Abstract:
:The goal of this study was to investigate small field output factors (OFs) for flat-tening filter-free (FFF) beams on a dedicated stereotactic linear accelerator-based system. From this data, the collimator exchange effect was quantified, and detector-specific correction factors were generated. Output factors for 16 jaw-collimated small fields (from 0.5 to 2 cm) were measured using five different detectors including an ion chamber (CC01), a stereotactic field diode (SFD), a diode detector (Edge), Gafchromic film (EBT3), and a plastic scintillator detector (PSD, W1). Chamber, diodes, and PSD measurements were performed in a Wellhofer water tank, while films were irradiated in solid water at 100 cm source-to-surface distance and 10 cm depth. The collimator exchange effect was quantified for rectangular fields. Monte Carlo (MC) simulations of the measured configurations were also performed using the EGSnrc/DOSXYZnrc code. Output factors measured by the PSD and verified against film and MC calculations were chosen as the benchmark measurements. Compared with plastic scintillator detector (PSD), the small volume ion chamber (CC01) underestimated output factors by an average of -1.0% ± 4.9% (max. = -11.7% for 0.5 × 0.5 cm2 square field). The stereotactic diode (SFD) overestimated output factors by 2.5% ± 0.4% (max. = 3.3% for 0.5 × 1 cm2 rectangular field). The other diode detector (Edge) also overestimated the OFs by an average of 4.2% ± 0.9% (max. = 6.0% for 1 × 1 cm2 square field). Gafchromic film (EBT3) measure-ments and MC calculations agreed with the scintillator detector measurements within 0.6% ± 1.8% and 1.2% ± 1.5%, respectively. Across all the X and Y jaw combinations, the average collimator exchange effect was computed: 1.4% ± 1.1% (CC01), 5.8% ± 5.4% (SFD), 5.1% ± 4.8% (Edge diode), 3.5% ± 5.0% (Monte Carlo), 3.8% ± 4.7% (film), and 5.5% ± 5.1% (PSD). Small field detectors should be used with caution with a clear understanding of their behaviors, especially for FFF beams and small, elongated fields. The scintillator detector exhibited good agreement against Gafchromic film measurements and MC simulations over the range of field sizes studied. The collimator exchange effect was found to be impor-tant at these small field sizes. Detector-specific correction factors were computed using the scintillator measurements as the benchmark.
journal_name
J Appl Clin Med Physjournal_title
Journal of applied clinical medical physicsauthors
Qin Y,Zhong H,Wen N,Snyder K,Huang Y,Chetty IJdoi
10.1120/jacmp.v17i6.6433subject
Has Abstractpub_date
2016-11-08 00:00:00pages
379-391issue
6issn
1526-9914journal_volume
17pub_type
杂志文章abstract::The purpose of this study was to describe our experience with 1.0T MR-SIM including characterization, quality assurance (QA) program, and features necessary for treatment planning. Staffing, safety, and patient screening procedures were developed. Utilization of an external laser positioning system (ELPS) and MR-compa...
journal_title:Journal of applied clinical medical physics
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journal_title:Journal of applied clinical medical physics
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journal_title:Journal of applied clinical medical physics
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journal_title:Journal of applied clinical medical physics
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更新日期:2017-03-01 00:00:00
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journal_title:Journal of applied clinical medical physics
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更新日期:2013-09-06 00:00:00
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journal_title:Journal of applied clinical medical physics
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更新日期:2018-05-01 00:00:00
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journal_title:Journal of applied clinical medical physics
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更新日期:2019-11-01 00:00:00
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journal_title:Journal of applied clinical medical physics
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更新日期:2020-12-05 00:00:00
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journal_title:Journal of applied clinical medical physics
pub_type: 杂志文章
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更新日期:2016-09-08 00:00:00
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journal_title:Journal of applied clinical medical physics
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更新日期:2016-03-08 00:00:00
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journal_title:Journal of applied clinical medical physics
pub_type: 杂志文章
doi:10.1120/jacmp.v6i2.2076
更新日期:2005-04-01 00:00:00
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journal_title:Journal of applied clinical medical physics
pub_type: 杂志文章
doi:10.1120/jacmp.v13i3.3729
更新日期:2012-05-10 00:00:00
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journal_title:Journal of applied clinical medical physics
pub_type: 杂志文章
doi:10.1120/jacmp.v16i5.5510
更新日期:2015-09-08 00:00:00
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journal_title:Journal of applied clinical medical physics
pub_type: 杂志文章
doi:10.1120/jacmp.v17i2.5797
更新日期:2016-03-08 00:00:00
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journal_title:Journal of applied clinical medical physics
pub_type: 杂志文章
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更新日期:2018-11-01 00:00:00
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更新日期:2016-03-08 00:00:00
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journal_title:Journal of applied clinical medical physics
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更新日期:2016-09-08 00:00:00
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pub_type: 临床试验,杂志文章
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journal_title:Journal of applied clinical medical physics
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更新日期:2014-03-06 00:00:00
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更新日期:2013-07-08 00:00:00
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journal_title:Journal of applied clinical medical physics
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更新日期:2014-03-06 00:00:00
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journal_title:Journal of applied clinical medical physics
pub_type: 杂志文章
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更新日期:2016-07-08 00:00:00
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journal_title:Journal of applied clinical medical physics
pub_type: 杂志文章
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更新日期:2016-11-08 00:00:00
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更新日期:2009-02-05 00:00:00
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journal_title:Journal of applied clinical medical physics
pub_type: 杂志文章
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更新日期:2016-11-08 00:00:00
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journal_title:Journal of applied clinical medical physics
pub_type: 杂志文章
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更新日期:2019-09-01 00:00:00