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Zeng G, Robertson M, Murphy J, Lamey M, Wang Y. SU-D-201-02: A Systematic Planning Quality Monitoring Program for VMAT Treatment. Med Phys 2016. [DOI: 10.1118/1.4955614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Carlone M, Harnett N, Harris W, Norrlinger B, MacPherson M, Lamey M, Anderson R, Oldham M. MO-DE-BRA-02: SIMAC: A Simulation Tool for Teaching Linear Accelerator Physics. Med Phys 2016. [DOI: 10.1118/1.4957218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Carlone M, Lamey M, Anderson R, MacPherson M. MO-F-16A-02: Simulation of a Medical Linear Accelerator for Teaching Purposes. Med Phys 2014. [DOI: 10.1118/1.4889173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Lamey M, Carlone M, Alasti H, Bissonnette JP, Borg J, Breen S, Coolens C, Heaton R, Islam M, van Proojen M, Sharpe M, Stanescu T, Jaffray D. Poster - Thur Eve - 05: Safety systems and failure modes and effects analysis for a magnetic resonance image guided radiation therapy system. Med Phys 2012; 39:4625. [DOI: 10.1118/1.4740112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Lamey M, Carlone M, Alasti H, Bissonnette J, Borg J, Breen S, Coolens C, Heaton R, Islam M, Sharpe M, Stanescu T, van Prooijen M, Jaffray D. SU-E-T-252: Safety Systems and Failure Modes and Effects Analysis for a Linear Accelerator - Magnetic Resonance Imager - Brachytherapy System. Med Phys 2011. [DOI: 10.1118/1.3612203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Lamey M, Field C, McKenzie M, Fallone BG. Poster - Thur Eve - 44: Short Term Development Effects of Gafchromic EBT2 Film. Med Phys 2010. [DOI: 10.1118/1.3476149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Lamey M, Yun J, Burke B, Rathee S, Fallone BG. Radio frequency noise from an MLC: a feasibility study of the use of an MLC for linac-MR systems. Phys Med Biol 2010; 55:981-94. [PMID: 20090187 DOI: 10.1088/0031-9155/55/4/005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Currently several groups are actively researching the integration of a megavoltage teletherapy unit with magnetic resonance (MR) imaging for real-time image-guided radiotherapy. The use of a multileaf collimator (MLC) for intensity-modulated radiotherapy for linac-MR units must be investigated. The MLC itself will likely reside in the fringe field of the MR and the motors will produce radio frequency (RF) noise. The RF noise power spectral density from a Varian 52-leaf MLC motor, a Varian Millennium MLC motor and a brushless fan motor has been measured as a function of the applied magnetic field using a near field probe set. For the Varian 52-leaf MLC system, the RF noise produced by 13 of 52 motors is studied as a function of distance from the MLC. Data are reported in the frequency range suitable for 0.2-1.5 T linac-MR systems. Below 40 MHz the Millennium MLC motor tested showed more noise than the Varian 52-leaf motor or the brushless fan motor. The brushless motor showed a small dependence on the applied magnetic field. Images of a phantom were taken by the prototype linac-MR system with the MLC placed in close proximity to the magnet. Several orientations of the MLC in both shielded and non-shielded configurations were studied. For the case of a non-shielded MLC and associated cables, the signal-to-noise ratio (SNR) was reduced when 13 of 52 MLC leaves were moved during imaging. When the MLC and associated cables were shielded, the measured SNR of the images with 13 MLC leaves moving was experimentally the same as the SNR of the stationary MLC image. When the MLC and cables are shielded, subtraction images acquired with and without MLC motion contains no systematic signal. This study illustrates that the small RF noise produced by functioning MLC motors can be effectively shielded to avoid SNR degradation. A functioning MLC can be incorporated into a linac-MR unit.
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Affiliation(s)
- M Lamey
- Department of Physics, University of Alberta, Alberta, T6G 2G7, Canada.
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Lamey M, Rathee S, Fallone BG. Sci-Fri AM(2): Brachy-07: Investigation of the Sources of RF Noise from the Modulator of a Linac. Med Phys 2009. [DOI: 10.1118/1.3244199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Lamey M, Yun J, Burke B, Rathee S, Fallone BG. Sci-Wed PM: Delivery-12: The Radiofrequency Noise from MLCs for a Linac-MR System. Med Phys 2009. [DOI: 10.1118/1.3244104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Lamey M, Burke B, Rathee S, Murray B, Fallone B. SU-FF-J-76: Radio Frequency Noise From Clinical Linear Accelerators. Med Phys 2009. [DOI: 10.1118/1.3181368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Lamey M, Burke B, Rathee S, Murray B, Fallone B. SU-FF-J-84: Shielding of Radio Frequency Noise From Clinical Linear Accelerators for the Linac-MR Project. Med Phys 2009. [DOI: 10.1118/1.3181376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Abstract
There is a great deal of interest in image-guided radiotherapy (IGRT), and to advance the state of IGRT, an integrated linear accelerator-magnetic resonance (linac-MR) system has been proposed. Knowledge of the radiofrequency (RF) emissions near a linac is important for the design of appropriate RF shielding to facilitate the successful integration of these two devices. The frequency spectra of both electric and magnetic fields of RF emission are measured using commercially available measurement probes near the treatment couch in three clinical linac vaults with distinct physical layouts. The magnitude spectrum of the RF power emitted from these three linacs is then estimated. The electric field spectrum was also measured at several distances from the linac modulator in order to assess the effects of variations in spatial location in the treatment vault. A large fraction of RF power is emitted at frequencies below 5 MHz. However, the measured RF power at the Larmor frequency (8.5 MHz) of the proposed 0.2 T MR in the linac-MR (0.4-14.6 microW m(-2)) is still large enough to cause artifacts in MR images. Magnetron-based linacs generally emit much larger RF power than klystron-based linacs. In the frequency range of 1-50 MHz, only slight variation in the measured electric field is observed as a function of measurement position. This study suggests that the RF emissions are strong enough to cause image artifacts in MRI systems.
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Affiliation(s)
- B Burke
- Department of Physics, University of Alberta, 11322-89th Avenue, Edmonton, Alberta, T6G 2G7, Canada.
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Lamey M, Burke B, Rathee S, Fallone BG, Carlone M. Sci-Thurs PM: Delivery-08: Investigation of the source of RF noise from a modulator for an MR-linac project. Med Phys 2008; 35:3400. [DOI: 10.1118/1.2965915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Burke B, Lamey M, Rathee S, Fallone B, Carlone M. SU-GG-T-180: Measurement Instrumentation to Determine RF Noise Generated by a Medical Linac. Med Phys 2008. [DOI: 10.1118/1.2961932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Lamey M, Burke B, Carlone M, Rathee S, Fallone B. SU-GG-T-186: Simulation of Room Distortion On Measurements of RF Noise Due to a Medical Linac. Med Phys 2008. [DOI: 10.1118/1.2961938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Carlone M, Lamey M, Steciw S, Burke B, Fallone B. TH-C-L100J-02: Study of RF Interference Between a Linear Accelerator and MRI. Med Phys 2007. [DOI: 10.1118/1.2761640] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Matei C, Buchmann L, Hannes WR, Hutcheon DA, Ruiz C, Brune CR, Caggiano J, Chen AA, D'Auria J, Laird A, Lamey M, Li ZH, Liu WP, Olin A, Ottewell D, Pearson J, Ruprecht G, Trinczek M, Vockenhuber C, Wrede C. Measurement of the cascade transition via the first excited state of 16O in the 12C(alpha,gamma)16O reaction, and its S factor in stellar helium burning. Phys Rev Lett 2006; 97:242503. [PMID: 17280274 DOI: 10.1103/physrevlett.97.242503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Indexed: 05/13/2023]
Abstract
Radiative alpha-particle capture into the first excited, J(pi)=0+ state of 16O at 6.049 MeV excitation energy has rarely been discussed as contributing to the 12C(alpha,gamma)16O reaction cross section due to experimental difficulties in observing this transition. We report here measurements of this radiative capture in 12C(alpha,gamma)16O for center-of-mass energies of E=2.22 MeV to 5.42 MeV at the DRAGON recoil separator. To determine cross sections, the acceptance of the recoil separator has been simulated in GEANT as well as measured directly. The transition strength between resonances has been identified in R-matrix fits as resulting both from E2 contributions as well as E1 radiative capture. Details of the extrapolation of the total cross section to low energies are then discussed [S6.0(300)=25(-15)(+16) keV b] showing that this transition is likely the most important cascade contribution for 12C(alpha,gamma)16O.
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Affiliation(s)
- C Matei
- Ohio University, Athens, Ohio, USA
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Bishop S, Azuma RE, Buchmann L, Chen AA, Chatterjee ML, D'Auria JM, Engel S, Gigliotti D, Greife U, Hernanz M, Hunter D, Hussein A, Hutcheon D, Jewett C, José J, King J, Kubono S, Laird AM, Lamey M, Lewis R, Liu W, Michimasa S, Olin A, Ottewell D, Parker PD, Rogers JG, Strieder F, Wrede C. 21Na(p,gamma)22Mg reaction and oxygen-neon novae. Phys Rev Lett 2003; 90:162501. [PMID: 12731972 DOI: 10.1103/physrevlett.90.162501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2002] [Indexed: 05/24/2023]
Abstract
The 21Na(p,gamma)22Mg reaction is expected to play an important role in the nucleosynthesis of 22Na in oxygen-neon novae. The decay of 22Na leads to the emission of a characteristic 1.275 MeV gamma-ray line. This report provides the first direct measurement of the rate of this reaction using a radioactive 21Na beam, and discusses its astrophysical implications. The energy of the important state was measured to be E(c.m.)=205.7+/-0.5 keV with a resonance strength omegagamma=1.03+/-0.16(stat)+/-0.14(sys) meV.
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Affiliation(s)
- S Bishop
- Simon Fraser University, Burnaby, British Columbia, Canada
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