, Canada
| | - Arman Sarfehnia
- Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada
| | - Jeffrey Siebers
- Department of Radiation Oncology, University of Virginia Health System, Charlottesville, Virginia, United States
| | - Laurent Tantôt
- Département de radio-oncologie, CIUSSS de l'Est-de-l'Île-de-Montréal - Hôpital Maisonneuve-Rosemont, Montreal, Quebec, Canada
| | - Naresh Tolani
- Department of Radiation Therapy, Michael E. DeBakey VA Medical Center, Houston, Texas, United States
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15
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Geurts MW, Jacqmin DJ, Jones LE, Kry SF, Mihailidis DN, Ohrt JD, Ritter T, Smilowitz JB, Wingreen NE. AAPM MEDICAL PHYSICS PRACTICE GUIDELINE 5.b: Commissioning and QA of treatment planning dose calculations-Megavoltage photon and electron beams. J Appl Clin Med Phys 2022; 23:e13641. [PMID: 35950259 PMCID: PMC9512346 DOI: 10.1002/acm2.13641] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 04/04/2022] [Accepted: 04/06/2022] [Indexed: 11/23/2022] Open
Abstract
The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education, and professional practice of medical physics. The AAPM has more than 8000 members and is the principal organization of medical physicists in the United States. The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States. Existing medical physics practice guidelines will be reviewed for the purpose of revision or renewal, as appropriate, on their fifth anniversary or sooner. Each medical physics practice guideline represents a policy statement by the AAPM, has undergone a thorough consensus process in which it has been subjected to extensive review, and requires the approval of the Professional Council. The medical physics practice guidelines recognize that the safe and effective use of diagnostic and therapeutic radiology requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guidelines and technical standards by those entities not providing these services is not authorized. The following terms are used in the AAPM practice guidelines:
Must and Must Not: Used to indicate that adherence to the recommendation is considered necessary to conform to this practice guideline. While must is the term to be used in the guidelines, if an entity that adopts the guideline has shall as the preferred term, the AAPM considers that must and shall have the same meaning. Should and Should Not: Used to indicate a prudent practice to which exceptions may occasionally be made in appropriate circumstances.
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Matuszak N, Kruszyna-Mochalska M, Skrobala A, Ryczkowski A, Romanski P, Piotrowski I, Kulcenty K, Suchorska WM, Malicki J. Nontarget and Out-of-Field Doses from Electron Beam Radiotherapy. Life (Basel) 2022; 12:858. [PMID: 35743890 PMCID: PMC9225003 DOI: 10.3390/life12060858] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 06/03/2022] [Accepted: 06/06/2022] [Indexed: 06/15/2023] Open
Abstract
In clinical radiotherapy, the most important aspects are the dose distribution in the target volume and healthy organs, including out-of-field doses in the body. Compared to photon beam radiation, dose distribution in electron beam radiotherapy has received much less attention, mainly due to the limited range of electrons in tissues. However, given the growing use of electron intraoperative radiotherapy and FLASH, further study is needed. Therefore, in this study, we determined out-of-field doses from an electron beam in a phantom model using two dosimetric detectors (diode E and cylindrical Farmer-type ionizing chamber) for electron energies of 6 MeV, 9 MeV and 12 MeV. We found a clear decrease in out-of-field doses as the distance from the field edge and depth increased. The out-of-field doses measured with the diode E were lower than those measured with the Farmer-type ionization chamber at each depth and for each electron energy level. The out-of-field doses increased when higher energy megavoltage electron beams were used (except for 9 MeV). The out-of-field doses at shallow depths (1 or 2 cm) declined rapidly up to a distance of 3 cm from the field edge. This study provides valuable data on the deposition of radiation energy from electron beams outside the irradiation field.
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Affiliation(s)
- Natalia Matuszak
- Department of Electroradiology, Poznan University of Medical Sciences, 61-866 Poznan, Poland; (M.K.-M.); (A.S.); (I.P.); (W.M.S.); (J.M.)
- Radiobiology Laboratory, Department of Medical Physics, Greater Poland Cancer Centre, 61-866 Poznan, Poland;
| | - Marta Kruszyna-Mochalska
- Department of Electroradiology, Poznan University of Medical Sciences, 61-866 Poznan, Poland; (M.K.-M.); (A.S.); (I.P.); (W.M.S.); (J.M.)
- Department of Medical Physics, Greater Poland Cancer Centre, 61-866 Poznan, Poland; (A.R.); (P.R.)
| | - Agnieszka Skrobala
- Department of Electroradiology, Poznan University of Medical Sciences, 61-866 Poznan, Poland; (M.K.-M.); (A.S.); (I.P.); (W.M.S.); (J.M.)
- Department of Medical Physics, Greater Poland Cancer Centre, 61-866 Poznan, Poland; (A.R.); (P.R.)
| | - Adam Ryczkowski
- Department of Medical Physics, Greater Poland Cancer Centre, 61-866 Poznan, Poland; (A.R.); (P.R.)
| | - Piotr Romanski
- Department of Medical Physics, Greater Poland Cancer Centre, 61-866 Poznan, Poland; (A.R.); (P.R.)
| | - Igor Piotrowski
- Department of Electroradiology, Poznan University of Medical Sciences, 61-866 Poznan, Poland; (M.K.-M.); (A.S.); (I.P.); (W.M.S.); (J.M.)
- Radiobiology Laboratory, Department of Medical Physics, Greater Poland Cancer Centre, 61-866 Poznan, Poland;
| | - Katarzyna Kulcenty
- Radiobiology Laboratory, Department of Medical Physics, Greater Poland Cancer Centre, 61-866 Poznan, Poland;
| | - Wiktoria Maria Suchorska
- Department of Electroradiology, Poznan University of Medical Sciences, 61-866 Poznan, Poland; (M.K.-M.); (A.S.); (I.P.); (W.M.S.); (J.M.)
- Radiobiology Laboratory, Department of Medical Physics, Greater Poland Cancer Centre, 61-866 Poznan, Poland;
| | - Julian Malicki
- Department of Electroradiology, Poznan University of Medical Sciences, 61-866 Poznan, Poland; (M.K.-M.); (A.S.); (I.P.); (W.M.S.); (J.M.)
- Department of Medical Physics, Greater Poland Cancer Centre, 61-866 Poznan, Poland; (A.R.); (P.R.)
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Pittomvils G, Bogaert E, Traneus E, Thysebaert P, De Wagter C. Measurement-based validation of a commercial Monte Carlo dose calculation algorithm for electron beams. Med Phys 2022; 49:4755-4767. [PMID: 35543491 DOI: 10.1002/mp.15685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 03/04/2022] [Accepted: 04/06/2022] [Indexed: 11/11/2022] Open
Abstract
PURPOSE This work presents the clinical validation of RayStation's electron Monte Carlo Code by use of diodes and plane parallel radiation detectors in homogenous and heterogeneous tissues. Results are evaluated against international accepted criteria. METHODS The Monte Carlo based electron beam dose calculation code was validated using diodes, air filled and liquid filled parallel radiation detectors on a Elekta Linac with beam energies of 4,6,8,10 and 12 MeV. Treatment setups with varying SSD's, different applicators, various cut-outs and oblique beam incidences were addressed, together with dose prediction behind lung, air and bone equivalent inserts. According to NCS (Netherlands Commission of Radiation Dosimetry) report 15 for non-standard treatment setups a dose agreement of 3 % in the δ1 region (high dose region around Zref ), a distance to agreement of 3 mm or a dose agreement of 10 % in the δ2 region (regions with high dose gradients) and 4 % in the δ4 region (photon tail/low dose region) were applied. During validation, clinical routine settings of 2×2×2 mm3 dose voxels and a statistically dose uncertainty of 0.6% (250 000 histories/cm2 ) were used. RESULTS RayStation's electron Monte Carlo code dose prediction was able to achieve the tolerances of NCS report 15. Output predictions as function of the SDD improve with energy and applicator size. Cut-out data revealed no field size neither energy dependence on the accuracy of the dose prediction. Excellent agreement for the oblique incidence data was achieved and maximum one voxel difference was obtained for the distance to agreement behind heterogeneous inserts. CONCLUSIONS The accuracy of RayStation's Monte Carlo based electron beam dose prediction for Elekta accelerators is confirmed for clinical treatment planning that is not only performed within an acceptable timeframe in terms of number of histories but also addresses for homogenous and heterogeneous media. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Geert Pittomvils
- Department of Radiotherapy, Ghent University Hospital, Corneel Heymanslaan 10, Gent, 9000, Belgium
| | - Evelien Bogaert
- Department of Radiotherapy, Ghent University Hospital, Corneel Heymanslaan 10, Gent, 9000, Belgium
| | - Erik Traneus
- RaySearch Laboratories AB, Eugeniavägen 8, Stockholm, 113 68, Sweden
| | - Pieternel Thysebaert
- Odisee Hogeschool-Universiteit Brussel, Bleekerijstraat 23-29, Brussel, 1000, Belgium
| | - Carlos De Wagter
- Department of Human Structure and Repair, Ghent University, Corneel Heymanslaan 10, Gent, 9000
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Keyak JH, Eijansantos ML, Rosecrance KG, Wong D, Feizi S, Meldosian AL, Peddinti P, Les CM, Skinner HB, Sehgal V. A preliminary safety assessment of vertebral augmentation with 32P brachytherapy bone cement. Phys Med Biol 2022; 67. [PMID: 35294928 PMCID: PMC9045587 DOI: 10.1088/1361-6560/ac5e5d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 03/16/2022] [Indexed: 11/12/2022]
Abstract
Abstract
Comprehensive treatment for vertebral metastatic lesions commonly involves vertebral augmentation (vertebroplasty or kyphoplasty) to relieve pain and stabilize the spine followed by multiple sessions of radiotherapy. We propose to combine vertebral augmentation and radiotherapy into a single treatment by adding 32P, a β-emitting radionuclide, to bone cement, thereby enabling spinal brachytherapy to be performed without irradiating the spinal cord. The goal of this study was to address key dosimetry and safety questions prior to performing extensive animal studies. The 32P was in the form of hydroxyapatite powder activated by neutron bombardment in a nuclear reactor. We performed ex vivo dosimetry experiments to establish criteria for safe placement of the cement within the sheep vertebral body. In an in vivo study, we treated three control ewes and three experimental ewes with brachytherapy cement containing 2.23–3.03 mCi 32P ml−1 to identify the preferred surgical approach, to determine if 32P leaches from the cement and into the blood, urine, or feces, and to identify unexpected adverse effects. Our ex vivo experiments showed that cement with 4 mCi 32P ml−1 could be safely implanted in the vertebral body if the cement surface is at least 4 mm from the spinal cord in sheep and 5 mm from the spinal cord in humans. In vivo, a lateral retroperitoneal surgical approach, ventral to the transverse processes, was identified as easy to perform while allowing a safe distance to the spinal cord. The blood, urine, and feces of the sheep did not contain detectable levels of 32P, and the sheep did not experience any neurologic or other adverse effects from the brachytherapy cement. These results demonstrate, on a preliminary level, the relative safety of this brachytherapy cement and support additional development and testing.
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Quantitative evaluation of dosimetric uncertainties associated with small electron fields. J Med Imaging Radiat Sci 2022; 53:273-282. [PMID: 35304080 DOI: 10.1016/j.jmir.2022.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 11/24/2021] [Accepted: 02/14/2022] [Indexed: 11/23/2022]
Abstract
INTRODUCTION Although many studies have investigated small electron fields, there are several dosimetric issues that are not well understood. This includes lack of charged particle equilibrium, lateral scatter, source occlusion and volume averaging of the detectors used in the measurement of the commissioning data. High energy electron beams are also associated with bremsstrahlung production that contributes to dose deposition, which is not well investigated, particularly for small electron fields. The goal of this work has been to investigate dosimetric uncertainties associated with small electron fields using dose measurements with different detectors as well as calculations with eMC dose calculation algorithm. METHODS Different dosimetric parameters including output factors, depth dose curves and dose profiles from small electron field cutouts were investigated quantitatively. These dosimetric parameters were measured using different detectors that included small ion chambers and diodes for small electron cutouts with diameters ranging from 15-50mm mounted on a 6 × 6cm2 cone with beam energies from 6-20MeV. RESULTS Large deviations existed between the output factors calculated with the eMC algorithm and measured with small detectors for small electron fields up to 55% for 6MeV. The discrepancy between the calculated and measured doses increased 10%-55% with decreasing electron beam energy from 20 MeV to 6 MeV for 15mm circular field. For electron fields with cutouts 20mm and larger, the measured and calculated doses agreed within 5% for all electron energies from 6-20MeV. For small electron fields, the maximal depth dose shifted upstream and becomes more superficial as the electron beam energy increases from 6-20MeV as measured with small detectors. DISCUSSION Large dose discrepancies were found between the measured and calculated doses for small electron fields where the eMC underestimated output factors by 55% for small circular electron fields with a diameter of 15 mm, particularly for low energy electron beams. The measured entrance doses and dmax of the depth dose curves did not agree with the corresponding values calculated by eMC. Furthermore, the measured dose profiles showed enhanced dose deposition in the umbra region and outside the small fields, which mostly resulted from dose deposition from the bremsstrahlung produced by high energy electrons that was not accounted for by the eMC algorithm due to inaccurate modeling of the lateral dose deposition from bremsstrahlung. CONCLUSION Electron small field dosimetry require more consideration of variations in beam quality, lack of charged particle equilibrium, lateral scatter loss and dose deposition from bremsstrahlung produced by energetic electron beams in a comprehensive approach similar to photon small field dosimetry. Furthermore, most of the commercially available electron dose calculation algorithms are commissioned with large electron fields; therefore, vendors should provide tools for the modeling of electron dose calculation algorithms for small electron fields.
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Dosimetric Characterization of Small Radiotherapy Electron Beams Collimated by Circular Applicators with the New Microsilicon Detector. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12020600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
High-energy small electron beams, generated by linear accelerators, are used for radiotherapy of localized superficial tumours. The aim of the present study is to assess the dosimetric performance under small radiation therapy electron beams of the novel PTW microSilicon detector compared to other available dosimeters. Relative dose measurements of circular fields with 20, 30, 40, and 50 mm aperture diameters were performed for electron beams generated by an Elekta Synergy linac, with energy between 4 and 12 MeV. Percentage depth dose, transverse profiles, and output factors, normalized to the 10 × 10 cm2 reference field, were measured. All dosimetric data were collected in a PTW MP3 motorized water phantom, at SSD of 100 cm, by using the novel PTW microSilicon detector. The PTW diode E and the PTW microDiamond were also used in all beam apertures for benchmarking. Data for the biggest field size were also measured by the PTW Advanced Markus ionization chamber. Measurements performed by the microSilicon are in good agreement with the reference values for all the tubular applicators and beam energies within the stated uncertainties. This confirms the reliability of the microSilicon detector for relative dosimetry of small radiation therapy electron beams collimated by circular applicators.
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Ali I, Alsbou N, Ahmad S. Quantitative evaluation of dosimetric uncertainties in electron therapy by measurement and calculation using the electron Monte Carlo dose algorithm in the Eclipse treatment planning system. J Appl Clin Med Phys 2022; 23:e13478. [PMID: 34822731 PMCID: PMC8803289 DOI: 10.1002/acm2.13478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 08/19/2021] [Accepted: 10/21/2021] [Indexed: 12/02/2022] Open
Abstract
In the electron beam radiation therapy, customized blocks are mostly used to shape treatment fields to generate conformal doses. The goal of this study is to investigate quantitatively dosimetric uncertainties associated with heterogeneities, detectors used in the measurement of the beam data commissioning, and modeling of the interactions of high energy electrons with tissue. These uncertainties were investigated both by measurements with different detectors and calculations using electron Monte Carlo algorithm (eMC) in the Eclipse treatment planning system. Dose distributions for different field sizes were calculated using eMC and measured with a multiple-diode-array detector (MapCheck2) for cone sizes ranging from 6 to 25 cm. The dose distributions were calculated using the CT images of the MapCheck2 and water-equivalent phantoms. In the umbra region (<20% isodose line), the eMC underestimated dose by a factor of 3 for high energy electron beams due to lack of consideration of bremsstrahlung emitted laterally that was not accounted by eMC in the low dose region outside the field. In the penumbra (20%-80% isodose line), the eMC overestimated dose (40%) for high energy 20 MeV electrons compared to the measured dose with small diodes in the high gradient dose region. This was mainly due to lack of consideration of volume averaging of the ion chamber used in beam data commissioning which was input to the eMC dose calculation algorithm. Large uncertainties in the CT numbers (25%) resulted from the image artifacts in the CT images of the MapCheck2 phantom due to metal artifacts. The eMC algorithm used the electron and material densities extracted from the CT numbers which resulted large dosimetric uncertainties (10%) in the material densities and corresponding stopping power ratios. The dose calculations with eMC are associated with large uncertainties particularly in penumbra and umbra regions and around heterogeneities which affect the low dose level that cover nearby normal tissue or critical structures.
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Affiliation(s)
- Imad Ali
- Department of Radiation OncologyUniversity of Oklahoma Health Sciences CenterOklahoma CityOklahomaUSA
| | - Nesreen Alsbou
- Department of Engineering and PhysicsUniversity of Central OklahomaEdmondOklahomaUSA
| | - Salahuddin Ahmad
- Department of Radiation OncologyUniversity of Oklahoma Health Sciences CenterOklahoma CityOklahomaUSA
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Saidi K, Kaanouch O, El Gouach H, Mesradi MR, Mkimel M, El Baydaoui R. Electron Beam Measurements Employing Electron Montecarlo Algorithm on TrueBeam STx® and Clinac iX® Linear Accelerators. Open Access Maced J Med Sci 2021. [DOI: 10.3889/oamjms.2021.7564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Electron beam measurement comparison between TrueBeam STx® and Clinac iX® established. Data evaluation of eMC-calculated and measured for TrueBeam STx® performed. Dosimetric parameters measured including depth dose curves for each applicator, percentage depth dose (PDDs) curves without applicator, the profile in-air for a large field size 40×40 cm2, and the Absolute Dose (cGy/MU) for each applicator using a large water phantom (PTW, Freiburg, Germany), employing Roos and Markus plane-parallel ionization chambers. The data were examined for five electron beams of Varian’s TrueBeam STx® and Clinac iX® machines. A comparison between measurement PDDs and calculated by the Eclipse electron Monte Carlo (eMC) algorithm was performed to validate Truebeam STx® commissioning. The measured data indicated that electron beam PDDs from the TrueBeam STx® machine are well matched to those from Clinac iX® machine. The quality index R50 for applicator 15×15 cm2 was in the tolerance intervals. However, Surface dose (Ds) increases with increasing energy for both accelerators. Comparisons between the measured and eMC-calculated values revealed that the R100, R90, R80, and R50 values mostly agree within 5 mm. Measured and calculated bremsstrahlung tail Rp correlates well statistically. Ds agrees mostly within 2%. Electron beams were successfully validated for TrueBeam STx®, a good agreement between modeled and measured data was observed.
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Dosimetric accuracy of a cross-calibration coefficient for plane-parallel ionization chamber obtained in low-energy electron beams using various cylindrical dosimeters. POLISH JOURNAL OF MEDICAL PHYSICS AND ENGINEERING 2021. [DOI: 10.2478/pjmpe-2021-0036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Abstract
Introduction: The accuracy of the cross-calibration procedure depends on ionization chamber type, both used as reference one and under consideration. Also, the beam energy and phantom medium could influence the precision of cross calibration coefficient, resulting in a systematic error in dose estimation and thus could influence the linac beam output checking. This will result in a systematic mismatch between dose calculated in treatment planning system and delivered to the patient.
Material and methods: The usage of FC65-G, CC13 and CC01 thimble reference chambers as well as 6, 9, and 15 MeV electron beams has been analyzed. A plane-parallel PPC05 chamber was calibrated since scarce literature data are available for this dosimeter type. The influence of measurement medium and an effective point of measurement (EPOM) on obtained results are also presented.
Results: Dose reconstruction precision of ~0.1% for PPC05 chamber could be obtained when cross-calibration is based on a thimble CC13 chamber. Nd,w,Qcross obtained in beam ≥ 9MeV gives 0.1 – 0.5% precision of dose reconstruction.
Without beam quality correction, 15 MeV Nd,w,Qcross is 10% lower than Co-60 Nd,w,0. Various EPOM shifts resulted in up to 0.6% discrepancies in Nd,w,Qcross values.
Conclusions: Ionization chamber with small active volume and tissue-equivalent materials supplies more accurate cross-calibration coefficients in the range of 6 – 15 MeV electron beams. In the case of 6 and 9 MeV beams, the exact position of an effective point of measurement is of minor importance. In-water cross-calibration coefficient can be used in a solid medium without loss of dose accuracy.
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Sweeping-beam technique with electrons for large treatment areas as total skin irradiation : Dosimetric and technical aspects of a modified Stanford technique. Strahlenther Onkol 2021; 198:47-55. [PMID: 34729625 DOI: 10.1007/s00066-021-01859-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 09/19/2021] [Indexed: 10/19/2022]
Abstract
PURPOSE Total skin electron beam therapy (TSEBT) is still a technical and therapeutic challenge today. Thus, we developed TSEBT using a sweeping-beam technique. METHODS For treatment delivery, a linear accelerator Versa HD (ELEKTA, Stockholm, Sweden) with high-dose-rate electrons (HDRE) was used with a dose rate of 9000 MU/min. Dosimetry quality assurance was performed by multiple measurements with film dosimetry, 2D array, and Roos chamber. RESULTS Clinical experience shows that treatment durations of 75 to 90 min are usual for the Stanford technique without using HDRE. With this new sweeping-beam irradiation technique, the total treatment time of a daily fraction could be reduced to 20 min while keeping over- and underdosing low. The treatment area is about 60 cm × 200 cm and the dose distribution is uniform within 2% and 5% in vertical and horizontal directions, respectively. Initially, the electron energy of 6 MeV is reduced to 3.2 MeV by 1‑cm polymethylmethacrylat (PMMA) scatter and the irradiation conditions of a source-surface distance (SSD) of 350 cm. The photon contamination drops to under 1%. CONCLUSION These results show that the mean dose to total skin varies between 1.3 and 1.8 Gy. The sweeping-beam technique with electrons has a homogeneous dose distribution in connection with a short treatment time.
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The Study of Field Equivalence Determined by the Modeled Percentage Depth Dose in Electron Beam Radiation Therapy. BIOMED RESEARCH INTERNATIONAL 2021; 2021:3397350. [PMID: 34660785 PMCID: PMC8519681 DOI: 10.1155/2021/3397350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 08/31/2021] [Accepted: 09/12/2021] [Indexed: 11/17/2022]
Abstract
Introduction This study presents an empirical method to model the curve of electron beam percent depth dose (PDD) by using the primary-tail function in electron beam radiation therapy. The modeling parameters N and n can be used to predict the minimal side length when the field size is reduced below that required for lateral scatter equilibrium (LSE) in electron radiation therapy. Methods and Materials The electrons' PDD curves were modeled by the primary-tail function in this study. The primary function included the exponential function and the main parameters of N and μ, while the tail function was composed of a sigmoid function with the main parameter of n. The PDD of five electron energies was modeled by the primary and tail function by adjusting the parameters of N, μ, and n. The R50 and Rp can be derived from the modeled straight line of 80% to 20% region of PDD. The same electron energy with different cone sizes was also modeled by the primary-tail function. The stopping power of different electron energies in different depths can also be derived from the parameters N, μ, and n. Results The main parameters N and n increase but μ decreases in the primary-tail function for characterizing the electron beam PDD when the electron energy increased. The relationship of parameter n, N, and ln(−μ) with electron energy are n = 31.667E0 − 88, N = 0.9975E0 − 2.8535, and ln(−μ) = −0.1355E0 − 6.0986, respectively. Percent depth dose was derived from the percent reading curve by multiplying the stopping power relevant to the depth in water at a certain electron energy. The stopping power of different electron energies can be derived from n and N with the following equation: stopping power = (−0.042ln(NE0) + 1.072)e(−nE0 · 5 · 10−5 + 0.0381)·x, where x is the depth in water. The lateral scatter equivalence (LSE) of the clinical electron beam can be described by the parameters E0, n, and N in the equation of Seq = (nE0 − NE0)0.288/(E0/nE0)0.0195. The LSE was compared with the root mean square scatter angular distribution method and shows the agreement of depth dose distributions within ±2%. Conclusions The PDD of the electron beam at different energies and cone sizes can be modeled with an empirical model to deal with what is the minimal field size without changing the percent depth dose when approximate LSE is given in centimeters of water.
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Baltz GC, Kirsner SM. Validation of spline modeling for calculation of electron insert factors for varian linear accelerators. J Appl Clin Med Phys 2021; 22:64-70. [PMID: 34609063 PMCID: PMC8598145 DOI: 10.1002/acm2.13430] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 09/01/2021] [Accepted: 09/07/2021] [Indexed: 10/29/2022] Open
Abstract
There are several methods available in the literature for predicting the insert factor for clinical electron beams. The purpose of this work was to build on a previously published technique that uses a bivariate spline model generated from elliptically parameterized empirical measurements. The technique has been previously validated for Elekta linear accelerators for limited clinical electron setups. The same model is applied to Varian machines to test its efficacy for use with these linear accelerators. Insert factors for specifically designed elliptical cutouts were measured to create spline models for 6, 9, 12, 16, and 20 MeV electron energies for four different cone sizes at source-to-surface distances (SSD) of 100, 105, and 110 cm. Insert factor validation measurements of patient cutouts and clinical standard cutouts were acquired to compare to model predictions. Agreement between predicted insert factors and validation measurements averaged 0.8% over all energies, cones, and clinical SSDs, with an uncertainty of 0.6% (1SD), and maximum deviation of 2.1%. The model demonstrated accurate predictions of insert factors using the minimum required amount of input data for small cones, with more input measurements required for larger cones. The results of this study provide expanded validation of this technique to predict insert factors for all energies, cones, and SSDs that would be used in most clinical situations. This level of accuracy and the ease of creating the model necessary for the insert factor predictions demonstrate its acceptability to use clinically for Varian machines.
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Affiliation(s)
- Garrett C Baltz
- Scripps MD Anderson Cancer Center, San Diego, California, USA
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Hilliard EN, Carver RL, Chambers EL, Kavanaugh JA, Erhart KJ, McGuffey AS, Hogstrom KR. Planning and delivery of intensity modulated bolus electron conformal therapy. J Appl Clin Med Phys 2021; 22:8-21. [PMID: 34558774 PMCID: PMC8504596 DOI: 10.1002/acm2.13386] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 11/30/2020] [Accepted: 06/23/2021] [Indexed: 12/05/2022] Open
Abstract
PURPOSE Bolus electron conformal therapy (BECT) is a clinically useful, well-documented, and available technology. The addition of intensity modulation (IM) to BECT reduces volumes of high dose and dose spread in the planning target volume (PTV). This paper demonstrates new techniques for a process that should be suitable for planning and delivering IM-BECT using passive radiotherapy intensity modulation for electrons (PRIME) devices. METHODS The IM-BECT planning and delivery process is an addition to the BECT process that includes intensity modulator design, fabrication, and quality assurance. The intensity modulator (PRIME device) is a hexagonal matrix of small island blocks (tungsten pins of varying diameter) placed inside the patient beam-defining collimator (cutout). Its design process determines a desirable intensity-modulated electron beam during the planning process, then determines the island block configuration to deliver that intensity distribution (segmentation). The intensity modulator is fabricated and quality assurance performed at the factory (.decimal, LLC, Sanford, FL). Clinical quality assurance consists of measuring a fluence distribution in a plane perpendicular to the beam in a water or water-equivalent phantom. This IM-BECT process is described and demonstrated for two sites, postmastectomy chest wall and temple. Dose plans, intensity distributions, fabricated intensity modulators, and quality assurance results are presented. RESULTS IM-BECT plans showed improved D90-10 over BECT plans, 6.4% versus 7.3% and 8.4% versus 11.0% for the postmastectomy chest wall and temple, respectively. Their intensity modulators utilized 61 (single diameter) and 246 (five diameters) tungsten pins, respectively. Dose comparisons for clinical quality assurance showed that for doses greater than 10%, measured agreed with calculated dose within 3% or 0.3 cm distance-to-agreement (DTA) for 99.9% and 100% of points, respectively. CONCLUSION These results demonstrated the feasibility of translating IM-BECT to the clinic using the techniques presented for treatment planning, intensity modulator design and fabrication, and quality assurance processes.
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Affiliation(s)
- Elizabeth N. Hilliard
- Department of Physics and AstronomyLouisiana State UniversityBaton RougeLouisianaUSA
| | - Robert L. Carver
- Department of Physics and AstronomyLouisiana State UniversityBaton RougeLouisianaUSA
- Mary Bird Perkins Cancer CenterBaton RougeLouisianaUSA
| | - Erin L. Chambers
- Department of Physics and AstronomyLouisiana State UniversityBaton RougeLouisianaUSA
| | - James A. Kavanaugh
- Department of Radiation OncologyWashington University School of MedicineSaint LouisMissouriUSA
| | | | - Andrew S. McGuffey
- Department of Physics and AstronomyLouisiana State UniversityBaton RougeLouisianaUSA
| | - Kenneth R. Hogstrom
- Department of Physics and AstronomyLouisiana State UniversityBaton RougeLouisianaUSA
- Mary Bird Perkins Cancer CenterBaton RougeLouisianaUSA
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Heath E, Mueller S, Guyer G, Duetschler A, Elicin O, Aebersold D, Fix MK, Manser P. Implementation and experimental validation of a robust hybrid direct aperture optimization approach for mixed-beam radiotherapy. Med Phys 2021; 48:7299-7312. [PMID: 34585756 PMCID: PMC9292851 DOI: 10.1002/mp.15258] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 08/30/2021] [Accepted: 09/16/2021] [Indexed: 12/24/2022] Open
Abstract
Purpose The objectives of the work presented in this paper were to (1) implement a robust‐optimization method for deliverable mixed‐beam radiotherapy (MBRT) plans within a previously developed MBRT planning framework; (2) perform an experimental validation of the delivery of robust‐optimized MBRT plans; and (3) compare PTV‐based and robust‐optimized MBRT plans in terms of target dose robustness and organs at risk (OAR) sparing for clinical head and neck and brain patient cases. Methods A robust‐optimization method, which accounts for translational setup errors, was implemented within a previously developed treatment planning framework for MBRT. The framework uses a hybrid direct aperture optimization method combining column generation and simulated annealing. A robust plan was developed and then delivered to an anthropomorphic head phantom using the Developer Mode of a TrueBeam linac. Planar dose distributions were measured and compared to the planned dose. Robust‐optimized and PTV‐based plans were developed for three clinical patient cases consisting of two head and neck cases and one brain case. The plans were compared in terms of the robustness to 5 mm shifts of the target volume dose as well as in terms of OAR sparing. Results Using a gamma criterion of 3%/2 mm and a dose threshold of 10%, the agreement between film measurements and dose calculations was better than 97.7% for the total plan and better than 95.5% for the electron component of the plan. For the two head and neck patient cases, the average clinical target volume (CTV) dose homogeneity index (V95%–V107%) over all the considered setup error scenarios was on average 19% lower for the PTV‐based plans and it had a larger standard deviation. The robust‐optimized plans achieved, on average, a 20% reduction in the OAR doses compared to the PTV‐based plans. For the brain patient case, the CTV dose homogeneity index was similar for the two plans, while the OAR doses were 22% lower, on average, for the robust‐optimized plan. No clear trend in terms of electron contributions was found across the three patient cases, although robust‐optimized plans tended toward higher electron beam energies. Conclusions A framework for robust optimization of deliverable MBRT plans has been developed and validated. PTV‐based MBRT were found to not be robust to setup errors, while the dose delivered by the robust‐optimized plans were clinically acceptable for all considered error scenarios and had better OAR sparing. This study shows that the robust optimization is a promising alternative to conventional PTV margins for MBRT.
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Affiliation(s)
- Emily Heath
- Carleton Laboratory for Radiotherapy Physics, Carleton University, Ottawa, Canada
| | - Silvan Mueller
- Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Gian Guyer
- Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Alisha Duetschler
- Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland.,Department of Physics, ETH Zurich, Zurich, Switzerland.,Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland
| | - Olgun Elicin
- Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Daniel Aebersold
- Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Michael K Fix
- Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Peter Manser
- Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland
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Ronga MG, Cavallone M, Patriarca A, Leite AM, Loap P, Favaudon V, Créhange G, De Marzi L. Back to the Future: Very High-Energy Electrons (VHEEs) and Their Potential Application in Radiation Therapy. Cancers (Basel) 2021; 13:4942. [PMID: 34638424 PMCID: PMC8507836 DOI: 10.3390/cancers13194942] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 09/27/2021] [Accepted: 09/28/2021] [Indexed: 12/14/2022] Open
Abstract
The development of innovative approaches that would reduce the sensitivity of healthy tissues to irradiation while maintaining the efficacy of the treatment on the tumor is of crucial importance for the progress of the efficacy of radiotherapy. Recent methodological developments and innovations, such as scanned beams, ultra-high dose rates, and very high-energy electrons, which may be simultaneously available on new accelerators, would allow for possible radiobiological advantages of very short pulses of ultra-high dose rate (FLASH) therapy for radiation therapy to be considered. In particular, very high-energy electron (VHEE) radiotherapy, in the energy range of 100 to 250 MeV, first proposed in the 2000s, would be particularly interesting both from a ballistic and biological point of view for the establishment of this new type of irradiation technique. In this review, we examine and summarize the current knowledge on VHEE radiotherapy and provide a synthesis of the studies that have been published on various experimental and simulation works. We will also consider the potential for VHEE therapy to be translated into clinical contexts.
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Affiliation(s)
- Maria Grazia Ronga
- Centre de Protonthérapie d’Orsay, Department of Radiation Oncology, Campus Universitaire, Institut Curie, PSL Research University, 91898 Orsay, France; (M.G.R.); (M.C.); (A.P.); (A.M.L.); (P.L.); (G.C.)
- Thales AVS Microwave & Imaging Sub-Systems, 78141 Vélizy-Villacoublay, France
| | - Marco Cavallone
- Centre de Protonthérapie d’Orsay, Department of Radiation Oncology, Campus Universitaire, Institut Curie, PSL Research University, 91898 Orsay, France; (M.G.R.); (M.C.); (A.P.); (A.M.L.); (P.L.); (G.C.)
| | - Annalisa Patriarca
- Centre de Protonthérapie d’Orsay, Department of Radiation Oncology, Campus Universitaire, Institut Curie, PSL Research University, 91898 Orsay, France; (M.G.R.); (M.C.); (A.P.); (A.M.L.); (P.L.); (G.C.)
| | - Amelia Maia Leite
- Centre de Protonthérapie d’Orsay, Department of Radiation Oncology, Campus Universitaire, Institut Curie, PSL Research University, 91898 Orsay, France; (M.G.R.); (M.C.); (A.P.); (A.M.L.); (P.L.); (G.C.)
- INSERM LITO U1288, Campus Universitaire, Institut Curie, PSL Research University, University Paris Saclay, 91898 Orsay, France
| | - Pierre Loap
- Centre de Protonthérapie d’Orsay, Department of Radiation Oncology, Campus Universitaire, Institut Curie, PSL Research University, 91898 Orsay, France; (M.G.R.); (M.C.); (A.P.); (A.M.L.); (P.L.); (G.C.)
| | - Vincent Favaudon
- INSERM U 1021-CNRS UMR 3347, Campus Universitaire, Institut Curie, PSL Research University, University Paris Saclay, 91898 Orsay, France;
| | - Gilles Créhange
- Centre de Protonthérapie d’Orsay, Department of Radiation Oncology, Campus Universitaire, Institut Curie, PSL Research University, 91898 Orsay, France; (M.G.R.); (M.C.); (A.P.); (A.M.L.); (P.L.); (G.C.)
| | - Ludovic De Marzi
- Centre de Protonthérapie d’Orsay, Department of Radiation Oncology, Campus Universitaire, Institut Curie, PSL Research University, 91898 Orsay, France; (M.G.R.); (M.C.); (A.P.); (A.M.L.); (P.L.); (G.C.)
- INSERM LITO U1288, Campus Universitaire, Institut Curie, PSL Research University, University Paris Saclay, 91898 Orsay, France
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Akino Y, Das IJ, Fujiwara M, Kaneko A, Masutani T, Mizuno H, Isohashi F, Suzuki O, Seo Y, Tamari K, Ogawa K. Characteristics of microSilicon diode detector for electron beam dosimetry. JOURNAL OF RADIATION RESEARCH 2021:rrab085. [PMID: 34559877 DOI: 10.1093/jrr/rrab085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 05/31/2021] [Indexed: 06/13/2023]
Abstract
A microSilicon™ (PTW type 60023), a new unshielded diode detector succeeding Diode E (model 60017, PTW), was characterized for electron beam dosimetry and compared with other detectors. Electron beams generated from a TrueBeam linear accelerator were measured using the microSilicon, Diode E, and microDiamond synthetic single-crystal diamond detector. Positional accuracy of microSilicon was measured by data collected in air and water. The percent depth dose (PDD), off-center ratio (OCR), dose-response linearity, dose rate dependence, and cone factors were evaluated. The PDDs were compared with data measured using a PPC40 plane-parallel ionization chamber. The maximum variations of depth of 50% and 90% of the maximum dose, and practical depth among all detectors and energies were 0.9 mm. The maximum variations of the bremsstrahlung dose among all detectors and energies were within 0.3%. OCR showed good agreement within 1% for the flat and tail regions. The microSilicon detector showed a penumbra width similar to microDiamond, whereas Diode E showed the steepest penumbra shape. All detectors showed good dose-response linearity and stability against the dose rate; only Diode E demonstrated logarithmic dose rate dependency. The cone factor measured with microSilicon was within ±1% for all energies and cone sizes. We demonstrated that the characteristics of microSilicon is suitable for electron beam dosimetry. The microSilicon detector can be a good alternative for electron beam dosimetry in terms of providing an appropriate PDD curve without corrections, high spatial resolution for OCR measurements and cone factors.
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Affiliation(s)
- Yuichi Akino
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan
- Department of Radiation Oncology, Suita Tokushukai Hospital, Suita, Osaka, 565-0814, Japan
| | - Indra J Das
- Department of Radiation Oncology, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA
| | - Masateru Fujiwara
- Department of Radiation Oncology, Suita Tokushukai Hospital, Suita, Osaka, 565-0814, Japan
| | - Akari Kaneko
- Department of Radiation Oncology, Suita Tokushukai Hospital, Suita, Osaka, 565-0814, Japan
| | - Takashi Masutani
- Department of Radiation Oncology, Suita Tokushukai Hospital, Suita, Osaka, 565-0814, Japan
| | - Hirokazu Mizuno
- Department of Central Radiology, Osaka Rosai Hospital, Sakai, Osaka, 591-8025, Japan
| | - Fumiaki Isohashi
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan
| | - Osamu Suzuki
- Osaka Heavy Ion Therapy Center, Osaka, 540-0008, Japan
| | - Yuji Seo
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan
| | - Keisuke Tamari
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan
| | - Kazuhiko Ogawa
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan
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Independent validation of a dedicated commissioning software and investigation of the direction dependence of the field symmetry for the LIAC intraoperative electron radiotherapy accelerator. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2021.109529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Skinner L, Knopp R, Wang YC, Dubrowski P, Bush KK, Limmer A, Trakul N, Million L, Marquez CM, Yu AS. CT-less electron radiotherapy simulation and planning with a consumer 3D camera. J Appl Clin Med Phys 2021; 22:128-136. [PMID: 34042253 PMCID: PMC8292688 DOI: 10.1002/acm2.13283] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 04/15/2021] [Accepted: 04/20/2021] [Indexed: 11/17/2022] Open
Abstract
Purpose Electron radiation therapy dose distributions are affected by irregular body surface contours. This study investigates the feasibility of three‐dimensional (3D) cameras to substitute for the treatment planning computerized tomography (CT) scan by capturing the body surfaces to be treated for accurate electron beam dosimetry. Methods Dosimetry was compared for six electron beam treatments to the nose, toe, eye, and scalp using full CT scan, CT scan with Hounsfield Unit (HU) overridden to water (mimic 3D camera cases), and flat‐phantom techniques. Radiation dose was prescribed to a depth on the central axis per physician’s order, and the monitor units (MUs) were calculated. The 3D camera spatial accuracy was evaluated by comparing the 3D surface of a head phantom captured by a 3D camera and that generated with the CT scan in the treatment planning system. A clinical case is presented, and MUs were calculated using the 3D camera body contour with HU overridden to water. Results Across six cases the average change in MUs between the full CT and the 3Dwater (CT scan with HU overridden to water) calculations was 1.3% with a standard deviation of 1.0%. The corresponding hotspots had a mean difference of 0.4% and a standard deviation of 1.9%. The 3D camera captured surface of a head phantom was found to have a 0.59 mm standard deviation from the surface derived from the CT scan. In‐vivo dose measurements (213 ± 8 cGy) agreed with the 3D‐camera planned dose of 209 ± 6 cGy, compared to 192 ± 6 cGy for the flat‐phantom calculation (same MUs). Conclusions Electron beam dosimetry is affected by irregular body surfaces. 3D cameras can capture irregular body contours which allow accurate dosimetry of electron beam treatment as an alternative to costly CT scans with no extra exposure to radiation. Tools and workflow for clinical implementation are provided.
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Affiliation(s)
| | - Rick Knopp
- Stanford Radiation oncology, Palo Alto, CA, USA
| | | | | | - Karl K Bush
- Stanford Radiation oncology, Palo Alto, CA, USA
| | | | | | | | | | - Amy S Yu
- Stanford Radiation oncology, Palo Alto, CA, USA
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Bayatiani MR, Fallahi F, Aliasgharzadeh A, Ghorbani M, Khajetash B, Seif F. A comparison of symmetry and flatness measurements in small electron fields by different dosimeters in electron beam radiotherapy. Rep Pract Oncol Radiother 2021; 26:50-58. [PMID: 33948302 DOI: 10.5603/rpor.a2021.0009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 12/23/2020] [Indexed: 11/25/2022] Open
Abstract
Background Symmetry and flatness are two quantities which should be evaluated in the commissioning and quality control of an electron beam in electron beam radiotherapy. The aim of this study is to compare symmetry and flatness obtained using three different dosimeters for various small and large fields in electron beam radiotherapy with linac. Materials and methods Beam profile measurements were performed in a PTW water phantom for 10, 15 and 18 MeV electron beams of an Elekta Precise linac for small and large beams (1.5 × 1.5 cm2 to 20 × 20 cm2 field sizes). A Diode E detector and Semiflex-3D and Advanced Markus ionization chambers were used for dosimetry. Results Based on the obtained results, there are minor differences between the responses from different dosimeters (Diode E detector and Semiflex-3D and Advanced Markus ionization chambers) in measurement of symmetry and flatness for the electron beams. The symmetry and flatness values increase with increasing field size and electron beam energy for small and large field sizes, while the increases are minor in some cases. Conclusions The results indicate that the differences between the symmetry and flatness values obtained from the three dosimeter types are not practically important.
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Affiliation(s)
- Mohamad Reza Bayatiani
- Medical Physics and Radiotherapy Department, School of Paramedical Sciences, Arak University of Medical Sciences and Khansari Hospital, Arak, Iran
| | - Fatemeh Fallahi
- Department of Medical Physics, School of Paramedical Sciences, Kashan University of Medical Sciences, Kashan, Iran
| | - Akbar Aliasgharzadeh
- Department of Medical Physics, School of Paramedical Sciences, Kashan University of Medical Sciences, Kashan, Iran
| | - Mahdi Ghorbani
- Biomedical Engineering and Medical Physics Department, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Benyamin Khajetash
- Medical Physics Department, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Fatemeh Seif
- Medical Physics and Radiotherapy Department, School of Paramedical Sciences, Arak University of Medical Sciences and Khansari Hospital, Arak, Iran
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Mutsakanyi S, du Plessis F. Characterization and dosimetry of photon multileaf collimated electron beams using Gafchromic film measurements. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2020.109266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Selection criteria for high-dose-rate surface brachytherapy and electron beam therapy in cutaneous oncology. J Contemp Brachytherapy 2021; 13:195-204. [PMID: 33897794 PMCID: PMC8060966 DOI: 10.5114/jcb.2021.105288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Accepted: 02/12/2021] [Indexed: 11/25/2022] Open
Abstract
Purpose High-dose-rate (HDR) brachytherapy is an alternative treatment to electron external beam radiation therapy (EBRT) of superficial skin lesions. The purpose of this study was to establish the selection criteria for HDR brachytherapy technique (HDR-BT) and EBRT in cutaneous oncology for various clinical scenarios. Material and methods The study consists of two parts: a) EBRT and HDR-BT treatment plans comparison analyzing clinical target volumes (CTVs) with different geometries, field sizes, and topologies, and b) development of a prediction model capable of characterization of dose distributions in HDR surface brachytherapy for various geometries of treatment sites. Results A loss of CTV coverage for the electron plans (D90, D95) was recorded up to 45%, when curvature of the applicator increased over 30°. Values for D2 cm3 for both plans were comparable, and they were in range of ±8% of prescription dose. An increase in higher doses (D0.5 cm3 and D0.1 cm3) was observed in HDR-BT plans, and it was greater for larger lesions. The average increase was 3.8% for D0.5 cm3 and 12.3% for D0.1 cm3. When CTV was approximately flat, electron plans were comparable with HDR-BT plans, having lower average D2 cm3, D0.5 cm3, and D0.1 cm3 of 7.7%. Degradation of quality of electron plans was found to be more dependent on target curvature than on CTV size. Conclusions Both EBRT and HDR-BT could be used in treatments of superficial lesions. HDR-BT revealed superior CTV coverage when the surface was very large, complex, curvy, or rounded, and when the topology was complicated. The prediction model can be used for an approximate calculation and quick assessment of radiation dose to organs-at-risk (OARs), at a depth or at a lateral distance from CTV.
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Yanagi Y, Tamura M, Monzen H, Matsumoto K, Takei Y, Noma K, Kida T. [Application of Real-time Variable Shape Tungsten Rubber for Nail Radiation Protection in the Total Skin Electron Beam (TSEB) Therapy]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2021; 77:145-152. [PMID: 33612692 DOI: 10.6009/jjrt.2021_jsrt_77.2.145] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
PURPOSE This study investigated whether real-time variable shape tungsten rubber (STR) could be applied for nail radiation protection in total skin electron beam (TSEB) therapy. METHODS Simulated finger phantoms were made from syringes filled with physiological saline of volumes 5, 10, 20, and 30 ml (inner diameters of 14.1, 17.0, 21.7, and 25.3 mm, respectively). Gafchromic film was applied to the phantom, and lead (thickness 1-3 mm) or STR (thickness 1-4 mm) with an area of 4´1.5 cm was used to cover the film. A 6 MeV electron beam with an 8 mm acrylic board was then used to irradiate the phantom. The source-surface distance (SSD) was 444 cm, the field size was 36´36 cm at SSD of 100 cm without an electron applicator, and the monitor unit was 2000 MU. The shielding rates were obtained from the dose profiles. RESULTS The mean values of the shielding rate values for all phantoms were 50.1, 97.6, and 98.7% for 1, 2, and 3 mm of lead, respectively, and -13.6, 53.9, 91.2, and 99.4% for 1, 2, 3, and 4 mm of STR, respectively. CONCLUSION STR with a thickness of 4 mm had the same shielding properties as lead with a thickness of 3 mm, which was an approximately 100% shielding rate. STR could therefore be used in TSEB therapy instead of lead.
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Affiliation(s)
- Yuya Yanagi
- Department of Radiology, Shiga University of Medical Science Hospital
| | - Mikoto Tamura
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University
| | - Hajime Monzen
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University
| | - Kenji Matsumoto
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University
- Department of Radiology, Kindai University Hospital
| | - Yoshiki Takei
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University
- Department of Radiology, Kindai University Nara Hospital
| | - Kazuo Noma
- Department of Radiology, Shiga University of Medical Science Hospital
| | - Tetsuo Kida
- Department of Radiology, Shiga University of Medical Science Hospital
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Determination of effective source to surface distance and cutout factor in small fields in electron beam radiotherapy: A comparison of different dosimeters. POLISH JOURNAL OF MEDICAL PHYSICS AND ENGINEERING 2020. [DOI: 10.2478/pjmpe-2020-0028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
Objective: The main purpose of this study is to calculate the effective source to surface distance (SSDeff) of small and large electron fields in 10, 15, and 18 MeV energies, and to investigate the effect of SSD on the cutout factor for electron beams a linear accelerator. The accuracy of different dosimeters is also evaluated.
Materials and methods: In the current study, Elekta Precise linear accelerator was used in electron beam energies of 10, 15, and 18 MeV. The measurements were performed in a PTW water phantom (model MP3-M). A Semiflex and Advanced Markus ionization chambers and a Diode E detector were used for dosimetry. SSDeff in 100, 105, 110, 115, and 120 cm SSDs for 1.5 × 1.5 cm2 to 5 × 5 cm2 (small fields) and 6 × 6 cm2 to 20 × 20 cm2 (large fields) field sizes were obtained. The cutout factor was measured for the small fields.
Results: SSDeff in small fields is highly dependent on energy and field size and increases with increasing electron beam energy and field size. For large electron fields, with some exceptions for the 20 × 20 cm2 field, this quantity also increases with energy. The SSDeff was increased with increasing beam energy and field size for all three detectors.
Conclusion: The SSDeff varies significantly for different field sizes or cutouts. It is recommended that SSDeff be determined for each electron beam size or cutout. Selecting an appropriate dosimetry system can have an effect in determining cutout factor.
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Chambers EL, Carver RL, Hogstrom KR. Useful island block geometries of a passive intensity modulator used for intensity-modulated bolus electron conformal therapy. J Appl Clin Med Phys 2020; 21:131-145. [PMID: 33207033 PMCID: PMC7769403 DOI: 10.1002/acm2.13079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 07/01/2020] [Accepted: 08/13/2020] [Indexed: 12/04/2022] Open
Abstract
PURPOSE This project determined the range of island block geometric configurations useful for the clinical utilization of intensity-modulated bolus electron conformal therapy (IM-BECT). METHODS Multiple half-beam island block geometries were studied for seven electron energies 7-20 MeV at 100 and 103 cm source-to-surface distance (SSD). We studied relative fluence distributions at 0.5 cm and 2.0 cm depths in water, resulting in 28 unique beam conditions. For each beam condition, we studied intensity reduction factor (IRF) values of 0.70, 0.75, 0.80, 0.85, 0.90, and 0.95, and hexagonal packing separations for the island blocks of 0.50, 0.75, 1.00, 1.25, and 1.50 cm, that is, 30 unique IM configurations and 840 unique beam-IM combinations. A combination was deemed acceptable if the average intensity downstream of the intensity modulator agreed within 2% of that intended and the variation in fluence was less than ±2%. RESULTS For 100 cm SSD, and for 0.5 cm depth, results showed that beam energies above 13 MeV did not exhibit sufficient scatter to produce clinically acceptable fluence (intensity) distributions for all IRF values (0.70-0.95). In particular, 20 MeV fluence distributions were unacceptable for any values, and acceptable 16 MeV fluence distributions were limited to a minimum IRF of 0.85. For the 2.0 cm depth, beam energies up to and including 20 MeV had acceptable fluence distributions. For 103 cm SSD and for 0.5 cm and 2.0 cm depths, results showed that all beam energies (7-20 MeV) had clinically acceptable fluence distributions for all IRF values (0.70-0.95). In general, the more clinically likely 103 cm SSD had acceptable fluence distributions with larger separations (r), which allow larger block diameters. CONCLUSION The geometric operating range of island block separations and IRF values (block diameters) producing clinically appropriate IM electron beams has been determined.
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Affiliation(s)
- Erin L. Chambers
- Department of Physics and AstronomyLouisiana State UniversityBaton RougeLAUSA
| | - Robert L. Carver
- Department of Physics and AstronomyLouisiana State UniversityBaton RougeLAUSA
- Mary Bird Perkins Cancer CenterBaton RougeLAUSA
| | - Kenneth R. Hogstrom
- Department of Physics and AstronomyLouisiana State UniversityBaton RougeLAUSA
- Mary Bird Perkins Cancer CenterBaton RougeLAUSA
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Winkler P, Odreitz-Stark S, Haas E, Thalhammer M, Partl R. Commissioning, dosimetric characterization and machine performance assessment of the LIAC HWL mobile accelerator for Intraoperative Radiotherapy. Z Med Phys 2020; 30:279-288. [PMID: 32682654 DOI: 10.1016/j.zemedi.2020.06.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 05/15/2020] [Accepted: 06/03/2020] [Indexed: 01/25/2023]
Abstract
BACKGROUND The LIAC HWL (Sordina IORT Technologies, Vicenza, Italy) is a recently designed mobile linear accelerator for intraoperative electron radiotherapy (IOeRT), producing high dose rate electron beams at four different energy levels. It features a software tool for the visualization of 2D dose distributions, which is based on Monte Carlo simulations. The aims of this work were to (i) assess the dosimetric characteristics of the accelerator, (ii) experimentally verify calculated data exported from the software and (iii) report on commissioning as well as performance of the system during the first year of operation. METHODS The electron energies of the LIAC HWL used in this study are 6, 8, 10 and 12 MeV. Diameters of the cylindrically shaped applicators range from 3 to 10cm. We studied two applicator sets with different length ratios of proximal and terminal applicator sections. Reference dosimetry, linearity as well as short- and long-term stability were measured with a PTW Advanced Markus chamber, relative depth dose and profiles were measured using an unshielded diode. Percentage-depth-dose (PDD) and transversal dose profile (TDP) data were exported from the simulation software LIACSim and compared with our measurements. RESULTS The device reaches dose rates up to 40Gy/min (for 12 MeV). Surface doses for the 10cm applicators are higher than 90%, X-ray background is below 0.6% for all energies. Simulations and measurements of PDD agreed well, with a maximum difference in the depth of the 50% isodose of 0.7mm for the flat-ended applicators and 1mm for the beveled applicators. The simulations slightly underestimate the dose in the lateral parts of the field (difference < 1.8% for flat-ended applicators). The two different applicator sets were dosimetrically equivalent. Long-term stability measurements for the first year of operation ranged from -2.1% to 1.6% (mean: -0.1%). CONCLUSIONS The system is dosimetrically well suited for IOeRT and performed stably and reliably. The software tool for visualization of dose distributions can be used to support treatment planning, following thorough validation.
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Affiliation(s)
- Peter Winkler
- Department of Therapeutic Radiology and Oncology, Medical University of Graz, Auenbrugger Platz 32, A-8036 Graz, Austria.
| | - Stefan Odreitz-Stark
- Department of Therapeutic Radiology and Oncology, Medical University of Graz, Auenbrugger Platz 32, A-8036 Graz, Austria
| | - Eva Haas
- Department of Therapeutic Radiology and Oncology, Medical University of Graz, Auenbrugger Platz 32, A-8036 Graz, Austria
| | - Martin Thalhammer
- Department of Therapeutic Radiology and Oncology, Medical University of Graz, Auenbrugger Platz 32, A-8036 Graz, Austria
| | - Richard Partl
- Department of Therapeutic Radiology and Oncology, Medical University of Graz, Auenbrugger Platz 32, A-8036 Graz, Austria
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Oraiqat I, Zhang W, Litzenberg D, Lam K, Sunbul NB, Moran J, Cuneo K, Carson P, Wang X, Naqa IE. An ionizing radiation acoustic imaging (iRAI) technique for real-time dosimetric measurements for FLASH radiotherapy. Med Phys 2020; 47:5090-5101. [PMID: 32592212 PMCID: PMC7722001 DOI: 10.1002/mp.14358] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/18/2020] [Accepted: 06/11/2020] [Indexed: 11/07/2022] Open
Abstract
PURPOSE FLASH radiotherapy (FLASH-RT) is a novel irradiation modality with ultra-high dose rates (>40 Gy/s) that have shown tremendous promise for its ability to enhance normal tissue sparing while maintaining comparable tumor cell eradication toconventional radiotherapy (CONV-RT). Due to its extremely high dose rates, clinical translation of FLASH-RT is hampered by risky delivery and current limitations in dosimetric devices, which cannot accurately measure, in real time, dose at deeper tissue. This work aims to investigate ionizing radiation acoustic imaging (iRAI) as a promising image-guidance modality for real-time deep tissue dose measurements during FLASH-RT. The underlying hypothesis is that iRAI can enable mapping of dose deposition with respect to surrounding tissue with a single linear accelerator (linac) pulse precision in real time. In this work, the relationship between iRAI signal response and deposited dose was investigated as well as the feasibility of using a proof-of-concept dual-modality imaging system of ultrasound and iRAI for treatment beam co-localization with respect to underlying anatomy. METHODS Two experimental setups were used to study the feasibility of iRAI for FLASH-RT using 6 MeV electrons from a modified Varian Clinac. First, experiments were conducted using a single element focused transducer to take a series of point measurements in a gelatin phantom, which was compared with independent dose measurements using GAFchromic film. Secondly, an ultrasound and iRAI dual-modality imaging system utilizing a phased array transducer was used to take coregistered two-dimensional (2D) iRAI signal amplitude images as well as ultrasound B-mode images, to map the dose deposition with respect to surrounding anatomy in an ex vivo rabbit liver model with a single linac pulse precision. RESULTS Using a single element transducer, iRAI measurements showed a highly linear relationship between the iRAI signal amplitude and the linac dose per pulse (r2 = 0.9998) with a repeatability precision of 1% and a dose resolution error <2.5% in a homogenous phantom when compared to GAFchromic film dose measurements. These phantom results were used to develop a calibration curve between the iRAI signal response and the delivered dose per pulse. Subsequently, a normalized depth dose curve was generated that agreed with film measurements with an RMSE of 0.0243, using correction factors to account for deviations in measurement conditions with respect to calibration. Experiments on the ex-vivo rabbit liver model demonstrated that a 2D iRAI image could be generated successfully from a single linac pulse, which was fused with the B-mode ultrasound image to provide information about the beam position with respect to surrounding anatomy in real time. CONCLUSION This work demonstrates the potential of using iRAI for real-time deep tissue dosimetry in FLASH-RT. Our results show that iRAI signals are linear with dose and can accurately map the delivered radiation dose with respect to soft tissue anatomy. With its ability to measure dose for individual linac pulses at any location within surrounding soft tissue while identifying where that dose is being delivered anatomically in real time, iRAI can be an indispensable tool to enable safe and efficient clinical translation of FLASH-RT.
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Affiliation(s)
- Ibrahim Oraiqat
- Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Wei Zhang
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Dale Litzenberg
- Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Kwok Lam
- Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Noora Ba Sunbul
- Department of Nuclear Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Jean Moran
- Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Kyle Cuneo
- Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Paul Carson
- Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Xueding Wang
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
- Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Issam El Naqa
- Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109, USA
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Takei Y, Kamomae T, Monzen H, Nakaya T, Sugita K, Suzuki K, Oguchi H, Tamura M, Nishimura Y. Feasibility of using tungsten functional paper as a thin bolus for electron beam radiotherapy. Phys Eng Sci Med 2020; 43:1101-1111. [PMID: 32785883 DOI: 10.1007/s13246-020-00910-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 07/25/2020] [Indexed: 11/30/2022]
Abstract
Containing 80% tungsten by weight, tungsten functional paper (TFP) is a radiation-shielding material that is lightweight, flexible, disposable, and easy to cut. Through experimental measurements and Monte Carlo simulations, we investigated the feasibility of using TFP as a bolus in electron beam radiotherapy. Commercial boluses of thickness 5 and 10 mm and from one to nine layers of TFPs (0.3-2.7 mm) were positioned on the surface of water-equivalent phantoms. The percentage depth dose curves and transverse dose profiles were measured using a 9-MeV electron beam from a clinical linear accelerator. Normalized to the value at the depth of maximum dose without bolus, the relative doses at the phantom surface for no bolus, 5-mm bolus, 10-mm bolus, 1 TFP, 3 TFPs, 6 TFPs, and 9 TFPs were 78%, 88%, 92%, 84%, 92%, 102%, and 112%, respectively; the therapeutic depths corresponding to a 90% dose level were 29.1 mm, 22.7 mm, 17.7 mm, 26.6 mm, 23.2 mm, 19.3 mm, and 15.8 mm, respectively. The TFP contributed to increased skin dose and provided dose uniformity within the target volume. However, it also resulted in increased lateral constriction and penumbra width. The results of Monte Carlo simulation produced similar trends as the experimental measurements. Our findings suggest that using TFP as a novel thin and flexible skin bolus for electron beam radiotherapy is feasible.
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Affiliation(s)
- Yoshiki Takei
- Department of Radiology, Kindai University Nara Hospital, 1248-1 Otoda-cho, Ikoma, Nara, 630-0293, Japan.,Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka, 589-8511, Japan
| | - Takeshi Kamomae
- Department of Radiology, Graduate School of Medicine, Nagoya University, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan
| | - Hajime Monzen
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka, 589-8511, Japan.
| | - Takayoshi Nakaya
- Department of Radiological Technology, Nagoya University Hospital, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 466-8560, Japan
| | - Kazuma Sugita
- Department of Radiological Technology, Nagoya University Hospital, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi, 466-8560, Japan
| | - Kentaro Suzuki
- Department of Radiological and Medical Laboratory Sciences, Graduate School of Medicine, Nagoya University, 1-1-20 Daiko-minami, Higashi-ku, Nagoya, Aichi, 461-8673, Japan
| | - Hiroshi Oguchi
- Department of Radiological and Medical Laboratory Sciences, Graduate School of Medicine, Nagoya University, 1-1-20 Daiko-minami, Higashi-ku, Nagoya, Aichi, 461-8673, Japan
| | - Mikoto Tamura
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka, 589-8511, Japan
| | - Yasumasa Nishimura
- Department of Radiation Oncology, Faculty of Medicine, Kindai University, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka, 589-8511, Japan
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Li R, Tseng W, Wu Q. Validation of the dosimetry of total skin irradiation techniques by Monte Carlo simulation. J Appl Clin Med Phys 2020; 21:107-119. [PMID: 32559022 PMCID: PMC7484841 DOI: 10.1002/acm2.12921] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 04/12/2020] [Accepted: 04/29/2020] [Indexed: 11/24/2022] Open
Abstract
Purpose To validate the dose measurements for two total skin irradiation techniques with Monte Carlo simulation, providing more information on dose distributions, and guidance on further technique optimization. Methods Two total skin irradiation techniques (stand‐up and lay‐down) with different setup were simulated and validated. The Monte Carlo simulation was primarily performed within the EGSnrc environment. Parameters of jaws, MLCs, and a customized copper (Cu) filter were first tuned to match the profiles and output measured at source‐to‐skin distance (SSD) of 100 cm where the secondary source is defined. The secondary source was rotated to simulate gantry rotation. VirtuaLinac, a cloud‐based Monte Carlo package, was used for Linac head simulation as a secondary validation. The following quantities were compared with measurements: for each field/direction at the treatment SSDs, the percent depth dose (PDD), the profiles at the depth of maximum, and the absolute dosimetric output; the composite dose distribution on cylindrical phantoms of 20 to 40 cm diameters. Results Cu filter broadened the FWHM of the electron beam by 44% and degraded the mean energy by 0.7 MeV. At SSD = 100 cm, MC calculated PDDs agreed with measured data within 2%/2 mm (except for the surface voxel) and lateral profiles agreed within 3%. At the treatment SSD, profiles and output factors of individual field matched within 4%; dmax and R80 of the simulated PDDs also matched with measurement within 2 mm. When all fields were combined on the cylindrical phantom, the dmax shifted toward the surface. For lay‐down technique, the maximum x‐ray contamination at the central axis was (MC: 2.2; Measurement: 2.1)% and reduced to 0.2% at 40 cm off the central axis. Conclusions The Monte Carlo results in general agree well with the measurement, which provides support in our commissioning procedure, as well as the full three‐dimensional dose distribution of the patient phantom.
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Affiliation(s)
- Ruiqi Li
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
| | - Wenchih Tseng
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
| | - Qiuwen Wu
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
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Rogers B, Lawrence J, Chmura J, Ehler E, Ferreira C. Dosimetric characterization of a novel 90Y source for use in the conformal superficial brachytherapy device. Phys Med 2020; 72:52-59. [PMID: 32200298 DOI: 10.1016/j.ejmp.2020.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 02/16/2020] [Accepted: 03/01/2020] [Indexed: 12/12/2022] Open
Abstract
PURPOSE To characterize the dose distribution in water of a novel beta-emitting brachytherapy source for use in a Conformal Superficial Brachytherapy (CSBT) device. METHODS AND MATERIALS Yttrium-90 (90Y) sources were designed for use with a uniquely designed CSBT device. Depth dose and planar dose measurements were performed for bare sources and sources housed within a 3D printed source holder. Monte Carlo simulated dose rate distributions were compared to film-based measurements. Gamma analysis was performed to compare simulated and measured dose rates from seven 90Y sources placed simultaneously using the CSBT device. RESULTS The film-based maximum measured surface dose rate for a bare source in contact with the surface was 3.35 × 10-7 cGy s-1 Bq-1. When placed in the source holder, the maximum measured dose rate was 1.41 × 10-7 cGy s-1 Bq-1. The Monte Carlo simulated depth dose rates were within 10% or 0.02 cm of the measured dose rates for each depth of measurement. The maximum film surface dose rate measured using a seven-source configuration within the CSBT device was 1.78 × 10-7 cGy s-1 Bq-1. Measured and simulated dose rate distribution of the seven-source configuration were compared by gamma analysis and yielded a passing rate of 94.08%. The gamma criteria were 3% for dose-difference and 0.07056 cm for distance-to-agreement. The estimated measured dose rate uncertainty was 5.34%. CONCLUSIONS 90Y is a unique source that can be optimally designed for a customized CSBT device. The rapid dose falloff provided a high dose gradient, ideal for treatment of superficial lesions. The dose rate uncertainty of the 90Y-based CSBT device was within acceptable brachytherapy standards and warrants further investigation.
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Affiliation(s)
- Brent Rogers
- University of Minnesota Medical School, Department of Radiation Oncology, United States.
| | - Jessica Lawrence
- University of Minnesota, College of Veterinary Medicine and Masonic Cancer Center, United States
| | - Jennifer Chmura
- University of Minnesota, Medical Devices Center, United States
| | - Eric Ehler
- University of Minnesota Medical School, Department of Radiation Oncology, United States
| | - Clara Ferreira
- University of Minnesota Medical School, Department of Radiation Oncology, United States
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Electron Scattering in Conventional Cell Flask Experiments and Dose Distribution Dependency. Sci Rep 2020; 10:482. [PMID: 31949176 PMCID: PMC6965637 DOI: 10.1038/s41598-019-57029-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 12/10/2019] [Indexed: 11/23/2022] Open
Abstract
Electron beam therapy (EBT) is commonly used for treating superficial and subdermal tumors. Previous cellular radiosensitivity research using EBT may be underestimating the contribution from flask wall scattering and the corresponding dose distribution. Single cell suspensions of Chinese hamster ovary (CHO) cells were plated on flasks and irradiated with 3, 4, 7, 9, and 18 MeV energy electron beams from two different institutions, and the spatial locations of surviving colonies were recorded. Gafchromic film dosimetry and Monte Carlo simulations were carried out to determine the spatial electron scattering contribution from the flask walls. Low electron irradiation resulted in an uneven surviving colony distribution concentrated near the periphery of the flasks, while spatial colony formation was statistically uniform at energies above 7 MeV. Our data demonstrates that without proper dosimetric corrections, studies using low energy electrons can lead to misinterpretations of energy dependent cellular radiosensitivity in culture vessels, and radiotherapeutic applications.
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Anusionwu PC, Alpuche Aviles JE, Pistorius S. The use of 0.5r cav as an effective point of measurement for cylindrical chambers may result in a systematic shift of electron percentage depth doses. J Appl Clin Med Phys 2020; 21:117-126. [PMID: 31898872 PMCID: PMC6964751 DOI: 10.1002/acm2.12797] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 10/29/2019] [Accepted: 11/22/2019] [Indexed: 11/29/2022] Open
Abstract
Electron dosimetry can be performed using cylindrical chambers, plane‐parallel chambers, and diode detectors. The finite volume of these detectors results in a displacement effect which is taken into account using an effective point of measurement (EPOM). Dosimetry protocols have recommended a shift of 0.5 rcav for cylindrical chambers; however, various studies have shown that the optimal shift may deviate from this recommended value. This study investigated the effect that the selection of EPOM shift for cylindrical chamber has on percentage depth dose (PDD) curves. Depth dose curves were measured in a water phantom for electron beams with energies ranging from 6 to 18 MeV. The detectors investigated were of three different types: diodes (Diode‐E PTW 60017 and SFD IBA), cylindrical (Semiflex PTW 31010, PinPoint PTW 31015, and A12 Exradin), and parallel plate ionization chambers (Advanced Markus PTW 34045 and Markus PTW 23343). Depth dose curves measured with Diode‐E and Advanced Markus agreed within 0.2 mm at R50 except for 18 MeV and extremely large field size. The PDDs measured with the Semiflex chamber and Exradin A12 were about 1.1 mm (with respect to the Advanced Markus chamber) shallower than those measured with the other detectors using a 0.5 rcav shift. The difference between the PDDs decreased when a Pinpoint chamber, with a smaller cavity radius, was used. Agreement improved at lower energies, with the use of previously published EPOM corrections (0.3 rcav). Therefore, the use of 0.5 rcav as an EPOM may result in a systematic shift of the therapeutic portion of the PDD (distances < R90). Our results suggest that a 0.1 rcav shift is more appropriate for one chamber model (Semiflex PTW 31010).
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Affiliation(s)
- Princess C Anusionwu
- CancerCare Manitoba, Winnipeg, Canada.,Department of Physics & Astronomy, University of Manitoba, Winnipeg, Canada
| | - Jorge E Alpuche Aviles
- CancerCare Manitoba, Winnipeg, Canada.,Department of Physics & Astronomy, University of Manitoba, Winnipeg, Canada.,Department of Radiology, University of Manitoba, Winnipeg, Canada
| | - Stephen Pistorius
- CancerCare Manitoba, Winnipeg, Canada.,Department of Physics & Astronomy, University of Manitoba, Winnipeg, Canada.,Department of Radiology, University of Manitoba, Winnipeg, Canada
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Miloichikova I, Bulavskaya A, Cherepennikov Y, Gavrikov B, Gargioni E, Belousov D, Stuchebrov S. Feasibility of clinical electron beam formation using polymer materials produced by fused deposition modeling. Phys Med 2019; 64:188-194. [PMID: 31515019 DOI: 10.1016/j.ejmp.2019.07.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 07/17/2019] [Accepted: 07/17/2019] [Indexed: 10/26/2022] Open
Abstract
The main challenge in electron external beam radiation therapy with clinical accelerators is the absence of integrated systems to form irregular fields. The current approach to provide conformal irradiation is to use additional metallic shaping blocks, with inefficient and expensive workflows. This work presents a simple method to form therapeutic electron fields using 3D printed samples. These samples are manufactured by fused deposition modeling, which can affect crucial properties, such as material homogeneity, due to the presence of residual air-filled cavities. The applicability of this method was therefore investigated with a set of experiments and Monte Carlo simulations aimed at determining the electron depth dose distribution in polymer materials. The results show that therapeutic electron beams with energies 6-20 MeV can be effectively absorbed using these polymeric samples. The model developed in this study provides a way to assess the dose distribution in such materials and to calculate the appropriate thickness of polymer samples for therapeutic electron beam formation. It is shown that for total absorption of 6 MeV electron beams the material thickness should be at least 4 cm, while this value should be at least 8 cm for 12 MeV and 11 cm for 20 MeV, respectively. The results can be used to further develop 3D printing procedures for medical electron beam profile formation, allowing the creation of a collimator or absorber with patient-specific configuration using rapid prototyping systems, thus contributing to improve the accuracy of dose delivery in electron radiotherapy within a short manufacturing time.
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Affiliation(s)
- Irina Miloichikova
- National Research Tomsk Polytechnic University, Lenina Avenue 30, 634050 Tomsk, Russia; Cancer Research Institute of Tomsk NRMC RAS, Kooperativny Street 5, 634050 Tomsk, Russia.
| | - Angelina Bulavskaya
- National Research Tomsk Polytechnic University, Lenina Avenue 30, 634050 Tomsk, Russia
| | - Yury Cherepennikov
- National Research Tomsk Polytechnic University, Lenina Avenue 30, 634050 Tomsk, Russia
| | - Boris Gavrikov
- Moscow City Oncology Hospital №62, Istra 27, 143423 Moscow, Russia
| | - Elisabetta Gargioni
- University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Dmitrij Belousov
- Institute of Automation and Electrometry SB RAS, Academician Koptyug Avenue 1, 630090 Novosibirsk, Russia
| | - Sergei Stuchebrov
- National Research Tomsk Polytechnic University, Lenina Avenue 30, 634050 Tomsk, Russia
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Visbal JW, Costa A. Inverse reconstruction of energy spectra of clinical electron beams using the generalized simulated annealing method. Radiat Phys Chem Oxf Engl 1993 2019. [DOI: 10.1016/j.radphyschem.2019.04.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Comprehensive evaluation of electron radiation dose using beryllium oxide dosimeters at breast radiotherapy. JOURNAL OF RADIOTHERAPY IN PRACTICE 2019. [DOI: 10.1017/s1460396919000190] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractIntroduction:In this study, the differences between calculated and measured dose values were then analysed to assess the performance, in terms of accuracy, of the tested treatment planning system (TPS) algorithms applied to calculate electron beam dose targeted and non-targeted the breast region.Materials and methods:The beryllium oxide (BeO) dosimeters placed on the female RANDO phantom were irradiated 12 MeV electron energy with medical linear accelerator and repeatedly read in the Risø thermoluminescence (TL)/optically stimulated luminescence (OSL) system via OSL method at least three times.Results:For electron treatment, one made quantitative comparisons of the dose distributions calculated by TPSs with those from the measurements by OSL at various points in the RANDO phantom.The mean dose measured from the dosimeters placed on the female RANDO phantom target left breast region was 160 cGy and non-target right breast region was 1·2 cGy. Analysis of Generalised Gaussian Pencil Beam (GGPB) and Electron Monte Carlo (eMC) algorithms for determined region mean point dose values, respectively, 174 and 164 cGy. Two algorithms for non-targeted region calculated same point dose values of 0·2 cGy.Conclusions:The results of this study showed that BeO dosimeters can be used with OSL method in radiotherapy applications and it is a very important tool for the determination of targeted/non-targeted absorbed dose.
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Yang X, Feng J, Wang F, Hu Y. Irradiation sterilization used for allogenetic tendon: a literature review of current concept. Cell Tissue Bank 2019; 20:129-139. [PMID: 31054008 DOI: 10.1007/s10561-019-09756-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Accepted: 02/13/2019] [Indexed: 01/27/2023]
Abstract
Tendon injury is a very common type of sports trauma, and its incidence has increased over the past decades. Surgical reconstruction with tendon allograft has been increasingly used to restore the motor function and stability of the injured site. However, the risk of disease transmission caused by allogeneic tendon transplantation has been a major problem for tissue bank researchers and clinicians. In order to eliminate the risk of disease transmission, a process of terminal sterilization is necessary. Ionizing irradiation, including gamma irradiation and electron beam irradiation is the most commonly used method for the terminal sterilization, which has been widely proved to be able to effectively inactivate the contained pathogens. Nevertheless, some accompanying damage to the mechanical and histological properties of collagen fibers in tendons will be caused. Therefore, more and more studies have begun to pay attention to the protective effect of radiation protection agents, including the radical scavengers and cross-linking agents, in the irradiation sterilization of allogeneic tendons.
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Affiliation(s)
- Xionggang Yang
- Graduate School, Tianjin Medical University, Tianjin, 300070, China
| | - Jiangtao Feng
- Graduate School, Tianjin Medical University, Tianjin, 300070, China
| | - Feng Wang
- Graduate School, Tianjin Medical University, Tianjin, 300070, China
| | - Yongcheng Hu
- Department of Orthopedic Oncology, Tianjin Hospital, Tianjin, 300211, China.
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Baghani HR, Heidarloo N, Aghamiri SMR, Mahdavi SR. Comparing the physical and dosimetric characteristics of cylindrical and beam shaper intraoperative radiotherapy applicators. Radiat Phys Chem Oxf Engl 1993 2019. [DOI: 10.1016/j.radphyschem.2019.01.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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