101
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Clinical use of diodes and micro-chambers to obtain accurate small field output factor measurements. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2015; 38:357-67. [DOI: 10.1007/s13246-015-0334-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2014] [Accepted: 02/19/2015] [Indexed: 12/22/2022]
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102
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Baluti F, Deloar HM, Lansley SP, Meyer J. Monte Carlo modelling the dosimetric effects of electrode material on diamond detectors. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2015; 38:101-8. [DOI: 10.1007/s13246-015-0329-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 01/07/2015] [Indexed: 10/24/2022]
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103
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Lárraga-Gutiérrez JM, Ballesteros-Zebadúa P, Rodríguez-Ponce M, García-Garduño OA, de la Cruz OOG. Properties of a commercial PTW-60019 synthetic diamond detector for the dosimetry of small radiotherapy beams. Phys Med Biol 2015; 60:905-24. [DOI: 10.1088/0031-9155/60/2/905] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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104
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Determination of small field output factors and correction factors using a Monte Carlo method for a 1000 MU/min CyberKnife® system equipped with fixed collimators. RADIAT MEAS 2014. [DOI: 10.1016/j.radmeas.2014.05.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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105
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Jafari SM, Alalawi AI, Hussein M, Alsaleh W, Najem MA, Hugtenburg RP, Bradley DA, Spyrou NM, Clark CH, Nisbet A. Glass beads and Ge-doped optical fibres as thermoluminescence dosimeters for small field photon dosimetry. Phys Med Biol 2014; 59:6875-89. [DOI: 10.1088/0031-9155/59/22/6875] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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106
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Francescon P, Beddar S, Satariano N, Das IJ. Variation of kQclin,Qmsr (fclin,fmsr) for the small-field dosimetric parameters percentage depth dose, tissue-maximum ratio, and off-axis ratio. Med Phys 2014; 41:101708. [PMID: 25281947 PMCID: PMC5175987 DOI: 10.1118/1.4895978] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 08/25/2014] [Accepted: 08/31/2014] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Evaluate the ability of different dosimeters to correctly measure the dosimetric parameters percentage depth dose (PDD), tissue-maximum ratio (TMR), and off-axis ratio (OAR) in water for small fields. METHODS Monte Carlo (MC) simulations were used to estimate the variation of kQclin,Qmsr (fclin,fmsr) for several types of microdetectors as a function of depth and distance from the central axis for PDD, TMR, and OAR measurements. The variation of kQclin,Qmsr (fclin,fmsr) enables one to evaluate the ability of a detector to reproduce the PDD, TMR, and OAR in water and consequently determine whether it is necessary to apply correction factors. The correctness of the simulations was verified by assessing the ratios between the PDDs and OARs of 5- and 25-mm circular collimators used with a linear accelerator measured with two different types of dosimeters (the PTW 60012 diode and PTW PinPoint 31014 microchamber) and the PDDs and the OARs measured with the Exradin W1 plastic scintillator detector (PSD) and comparing those ratios with the corresponding ratios predicted by the MC simulations. RESULTS MC simulations reproduced results with acceptable accuracy compared to the experimental results; therefore, MC simulations can be used to successfully predict the behavior of different dosimeters in small fields. The Exradin W1 PSD was the only dosimeter that reproduced the PDDs, TMRs, and OARs in water with high accuracy. With the exception of the EDGE diode, the stereotactic diodes reproduced the PDDs and the TMRs in water with a systematic error of less than 2% at depths of up to 25 cm; however, they produced OAR values that were significantly different from those in water, especially in the tail region (lower than 20% in some cases). The microchambers could be used for PDD measurements for fields greater than those produced using a 10-mm collimator. However, with the detector stem parallel to the beam axis, the microchambers could be used for TMR measurements for all field sizes. The microchambers could not be used for OAR measurements for small fields. CONCLUSIONS Compared with MC simulation, the Exradin W1 PSD can reproduce the PDDs, TMRs, and OARs in water with a high degree of accuracy; thus, the correction used for converting dose is very close to unity. The stereotactic diode is a viable alternative because it shows an acceptable systematic error in the measurement of PDDs and TMRs and a significant underestimation in only the tail region of the OAR measurements, where the dose is low and differences in dose may not be therapeutically meaningful.
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Affiliation(s)
- Paolo Francescon
- Department of Radiation Oncology, Ospedale Di Vicenza, Viale Rodolfi, Vicenza 36100, Italy
| | - Sam Beddar
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77005
| | - Ninfa Satariano
- Department of Radiation Oncology, Ospedale Di Vicenza, Viale Rodolfi, Vicenza 36100, Italy
| | - Indra J Das
- Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, Indiana 46202
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107
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Papaconstadopoulos P, Tessier F, Seuntjens J. On the correction, perturbation and modification of small field detectors in relative dosimetry. Phys Med Biol 2014; 59:5937-52. [DOI: 10.1088/0031-9155/59/19/5937] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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108
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Liu PZ, Suchowerska N, McKenzie DR. Can small field diode correction factors be applied universally? Radiother Oncol 2014; 112:442-6. [DOI: 10.1016/j.radonc.2014.08.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 07/09/2014] [Accepted: 08/07/2014] [Indexed: 11/26/2022]
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109
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Kamio Y, Bouchard H. Correction-less dosimetry of nonstandard photon fields: a new criterion to determine the usability of radiation detectors. Phys Med Biol 2014; 59:4973-5002. [DOI: 10.1088/0031-9155/59/17/4973] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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110
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Krauss A, Kapsch RP. Experimental determination ofkQfactors for cylindrical ionization chambers in 10 cm × 10 cm and 3 cm × 3 cm photon beams from 4 MV to 25 MV. Phys Med Biol 2014; 59:4227-46. [DOI: 10.1088/0031-9155/59/15/4227] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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111
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Azangwe G, Grochowska P, Georg D, Izewska J, Hopfgartner J, Lechner W, Andersen CE, Beierholm AR, Helt-Hansen J, Mizuno H, Fukumura A, Yajima K, Gouldstone C, Sharpe P, Meghzifene A, Palmans H. Detector to detector corrections: A comprehensive experimental study of detector specific correction factors for beam output measurements for small radiotherapy beams. Med Phys 2014; 41:072103. [DOI: 10.1118/1.4883795] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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112
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Moignier C, Huet C, Makovicka L. Determination of the kQclin,Qmsrfclin,fmsr correction factors for detectors used with an 800 MU/min CyberKnife®
system equipped with fixed collimators and a study of detector response to small photon beams using a Monte Carlo method. Med Phys 2014; 41:071702. [DOI: 10.1118/1.4881098] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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113
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Benmakhlouf H, Sempau J, Andreo P. Output correction factors for nine small field detectors in 6 MV radiation therapy photon beams: A PENELOPE Monte Carlo study. Med Phys 2014; 41:041711. [DOI: 10.1118/1.4868695] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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114
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Charles PH, Crowe SB, Kairn T, Knight R, Hill B, Kenny J, Langton CM, Trapp JV. The influence of Monte Carlo source parameters on detector design and dose perturbation in small field dosimetry. ACTA ACUST UNITED AC 2014. [DOI: 10.1088/1742-6596/489/1/012006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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115
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Charles PH, Cranmer-Sargison G, Thwaites DI, Crowe SB, Kairn T, Knight RT, Kenny J, Langton CM, Trapp JV. A practical and theoretical definition of very small field size for radiotherapy output factor measurements. Med Phys 2014; 41:041707. [DOI: 10.1118/1.4868461] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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116
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Bassinet C, Huet C, Derreumaux S, Brunet G, Chéa M, Baumann M, Lacornerie T, Gaudaire-Josset S, Trompier F, Roch P, Boisserie G, Clairand I. Small fields output factors measurements and correction factors determination for several detectors for a CyberKnife® and linear accelerators equipped with microMLC and circular cones. Med Phys 2014; 40:071725. [PMID: 23822429 DOI: 10.1118/1.4811139] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The use of small photon fields is now an established practice in stereotactic radiosurgery and radiotherapy. However, due to a lack of lateral electron equilibrium and high dose gradients, it is difficult to accurately measure the dosimetric quantities required for the commissioning of such systems. Moreover, there is still no metrological dosimetric reference for this kind of beam today. In this context, the first objective of this work was to determine and to compare small fields output factors (OF) measured with different types of active detectors and passive dosimeters for three types of facilities: a CyberKnife(®) system, a dedicated medical linear accelerator (Novalis) equipped with m3 microMLC and circular cones, and an adaptive medical linear accelerator (Clinac 2100) equipped with an additional m3 microMLC. The second one was to determine the kQclin,Qmsr (fclin,fmsr) correction factors introduced in a recently proposed small field dosimetry formalism for different active detectors. METHODS Small field sizes were defined either by microMLC down to 6 × 6 mm(2) or by circular cones down to 4 mm in diameter. OF measurements were performed with several commercially available active detectors dedicated to measurements in small fields (high resolution diodes: IBA SFD, Sun Nuclear EDGE, PTW 60016, PTW 60017; ionizing chambers: PTW 31014 PinPoint chamber, PTW 31018 microLion liquid chamber, and PTW 60003 natural diamond). Two types of passive dosimeters were used: LiF microcubes and EBT2 radiochromic films. RESULTS Significant differences between the results obtained by several dosimetric systems were observed, particularly for the smallest field size for which the difference in the measured OF reaches more than 20%. For passive dosimeters, an excellent agreement was observed (better than 2%) between EBT2 and LiF microcubes for all OF measurements. Moreover, it has been shown that these passive dosimeters do not require correction factors and can then be used as reference dosimeters. Correction factors for the active detectors have then been determined from the mean experimental OF measured by the passive dosimeters. CONCLUSIONS Four sets of correction factors needed to apply the new small field dosimetry formalism are provided for several active detectors. A protocol for small photon beams OF determination based on passive dosimeters measurements has been recently proposed to French radiotherapy treatment centers.
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Affiliation(s)
- C Bassinet
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), BP17, 92262 Fontenay-aux-Roses Cedex, France.
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117
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Lechner W, Palmans H, Sölkner L, Grochowska P, Georg D. Detector comparison for small field output factor measurements in flattening filter free photon beams. Radiother Oncol 2013; 109:356-60. [DOI: 10.1016/j.radonc.2013.10.022] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 10/11/2013] [Accepted: 10/19/2013] [Indexed: 11/28/2022]
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118
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Underwood TSA, Winter HC, Hill MA, Fenwick JD. Mass-density compensation can improve the performance of a range of different detectors under non-equilibrium conditions. Phys Med Biol 2013; 58:8295-310. [DOI: 10.1088/0031-9155/58/23/8295] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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119
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Benítez E, Casado F, García-Pareja S, Martín-Viera J, Moreno C, Parra V. Evaluation of a liquid ionization chamber for relative dosimetry in small and large fields of radiotherapy photon beams. RADIAT MEAS 2013. [DOI: 10.1016/j.radmeas.2013.08.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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120
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A methodological approach to reporting corrected small field relative outputs. Radiother Oncol 2013; 109:350-5. [PMID: 24183867 DOI: 10.1016/j.radonc.2013.10.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Revised: 09/27/2013] [Accepted: 10/01/2013] [Indexed: 10/26/2022]
Abstract
PURPOSE The goal of this work was to set out a methodology for measuring and reporting small field relative output and to assess the application of published correction factors across a population of linear accelerators. METHODS AND MATERIALS Measurements were made at 6 MV on five Varian iX accelerators using two PTW T60017 unshielded diodes. Relative output readings and profile measurements were made for nominal square field sizes of side 0.5 to 1.0 cm. The actual in-plane (A) and cross-plane (B) field widths were taken to be the FWHM at the 50% isodose level. An effective field size, defined as √FS eff=A · B, was calculated and is presented as a field size metric. FSeff was used to linearly interpolate between published Monte Carlo (MC) calculated [Formula in text] values to correct for the diode over-response in small fields. RESULTS The relative output data reported as a function of the nominal field size were different across the accelerator population by up to nearly 10%. However, using the effective field size for reporting showed that the actual output ratios were consistent across the accelerator population to within the experimental uncertainty of ± 1.0%. Correcting the measured relative output using [Formula in text] at both the nominal and effective field sizes produce output factors that were not identical but differ by much less than the reported experimental and/or MC statistical uncertainties. CONCLUSIONS In general, the proposed methodology removes much of the ambiguity in reporting and interpreting small field dosimetric quantities and facilitates a clear dosimetric comparison across a population of linacs.
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121
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Cranmer-Sargison G, Liu PZY, Weston S, Suchowerska N, Thwaites DI. Small field dosimetric characterization of a new 160-leaf MLC. Phys Med Biol 2013; 58:7343-54. [DOI: 10.1088/0031-9155/58/20/7343] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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122
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Underwood TSA, Winter HC, Hill MA, Fenwick JD. Detector density and small field dosimetry: Integral versus point dose measurement schemes. Med Phys 2013; 40:082102. [DOI: 10.1118/1.4812687] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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123
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Charles PH, Crowe SB, Kairn T, Knight RT, Hill B, Kenny J, Langton CM, Trapp JV. Monte Carlo-based diode design for correction-less small field dosimetry. Phys Med Biol 2013; 58:4501-12. [DOI: 10.1088/0031-9155/58/13/4501] [Citation(s) in RCA: 43] [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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124
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Fenwick JD, Kumar S, Scott AJD, Nahum AE. Using cavity theory to describe the dependence on detector density of dosimeter response in non-equilibrium small fields. Phys Med Biol 2013; 58:2901-23. [DOI: 10.1088/0031-9155/58/9/2901] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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125
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Wagner A, Crop F, Lacornerie T, Vandevelde F, Reynaert N. Use of a liquid ionization chamber for stereotactic radiotherapy dosimetry. Phys Med Biol 2013; 58:2445-59. [DOI: 10.1088/0031-9155/58/8/2445] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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126
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Czarnecki D, Zink K. Monte Carlo calculated correction factors for diodes and ion chambers in small photon fields. Phys Med Biol 2013; 58:2431-44. [DOI: 10.1088/0031-9155/58/8/2431] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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127
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Morin J, Béliveau-Nadeau D, Chung E, Seuntjens J, Thériault D, Archambault L, Beddar S, Beaulieu L. A comparative study of small field total scatter factors and dose profiles using plastic scintillation detectors and other stereotactic dosimeters: The case of the CyberKnife. Med Phys 2013; 40:011719. [DOI: 10.1118/1.4772190] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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128
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Charles PH, Crowe SB, Kairn T, Kenny J, Lehmann J, Lye J, Dunn L, Hill B, Knight RT, Langton CM, Trapp JV. The effect of very small air gaps on small field dosimetry. Phys Med Biol 2012; 57:6947-60. [DOI: 10.1088/0031-9155/57/21/6947] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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129
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Cranmer-Sargison G, Weston S, Evans JA, Sidhu NP, Thwaites DI. Monte Carlo modelling of diode detectors for small field MV photon dosimetry: detector model simplification and the sensitivity of correction factors to source parameterization. Phys Med Biol 2012; 57:5141-53. [DOI: 10.1088/0031-9155/57/16/5141] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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130
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Scott AJD, Kumar S, Nahum AE, Fenwick JD. Characterizing the influence of detector density on dosimeter response in non-equilibrium small photon fields. Phys Med Biol 2012; 57:4461-76. [DOI: 10.1088/0031-9155/57/14/4461] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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131
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Sterpin E, Mackie TR, Vynckier S. Monte Carlo computed machine-specific correction factors for reference dosimetry of TomoTherapy static beam for several ion chambers. Med Phys 2012; 39:4066-72. [DOI: 10.1118/1.4722752] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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