Dataset Information

The combination of the error correction methods of GAFCHROMIC EBT3 film.

ABSTRACT:

Purpose

The aim of this study was to combine a set of methods for use of radiochromic film dosimetry, including calibration, correction for lateral effects and a proposed triple-channel analysis. These methods can be applied to GAFCHROMIC EBT3 film dosimetry for radiation field analysis and verification of IMRT plans.

Methods

A single-film exposure was used to achieve dose calibration, and the accuracy was verified based on comparisons with the square-field calibration method. Before performing the dose analysis, the lateral effects on pixel values were corrected. The position dependence of the lateral effect was fitted by a parabolic function, and the curvature factors of different dose levels were obtained using a quadratic formula. After lateral effect correction, a triple-channel analysis was used to reduce disturbances and convert scanned images from films into dose maps. The dose profiles of open fields were measured using EBT3 films and compared with the data obtained using an ionization chamber. Eighteen IMRT plans with different field sizes were measured and verified with EBT3 films, applying our methods, and compared to TPS dose maps, to check correct implementation of film dosimetry proposed here.

Results

The uncertainty of lateral effects can be reduced to ±1 cGy. Compared with the results of Micke A et al., the residual disturbances of the proposed triple-channel method at 48, 176 and 415 cGy are 5.3%, 20.9% and 31.4% smaller, respectively. Compared with the ionization chamber results, the difference in the off-axis ratio and percentage depth dose are within 1% and 2%, respectively. For the application of IMRT verification, there were no difference between two triple-channel methods. Compared with only corrected by triple-channel method, the IMRT results of the combined method (include lateral effect correction and our present triple-channel method) show a 2% improvement for large IMRT fields with the criteria 3%/3 mm.

SUBMITTER: Li Y

PROVIDER: S-EPMC5531657 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Publications

The combination of the error correction methods of GAFCHROMIC EBT3 film.

Li Yinghui Y Chen Lixin L Zhu Jinhan J Liu Xiaowei X

PloS one 20170727 7

<h4>Purpose</h4>The aim of this study was to combine a set of methods for use of radiochromic film dosimetry, including calibration, correction for lateral effects and a proposed triple-channel analysis. These methods can be applied to GAFCHROMIC EBT3 film dosimetry for radiation field analysis and verification of IMRT plans.<h4>Methods</h4>A single-film exposure was used to achieve dose calibration, and the accuracy was verified based on comparisons with the square-field calibration method. Bef ...[more]

PMID: 28750023

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Project description:BackgroundRefractive errors are the most common vision problem and prove to be a significant health issue. There are several methods for correction of refractive errors including spectacles, contact lenses and refractive surgery. Nowadays, the reliance on contact lenses and glasses is decreased by means of refractive eye surgery. Our study aimed to determine the awareness of refractive surgery among undergraduate medical students and their preferred method of refractive error correction.MethodThis was a cross-sectional study that was conducted among a sample size of 374 medical students at King Abdul-Aziz University Hospital, Jeddah, Saudi Arabia in June-August 2020. Data were collected through a questionnaire which consisted of 20 questions to assess the demographics, awareness about refractive surgery and preferred method of correction. The data were entered using Microsoft Excel 2016 and analyzed by SPSS version 21.ResultsOur results showed that 177 of participants had refractive errors. Most participants complained of myopia (66.7%) and the most preferred correction method was spectacles (45.8%). Among users of spectacles, 53.7% found the spectacles comfortable due to ease of use. Majority of the students (92.1%) were aware of refractive surgery and 73% of them were willing to undergo refractive surgery. Many obtained their information regarding these procedures from family and friends (55.1%). The remaining refused to undergo surgery and the primary reason was fear of the complications of the procedure (14.1%).ConclusionThough corrective refractive surgery is a commonly performed procedure, extensive knowledge regarding this correction method and its complications is poor among medical students. The results showed that the majority have heard of refractive surgery, however, fear of undergoing surgery was still present. We suggest that refractive error correction surgery be taught by physicians during Ophthalmology rotations so that knowledge may be gained from more reliable sources.

Dataset Information

The combination of the error correction methods of GAFCHROMIC EBT3 film.

Purpose

Methods

Results

Publications

The combination of the error correction methods of GAFCHROMIC EBT3 film.

Similar Datasets

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