RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY

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RADIATION PROTECTION INDIAGNOSTIC
ANDINTERVENTIONAL RADIOLOGY
IAEA Training Material on Radiation Protection in
Diagnostic and Interventional Radiology

• Part 16.4 Optimization of protection in
  fluoroscopy
• Practical exercise

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Overview / Contents

• To become familiar with quality control test in
  fluoroscopy
• To measure the low contrast resolution and noise
  according to the suggested procedures
• Interpretation of results

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Part 16.4 Optimization of protection in
fluoroscopy
IAEA Training Material on Radiation Protection in
Diagnostic and Interventional Radiology

• Low contrast resolution and noise

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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

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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.

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Leeds Fluoroscopy Phantom Noise and contrast loss

• Incorporates
• 19 discs, each of diameter 11 mm, of different
  X-Ray contrasts.

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Leeds Fluoroscopy Phantom Noise and contrast loss

• Typical fluoroscopic image of the test object.
• N.B.
• View the small circles at center
• Count the number of circle sizes seen

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Leeds Fluoroscopy Phantom Noise and contrast loss
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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
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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.

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Leeds Fluoroscopy Phantoms Overall Imaging
Performance
Typical fluoroscopic image of the test object.
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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