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Zhai Y, Neumeyer C, Dellas J, Greenough N, Kalish M, Petrella J, Que W, Raftopoulos S. Prototype Coil Evaluation for NSTX-U Replacement Inner Poloidal Field Coils. Fusion Science and Technology 2019. [DOI: 10.1080/15361055.2019.1610314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Y. Zhai
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey
| | - C. Neumeyer
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey
| | - J. Dellas
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey
| | - N. Greenough
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey
| | - M. Kalish
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey
| | - J. Petrella
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey
| | - W. Que
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey
| | - S. Raftopoulos
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey
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Gerhardt SP, Erickson K, Kaita R, Lawson J, Mozulay R, Mueller D, Que W, Rahman N, Schneider H, Smalley G, Tresemer K. Magnetic diagnostics for equilibrium reconstruction and realtime plasma control in NSTX-Upgrade. Rev Sci Instrum 2014; 85:11E807. [PMID: 25430372 DOI: 10.1063/1.4889781] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This paper describes aspects of magnetic diagnostics for realtime control in National Spherical Torus Experiment-Upgrade (NSTX-U). The sensor arrangement on the upgraded center column is described. New analog and digital circuitry for processing the plasma current Rogowski data are presented. An improved algorithm for estimating the plasma vertical velocity for feedback control is presented.
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Affiliation(s)
- S P Gerhardt
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - K Erickson
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - R Kaita
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - J Lawson
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - R Mozulay
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - D Mueller
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - W Que
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - N Rahman
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - H Schneider
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - G Smalley
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - K Tresemer
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
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Pignol J, Keller B, Rakovitch E, Sankreacha R, Que W. Immediate Tolerance of Permanent Breast 103-Pd Seed Implant (PBSI) as the Sole Adjuvant Treatment of Early Stage Breast Cancer. Int J Radiat Oncol Biol Phys 2005. [DOI: 10.1016/j.ijrobp.2005.07.313] [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: 11/28/2022]
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Pignol JP, Keller B, Rakovitch E, Sankracha R, Que W. 76 Permanent breast seed implant using 103pd as the sole adjuvant radiation treatment for early stage breast cancer: Interim analysis of an ongoing phase I/II trial. Radiother Oncol 2005. [DOI: 10.1016/s0167-8140(05)80237-3] [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: 10/23/2022]
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Abstract
The 'tongue-and-groove problem' in step-and-shoot delivery of intensity modulated radiotherapy is investigated. A 'tongue-and-groove' index (TGI) is introduced to quantify the 'tongue-and-groove' effect in step-and-shoot delivery. Four different types of leaf sequencing methods are compared. The sliding window method and the reducing level method use the same number of field segments to deliver the same intensity map, but the TGI is much less for the reducing level method. The leaf synchronization method of Van Santvoort and Heijmen fails in step-and-shoot delivery, but a new method inspired by the method of Van Santvoort and Heijmen is shown to eliminate 'tongue-and-groove' underdosage completely.
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Affiliation(s)
- W Que
- MPCS, Ryerson University, 350 Victoria Street, Toronto, Ontario, M5B 2K3, Canada
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Abstract
Radiation exposure to the public is estimated if the body of an I-125 prostate implant patient is cremated. Precautions regarding the handling of cremated remains are suggested. Cremation can be performed safely at any time.
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Affiliation(s)
- W Que
- MPCS, Ryerson University, 350 Victoria Street, Toronto, Ontario, Canada M5B 2K3
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Abstract
In the "stop and shoot" method of intensity modulated radiation therapy, it is desirable to use an efficient multileaf collimator (MLC) field segmentation algorithm in the sense that it translates beam intensity maps into the least number of MLC field segments. In this work, we compare the performance of eight different algorithms, including the ones by Bortfeld et al., Galvin et al., Xia and Verhey, the Siemens IMFAST algorithm, and four other algorithms which have not been studied before. We find that the algorithm of Xia and Verhey is most frequently the algorithm that needs the least MLC field segments. However, no single algorithm is the most efficient for all clinical cases or intensity maps. This suggests that it is desirable to have multiple algorithms available in a clinical treatment planning system which will search through all algorithms automatically and find the most efficient delivery sequence for a given treatment. Each intensity map in a treatment could be delivered by a different algorithm, whichever is the most efficient for that map. It is pointed out that when the background intensity level is not zero, it is not always efficient to deliver a segment to bring the background level down to zero.
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Affiliation(s)
- W Que
- Department of Medical Biophysics, University of Toronto, Toronto Sunnybrook Regional Cancer Center, Ontario, Canada.
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Que W, Rowlands JA. X-ray photogeneration in amorphous selenium: Geminate versus columnar recombination. Phys Rev B Condens Matter 1995; 51:10500-10507. [PMID: 9977744 DOI: 10.1103/physrevb.51.10500] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Abstract
This is a theoretical study of the inherent spatial resolution of the latent image on the surface of an amorphous selenium (a-Se) plate used for diagnostic x-ray imaging. The following effects are considered: (A) ranges of primary photoelectrons; (B) reabsorption of K fluorescence; (C) reabsorption of Compton scattered photons; (D) diffusion; (E) the geometric effect due to oblique incidence of x rays; (F) electrostatic effect; and (G) the space charge effect. The modulation transfer function of a-Se in the diagnostic x-ray energy range has been estimated. In conclusion, (A) and (E) are the main factors limiting the resolution, and for diagnostic x rays, the inherent spatial resolution of a-Se plates is much better than that of CsI layers used in x-ray image intensifiers.
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Affiliation(s)
- W Que
- Sunnybrook Health Science Centre, University of Toronto, Ontario, Canada
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Walker MB, Buyers WJ, Tun Z, Que W, Menovsky AA, Garrett JD. Nature of the order parameter in the heavy-fermion system URu2Si2. Phys Rev Lett 1993; 71:2630-2633. [PMID: 10054730 DOI: 10.1103/physrevlett.71.2630] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Que W, Walker MB. Generalized Frenkel-Kontorova model for structural modulations in bismuth high-Tc superconductors and related compounds. Phys Rev B Condens Matter 1992; 46:14772-14778. [PMID: 10003575 DOI: 10.1103/physrevb.46.14772] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Walker MB, Que W. Structural model for the incommensurate bismuth high-Tc superconductors. Phys Rev B Condens Matter 1992; 45:8085-8090. [PMID: 10000619 DOI: 10.1103/physrevb.45.8085] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Que W, Kirczenow G, Castao E. Nonlocal theory of collective excitations in quantum-dot arrays. Phys Rev B Condens Matter 1991; 43:14079-14090. [PMID: 9997277 DOI: 10.1103/physrevb.43.14079] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Que W. Quantum theory of plasmons in lateral multiwire superlattices: Intrasubband plasmons and their coupling to intersubband plasmons. Phys Rev B Condens Matter 1991; 43:7127-7135. [PMID: 9998176 DOI: 10.1103/physrevb.43.7127] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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