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Renaud J, Sarfehnia A, Bancheri J, Seuntjens J. Absolute dosimetry of a 1.5 T MR-guided accelerator-based high-energy photon beam in water and solid phantoms using Aerrow. Med Phys 2019; 47:1291-1304. [PMID: 31834640 DOI: 10.1002/mp.13968] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 12/03/2019] [Accepted: 12/05/2019] [Indexed: 11/09/2022] Open
Abstract
PURPOSE In this work, the fabrication, operation, and evaluation of a probe-format graphite calorimeter - herein referred to as Aerrow - as an absolute clinical dosimeter of high-energy photon beams while in the presence of a B = 1.5 T magnetic field is described. Comparable to a cylindrical ionization chamber (IC) in terms of utility and usability, Aerrow has been developed for the purpose of accurately measuring absorbed dose to water in the clinic with a minimum disruption to the existing clinical workflow. To our knowledge, this is the first reported application of graphite calorimetry to magnetic resonance imaging (MRI)-guided radiotherapy. METHODS Based on a previously numerically optimized and experimentally validated design, an Aerrow prototype capable of isothermal operation was constructed in-house. Graphite-to-water dose conversions as well as magnetic field perturbation factors were calculated using Monte Carlo, while heat transfer and mass impurity corrections and uncertainties were assessed analytically. Reference dose measurements were performed in the absence and presence of a B = 1.5 T magnetic field using Aerrow in the 7 MV FFF photon beam of an Elekta MRI-linac and were directly compared to the results obtained using two calibrated reference-class IC types. The feasibility of performing solid phantom-based dosimetry with Aerrow and the possible influence of clearance gaps is also investigated by performing reference-type dosimetry measurements for multiple rotational positions of the detector and comparing the results to those obtained in water. RESULTS In the absence of the B-field, as well as in the parallel orientation while in the presence of the B-field, the absorbed dose to water measured using Aerrow was found to agree within combined uncertainties with those derived from TG-51 using calibrated reference-class ICs. Statistically significant differences on the order of (2-4)%, however, were observed when measuring absorbed dose to water using the ICs in the perpendicular orientation in the presence of the B-field. Aerrow had a peak-to-peak response of about 0.5% when rotated within the solid phantom regardless of whether the B-field was present or not. CONCLUSIONS This work describes the successful use of Aerrow as a straightforward means of measuring absolute dose to water for large high-energy photon fields in the presence of a 1.5 T B-field to a greater accuracy than currently achievable with ICs. The detector-phantom air gap does not appear to significantly influence the response of Aerrow in absolute terms, nor does it contribute to its rotational dependence. This work suggests that the accurate use of solid phantoms for absolute point dose measurement is possible with Aerrow.
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Affiliation(s)
- James Renaud
- Metrology Research Centre, National Research Council Canada, Ottawa, ON, K1T 0R6, Canada.,Medical Physics Unit, McGill University, Montréal, QC, H4A 3J1, Canada
| | - Arman Sarfehnia
- Medical Physics Unit, McGill University, Montréal, QC, H4A 3J1, Canada.,Department of Radiation Oncology, University of Toronto, Toronto, ON, M5S 3E2, Canada
| | - Julien Bancheri
- Medical Physics Unit, McGill University, Montréal, QC, H4A 3J1, Canada
| | - Jan Seuntjens
- Medical Physics Unit, McGill University, Montréal, QC, H4A 3J1, Canada
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Bancheri J, Seuntjens J, Sarfehnia A, Renaud J. Density effects of silica aerogel insulation on the performance of a graphite probe calorimeter. Med Phys 2019; 46:1874-1882. [DOI: 10.1002/mp.13426] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 01/02/2019] [Accepted: 01/17/2019] [Indexed: 11/07/2022] Open
Affiliation(s)
- Julien Bancheri
- Medical Physics Unit McGill University Montréal QC H4A 3J1Canada
| | - Jan Seuntjens
- Medical Physics Unit McGill University Montréal QC H4A 3J1Canada
| | - Arman Sarfehnia
- Medical Physics Unit McGill University Montréal QC H4A 3J1Canada
- Department of Radiation Oncology University of Toronto Toronto ON M5S 3E2Canada
| | - James Renaud
- Medical Physics Unit McGill University Montréal QC H4A 3J1Canada
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Renaud J, Sarfehnia A, Bancheri J, Seuntjens J. Aerrow: A probe-format graphite calorimeter for absolute dosimetry of high-energy photon beams in the clinical environment. Med Phys 2017; 45:414-428. [DOI: 10.1002/mp.12669] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 10/05/2017] [Accepted: 10/27/2017] [Indexed: 11/06/2022] Open
Affiliation(s)
- James Renaud
- Medical Physics Unit; McGill University; Montréal QC Canada
| | - Arman Sarfehnia
- Medical Physics Unit; McGill University; Montréal QC Canada
- Department of Radiation Oncology; University of Toronto; Toronto ON Canada
| | | | - Jan Seuntjens
- Medical Physics Unit; McGill University; Montréal QC Canada
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Stevenson AW, Di Lillo F. Estimating the absolute flux distribution for a synchrotron X-ray beam using ionization-chamber measurements with various filters. JOURNAL OF SYNCHROTRON RADIATION 2017; 24:939-953. [PMID: 28862616 DOI: 10.1107/s1600577517009274] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 06/20/2017] [Indexed: 06/07/2023]
Abstract
It is shown that an extensive set of accurate ionization-chamber measurements with a primary polychromatic synchrotron X-ray beam transmitted through various filter combinations/thicknesses can be used to quite effectively estimate the absolute flux distribution. The basic technique is simple but the `inversion' of the raw data to extract the flux distribution is a fundamentally ill-posed problem. It is demonstrated, using data collected at the Imaging and Medical Beamline (IMBL) of the Australian Synchrotron, that the absolute flux can be quickly and reliably estimated if a suitable choice of filters is made. Results are presented as a function of the magnetic field (from 1.40 to 4.00 T) of the superconducting multi-pole wiggler insertion device installed at IMBL. A non-linear least-squares refinement of the data is used to estimate the incident flux distribution and then comparison is made with calculations from the programs SPECTRA, XOP and spec.exe. The technique described is important not only in estimating flux itself but also for a variety of other, derived, X-ray properties such as beam quality, power density and absorbed-dose rate. The applicability of the technique with a monochromatic X-ray beam for which there is significant harmonic contamination is also demonstrated. Whilst absolute results can also be derived in this monochromatic beam case, relative (integrated) flux values are sufficient for our primary aim of establishing reliable determinations of the percentages of the various harmonic components.
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Affiliation(s)
- Andrew W Stevenson
- Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | - Francesca Di Lillo
- Department of Physics `Ettore Pancini', Università di Napoli Federico II, Naples, Italy
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Stevenson AW, Crosbie JC, Hall CJ, Häusermann D, Livingstone J, Lye JE. Quantitative characterization of the X-ray beam at the Australian Synchrotron Imaging and Medical Beamline (IMBL). JOURNAL OF SYNCHROTRON RADIATION 2017; 24:110-141. [PMID: 28009552 DOI: 10.1107/s1600577516015563] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 10/04/2016] [Indexed: 06/06/2023]
Abstract
A critical early phase for any synchrotron beamline involves detailed testing, characterization and commissioning; this is especially true of a beamline as ambitious and complex as the Imaging & Medical Beamline (IMBL) at the Australian Synchrotron. IMBL staff and expert users have been performing precise experiments aimed at quantitative characterization of the primary polychromatic and monochromatic X-ray beams, with particular emphasis placed on the wiggler insertion devices (IDs), the primary-slit system and any in vacuo and ex vacuo filters. The findings from these studies will be described herein. These results will benefit IMBL and other users in the future, especially those for whom detailed knowledge of the X-ray beam spectrum (or `quality') and flux density is important. This information is critical for radiotherapy and radiobiology users, who ultimately need to know (to better than 5%) what X-ray dose or dose rate is being delivered to their samples. Various correction factors associated with ionization-chamber (IC) dosimetry have been accounted for, e.g. ion recombination, electron-loss effects. A new and innovative approach has been developed in this regard, which can provide confirmation of key parameter values such as the magnetic field in the wiggler and the effective thickness of key filters. IMBL commenced operation in December 2008 with an Advanced Photon Source (APS) wiggler as the (interim) ID. A superconducting multi-pole wiggler was installed and operational in January 2013. Results are obtained for both of these IDs and useful comparisons are made. A comprehensive model of the IMBL has been developed, embodied in a new computer program named spec.exe, which has been validated against a variety of experimental measurements. Having demonstrated the reliability and robustness of the model, it is then possible to use it in a practical and predictive manner. It is hoped that spec.exe will prove to be a useful resource for synchrotron science in general, and for hard X-ray beamlines, whether they are based on bending magnets or insertion devices, in particular. In due course, it is planned to make spec.exe freely available to other synchrotron scientists.
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Affiliation(s)
- Andrew W Stevenson
- Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | - Jeffrey C Crosbie
- School of Science, RMIT University, GPO Box 2476, Melbourne, Victoria 3001, Australia
| | - Christopher J Hall
- Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | - Daniel Häusermann
- Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | - Jayde Livingstone
- Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | - Jessica E Lye
- School of Science, RMIT University, GPO Box 2476, Melbourne, Victoria 3001, Australia
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Ford E, Deye J. Current Instrumentation and Technologies in Modern Radiobiology Research—Opportunities and Challenges. Semin Radiat Oncol 2016; 26:349-55. [DOI: 10.1016/j.semradonc.2016.06.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Butler DJ, Lye JE, Wright TE, Crossley D, Sharpe PHG, Stevenson AW, Livingstone J, Crosbie JC. Absorbed dose determination in kilovoltage X-ray synchrotron radiation using alanine dosimeters. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2016; 39:943-950. [PMID: 27585452 DOI: 10.1007/s13246-016-0479-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 08/25/2016] [Indexed: 11/28/2022]
Abstract
Alanine dosimeters from the National Physical Laboratory (NPL) in the UK were irradiated using kilovoltage synchrotron radiation at the imaging and medical beam line (IMBL) at the Australian Synchrotron. A 20 × 20 mm2 area was irradiated by scanning the phantom containing the alanine through the 1 mm × 20 mm beam at a constant velocity. The polychromatic beam had an average energy of 95 keV and nominal absorbed dose to water rate of 250 Gy/s. The absorbed dose to water in the solid water phantom was first determined using a PTW Model 31014 PinPoint ionization chamber traceable to a graphite calorimeter. The alanine was read out at NPL using correction factors determined for 60Co, traceable to NPL standards, and a published energy correction was applied to correct for the effect of the synchrotron beam quality. The ratio of the doses determined by alanine at NPL and those determined at the synchrotron was 0.975 (standard uncertainty 0.042) when alanine energy correction factors published by Waldeland et al. (Waldeland E, Hole E O, Sagstuen E and Malinen E, Med. Phys. 2010, 37, 3569) were used, and 0.996 (standard uncertainty 0.031) when factors by Anton et al. (Anton M, Büermann L., Phys Med Biol. 2015 60 6113-29) were used. The results provide additional verification of the IMBL dosimetry.
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Affiliation(s)
- D J Butler
- Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Yallambie, Victoria, 3085, Australia.
| | - J E Lye
- Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Yallambie, Victoria, 3085, Australia
| | - T E Wright
- Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Yallambie, Victoria, 3085, Australia
| | - D Crossley
- National Physical Laboratory, Teddington, UK
| | | | - A W Stevenson
- Australian Synchrotron, 800 Blackburn Road, Clayton, VIC, 3168, Australia
| | - J Livingstone
- Australian Synchrotron, 800 Blackburn Road, Clayton, VIC, 3168, Australia
| | - J C Crosbie
- School of Science, RMIT University, 124 La Trobe Street, Melbourne, VIC, 3000, Australia.,William Buckland Radiotherapy Centre, Alfred Hospital, Commercial Road, Melbourne, VIC, 3004, Australia
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Fournier P, Crosbie JC, Cornelius I, Berkvens P, Donzelli M, Clavel AH, Rosenfeld AB, Petasecca M, Lerch MLF, Bräuer-Krisch E. Absorbed dose-to-water protocol applied to synchrotron-generated x-rays at very high dose rates. Phys Med Biol 2016; 61:N349-61. [DOI: 10.1088/0031-9155/61/14/n349] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Kron T, Lehmann J, Greer PB. Dosimetry of ionising radiation in modern radiation oncology. Phys Med Biol 2016; 61:R167-205. [DOI: 10.1088/0031-9155/61/14/r167] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Lye JE, Harty PD, Butler DJ, Crosbie JC, Livingstone J, Poole CM, Ramanathan G, Wright T, Stevenson AW. Absolute dosimetry on a dynamically scanned sample for synchrotron radiotherapy using graphite calorimetry and ionization chambers. Phys Med Biol 2016; 61:4201-22. [DOI: 10.1088/0031-9155/61/11/4201] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Gagliardi FM, Cornelius I, Blencowe A, Franich RD, Geso M. High resolution 3D imaging of synchrotron generated microbeams. Med Phys 2015; 42:6973-86. [DOI: 10.1118/1.4935410] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Butler DJ, Stevenson AW, Wright TE, Harty PD, Lehmann J, Livingstone J, Crosbie JC. High spatial resolution dosimetric response maps for radiotherapy ionization chambers measured using kilovoltage synchrotron radiation. Phys Med Biol 2015; 60:8625-41. [PMID: 26510214 DOI: 10.1088/0031-9155/60/22/8625] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Small circular beams of synchrotron radiation (0.1 mm and 0.4 mm in diameter) were used to irradiate ionization chambers of the types commonly used in radiotherapy. By scanning the chamber through the beam and measuring the ionization current, a spatial map of the dosimetric response of the chamber was recorded. The technique is able to distinguish contributions to the large-field ionization current from the chamber walls, central electrode and chamber stem. Scans were recorded for the NE 2571 Farmer chamber, the PTW 30013, IBA FC65-G Farmer-type chambers, the NE 2611A and IBA CC13 thimble chambers, the PTW 31006 and 31014 pinpoint chambers, the PTW Roos and Advanced Markus plane-parallel chambers, and the PTW 23342 thin-window soft x-ray chamber. In all cases, large contributions to the response arise from areas where the incident beam grazes the cavity surfaces. Quantitative as well as qualitative information about the relative chamber response was extracted from the maps, including the relative contribution of the central electrode. Line scans using monochromatic beams show the effect of the photon energy on the chamber response. For Farmer-type chambers, a simple Monte Carlo model was in good agreement with the measured response.
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Affiliation(s)
- D J Butler
- Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Yallambie, Victoria 3085, Australia
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