IAEAInternational Atomic Energy Agency

RADIATION PROTECTION INDIAGNOSTIC AND

INTERVENTIONAL RADIOLOGY

Part 16.3: Optimization of protection in fluoroscopy

Practical exercise

IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

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Overview / Objectives

• To become familiar with quality control tests in fluoroscopy.

• To measure the high contrast resolution

• Interpretation of results

IAEAInternational Atomic Energy Agency

Part 16.3: Optimization of protection in fluoroscopy

High contrast spatial resolution

IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

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High contrast resolution

Purpose :• to measure the high contrast resolution of the

fluoroscopy system

Equipment :• image quality phantom (Leeds phantom)

• 2 mm Cu filter

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Leeds Test Phantom 18FG to be used for Leeds Test Phantom 18FG to be used for routine image quality controlroutine image quality control

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Details of the test object (Leeds Test Details of the test object (Leeds Test 18FG) to be used for routine image quality 18FG) to be used for routine image quality controlcontrol

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Leeds test object Leeds test object is placed at the is placed at the entrance of the entrance of the image intensifierimage intensifier

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Centering sometimes can be difficultCentering sometimes can be difficult

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An alternative solution to centring the An alternative solution to centring the Leeds test object for image quality Leeds test object for image quality evaluationevaluation

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Another possible solution— tape the Cu Another possible solution— tape the Cu filter together with the test object.filter together with the test object.

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Do not forget

• To angle test object at 45°

to TV scan lines

• The best results are in center of intensifier field

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Test object and filters placed at the Test object and filters placed at the image intensifierimage intensifier

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Test object image (23 cm field size)Test object image (23 cm field size)

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Test object image (17 cm field size)Test object image (17 cm field size)

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The best results are in the center of image field

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Do not forget to angle test object at 45° to TV raster lines to avoid Moire patterns

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High contrast resolution test object

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Leeds Fluoroscopy Phantom (spatial resolution)

Incorporates:• a test pattern with bar

patterns with spatial frequencies ranging from 0.5 to 5.0 cycles (line pairs) per mm.

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Leeds Fluoroscopy Phantom (spatial resolution)

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Spatial resolution

Interpretation of resultsInterpretation of results

Analysis depends on the phantom used (Leeds)

The resolution limit is normally measured at the centre of the image field. It should correspond to the following values:

Field size diameter

Resolution limit

cm Lp/mm 30 - 35 >1.0 22 - 25 >1.25 15 – 18 >1.6

IAEA

Where to Get More Information

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Quality Control in Diagnostic Imaging, Gray JE, Winkler NT, Stears J, Frank ED. Available at no cost. http://www.diquad.com/QC%20Book.html