Transcript IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY Part 19.07: Optimization of protection in Mammography Practical.

IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology
RADIATION PROTECTION IN
DIAGNOSTIC AND
INTERVENTIONAL RADIOLOGY
Part 19.07: Optimization of protection in
Mammography
Practical exercise
IAEA
International Atomic Energy Agency
Overview
• To be able to apply quality control protocol
to mammography equipment
• To determine the spatial resolution (lp/mm)
both parallel and perpendicular to the tube
axis using
• This is an evaluation of the whole system
(blur due to focal spot combined with the
film-screen system)
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19.07 : Optimization of protection in Mammography
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IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology
Part 19.07: Optimization of protection in
Mammography
Phantom image quality evaluation
IAEA
International Atomic Energy Agency
Image quality - spatial resolution
• The spatial resolution can be measured by
imaging two resolution lead bar patterns,
(20 line pairs/mm)
• These should be placed on top of the PMMA
plates (45 mm total thickness) to measure
worst-case resolution.
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Image quality - spatial resolution
• Image the patterns at the reference point
• Determine the resolution in both directions using a
6X magnifying loupe.
Note: In some cases the three bars may blur but
there are smaller bars visible. This is known as
false resolution—there will be fewer bars visible in
the area with false resolution. The resolution is the
smallest group where all bars are just visible.
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Image quality - spatial resolution
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Image quality - spatial resolution
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Image quality phantom
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Image quality - spatial resolution
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Image quality - spatial resolution
• The distance from the chest wall edge is
critical, but the position parallel to the thorax
side is not critical within ± 5 cm from the
reference point.
• Resolution is generally lower parallel to the
tube axis due to the asymmetrical shape of
the focal spot.
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Image quality - spatial resolution
Limiting value :
> 12 lp/mm acceptable
> 15 lp/mm desirable at the
reference point
Frequency :
Weekly
Equipment :
PMMA plates 150 x 240 mm,
resolution pattern(s) up
to 20 lp/mm, 6X magnifying loupe
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Where to Get More Information
European protocol for the quality control of the
physical and technical aspects of mammography
screening.
http://euref.org/index.php?option=com_phocado
wnload&view=category&id=1&Itemid=8
American College of Radiology Mammography
Quality Control Manual, Reston VA, 1999.
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