Quality Control Testing of Stereotactic Breast
Biopsy Units
Fischer Fluoro Scan
Allen F. Hrejsa Ph.D.
Advocate Lutheran General Hospital
General Description of Fischer Unit
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SID 68.2 cm 0.3 mm Focal Spot
Image acquired at 1024 x 1024
Fiber Optic Coupled CCD
50 x 50 mm image area
High Frequency Generator
– Allows AEC in Std. Low or High
– Or Manual
Turning on Unit
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Finding the power switches
Table and Image Detector
Table enable/disable
Computer
Generator
X-ray Tube Head
• Field Light Switch
• Collimator insert
• Work lights
Compression Paddle
• Manual Slide Action
• Automatic via foot peddle only
Mammovision/Mammotest Software
• Turning on computer brings up initial Screen
• Software base is DOS and or Windows 3.1
• Image capture requires remembering some older operating
system commands (not crucial for basic tests)
Flat Field Calibration First
• Go to Utilities
• Daily Calibration
• Follow instructions
– Insert Flat field phantom (Fischer Supplied)
– Make 8 exposures at recommended technique
Making Exposures
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Testing will require multiple Exposures
Will save some for analysis later
All exposure are controlled by Software
Set up dummy patient: Physics Test
Enter Patient number: 1234
Start Study
SKIP SPOT FILM
Skip Digital Scout Film Screen
• Next screen will allow exposure
• Need to set generator to match Software settings
– Manual or AEC
Ask Tech to do Phantom Biopsy
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Techs set up needle unit
Should use vacuum unit if used by site
Dedicate a needle assembly for Demo
Go through complete biopsy procedure
Pick a mass that is closest to tube
– Avoids error message that needle will hit backplane (a “no no”)
Results of “Biopsy”
• Should see needle at mass
• Post fire needle should extend beyond mass
• Extraction system should have a piece of the mass to deposit.
Collimator Test/Focal Spot
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“paper cassette” with mam film
Can get 4 exposures on one 8 x 10
Tape cassette to Detector
Set compression paddle 4.5 cm from detector.
Tape test tool to compression paddle (centered) expose and save
image
Focal Spot
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Move film to an unexposed quadrant
Set up high contrast line pair phantom
Expose, save image
Rotate line pair expose and save image
Process film and evaluate (gives system focal spot evaluation)
Evaluate images on screen as well
Needed Exposures
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2, 4, 6, 8cm phantom AEC modes
ACR or Mini Phantom
Save after each exposure for analysis
Will use 4 cm phantom image for artifact evaluation and
uniformity
Saving vs. Not Saving Image
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Digital Scout
After exposure click save and then yes
Now ready for next exposure
To not save after exposure
Hit Cancel and then yes
Then ready for next exposure.
Other Exposures
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kVp
Output as a function of kVp
HVL
Require multiple exposures none of which need to be saved.
Should put an absorber in front of the detector (1/4” Al, thin Pb,
Steel or Cu) to protect the CCD and prevent ghost image
Image analysis from Patient Views
• Can do region of interest while viewing patient images
• Limited to mean value in ROI
• Need to go to utilities and select stored images to get mean, min,
max and std
Utilities
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Need to select images and load into A B C D temporary holding
Select ROI
Select Statistics
Can also do various plots of ROI
Monitor Evaluation
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Need to back out of Patient exam mode
Get to startup screen
Select Utilities
Setup (a dangerous place)
Have to log in (fischer)
Select monitor patterns
DON’T mess with other Choices
Hard Copy Evaluation
• Learn how to send images to hard copy unit
• Use whatever test images are available in hard copy unit (step
wedge etc)
• Send phantom image
• Send SMPTE
• Evaluate