Transcript IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY Part 16.3: Optimization of protection in fluoroscopy Practical.

IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology
RADIATION PROTECTION IN
DIAGNOSTIC AND
INTERVENTIONAL RADIOLOGY
Part 16.3: Optimization of protection in
fluoroscopy
Practical exercise
IAEA
International Atomic Energy Agency
Overview / Objectives
• To become familiar with quality control
tests in fluoroscopy.
• To measure the high contrast resolution
• Interpretation of results
IAEA
16.3: Optimization of protection in fluoroscopy
2
IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology
Part 16.3: Optimization of protection in
fluoroscopy
High contrast spatial resolution
IAEA
International Atomic Energy Agency
High contrast resolution
Purpose :
• to measure the high contrast resolution of the
fluoroscopy system
Equipment :
• image quality phantom (Leeds phantom)
• 2 mm Cu filter
IAEA
16.3: Optimization of protection in fluoroscopy
4
Leeds Test Phantom 18FG to be used for
routine image quality control
IAEA
16.3: Optimization of protection in fluoroscopy
5
Details of the test object (Leeds Test 18FG)
to be used for routine image quality control
IAEA
16.3: Optimization of protection in fluoroscopy
6
Leeds test object
is placed at the
entrance of the
image intensifier
IAEA
16.3: Optimization of protection in fluoroscopy
7
Centering sometimes can be difficult
IAEA
16.3: Optimization of protection in fluoroscopy
8
An alternative solution to centring the
Leeds test object for image quality
evaluation
IAEA
16.3: Optimization of protection in fluoroscopy
9
Another possible solution— tape the Cu
filter together with the test object.
IAEA
16.3: Optimization of protection in fluoroscopy
10
Do not forget
• To angle test object at 45°
to TV scan lines
• The best results are in center of intensifier
field
IAEA
16.3: Optimization of protection in fluoroscopy
11
Test object and filters placed at the
image intensifier
IAEA
16.3: Optimization of protection in fluoroscopy
12
Test object image (23 cm field size)
IAEA
16.3: Optimization of protection in fluoroscopy
13
Test object image (17 cm field size)
IAEA
16.3: Optimization of protection in fluoroscopy
14
The best results are in the center of
image field
IAEA
16.3: Optimization of protection in fluoroscopy
15
Do not forget to angle test object at 45° to
TV raster lines to avoid Moire patterns
IAEA
16.3: Optimization of protection in fluoroscopy
16
High contrast resolution test object
IAEA
16.3: Optimization of protection in fluoroscopy
17
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.
IAEA
16.3: Optimization of protection in fluoroscopy
18
Leeds Fluoroscopy Phantom
(spatial resolution)
IAEA
16.3: Optimization of protection in fluoroscopy
19
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
cm
30 - 35
22 - 25
15 – 18
IAEA
Resolution limit
Lp/mm
>1.0
>1.25
>1.6
16.3: Optimization of protection in fluoroscopy
20
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
IAEA
15.3: Optimization of protection in radiography
21