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IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology. RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY. Part 16.4: Optimization of protection in fluoroscopy Practical exercise. Overview / Contents.
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IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology RADIATION PROTECTION INDIAGNOSTIC ANDINTERVENTIONAL RADIOLOGY Part 16.4: Optimization of protection in fluoroscopy Practical exercise
Overview / Contents • To become familiar with quality control tests in fluoroscopy • To measure the low contrast resolution and noise according to the suggested procedures • Interpretation of results 16.4: Optimization of protection in fluoroscopy
IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology Part 16.4: Optimization of protection in fluoroscopy Low contrast resolution and noise
Low contrast resolution and noise Purpose : • to measure the low contrast resolution and the influence of noise on low contrast detectability Equipment : • image quality phantom (Leeds phantom) • 2 mm Cu filter 16.4: Optimization of protection in fluoroscopy
Low contrast resolution • The low contrast resolution determines the size of detail that can be visibly reproduced when there is only a small difference in density relative to the surrounding area • Low contrast resolution is considerably limited by noise. • The perception threshold in relation to contrast and detail size can be determined, for example, by means of a contrast-detail curve. 16.4: Optimization of protection in fluoroscopy
Leeds Fluoroscopy PhantomNoise and contrast loss • Incorporates: • 19 discs, each 11 mm diameter, of different x-ray contrasts. 16.4: Optimization of protection in fluoroscopy
Leeds Fluoroscopy Phantom Noise and contrast loss • Typical fluoroscopic image of the test object. View the small circles at center and • count the number of visible circles Images from: http://www.leedstestobjects.com/modules/products/product_setup/file_library/SFS%20SET%20product%20specifications.pdf 16.4: Optimization of protection in fluoroscopy
Leeds Fluoroscopy Phantom Noise and contrast loss 16.4: Optimization of protection in fluoroscopy
Noise and contrast loss Interpretation of results The threshold contrast is determined by the detail which can only just be detected. The threshold contrast of a modern system in average adjustment should not be greater than the following values: 16.4: Optimization of protection in fluoroscopy
Leeds Fluoroscopy Phantoms Overall Imaging Performance • Incorporates: • 108 discs in 12 groups of different diameters; in each group there are 9 discs of different X-Ray contrasts. • Is used to assess the threshold-contrast detail-detectability. 16.4: Optimization of protection in fluoroscopy
Leeds Fluoroscopy Phantoms Overall Imaging Performance Typical fluoroscopic image of the test object. 16.4: Optimization of protection in fluoroscopy
Leeds Fluoroscopy Phantoms Overall Imaging Performance Interpretation of results Data are plotted as a function of detail diameter. Threshold detection index is defined as H (A) = [C(A) A]-1 16.4: Optimization of protection in fluoroscopy
Where to Get More Information Quality Control in Diagnostic Imaging, Gray JE, Winkler NT, Stears J, Frank ED. Available at no cost. http://www.diquad.com/QC%20Book.html 15.3: Optimization of protection in radiography