This document discusses optimizing protection during fluoroscopy by measuring high contrast spatial resolution using a Leeds test phantom. It provides instructions on performing the test, including using a 2mm copper filter and ensuring the phantom is centered and angled at 45 degrees. The best results are obtained in the center of the image field. Spatial resolution limits should be above 1 lp/mm for a 30-35cm field size, 1.25 lp/mm for 22-25cm, and 1.6 lp/mm for a 15-18cm field size. Additional resources are provided.

1. IAEA
International Atomic Energy Agency

2. IAEA
International Atomic Energy Agency
Mohammad Reza Deevband, Ph.D.
Medical engineering and medical physics section
Shahid Beheshti Medical Science University
High contrast spatial resolution

3. IAEA 16.3: Optimization of protection in fluoroscopy 3
Overview / Objectives
• To become familiar with quality control
tests in fluoroscopy.
• To measure the high contrast resolution
• Interpretation of results

4. IAEA 16.3: Optimization of protection in fluoroscopy 4
High contrast resolution
Purpose :
• to measure the high contrast resolution of the
fluoroscopy system
Equipment :
• image quality phantom (Leeds phantom)
• 2 mm Cu filter

5. IAEA 16.3: Optimization of protection in fluoroscopy 5
Leeds Test Phantom 18FG to be used for
routine image quality control

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

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

8. IAEA 16.3: Optimization of protection in fluoroscopy 8
Centering sometimes can be difficult

9. IAEA 16.3: Optimization of protection in fluoroscopy 9
An alternative solution to centring the
Leeds test object for image quality
evaluation

10. IAEA 16.3: Optimization of protection in fluoroscopy 10
Another possible solution— tape the Cu
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
image intensifier

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Test object image (23 cm field size)

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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 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

21. IAEA
Where to Get More Information
15.3: Optimization of protection in radiography 21
Quality Control in Diagnostic Imaging, Gray JE,
Winkler NT, Stears J, Frank ED. Available at no
cost. http://www.diquad.com/QC%20Book.html