CR/QA RADCHEX

1
CR/QA RADCHEX

2
History of digital imaging

• Early, crude digital detectors were developed in
  the 1970s
• Image quality was problematic
• Processing time of digital images was untenable
• Viewing, transfer and storage of digital data was
  not ready for clinical application
• Digital radiography was first marketed in the
  1980s
• Based on a way to improve image quality
• Used post processing to extract maximum
  information from each image
• Potential for reduced dose with fewer repeat
  images
• Early commercialization slowed by detector cost
• CR (Computed Radiography) using photostimulable
  plate hit its stride in the early 90s
• CR can be used with existing x-ray system and
  deployed like film/screen cassettes- big economic
  benefit
• CR plagued by marginal image quality at first
  when used at film/screen dose levels

3
History of digital imaging (cont.)

• CR vendors refine CR systems for better imaging
  quality
• New phosphor science and system improvements
  bring wide acceptance
• PACS developments enable filmless conventional
  radiography
• Dose creep
• Direct Digital Radiography (DDR) finds increased
  acceptance today but CR is still preferred by
  many
• The lines between CR and DR are beginning to blur
  as both technologies evolve
• CR companies begin marketing CR systems with
  on-board plate readers and self contained x-ray
  system
• Digital mammography expands with both DDR and CR
  technology employed
• MQSA will refine QA requirements for FFDM
  applications

CR and DR system use is global and will
eventually replace all film/screen applications
4
How a CR system operates

• Photo Stimulated Phosphor (PSP) is exposed to
  x-ray
• X-rays cause phosphor to store invisible light
  image
• Image Plate (IP) removed and placed into reader
  and exposed to laser light
• IP then releases visible light which is fed to a
  computer for image processing

CR operates in a similar manner for all OEM
suppliers
5
How a CR system operates (cont.)

• Plate reader has a light sensor that detects and
  measures light given off by IP (light value)
• Every OEM provides a different value for this
  light and calls it by different names
• Fuji, Konica/Minolta and Philips S
• Afga LgM
• Kodak El

Bottom line it is x-ray produced light!
6
Each OEM calibrates its plate reader differently

• Different because each OEM needs to link their
  light exposure index value back to the x-rays
  that produce the image because each system
  differs in its speed (conversion efficiency)
• Technologists use the light exposure index value
  to confirm the right amount of light was produced
• For the particular type of exam
• To ensure the patient has been appropriately
  exposed to x-rays
• OEMs give technologists a range of acceptable
  light exposure index values, appropriate for
  various types of exams
• Fuji, Konica/Minolta, Philips S 200
• Agfa LgM 2.2
• Kodak EL 2000

7
Lets look at this x-ray/light relationship
closely

• Plate reader light sensor is downstream of image
  production
• Plate reader only looks at light to construct
  image
• Upstream is where the plate is exposed to x-rays
• CR OEMs calibrate each plate reader using one
  factory x-ray machine tube with same Al
  filtration, and measure using a single
  well-calibrated dosimeter so each plate reader is
  perfectly calibrated each reader produced is
  balanced or matched to every other reader
• Eg for a dosimeter value of 1 mR, the Fuji S or
  Light Exposure Index is 200

Bottom line the conversion efficiency of the PSP
is linked to a single light output value for a
given x-ray input value and everything is
perfectright?
8
Wrong! Plate readers are mis-calibrated when they
get to the field

• The perfectly calibrated factory plate readers
  are mis-calibrated when they are installed due to
  variations in
• Service staff (x-ray and CR OEM disharmony)
• Many different x-ray machines
• Dosimeters are in different states of
  calibration
• Hospital x-ray tubes with different x-ray beams
  conditions
• Instead of factory-matched and balanced readers,
  each reader re-calibration now maintains its
  memory of the x-ray beam condition and dosimeter
  variation used to calibrate it in the field!

Bottom line the variation between and among
plate readers in a single hospital department can
be as much as 80
9
Magnitude of mis-calibration

• Conversion efficiency values change with small
  change in x-ray beam condition
• For the same one mR x-ray exposure, the light
  output from the IP can vary by as much as 80 as
  the x-ray beam filtration changes

10
Variation in field plate readers

• Variation among four field plate readers
  calibration in a single department over 45 days
• The four Fuji readers should have the same S, if
  well calibrated
• Need for traceable plate reader calibration to
  identify abnormal readings on day 16
• Daily QC on x-ray and CR system would have caught
  abnormality

Bottom line CR RADCHEX would have easily
detected the abnormality
11
How CR RADCHEX works

• CR RADCHEX is a chameleon
• Configured to mimic any of the available CR OEM
  plate readers using interactive software
• Calibrated at the Fluke Biomedical Global
  Calibration Lab

A calibrated, traceable, portable plate reader
12
How CR RADCHEX works (cont.)
13
How CR RADCHEX works (cont.)

• CR RADCHEX is a downstream meter compared to a
  dosimeter since it, like the reader, measures
  x-ray-produced light
• CR RADCHEX has the same energy dependence to
  x-rays as a CR plate the same x-ray to light
  conversion efficiency so it can be used to
  calibrate other plate readers as well as all CR
  AEC systems
• CR RADCHEX doesnt need to travel upstream or up
  the waterfall to the x-ray side of the imaging
  plate
• Bottom Line use a traceable, calibrated light
  meter (CR RADCHEX) to calibrate another light
  meter (CR plate reader).

After all, one wouldnt use a light meter to
calibrate a dosimeter!
14
How CR RADCHEX works (cont.)

• The CR RADCHEX need not be exposed to a laser to
  give up its light image
• CR RADCHEX measures light immediately upon
  exposure to x-rays
• Using a dosimeter, one waits 10-15 minutes for
  imaging plate to stabilize before processing
• CR RADCHEX can calibrate the AEC to produce the
  same light signal for any patient thickness or
  kVp without waiting 10-15 minutes and without
  using a plate reader

Bottom line CR RADCHEX can calibrate
radiographic AEC systems in under an hour and
mammography AEC systems in about two hours,
resulting in tremendous time and cost savings in
addition to accuracy.
15
How CR RADCHEX works (cont.)

• The CR RADCHEX x-ray to light converter
  physically fits into any place a CR imaging plate
  fits
• Of benefit when placing the converter into the
  X-ray machines IP holder (Bucky) during AEC
  calibration

Bottom line CR RADCHEX is a chameleon
16
How CR RADCHEX works (cont.)

• The CR RADCHEX is immune to upstream field x-ray
  machine, dosimeter and tube filtration variations
• Therefore it can be used to re-establish the
  perfect calibration the plate reader had from
  the CR OEM factory
• The light measurement value (CRLU, CR Light
  Units) is traceable back to the Fluke Biomedical
  Global Calibration Lab calibration condition and
  OEM calibration specifications
• Not to upstream x-ray machine, dosimeter and
  x-ray tube filtration conditions

17
How CR RADCHEX works (cont.)

• CR RADCHEX is supplied with a 1.5 mm copper
  reference filter
• Strapped to exit side of x-ray tube collimator
  during plate reader assessment calibration
• X-ray beam is heavily filtered by copper filter
  gives meter a source of consistent x-rays from
  one x-ray tube to another

18
How CR RADCHEX works (cont.)

• CR RADCHEX software looks at the x-ray-produced
  light from the stable x-ray beam converts the
  light output to any OEM light exposure index
  value
• CR RADCHEX software also converts any light
  signal to all OEM-specified calibration
  conditions hence reads out in S, LgM, and EI
  values as well as a generic CRLU value for any
  and all x-ray exposures
• CR RADCHEX also provides an estimated mR value
  for radiation exposing the imaging plate at the
  calibration point

19
How CR RADCHEX works (cont.)

• Bottom line
• Any and all plate readers can once again be
  re-calibrated to the perfect OEM factory
  calibration specifications
• Hence, all plate readers are once again balanced
  and matched to each other
• In addition, each plate reader calibration can be
  verified since each CR RADCHEX meter is
  calibrated and traceable to the GCL, PTB or NIST
  defined x-ray technique

20
Implications for well-calibrated CR systems

• Implications for well-calibrated AEC systems and
  plate readers are extreme
• Medical imaging QA standpoint
• If images from four mis-calibrated plate readers
  in a department are sent to a PACS, the images
  will have different signal-to-noise values, even
  though technologists have used what they thought
  were the same S
• The image processing software may or may not
  correct for the various signal to noise
  variations leading to radiologist frustration and
  possible diagnostic deficiencies
• Patients in this situation are exposed to varying
  x-ray doses for the same exam from these four
  different mis-calibrated plate readers

Not imaging or ALARA friendly
21
QA RADCHEX option

• QA RADCHEX is a cost effective alternative to the
  CR RADCHEX
• QA RADCHEX
• Performs the same basic functions as the CR
  RADCHEX without the need for a laptop computer
• The QA RADCHEX cassette contains a LCD readout
  and displays CRLU and speed values (compared to
  film/screen)
• Data can be manually entered on a template with
  the software supplied if desired
• QA RADCHEX is ideal for QA personnel to conduct
  periodic assessment of CR system function
• Both the CR RADCHEX and QA RADCHEX can be used
  to assess Plate Reader and x-ray System AEC
  calibration

QA and CR RADCHEX are QA timesavers
22
How do CR and QA RADCHEX benefit customers?

• Who are the customers?
  What are their issues?
• DX Service OEM (CR RADCHEX)
  Productivity/calibration integrity
• CR OEM (CR RADCHEX)
  Productivity/image quality
• ISO Service OEM (CR RADCHEX)
  Productivity/service integrity
• Biomedical Engineers/Technicians (CR RADCHEX)
  Productivity/service integrity
• Radiology Administrators (QA RADCHEX)
  System uptime/image quality
• Radiology QA Technologists (QA RADCHEX)
  Image quality/consistency
• DX Medical Physicists (CR or QA RADCHEX)
  Image quality/dose
• Health Physicists (CR or QA RADCHEX)
  Dose
• Economic justification-OEM service example
• Calibrating AEC for CR site using conventional
  methods (CR plate/reader/dosimeter)
• will consume 8 hours of service time worth
  3,200.00 (_at_400.00/hr.)
• Calibrating AEC using CR RADCHEX in place of CR
  Plate/reader/dosimeter will consume
• less than 2 hours. The difference (6 hours) will
  pay for a CR RADCHEX in just over one application
• That 6 hour savings pertains to the productivity
  of the OEM or the cost for service to the site

CR RADCHEX
23
Frequently asked questions

• FAQS
• What does this device gain for me as a
  technologist?
• The ability to quickly verify the correct
  performance of AEC before calling in expensive
  service.
• How does my job as a service engineer/biomedical
  engineer benefit?
• A. Save significant time increasing
  productivity and provide high integrity results
• How can the system help me in a multiple CR
  system environment?
• A. A standardized, traceable QA tool to
  balance all systems for consistent dose/image
  quality
• How can I justify the purchase?
• The time saved in a single calibration
  application could pay for the device
• What are my alternatives?
• Use a dosimeter/plate/reader method and try to
  balance radiation and light energies (difficult)
• What happens as image-recording media advances?
  Obsolescence?
• A CR System speed and calibration routine
  changes can be accommodated by software upgrades

CR RADCHEX
24
Frequently asked questions (cont.)

• FAQS
• 7. Why cant I just use a dosimeter to do
  the same thing?
• Dosimeters measure x-ray dose and plate readers
  measure light two different energies
• leaving room for errors. The CR
  RADCHEX is a radiation stimulated light meter
  traceable
• to the Global Calibration Lab
• 8. Who else sells this technology?
• A. No one. It is exclusive to Fluke
  Biomedical
• 9. What about mammography?
• A. A special version of the CR RADCHEX
  called CR MAMCHEX (and QA MAMCHEX) will be
  introduced for CR mammography applications
• 10. Can I use the CR RADCHEX with my
  screen/film systems for AEC Calibration and
  tracking?
• The AEC 6 system is available for screen/film
  systems and provides the same time saving
  advantages for calibrating and QA of AEC

CR/QA RADCHEX
25
Questions?

• For more information about this or other
  diagnostic imaging quality-assurance topics,
  please contact sales_at_flukebiomedical.com.