Transcript RADIATION PROTECTION IN DIAGNOSTIC RADIOLOGY

IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology
RADIATION PROTECTION IN
DIAGNOSTIC AND
INTERVENTIONAL RADIOLOGY
Part 19.08: Optimization of protection in
Mammography
Practical exercise
IAEA
International Atomic Energy Agency
Overview
• To be able to apply quality control protocols
to mammography equipment
• To carry out film sensitometry-densitometry
• Interpretation of results
IAEA
19.08 : Optimization of protection in Mammography
2
IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology
Part 19.08: Optimization of protection in
Mammography
Processor evaluation
IAEA
International Atomic Energy Agency
Sensitometry (1)
• Use a sensitometer to expose a film to light
and insert the exposed side into the
processor first
• Measure the optical densities of the stepwedge with a densitometer
IAEA
19.08 : Optimization of protection in Mammography
4
Sensitometry (2)
• The values of interest are the base-plus-fog
level of the film, the mid-density, and density
difference
IAEA
19.08 : Optimization of protection in Mammography
5
Densitometer
IAEA
19.08 : Optimization of protection in Mammography
6
Sensitometric strip
IAEA
19.08 : Optimization of protection in Mammography
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
A method of exposing film by means of a
sensitometer and assessing the response
of film to exposure and development
7
Film sensitometry parameters
• Base + fog: The optical density of a film due to its base
density plus any action of the developer on the unexposed
emulsion, or possibly darkroom fog
• Mid-Density: Measured on a step of the wedge with an
optical density close to, but not less than 1.20. The middensity is related to the speed of the film.
• Density Difference: The difference between two steps on
the wedge closest to 0.45 and 2.20.
• Note: The steps producing these densities are chosen with
fresh chemistry and film. These same steps are then used
for all future quality control measurements.
IAEA
19.08 : Optimization of protection in Mammography
8
Control film
One, or more, box(es) of film selected and used only
for quality control purposes. When changing from
one control emulsion to another a cross-over
procedure must be carried out (see ACR QC
Manual).
The control film must be the same emulsion type as
is usually processed in the processor. If more than
one type of film is processed, e.g., mammography
and general radiography films, both types of film
must be used for quality control purposes.
IAEA
19.08 : Optimization of protection in Mammography
9
Processor QC Essentials
• A photographic step wedge should be
exposed daily and processed before any
clinical films are processed.
• Densities should be plotted on a control
chart (see Chapters 2 and 5, Gray, et al. for
details on control charts, and ACR
Mammography QC Manual)
IAEA
19.08 : Optimization of protection in Mammography
10
Control limits for mammography films
•
IAEA
19.08 : Optimization of protection in Mammography
11
Key to processor QC
• The key to processor is consistency in all
aspects—
• Using the same sensitometer and densitometer
• Using the same control emulsion (or carrying out a
crossover procedure when going to a new emulsion
batch)
• Immediately plotting the data on a control chart and
analyzing the chart to determine if correction action is
needed
• Recording the correction action for future reference
IAEA
19.8 : Optimization of protection in Mammography
12
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_phocadownload&
view=category&id=1&Itemid=8
American College of Radiology Mammography Quality
Control Manual, Reston VA, 1999.
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
19.08 : Optimization of protection in Mammography
13