Fluoroscopic Imaging Equipment
Guidelines for Detector Input Dose Settings
and Image Optimization
Fluoroscopy Evaluation
Patient Dose
Image Quality
kVp
RELATIVE EERD vs
210%
- 22 cm FOV Direct
Shimadzu Bransist
(Se/TFT)
Flat Panel Detector
FOV Indirect Flat
Philips Xper - 22 cm
Panel Detector (CsI(Tl)/TFT)
190%
180%
170%
- 42 cm FOV Indirect
Siemens Artis Zee
(CsI(Tl)/TFT)
Flat Panel Detector
- 22 cm FOV X-ray
Siemens Siregraph
Image Intensifier Detector
160%
150%
140%
Entrance Air
Kerma for 22
cm FOV
(Measure d at
Intervent ional
Ref Point)
140
120%
110%
100%
Air Kerma Rate
(mGy/min)
130%
No Grid-70 k V
10R AF 2k W 4ms/
mic rof ocus
7ms
Note: Thi s one
at 40 nGy /pulse
and 10 pps
100kV 10R A F
2kW smallf oc us
120
No Grid-70kV
10R A F 2kW 4ms
/7ms
mic rof ocus
Note: Thi s one
at 23 nGy /pulse
and 30 pps
80kV 10R 0302
3kW smallfoc us
Note: Thi s one
at 36 nGy /pulse
and 15 pps
s o meas . Dos
e was mul tiplied
by 2
I nt erv ent ional
IQ 2
100
90%
80%
40
50
60
70
80
90
100
110
kVp
Phil Rauch
Henry Ford Health Systems
Detroit, MI
Patient Entrance
Rate
Detector Exposure
Normalized to Minimum
200%
80kV 10R 0302
2kW smallfoc us
Note: Thi s one
at 36 nGy /pulse
and 15 pps
s o meas . Dos
e was mul tiplied
by 2
70kV 10R A F
2kW 5ms/8ms
mic rofoc us
80
80kV 10R A F
2kW smallf ocus
80kV 10R 02 3k
W small
60
I nt erv ent ional
focus
IQ 1 (no DHHS)
70kV 10R A F
2kW microfocus
40
70kV Servic e
02
70kV 10R A F
3kW 6ms/9ms
small focus
70kV 10R A F
3kW 8ms/12ms
smallf oc us
20
70kV 10R 02 3k
W small
70kV 10R 02 2k
W small
0
focus
focus
70kV 20R A F
3kW smallf ocus
4
6
70kV 10R A F
3kW smallf ocus
8
Nominal Phantom
Thickness (inches)
10
70kV 20R A F
3kW 8ms/12ms
smallf oc us
70kV Servic e
00
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
Dose Reduction vs Image Quality
Dose Reduction vs Image Quality
Dose reduction depends on….
….technology
….proper equipment design
….proper set up of equipment parameters
….proper utilization of the equipment
….knowledge and skill of the radiologist
Image quality depends on….
….technology
….proper equipment design
….proper set up of equipment parameters
….proper utilization of the equipment
….knowledge and skill of the radiologist
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
1
What is the Patient Dose?
What is the Exam Protocol?
What is the exam protocol?
2009 AAPM Meeting-Phil Rauch
Entrance Air Kerma for 22 cm FOV
(Measured at Interventional Ref Point)
140
Patient dose (and image quality) are highly
dependent on the exam protocol setting
80kV 10R 0302 2kW smallfocus
Note: This one at 36 nGy/pulse and 15 pps
so meas. Dose was multiplied by 2
70kV 10R AF 2kW 5ms/8ms microfocus
100
80kV 10R AF 2kW smallfocus
80
Entrance Air Kerma for 22 cm FOV
(Measured at Interventional Ref Point)
No Grid-70 kV 10R AF 2kW 4ms/7ms
microfocus
Note: This one at 40 nGy/pulse and 10 pps
100kV 10R AF 2kW smallfocus
No Grid-70kV 10R AF 2kW 4ms/7ms
microfocus
Note: This one at 23 nGy/pulse and 30 pps
80kV 10R 0302 3kW smallfocus
Note: This one at 36 nGy/pulse and 15 pps
so meas. Dose was multiplied by 2
Interventional IQ 2
80kV 10R 02 3kW smallfocus
FDA Limit
Interventional IQ 1 (no DHHS)
70kV 10R AF 2kW microfocus
60
70kV Service 02
70kV 10R AF 3kW 6ms/9ms smallfocus
40
70kV 10R AF 3kW 8ms/12ms smallfocus
70kV 10R 02 3kW smallfocus
70kV 10R 02 2kW smallfocus
20
70kV 20R AF 3kW smallfocus
Patient Entrance Air Kerma Rate (mGy/min)
Patient Entrance Air Kerma Rate (mGy/min)
140
120
2009 AAPM Meeting-Phil Rauch
120
No Grid-70 kV 10R AF 2kW 4ms/7ms
microfocus
Note: This one at 40 nGy/pulse and 10 pps
100kV 10R AF 2kW smallfocus
No Grid-70kV 10R AF 2kW 4ms/7ms
microfocus
Note: This one at 23 nGy/pulse and 30 pps
80kV 10R 0302 3kW smallfocus
Note: This one at 36 nGy/pulse and 15 pps
so meas. Dose was multiplied by 2
Interventional IQ 2
Low doses for this protocol may be
appropriate for pediatric imaging
80kV 10R 0302 2kW smallfocus
Note: This one at 36 nGy/pulse and 15 pps
so meas. Dose was multiplied by 2
70kV 10R AF 2kW 5ms/8ms microfocus
100
80kV 10R AF 2kW smallfocus
80
80kV 10R 02 3kW smallfocus
FDA Limit
Interventional IQ 1 (no DHHS)
70kV 10R AF 2kW microfocus
60
70kV Service 02
70kV 10R AF 3kW 6ms/9ms smallfocus
40
70kV 10R AF 3kW 8ms/12ms smallfocus
70kV 10R 02 3kW smallfocus
70kV 10R 02 2kW smallfocus
20
70kV 20R AF 3kW smallfocus
70kV 10R AF 3kW smallfocus
0
70kV 10R AF 3kW smallfocus
0
4
6
8
Nominal Phantom Thickness (inches)
2009 AAPM Meeting-Phil Rauch
10
70kV 20R AF 3kW 8ms/12ms smallfocus
4
70kV Service 00
6
8
Nominal Phantom Thickness (inches)
10
70kV 20R AF 3kW 8ms/12ms smallfocus
70kV Service 00
2009 AAPM Meeting-Phil Rauch
2
Entrance Air Kerma for 22 cm FOV
(Measured at Interventional Ref Point)
Patient Entrance Air Kerma Rate (mGy/min)
140
120
100
No Grid-70 kV 10R AF 2kW 4ms/7ms
microfocus
Note: This one at 40 nGy/pulse and 10 pps
100kV 10R AF 2kW smallfocus
Image Quality Assessment
No Grid-70kV 10R AF 2kW 4ms/7ms
microfocus
Note: This one at 23 nGy/pulse and 30 pps
80kV 10R 0302 3kW smallfocus
Note: This one at 36 nGy/pulse and 15 pps
so meas. Dose was multiplied by 2
Interventional IQ 2
Settings optimized for low
dose pediatric imaging may
not be appropriate for adults
80kV 10R 0302 2kW smallfocus
Note: This one at 36 nGy/pulse and 15 pps
so meas. Dose was multiplied by 2
70kV 10R AF 2kW 5ms/8ms microfocus
80kV 10R AF 2kW smallfocus
80
80kV 10R 02 3kW smallfocus
FDA Limit
Interventional IQ 1 (no DHHS)
70kV 10R AF 2kW microfocus
60
70kV Service 02
70kV 10R AF 3kW 6ms/9ms smallfocus
40
70kV 10R AF 3kW 8ms/12ms smallfocus
70kV 10R 02 3kW smallfocus
70kV 10R 02 2kW smallfocus
20
70kV 20R AF 3kW smallfocus
70kV 10R AF 3kW smallfocus
0
4
6
8
Nominal Phantom Thickness (inches)
10
70kV 20R AF 3kW 8ms/12ms smallfocus
70kV Service 00
2009 AAPM Meeting-Phil Rauch
Image Quality Assessment
2009 AAPM Meeting-Phil Rauch
Image Quality Assessment
Evaluation
Descriptors
(HVS)
Contrast
Edge
Detection
Noise
Sharpness
Pattern
Recognition
Saturation
Comparison
Artifacts
Assessment
Relevance
Conclusion
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
3
Is Pulse Width Important?
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
Fluoroscopic Image Quality
me
(Fra n
Blur gratio
inte ime)
T
Is Pulse Width Important?
Exposure ON-time – Pulsed vs Cont
Image Intensifier
Flat Panel
Pulsed Fluoro*
(30 pulses per sec)
*Displayed at 7.5 fps
2009 AAPM Meeting-Phil Rauch
Continuous Fluoro*
(30 video frames per sec)
*Displayed at 7.5 fps
2009 AAPM Meeting-Phil Rauch
4
Fluoroscopic Image Quality
me
Fra ation
gr
inte ime
t
LAG
(Sig
rete nal
ntion
)
Image Intensifier
Fluoroscopic Image Quality
me
Fra ation
gr
inte ime
t
LAG
(Sig
rete nal
ntion
)
Flat Panel
Image Intensifier
Flat Panel
Rec
ur
filt sive
s et er
ting
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
Blur versus Recursive Filtering
Blur versus Recursive Filtering
Continuous Fluoroscopy
Pulsed Fluoroscopy
Continuous Fluoroscopy
Pulsed Fluoroscopy
Without Recursive Filtering
With Recursive Filtering
Without Recursive Filtering
With Recursive Filtering
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
5
Fluoroscopic Image Quality
me
Fra ation
gr
inte ime
t
LAG
(Sig
rete nal
ntion
)
Image Intensifier
Perceptual Integration
Where are the 3’s
Flat Panel
Rec
ur
filt sive
set er
ting
l
tua
cep ion
Per grat
e
int
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
Perceptual Integration
Perceptual Integration
Where are the 3’s
Where are the 3’s
30 Frames/sec
2009 AAPM Meeting-Phil Rauch
8 Frames/sec
2009 AAPM Meeting-Phil Rauch
6
Wedge
Filter
Acquisition
Type
Spatial
Beam
Shaping
Collimation
without
Radiation
Geometry
Iris
(Lead)
Measurement
Video
Camera
Last Image Hold
SID
SSD
FOV
Electronic
Zoom
Fluoroscopy
ON-Time
Generator Fluoroscopy Power Curves
Normal Level
FDA
Max
FDA
21CFR
Patient
Exposure
High Level
Minimum
Filtration
Patient Size
Dose
Mode
EERD
†
Scatter to
Primary Ratio
Spectral
Filtration
X-ray
Generator
120
Noise
Anti-scatter
Grid
110
Dynamic
Range
Detector
Characteristics
Spatial
Resolution
Pulsed
Fluoroscopy
Fluoroscopy
Waveform
Grid
Control
100
Cont. Low - 30 (video) fps
90
MTF
80
Luminance
Display
Characteristics
kV
X-ray
Tube
DQE
Image
Quality
Contrast
Resolution
Temporal
Resolution
kV-mA
Power Curves
130
Normal
Scan
Slow
Scan
SNR
Spectral
Beam
Shaping
Generator Fluoroscopy Technique
Iris
(Optical)
Image Size
kVp
Beam
Alignment
70
Contrast
60
Pulse Width
Gamma
0.0
0.5
Continuous
Fluoroscopy
†
EERD = Entrance Exposure Rate to Detector
2.0
2.5
3.0
3.5
4.0
2009 AAPM Meeting-Phil Rauch
Generator Fluoroscopy Technique
Generator Fluoroscopy Power Curves
Generator Fluoroscopy Power Curves
130
130
120
120
110
110
Cont. Norm - 30 (video) fps
kVp
kVp
1.5
mA
Generator Fluoroscopy Technique
100
1.0
Pulse Rate
90
100
Pulsed - 30 pps
Cont. Norm - 30 (video) fps
90
Cont. Low - 30 (video) fps
Cont. Low - 30 (video) fps
80
80
70
70
60
60
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0.0
0.5
mA
2009 AAPM Meeting-Phil Rauch
1.0
1.5
2.0
2.5
3.0
3.5
4.0
mA
2009 AAPM Meeting-Phil Rauch
7
Generator Fluoroscopy Technique
Generator Fluoroscopy Technique
Generator Fluoroscopy Power Curves
Generator Fluoroscopy Power Curves
90
90
80
80
kVp
100
kVp
100
70
70
60
60
H ig h D o s e P u ls e d - 3 . 7 5 p p s / 0 .2 m m C u S p e c t ra l F ilt e r
N o rm a l D o s e P u ls e d - 3 . 7 5 p p s / 0 . 2 m m C u S p e c t ra l F ilt e r
N o rm a l D o s e P u ls e d - 3 . 7 5 p p s / 0 . 2 m m C u S p e c t ra l F ilt e r
50
50
0
5
10
15
20
25
30
35
40
45
0
5
10
15
20
mA
25
30
35
40
45
mA
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
Generator Fluoroscopy Technique
Generator Fluoroscopy Technique
Generator Fluoroscopy Power Curves
Generator Fluoroscopy Power Curves
90
90
80
80
kVp
100
kVp
100
70
70
60
60
H ig h P u ls e d - 15 p p s / 0 . 2 m m C u S p e c t ra l F ilte r
N o rm a l D o s e P u ls e d - 15 p p s / 0 . 2 m m C u S p e c t ra l F ilt e r
N o rm a l D o s e P u ls e d - 15 p p s / 0 . 2 m m C u S p e c t ra l F ilt e r
50
50
0
5
10
15
20
25
30
35
40
45
0
mA
2009 AAPM Meeting-Phil Rauch
5
10
15
20
25
30
35
40
45
mA
2009 AAPM Meeting-Phil Rauch
8
Generator Fluoroscopy Technique
Generator Fluoroscopy Technique
Generator Fluoroscopy Power Curves
Generator Fluoroscopy Power Curves
100
90
90
80
80
kVp
kVp
100
70
70
60
60
High Dose Continuous / 0.2mm Cu Spectral Filter)
Normal Dose Continuous / 0.2mm Cu Spectral Filter
Normal Dose Continuous / 0.2mm Cu Spectral Filter
50
50
0
5
10
15
20
25
30
35
40
45
0
5
10
15
20
mA
25
30
35
40
45
mA
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
Entrance Exposure Rate to Detector
EERD Test Conditions
RELATIVE EERD vs kVp
210%
200%
Detector Exposure Rate
Normalized to Minimum
Solid state
detectors must be
positioned outside
the automatic dose
rate measurement
field
190%
180%
170%
Siemens Siregraph - 22 cm FOV X-ray
Image Intensifier Detector
160%
150%
140%
130%
120%
110%
100%
90%
80%
40
50
60
70
80
90
100
110
kVp
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
9
EERD Test Conditions
EERD Test Conditions
RELATIVE EERD vs kVp
RELATIVE EERD vs kVp
210%
210%
200%
Detector Exposure Rate
Normalized to Minimum
Detector Exposure Rate
Normalized to Minimum
200%
190%
Siemens Artis Zee - 42 cm FOV Indirect
Flat Panel Detector (CsI(Tl)/TFT)
180%
170%
160%
Siemens Siregraph - 22 cm FOV X-ray
Image Intensifier Detector
150%
140%
130%
120%
110%
100%
190%
170%
Siemens Artis Zee - 42 cm FOV Indirect
Flat Panel Detector (CsI(Tl)/TFT)
160%
150%
Siemens Siregraph - 22 cm FOV X-ray
Image Intensifier Detector
140%
130%
120%
110%
100%
90%
90%
80%
80%
40
50
60
70
80
90
100
40
110
50
60
70
80
90
100
110
kVp
kVp
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
EERD Test Conditions
EERD Test Conditions
EERD for Different Attenuators
RELATIVE EERD vs kVp
250
210%
Acrylic (inches)
190%
EERD (micro-R per sec)
200%
Detector Exposure Rate
Normalized to Minimum
Philips Xper - 22 cm FOV Indirect Flat
Panel Detector (CsI(Tl)/TFT)
180%
Shimadzu Bransist - 22 cm FOV Direct
Flat Panel Detector (Se/TFT)
180%
Philips Xper - 22 cm FOV Indirect Flat
Panel Detector (CsI(Tl)/TFT)
170%
160%
Siemens Artis Zee - 42 cm FOV Indirect
Flat Panel Detector (CsI(Tl)/TFT)
150%
Siemens Siregraph - 22 cm FOV X-ray
Image Intensifier Detector
140%
130%
120%
110%
200
Aluminum (inches)
Copper (mm)
150
100
50
100%
90%
0
80%
40
50
60
70
80
90
100
110
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0
kVp
2009 AAPM Meeting-Phil Rauch
Attenuator Thickness
2009 AAPM Meeting-Phil Rauch
10
Image Quality: What is it?
“Image quality depends only on intrinsic, objective
physical characteristics of an imaging system, and can
be measured independently of an observer”
Detector Input Dose Rates (FP)
Image Intensifier
Detector Metrics
Flat Panel
Definitions courtesy Ralph Schaetzing, Agfa Corp.
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
Image Detector
Pixel Pitch – Estimated Resolution
Indirect Conversion FPD
Pixel Pitch
Detector
Safire (a-Se, a-Si TFT)
Philips, Siemens (CsI(Tl), a-Si TFT) - Angio
Philips, Siemens (CsI(Tl), a-Si TFT) - Cardiac
GE, Revolution (CsI(Tl), a-Si TFT)
2009 AAPM Meeting-Phil Rauch
Mfg.
Shimadzu
Trixell
Trixell
GE
Pixel Nyquist Nyquist x 2^(.5)
Pitch (lp/mm)
(lp/mm)
0.150 3.33
4.71
0.154 3.25
4.59
0.184 2.72
3.84
0.200 2.50
3.54
Mesh Lines
per Inch at
45-degrees
120
117
98
90
2009 AAPM Meeting-Phil Rauch
11
Actual Resolution
Image Quality Assessment
Detroit Phantom
Archived 512 x 512
Archived 1024 x 1024
2009 AAPM Meeting-Phil Rauch
Image Quality Assessment
2009 AAPM Meeting-Phil Rauch
Image Quality Assessment
FOV Coverage
Motion blur
Resolution
Contrast to noise
Comparison with other
fluoroscopy equipment
Rotational Angiography
3D Reconstruction
Recursive Filter effects
Image processing effects
Pixel matrix effects
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
12
Image Quality Assessment
FOV Coverage
Motion blur
Resolution
Contrast to noise
Comparison with other
fluoroscopy equipment
Rotational Angiography
3D Reconstruction
Recursive Filter effects
Image processing effects
Pixel matrix effects
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
Rotational Angiography
Digital Radiograph
2009 AAPM Meeting-Phil Rauch
Image Quality Assessment
Rotational Angiography
Image Quality Assessment
Digital Radiograph
Image Quality Assessment
3-D Reconstruction
Digital Radiograph
2009 AAPM Meeting-Phil Rauch
13
Image Detector (Fluoro LIH)
Image Detector (Fluoro LIH)
Indirect Conversion FPD
Can you match the fluoroscopy LIH
image to the detector?
A. Image Intensifier
B. Indirect Flat Panel
C. Direct Flat Panel
?
2009 AAPM Meeting-Phil Rauch
Image Detector (Fluoro LIH)
Car Moving
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
Image Detector (Fluoro LIH)
Car Stationary
2009 AAPM Meeting-Phil Rauch
14
Resolution
Resolution
Can you see a 50- moving wire using a flat panel
detector with a pixel pitch of 150-? With a pixel
pitch of 200-?
Direct Capture, 150- pixel pitch
Indirect Capture, 200- pixel pitch
Wire size numbers are located below the corresponding wire
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
Image Detector (Fluoro LIH)
Detector Input Dose Rates (XRII)
Indirect Conversion FPD
Cannot rely on reported detector metrics
alone. Must understand and appropriately
utilize optimum technical settings and
image processing
2009 AAPM Meeting-Phil Rauch
Dose Rate
Selection
Field of View
Selection
2009 AAPM Meeting-Phil Rauch
15
Detector Input Dose Rates (XRII)
Detector Input Dose Rates (XRII)
Dose Rate
Selection
Dose Rate
Selection
Low
Norm
High
Low
Field of View
Selection
Field of View
Selection
40 cm
30 cm
22 cm
17 cm
30 cm
Continuous Fluoroscopy: Input dose per frame of fluoroscopy?
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
Detector Input Dose Rates (XRII)
•
•
•
Low Dose Mode
Cont. Fluoroscopy
30 cm FOV
Detector Input Dose/Fr?
A.
B.
C.
D.
E.
F.
•
•
•
Low
0.37 µR (3.2 nGy)
0.75 µR (6.6 nGy)
30 cm
1.5 µR (13.1 nGy)
3.0 µR (26.3 nGy)
……values assume FDA minimum beam filtration
6.0 µR (52.6 nGy)
No Clue
2009 AAPM Meeting-Phil Rauch
Detector Input Dose Rates (XRII)
Low Dose Mode
Cont. Fluoroscopy
30 cm FOV
Detector Input Dose/Fr?
A.
B.
C.
D.
E.
F.
Low
0.37 µR (3.2 nGy)
0.75 µR (6.6 nGy)
30 cm
1.5 µR (13.1 nGy)
3.0 µR (26.3 nGy)
……values assume FDA minimum beam filtration
6.0 µR (52.6 nGy)
No Clue
2009 AAPM Meeting-Phil Rauch
16
Detector Input Dose Rates (XRII)
•
•
•
Low Dose Mode
Cont. Fluoroscopy
30 cm FOV
•
•
•
Detector Input Dose/Fr?
A.
B.
C.
D.
E.
F.
Low Dose Mode
Cont. Fluoroscopy
30 cm FOV
Detector Input Dose/Fr?
1x 1.5x 3.0x
0.37 µR (3.2 nGy)
0.75 µR (6.6 nGy)
1.5 µR (13.1 nGy)
3.0 µR (26.3 nGy)
……values assume FDA minimum beam filtration
6.0 µR (52.6 nGy)
……can use 2x these values if minimum 0.2 mm Cu
No Clue
beam filtration is utilized
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
Detector Input Dose Rates (XRII)
•
•
•
Detector Input Dose Rates (XRII)
Low Dose Mode
Cont. Fluoroscopy
30 cm FOV
Detector Input Dose/Fr?
Video Frame Rate
What is the video frame rate in the U.S.A.?
Ans: 30 video frames per second
1x 1.5x 3.0x
40 cm
30 cm
22 cm
17 cm
Detector dose scales inversely as either the
ratio of the FOV, or as the ratio squared
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
17
Detector Input Dose Rates (XRII)
Rauch's 30-30-30 Rule:
For a nominal 30 cm image intensifier field of view (FOV),
Pulse rate of 30 pps,
Set the EERD to 30 3R/sec
For other FOV's, scale by either the ratio of the FOV (auto
optical lens aperture) or the square of the ratio
For spectral beam filtration…
0.1 mm Cu equivalent, multiply by 1.41
0.2 mm Cu equivalent, multiply by 2
Detector Input Dose Rates (FP)
Image Intensifier
Detector Metrics
(Fluoroscopy Doses)
Flat Panel
Adapted from Koch, A., Macherel, J.M., Wirth, T., de Groot, P., Ducourant, T., Couder, D.,
Moy, J.P., & Calais, E. (2001). Detective quantum efficiency of an X-ray image intensifier
chain as a benchmark for amorphous silicon flat panel detectors, Proc. SPIE, 4320, 115-20
For flat panel, special consideration is required!!
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
Detector Input Dose Rates (FP)
Detector Metrics
(Fluoroscopy Doses)
Pixel Pitch – Air Kerma per Pixel
Image Intensifier
Pixel Pitch
Flat Panel
“The minimum operating dose level is defined by the
magnitude of the noise arising in the AM array and
readout electronics. This typically sets the lower
operating limit for detector dose at 20-50 nGy.”
Cowen AR et al., Solid-state, flat-panel, digital radiography detectors and their
physical imaging characteristics, Clin Radiol (2008)
2009 AAPM Meeting-Phil Rauch
Detector
Safire (a-Se, a-Si TFT)
Philips, Siemens (CsI(Tl), a-Si TFT) - Angio
Philips, Siemens (CsI(Tl), a-Si TFT) - Cardiac
GE, Revolution (CsI(Tl), a-Si TFT)
Mfg.
Shimadzu
Trixell
Trixell
GE
Pixel
Pitch
0.150
0.154
0.184
0.200
For the transition from XRII
to Flat Panel, the required
EERD can be estimated by
determining the air kerma
required for the XRII when it
is operating at the same pixel
pitch at that for the flat
panel.
2009 AAPM Meeting-Phil Rauch
18
Pixel Pitch vs Input Dose
Pixel
Pitch
(mm)
Equivalent
XRII Diam (cm)
for 1024 Pixels Diam^2
Pixel Pitch vs Input Dose
Ratio wrt
30 cm EERD EERD
FOV
(µR) (nGy)
XRII
Pixel
Pitch
(mm)
Equivalent
XRII Diam (cm)
for 1024 Pixels Diam^2
XRII
0.293
30.00
900.00
1.00
1.00*
8.76
0.293
15.36
15.77
18.84
20.48
235.93
248.68
355.01
419.43
3.81
3.62
2.54
2.15
3.81
3.62
2.54
2.15
33.42
31.70
22.21
18.80
0.150
0.154
0.184
0.200
Flat Panel
0.150
0.154
0.184
0.200
30.00
900.00
1.00
1.00*
8.76
15.36
15.77
18.84
20.48
235.93
248.68
355.01
419.43
3.81
3.62
2.54
2.15
3.81
3.62
2.54
2.15
33.42
31.70
22.21
18.80
Flat Panel
*Per Rauch’s 30-30-30 rule
*Per Rauch’s 30-30-30 rule
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
Pixel Pitch vs Input Dose
Pixel
Pitch
(mm)
Ratio wrt
30 cm EERD EERD
FOV
(µR) (nGy)
Equivalent
XRII Diam (cm)
for 1024 Pixels Diam^2
Pixel Pitch vs Input Dose
Ratio wrt
30 cm EERD EERD
FOV
(µR) (nGy)
XRII
0.293
Equivalent
XRII Diam (cm)
for 1024 Pixels Diam^2
Ratio wrt
30 cm EERD EERD
FOV
(µR) (nGy)
XRII
30.00
900.00
1.00
1.00*
8.76
0.293
15.36
15.77
18.84
20.48
235.93
248.68
355.01
419.43
3.81
3.62
2.54
2.15
3.81
3.62
2.54
2.15
33.42
31.70
22.21
18.80
0.150
0.154
0.184
0.200
Flat Panel
0.150
0.154
0.184
0.200
Pixel
Pitch
(mm)
30.00
900.00
1.00
1.00*
8.76
15.36
15.77
18.84
20.48
235.93
248.68
355.01
419.43
3.81
3.62
2.54
2.15
3.81
3.62
2.54
2.15
33.42
31.70
22.21
18.80
Flat Panel
*Per Rauch’s 30-30-30 rule
*Per Rauch’s 30-30-30 rule
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
19
Pixel Pitch vs Input Dose
Pixel
Pitch
(mm)
Equivalent
XRII Diam (cm)
for 1024 Pixels Diam^2
Pixel Pitch vs Input Dose
Ratio wrt
30 cm EERD EERD
FOV
(µR) (nGy)
XRII
0.293
Equivalent
XRII Diam (cm)
for 1024 Pixels Diam^2
Ratio wrt
30 cm EERD EERD
FOV
(µR) (nGy)
XRII
30.00
900.00
1.00
1.00*
8.76
0.293
15.36
15.77
18.84
20.48
235.93
248.68
355.01
419.43
3.81
3.62
2.54
2.15
3.81
3.62
2.54
2.15
33.42
31.70
22.21
18.80
0.150
0.154
0.184
0.200
Flat Panel
0.150
0.154
0.184
0.200
Pixel
Pitch
(mm)
30.00
900.00
1.00
1.00*
8.76
15.36
15.77
18.84
20.48
235.93
248.68
355.01
419.43
3.81
3.62
2.54
2.15
3.81
3.62
2.54
2.15
33.42
31.70
22.21
18.80
Flat Panel
*Per Rauch’s 30-30-30 rule
*Per Rauch’s 30-30-30 rule
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
Detector Input Dose Rates
Dose Per Pulse (<30 pps)
For pulse rates lower than 30 pps, use Aufrichtig*
perceptual pulsed fluoroscopy scale factor to adjust
dose per frame for different frame rates
1x 1.5x 3.0x
(Dose/Pulse)2 = (Dose/Pulse)1*SQRT[(Pulse Rate)1/(Pulse Rate)2]
Example: Change from 30pps to 7.5 pps
What about pulsed fluoroscopy?
(Dose/Pulse)2 = (Dose/Pulse)1*SQRT[30/7.5]
= (Dose/Pulse)1*2
*Perceptual comparison of pulsed and continuous fluoroscopy, Richard Aufrichtig,
Med. Phys. 21 (2), February 1994
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
20
Dose Per Pulse (<30 pps)
C-arm Dose Rates
Mobile C-arm Operational Settings
For pulse rates lower than 30 pps, use Aufrichtig*
perceptual pulsed fluoroscopy scale factor to adjust
dose per frame for different frame rates
For pulse rate of 5 per second or lower, use
the Aufrichtig calculated value for 5 pps
(The retina can only retain an image for 200 ms, so there is
no integration of noise for pulse rates of 5 pps or lower)
2009 AAPM Meeting-Phil Rauch
Operational Mode
Max Dose Rate
(mGy/min)
6
37
Low dose
Boost Continuous
9
55
Default dose
Non-boost Continuous
12
67
Default dose
Boost Continuous
22
148
Low dose
Non-boost Pulsed
6
82
Low dose
Boost Pulsed
37
2833
Default dose
Non-boost Pulsed
12
132
Default dose
Boost Pulsed
74
3143
Acquisition Modes
1
2
3
2009 AAPM Meeting-Phil Rauch
EERD 1
(nGy/pulse)
Low dose
Non-boost Continuous
Operator can store 0 to 30
frames/sec (maxed at selected
pulse rate
15, 30 pps
Ability to select “Low dose”
Ability to use the two foot pedals
All frames recorded
15, 30 pps
Ability to select “Low dose”
Ability to use the two foot pedals
All frames recorded
C-arm Dose Rates
EERD and Max Dose Rate (FDA)
Mobile C-arm Operational Settings
– Left: Normal Fluoro
– Right: Boost Fluoro
– Left: Normal Fluoro
– Right: Boost Fluoro
Operator can store 0 to 30
frames/sec (maxed at selected
pulse rate
2009 AAPM Meeting-Phil Rauch
C-arm Dose Rates
Cont., 8, 4, 2, 1 pps
Ability to select “Low” dose
Two foot pedals:
Cont., 8, 4, 2, 1 pps
Ability to select “Low” dose
Two foot pedals:
Acquisition Modes
*Perceptual comparison of pulsed and continuous fluoroscopy, Richard Aufrichtig,
Med. Phys. 21 (2), February 1994
XRII Imaging System (31cm FOV)
Filtration equiv to 0.1 mm Cu
Fluoro modes:
XRII Imaging System (31cm FOV)
Filtration equiv to 0.1 mm Cu
Fluoro modes:
EERD per pulse is the same for all pulse rates
Data for 8pps & 4pps; scales with pulse rate below 4pps
Data for 30pps; scales with pulse rate, except 8pps and
4pps have the same max rate due to change in pulse width
EERD and Max Dose Rate (FDA)
Dose Rate Analysis
Operational Mode
EERD 1
(nGy/pulse)
Max Dose Rate
(mGy/min)
Low dose
Non-boost Continuous
6
37
Low dose
Boost Continuous
9
55
Default dose
Non-boost Continuous
12
67
Default dose
Boost Continuous
22
148
Are these values acceptable?
Values exceed the FDA limits of 176
mGy/min for high dose fluoroscopy
EERD dose not change with pulse
rate, so the same detector dose is
delivered at 1pps as at 30pps
Appears to be pulsed fluoroscopy….
….but the 15pps and 30pps are
labeled “Cine”, and all frames are
recorded.
The FDA limits do not apply
1
2
3
2009 AAPM Meeting-Phil Rauch
Low dose
Non-boost Pulsed
6
82
Low dose
Boost Pulsed
37
2833
Default dose
Non-boost Pulsed
12
132
Default dose
Boost Pulsed
74
3143
EERD per pulse is the same for all pulse rates
Data for 8pps & 4pps; scales with pulse rate below 4pps
Data for 30pps; scales with pulse rate, except 8pps and
4pps have the same max rate due to change in pulse width
21
Entrance Exposure Rate to Detector
EERD and Max Dose Rate (FDA)
EERD Analysis
Using Rauch 30-30-30 rule,
adjustment for filtration, and
Aufrichtig scale, expect 11.6 nGy
per pulse for 30 pps†
Measured default non-boost values
are in agreement for 30pps
However, for pulsed mode the
dose does not change as the pulse
rate is reduced (Does not follow
the Aufrichtig scale)
Result is too low a dose for the
lower pulse rates, which may
discourage operators from using
the lower rates
Operational Mode
Max Dose Rate
(mGy/min)
Operational Mode
EERD 1
(nGy/pulse)
Max Dose Rate
(mGy/min)
Low dose
Non-boost Continuous
6
37
6
37
9
55
Low dose
Boost Continuous
9
55
Default dose
Non-boost Continuous
12
67
Default dose
Non-boost Continuous
12
67
Default dose
Boost Continuous
22
148
Default dose
Boost Continuous
22
148
Low dose
Non-boost Pulsed
2
2009 AAPM Meeting-Phil Rauch
6
82
Low dose
Non-boost Pulsed
6
82
Low dose
Boost Pulsed
37
2833
Low dose
Boost Pulsed
37
2833
Default dose
Non-boost Pulsed
12
132
Default dose
Non-boost Pulsed
12
132
Default dose
Boost Pulsed
74
3143
Default dose
Boost Pulsed
74
3143
EERD per pulse is the same for all pulse rates
Data for 8pps & 4pps; scales with pulse rate below 4pps
Data for 30pps; scales with pulse rate, except 8pps and
4pps have the same max rate due to change in pulse width
Entrance Exposure Rate to Detector
EERD and Max Dose Rate (FDA)
Analysis
Operational Mode
EERD 1
(nGy/pulse)
Max Dose Rate
(mGy/min)
Low dose
Non-boost Continuous
6
37
Low dose
Boost Continuous
9
55
Default dose
Non-boost Continuous
12
67
Default dose
Boost Continuous
22
148
Low dose
Non-boost Pulsed
6
82
Low dose
Boost Pulsed
37
2833
Default dose
Non-boost Pulsed
12
132
Default dose
Boost Pulsed
74
3143
1
2
3
2009 AAPM Meeting-Phil Rauch
Expect low dose mode to be about
1/2 to 2/3 of the default dose
Measured non-boost values are in
agreement
Low dose
Boost Continuous
3
Expected values for default boost
pulsed would be 2x to 3x the nonboost values
Measured default boost pulsed
values are 6x larger than nonboost
EERD and Max Dose Rate (FDA)
Analysis
Low dose
Non-boost Continuous
1
†8.76nGy*(30/31)2*SQRT(30/30)*1.41
EERD 1
(nGy/pulse)
Entrance Exposure Rate to Detector
EERD per pulse is the same for all pulse rates
Data for 8pps & 4pps; scales with pulse rate below 4pps
Data for 30pps; scales with pulse rate, except 8pps and
4pps have the same max rate due to change in pulse width
1
2
3
2009 AAPM Meeting-Phil Rauch
EERD per pulse is the same for all pulse rates
Data for 8pps & 4pps; scales with pulse rate below 4pps
Data for 30pps; scales with pulse rate, except 8pps and
4pps have the same max rate due to change in pulse width
Entrance Exposure Rate to Detector
EERD and Max Dose Rate (FDA)
Analysis
Using Rauch 30-30-30 rule,
adjustment for filtration, and
Aufrichtig scale, expect 28.4 to
56.8 nGy per pulse for boost at 5
pps or lower†
Measured default boost value is
much larger than this estimate
Furthermore, the dose does not
change as the pulse rate is
increased (Does not follow the
Aufrichtig scale)
Result is much larger than
necessary doses for the higher
frame rates
Operational Mode
EERD 1
(nGy/pulse)
Max Dose Rate
(mGy/min)
Low dose
Non-boost Continuous
6
37
Low dose
Boost Continuous
9
55
Default dose
Non-boost Continuous
12
67
Default dose
Boost Continuous
22
148
1
†8.76nGy*(30/31)2*SQRT(30/5)*2
2
3
2009 AAPM Meeting-Phil Rauch
Low dose
Non-boost Pulsed
6
82
Low dose
Boost Pulsed
37
2833
Default dose
Non-boost Pulsed
12
132
Default dose
Boost Pulsed
74
3143
EERD per pulse is the same for all pulse rates
Data for 8pps & 4pps; scales with pulse rate below 4pps
Data for 30pps; scales with pulse rate, except 8pps and
4pps have the same max rate due to change in pulse width
22
Rauch’s 30-30-30 Rule
Use the previous type analysis to determine how
the vendor specified or measured EERD compares
with the expected values
Use the rule to compare measured values with the
expected change in EERD whenever there are
variations in the field of view, filtration, or pulse
rate
Image Quality: What is it?
“Image quality depends only on intrinsic, objective
physical characteristics of an imaging system, and can
be measured independently of an observer”
“Image quality is whatever the observer says it is (i.e.,
it is a subjective perception of the image, ‘in the eye of
the beholder’)”
Definitions courtesy Ralph Schaetzing, Agfa Corp.
2009 AAPM Meeting-Phil Rauch
2009 AAPM Meeting-Phil Rauch
Fluoroscopic Image Quality
Biliary endoscopic catheterization
Mobile C-arm
Gastroenterology clinic (No X-ray techs)
1024 x 1280 x 12 bit image
Secondary capture of fluoro frame
Human Visual Perception
2009 AAPM Meeting-Phil Rauch
23
Observations
Mottled
Blurred, probably due to long pulse width
Low dynamic range
Lack of detail
Fluoro Frame
8-Bit Grayscale
512 x 512 Matrix
Flat Detector
Modality Image downsized from 10242
Inappropriate anatomical setting
No x-ray technique or image processing
information available in the DICOM
metadata
Fluoro Frame
12-Bit Grayscale
1024 x 1024 Matrix
Flat Detector
Modality Store Monitor Image
Fluoro Frame
8-Bit Grayscale
768 x 576 Matrix
XRII
Digital Video Screen Capture via DVR
Fluoro Frame
12-Bit Grayscale
1024 x 1024 Matrix
Flat Detector
Modality Store Monitor Image
Fluoro Frame
8-Bit Grayscale
768 x 576 Matrix
XRII
Digital Video Screen Capture via DVR
Fluoro Frame
8-Bit Grayscale
884 x 884 Matrix
XRII
Screen Capture via Paxport
24
Dynamic Range
2009 AAPM Meeting-Phil Rauch
Fluoroscopy – Vascular Mode
Digital Radiography
Trixell Pixium 4700 (0.154 µ; 2480 x 1910 matrix
Trixell Pixium 4600 (0.143 µ; 3001 x 3001 matrix
Video Bandwidth
•Three display monitors provide with installation
(Live fluoroscopy, Roadmap, Reference)
•A single video graphics display card is used to simultaneously paint all
three images and graphics
Fluoroscopy – Vascular Mode
Fluoroscopy – Cardiac Mode
Trixell Pixium 4700 (0.154 µ; 2480 x 1910 matrix
Trixell Pixium 4700 (0.154 µ; 2480 x 1910 matrix
•Result is a loss of resolution when compared with the display of single
images on a modality workstation or on PACS
2009 AAPM Meeting-Phil Rauch
25
Test Your Knowledge
Test Your Knowledge
Question:
Name two ways the vessel
contrast can appear as in
this image
Answer:
1. Start injection of
contrast well before
starting the run
2. Change the mask to a
frame after the contrast
has filled some vessels
2009 AAPM Meeting-Phil Rauch
Test Your Knowledge
Why are these image so different?
2009 AAPM Meeting-Phil Rauch
Test Your Knowledge
Why are these image so different?
72 kVp, 250 mA, 8 ms
1024 x 1024 x 8 bits
2009 AAPM Meeting-Phil Rauch
65 kVp, 15 mA, 13 ms
512 x 512 x 8 bits
2009 AAPM Meeting-Phil Rauch
26
Image Quality Analysis
Spectral filtration
Bolus filters
Generator power curves
Pulse width
Grid vs Non-grid
Collimation
Detector dose per
image
Anatomical program
selection
Recursive filter setting
Edge enhancement
Harmonization (Dynamic
Range(
Pixel matrix and bit depth
for acquisition
Pixel matrix and bit depth
stored
Pixel matrix and bit depth
archived
2009 AAPM Meeting-Phil Rauch
Image Interpretation
Successful interpretation depends on…
Image Attributes
Human Observer (education, experience)
Human Visual Perception
Pattern Recognition
Clarity of the imaging task
Minimal external distractions
Level of confidence
2009 AAPM Meeting-Phil Rauch
Image Quality: What is it?
“Image quality depends only on intrinsic, objective
physical characteristics of an imaging system, and can
be measured independently of an observer”
“Image quality is whatever the observer says it is (i.e.,
it is a subjective perception of the image, ‘in the eye of
the beholder’)”
“Image quality is defined by an observer's ability to
achieve an acceptable level of performance for a
specified task”
Definitions courtesy Ralph Schaetzing, Agfa Corp.
2009 AAPM Meeting-Phil Rauch
Conclusions
Image quality is not just detector metrics
Image quality is not just a subjective impression
Image quality for fluoroscopy must be assessed
with moving objects in order to get a complete
understanding of performance
Use pulsed fluoroscopy and the Aufrichtig scale to
produce better images, not solely to reduce dose
2009 AAPM Meeting-Phil Rauch
27
Final Imaging Task
How can this be true?
Thank you
Below the
four parts
are reordered
Phil Rauch
philr@rad.hfh.edu
The four
parts are
exactly the
same as
those used
above
Why is there an extra square?
2009 AAPM Meeting-Phil Rauch
28