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The use of computed radiography plates to determine light and radiation field coincidence.

ABSTRACT: Photo-stimulable phosphor computed radiography (CR) has characteristics that allow the output to be manipulated by both radiation and optical light. The authors have developed a method that uses these characteristics to carry out radiation field and light field coincidence quality assurance on linear accelerators.CR detectors from Kodak were used outside their cassettes to measure both radiation and light field edges from a Varian linear accelerator. The CR detector was first exposed to a radiation field and then to a slightly smaller light field. The light impinged on the detector's latent image, removing to an extent the portion exposed to the light field. The detector was then digitally scanned. A MATLAB-based algorithm was developed to automatically analyze the images and determine the edges of the light and radiation fields, the vector between the field centers, and the crosshair center. Radiographic film was also used as a control to confirm the radiation field size.Analysis showed a high degree of repeatability with the proposed method. Results between the proposed method and radiographic film showed excellent agreement of the radiation field. The effect of varying monitor units and light exposure time was tested and found to be very small. Radiation and light field sizes were determined with an uncertainty of less than 1 mm, and light and crosshair centers were determined within 0.1 mm.A new method was developed to digitally determine the radiation and light field size using CR photo-stimulable phosphor plates. The method is quick and reproducible, allowing for the streamlined and robust assessment of light and radiation field coincidence, with no observer interpretation needed.

SUBMITTER: Kerns JR

PROVIDER: S-EPMC3808487 | biostudies-other | 2013 Nov

REPOSITORIES: biostudies-other

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Project description:ObjectiveAssessing the advantage of x-ray dark-field contrast over x-ray transmission contrast in radiography for the detection of developing radiation-induced lung damage in mice.MethodsTwo groups of female C57BL/6 mice (irradiated and control) were imaged obtaining both contrasts monthly for 28 weeks post irradiation. Six mice received 20 Gy of irradiation to the entire right lung sparing the left lung. The control group of six mice was not irradiated. A total of 88 radiographs of both contrasts were evaluated for both groups based on average values for two regions of interest, covering (irradiated) right lung and healthy left lung. The ratio of these average values, R, was distinguished between healthy and damaged lungs for both contrasts. The time-point when deviations of R from healthy lung exceeded 3σ was determined and compared among contrasts. The Wilcoxon-Mann-Whitney test was used to test against the null hypothesis that there is no difference between both groups. A selection of 32 radiographs was assessed by radiologists. Sensitivity and specificity were determined in order to compare the diagnostic potential of both contrasts. Inter-reader and intra-reader accuracy were rated with Cohen's kappa.ResultsRadiation-induced morphological changes of lung tissue caused deviations from the control group that were measured on average 10 weeks earlier with x-ray dark-field contrast than with x-ray transmission contrast. Sensitivity, specificity, and accuracy doubled using dark-field radiography.ConclusionX-ray dark-field radiography detects morphological changes of lung tissue associated with radiation-induced damage earlier than transmission radiography in a pre-clinical mouse model.Key points• Significant deviations from healthy lung due to irradiation were measured after 16 weeks with x-ray dark-field radiography (p = 0.004). • Significant deviations occur on average 10 weeks earlier for x-ray dark-field radiography in comparison to x-ray transmission radiography. • Sensitivity and specificity doubled when using x-ray dark-field radiography instead of x-ray transmission radiography.

Project description:PurposeSimulation is used within medical radiation science training. Recent global events and simulation resource uptake has led to significant changes. The aim of this study was to capture post COVID-19 trends and activity of simulation-based education (SBE) in diagnostic radiography and radiation therapy.MethodsAn online survey was designed to investigate the role of simulation within diagnostic radiography and radiation therapy education. Survey design was based on literature and experience within the research team. Questions were based around access and use of simulation, future trends and the effects of COVID-19. Participants were diagnostic radiography and/or radiation therapy educators. Data captured in this study was undertaken in March 2022 and compared with previous data from Bridge and colleagues (2021).ResultsSixty-seven responses were received across five continents (two from North/South America), Europe was the most widely represented (n = 58, 87%). Fifty-three (79%) of participants reported that they use simulation as part of their teaching and learning. Twenty-seven (51%) respondents reported that they had increased their use of simulation because of COVID-19. Sixteen (30%) respondents stated that they were now able to enrol more students because of the pandemic. Fixed models and immersive environments were the two most common simulation activities. Participants reported, to different degrees, that simulation was used across all parts of the curriculum.ConclusionsSimulation is deeply embedded into diagnostic radiography and radiation therapy education. Evidence suggests that the growth of simulation may be slowing. Opportunities exist for the development of guidance, training and best practice resources around simulation.Implications for practiceSimulation is a key pedagogical approach for diagnostic radiography and radiation therapy education. Key stakeholders now need to work collaboratively to define standards and best practices.

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The use of computed radiography plates to determine light and radiation field coincidence.

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