Fuji Computed Radiography Systems for
Mammography
TU-E-517C-2
Fuji Computed Radiography
Systems for
Mammography
Robert A. Uzenoff
Fujifilm Medical Systems USA
Stamford, Connecticut
uzenoff@fujimed.com
Objectives
† Physical principles of photostimulable
luminescence imaging, emphasizing most
recent advances
† Understand modifications to
manufacturer’s QC program to account for
technology advances, changes due to
mammography
† Factors in acceptance testing, QC,
assessing and adjusting image processing
2
1
Digital
Film Optical Density
Screen-film
Acquire
Acquire
Process
Display
Store
Process
Display
4
10,000
CR plate
1,000
Film-screen
(400 speed)
3
Overexposed 100
2
Correctly exposed
1
0
0.01
Store
10
Underexposed
0.1
1
20000 2000 200
10
20
Relative intensity of PSL
Dynamic Range of CR and S/F
Screen-film’s functions decoupled.
1
100 Exposure, mR
2
Sensitivity (S)
3
4
Equipment appearance
Detection geometry, conversion
Imaging plate
† Detection geometry
Image reader
Dry imager
„ Array of discrete detectors, 2D large
area (full-field) or ~1D slot
„ Continuous detector sampled on readout
† X-ray conversion
„ X-ray → light (scintillator/phosphor) →
converter (photodiode/PMT) → e„ X-ray → e- (a-Se)
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R Uzenoff*, Fujifilm Medical Systems USA
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1
Fuji Computed Radiography Systems for
Mammography
TU-E-517C-2
Example of output film formats
Image Acquisition in FCR
Imaging
Reading Unit
Exposure
plate
X-Ray tube
Optical
Scanner
Laser
Beam
Patient
Light
Erasing
unit
Principles Employed In Image Acquisition,
Reading and Erasure
7
Storage Phosphor Reading System
Optical
Scanner
8
Image Formation Process and
Image Quality Factors
Imaging
Plate
Photomultiplier Tube
Absorbed
X-ray
Photon
Laser Beam
Light
Guide
Trapped
Electron
Light
Photon
PMT
Photo
Electron
Electrical
Circuit
Analog
Electric
Signal
A/D
converter
Digital
Image
Data
A/D
Converter
X-ray photon
Noise
Imaging
Plate
MTF
of IP
Motor
Structure
Noise
(Fixed Noise)
Light Photon
Noise
Electrical
Noise
(Fixed Noise)
MTF
of scanner
Quantization
Noise
(Fixed Noise)
MTF of Electronics
9
Noise Components of FCR (0.5mR)
(example for general radiography )
„ Dual-side reading
„ 50µ pixel pitch
3.0
-5
2
Imaging Technology for
FCR Mammography
† Image reading
4.0
Noise Power ( X 10 mm )
10
† Image processing
2.0
„ Multi-objective frequency processing (MFP)
„ Pattern enhancement for mammography (PEM)
„ Computer-aided diagnosis (works in progress)
Light Photon Noise
1.0
Fixed Noise
X-ray Photon Noise
0.0
0
1
2
3
4
5
Spatial Frequency(c/mm)
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R Uzenoff*, Fujifilm Medical Systems USA
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2
Fuji Computed Radiography Systems for
Mammography
TU-E-517C-2
New Features of IP for
dual-side reading
Layer Structure of Imaging Plates
† Transparent support
† Thicker Phosphor Layer (higher X-ray
absorption)
† Finer grain phosphor (higher
sharpness, lower IP structure noise)
Coating for
Preventing
Coating for
Preventing
PET FILM
Protective Layer
PET FILM
BaF(Br,I):Eu2+
Phosphor
Layer
Base Film
(PET)
Electrically
Conductive
Layer
Phosphor
Layer
BaF(Br,I):Eu2+
Transparent
Electrically
Conductive
Layer
Transparent
Base Film
(PET)
Coating for
Preventing
Imaging Plate for
Single Side Reading
Imaging Plate for
Dual Side Reading
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14
Both-sides Reading
Image Reading Technology/
Dual Side Reading
Protective
layer
Photo-detector
† Optimum addition ratio at each
frequency
† Fast filtering technology by real space
filter
† Imaging Plates for dual-side reading
† Edge transportation of imaging plates
(built-in)
† Dual-side erasing
Laser
Beam
Optical
Guide
Phosphor
Layer
Mirror
Emission
Imaging Plate
Transparent
Support
Imaging
Plate
Optical Guide
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16
Photo-detector
Both-Sides Reading Technology
Applied to FCR Mammography
Erasure
1.2
Erasure Lamp
Erasure Lamp
Phosphor Layer
Phosphor Layer
Base Film
Base Film
Single Side Reading
Erasure
Absorption Ratio
1
Proposed system
0.8
Current system
0.6
0.4
0.2
Erasure Lamp
Dual Side Reading
Erasure
0
0.0
10.0
15.0
20.0
25.0
30.0
Energy of X-ray Photons
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R Uzenoff*, Fujifilm Medical Systems USA
5.0
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3
Fuji Computed Radiography Systems for
Mammography
TU-E-517C-2
Dual Side Reading Technology
Applied to FCR Mammography
Both-Sides Reading Technology
Applied to FCR Mammography
5.0E+05
（18mR）
0.5cy/mm
4.0E+05
1.0
IMAGE2
3.0E+05
Response
NEQ
1.0cy/mm
1.5cy/mm
2.0cy/mm
2.0E+05
2.5cy/mm
IMAGE2
IMAGE1
IMAGE1
3.0cy/mm
1.0E+05
0.8：0.2
0.9：0.1
Front 1.0
0.7：0.3
0.6：0.4
0.5：0.5
0.4：0.6
0.3：0.7
0.2：0.8
0.1：0.9
Back 1.0
4.0cy/mm
0.0E+00
0.0
Spatial Frequency
Addition Ratio（front：back）
19
Both-Sides Reading Technology
Applied to FCR Mammography
20
Versatility of digital processing
Screen-film
Digital
Speed/noise
Fixed by
SF/processing
Selectable
Gradation
Fixed by
SF/processing
Selectable:
globally, nonlinearly f(x,y…)
Spatial frequency
Fixed by SF
Selectable:
globally, nonlinearly f(x,y…)
Image
presentation
Single
Multiple possible, if
necessary
1.0E+06
NEQ
Both Sides Reading Method
by use of Spatial Filter
1.0E+05
Single Side
Reading Method
1.0E+04
0.0
1.0
2.0
3.0
4.0
5.0
Spatial Frequency (cycle/mm)
21
22
Exam Display Menu
Histogram Analysis
† Operator registers each IP with the
image reader before reading
† Operator selects patient ID, exam
“menu”, options
† “Menu” determines reading and
display parameters
† Processed image indicates display
parameters.
†Histogram width is controlled by kVp and
patient absorption
†The FCR reader identifies the lowest amount
of radiation (Smin/S1) and highest
(Smax/S2)
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Fuji Computed Radiography Systems for
Mammography
TU-E-517C-2
What is the S-number?
S-number
† Center histogram,
centered at 1.0 mR
S = 200
† Left histogram,
centered at 0.01 mR
S = 2000
† Right histogram,
centered at 10 mR
S = 20
† Three different
mAs exposures
† The histogram
shape is the
same
† The position on
the exposure
axis changes.
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26
What is the S-number?
Factors that affect S-number
† For general radiography
S = 200 for 1 mR exposure, 80 kVp
(no additional filtration) at 72 in. SID
† For mammography
S=120 for 20 mR
† S derived from the histogram
† S represents the midpoint of the
usable portion of the histogram
† Not only exposure, but
„ scatter (more scatter → higher S-number
„ distance- SID and OFD (dose and
scatter)
„ collimation
„ menu selection (histogram analysis)
„ Delay in processing from time of
exposure
27
S-number Ranges
Chest, General
Skull
Spine
Extremities
Chest, Pedi.
200-600
100-400
100-400
75-200
200-700
Chest, Port.
Abdomen
GI
“L” value (latitude)
100-400
100-400
100-300
Breast
Abdomen, Pedi.
28
50-100
200-700
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R Uzenoff*, Fujifilm Medical Systems USA
† L represents the number of decades
covered by exposure
† Each exposure menu limits minimum
and maximum L
† General radiography 1.7 < L < 2.3
† For mammography 2.2 < L < 2.7
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Fuji Computed Radiography Systems for
Mammography
TU-E-517C-2
S-number and L-values
and Image Quality
Image Transformation
† S-numbers and “L” values provide a
valuable tool in image problem
analysis
† Images should not be critiqued by Snumber alone.
† It is very important to view the whole
image.
† Image quality improvement
„ Visibility improvement (gradation,
frequency processing)
† Image reconstruction
„ CT, energy subtraction
† Image correction
„ Enlargement, rotation, gain/offset,
“dead” pixels
† Image data compression and
expansion
31
Digital image processing
classification
Two Image Transformation Cases
1. MFP: Multi-objective Frequency
Processing
Output data
Image
Description
Image
transformation
Image
measurement
Image
recognition
Input data
Image
32
2. PEM: Pattern Enhancement
processing for Mammography
Image
generation
Description
33
MFP Motivation
MFP and PEM Domains
Point
Structure
† According to the diagnostic purpose,
display in a single image
MFP
Microcalcification
Mass
„ Wide dynamic range retaining detail
without enhancing noise
„ Regions previously invisible, naturally
„ Suppress enhancing structures outside
the body (e.g. metal)
PEM
Shape
Spicular
† Applicable to hard copy as well as
soft copy display diagnosis
Ducts / Vessels
Line
Structure
Low
34
High
Spatial Frequency
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Fuji Computed Radiography Systems for
Mammography
TU-E-517C-2
MFP Overview
MFP Features
1. Frequency enhancing function that
enhances shadows of points and
lines
+
2. Dynamic Range Compression (DRC)
function that compresses the image’s
dynamic range
† Wide latitude information, density
contrast information and edge
shape information can be
displayed on one image at the
same time
† Non-linear frequency enhancement
processing according to the image
contrast
37
38
MFP and USM images
MFP and USM Response
Enhancement of high frequency content is possible with richer low frequency content compared to USM
Response
8.0
6.0
USM(RN7)
MFP
USM(RN1)
1.0
0.00.01
0.05
0.1
0.5
1.0
Spatial Frequency (Cycles/mm)
5.0
39
USM
MFP
40
PEM-detected microcalcifications
PEM motivation
Considering that fine calcifications are
likely to be less visible on digital
mammograms, invent and develop
processing using image recognition
technology to extract and enhance
locations that look like calcification
images.
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R Uzenoff*, Fujifilm Medical Systems USA
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Fuji Computed Radiography Systems for
Mammography
PEM Block Diagram
Effect of PEM
Non-calcification edge
PEM
enhancement with same noise
Stronger Enhancement of Microcalcifications with Same Noise Level
Combination
Processing
Edge
detection
processing
•Strong enhancement of
microcalcification with
same noise level
- OR •Same enhancement level
with suppression of noise
level
TU-E-517C-2
Calcification
position
detection
Original
processing
Image
Using mathematical morphology filter
With multiple structuring element
Calcification
edge
information
Detection of center
of calcification image
43
PEM enhancement with noise suppression
PEM
Original Image
44
Quality Control Tests
Same Enhancement Level and Suppression of Noise Level
† FCR Mammography Control Manual,
November 6, 2001
† AAPM Task Group #10
† Yaffe et al, Quality Control Procedures
for Full-field Digital Mammography v.
2.03 ACRIN #6652 (DMIST)
Original Image
PEM
45
46
Quality Control Daily Tests
Quality Control Weekly Tests
FCR Test
DMIST Equivalent
FCR Test
DMIST Equivalent
Imaging Room
Cleanliness
Darkroom / Printer
Area Cleanliness
Clean CR Reader and
Work Area – CR only
Laser Printer Phantom
Image Quality
Erase Imaging Plates
– CR only
Phantom Images
Phantom Image
Quality Test
Viewing conditions
Dry Laser Printer QC
Erase Imaging Plates
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R Uzenoff*, Fujifilm Medical Systems USA
Viewbox and viewing
conditions
Imaging Room
Cleanliness
Cleaning of CR air
vents – CR only
Monitor cleaning
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Fuji Computed Radiography Systems for
Mammography
TU-E-517C-2
Quality Control Monthly Tests
Quality Control Quarterly Tests
FCR Test
DMIST Equivalent
FCR Test
DMIST Equivalent
Visual checklist
Visual checklist
Repeat Analysis
Repeat Analysis
Analysis of fixer
retention – wet
processing
Mechanical inspection
(daily)
Monitor cleaning
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50
Quality Control Semi-annual Tests
Quality Control Annual Tests
FCR Test
DMIST Equivalent
FCR Test
Compression
Compression force
test
Noise, linearity, and
geometric distortion
Mammo unit assembly Mammo unit assembly
Laser jitter
DMIST Equivalent
Collimation
Collimation
kVp accuracy and
reproducibility
Beam quality, HVL
kVp accuracy and
reproducibility
Beam quality, HVL
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52
Quality Control Annual Tests
Quality Control Annual Tests
FCR Test
DMIST Equivalent
FCR Test
DMIST Equivalent
Artifact evaluation
Artifact evaluation
AEC
Thickness tracking
Breast ESE, MGD
Breast ESE, MGD
Radiation Output
Tube output: mR/mAs
vs. kVp
MAP image quality
Image quality
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R Uzenoff*, Fujifilm Medical Systems USA
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Fuji Computed Radiography Systems for
Mammography
TU-E-517C-2
Questions?
Quality Control As-needed Tests
FCR Test
DMIST Equivalent
Imaging Plate
maintenance
Inspection and
cleaning of imaging
plates
Inspection and
cleaning of imaging
plate cassettes
Imaging plate fogging
– CR only
Imaging plate fog
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R Uzenoff*, Fujifilm Medical Systems USA
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