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IAEA Training Material on Radiation Protection in Cardiology

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IAEA
International Atomic Energy Agency
Optimization of Radiation
Protection in Cardiology
L9
Educational Objectives
1. Optimization in interventional cardiology
2. Ways to improve the radiation protection
aspect of procedure (balancing diagnostic
information versus patient doses)
3. A single-centre’s (Udine, Italy) experience
with optimization and flat panel detector
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
2
IAEA
Is this statement “True” or “False”?
1. Switching from old angiography machine
with image intensifier to a new machine with
flat-panel detector will definitely reduce
patient radiation dose.
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Have you ever paid
attention to this?
In room dosimetric indications
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
4
IAEA
Do you know how to interpret these data?
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Reality check……
Dose Information and Dose Reports
• Understanding the dose information available in the
cath. lab.?
• Do you follow (and archive) patient dose reports?
• Understanding the dose values in your occupational
dose report?
• Can you make out if the dose values as depicted in
the monitor in cath. lab. are “normal” or “too high”?
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Reality check……
Knowing your X ray machine
• What is the “cost” in radiation dose you are
“paying” for the image quality you want?
• Have you evaluated whether fewer images with lower
image quality are acceptable?
• Do you know the dose rate values and dose/image for
the different operation modes?
• Do you know the difference in dose for the different
field of view (FOV) formats (magnification)?
• Do you know how to use the newer dose-reducing
features?
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Siemens Axiom Artis, Fluoro
low dose
20 cm PMMA
13 пЃ­Gy/fr (entrance PMMA)
Radiation Protection in Cardiology
Siemens Axiom Artis
Cine normal mode
20 cm PMMA
177 пЃ­Gy/fr (entrance PMMA)
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Optimization means ...
• To avoid acquiring more images than
necessary:
• Take care of the fluoroscopy time.
• Take care of the number of series.
• Take care of the number of frames per series.
• To avoid acquiring images with more quality
(and more dose) than necessary:
• It could be possible to accept sometimes some noisy
images in fluoroscopy and also in cine acquisitions.
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Optimization of Radiation Protection
• Minimization of dose to patient and staff
should not be the goal
• Must optimize dose to patient and minimize
dose to staff
• Optimized patient dose rate should have
sufficient dose rate to provide adequate image
quality
If image quality is inadequate, then any
radiation dose results in needless radiation
dose!
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
10
IAEA
IAEA
International Atomic Energy Agency
One of the center's experience with
new angiographic machine having
flat panel detector
Video Signal
Video
Camera
Readout Electronics
Electrons
2,400
Motorized
Iris
CCD or PUT
Light
400,000
Output screen
Digital Data
Electrons
400
Read Out Electronics
Light
3,000
Cesium Iodide (CsI)
1
Photons
DETECTOR
Image
Intensifier
Photo-cathode
Electrons
Amorphous Silicon Panel
(Photodiode/Transistor Array)
Light
Cesium Iodide (CsI)
Particles #
Photons
Image
Intensifier
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
Flat-panel
12
IAEA
IAEA
International Atomic Energy Agency
Anticipated per-frame dose
reduction with Digital Flat
Panel technology is 30%
Coronary Angiography and Angioplasty
Udine, years 1990-2002
Philips Integris 3000 (1995)
Philips OM 200 (1983)
2000
diagnostic
PCI
1500
performed by 3
interventionalists
except in 1998
1000
500
0
'90
'91
'92
'93
Radiation Protection in Cardiology
'94
'95
'96
'97
'98
'99
'00
'01
'02
Lecture 9: Optimization of Radiation Protection in Cardiology
'03
14
IAEA
GE Innova 2000 (angiographic machine with
digital flat panel technology) at Udine Center
• Activity started
пѓ�04/12/2002
• Jan - Oct 2003
пѓ�1421 procedures (79% of total)
• 1019
diagnostic coronary angiography
• 402
percutaneous coronary angioplasty
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Comparison of Philips H 3000 and Innova 2000 in PCI
-- Characteristics of patients
90
77
80
70
66
78
H 3000: 588 pts, 90% of tot.
treated in the year 2002
66
60
56
53
50
Innova: 274 pts, 67% of tot.
treated between Jan-Oct 2003
38.5
40
31.2 30.8
35.4
33.4
30.8
30
20
10
1.9 1.9
0
age
(y)
male sex (%)
Radiation Protection in Cardiology
BSA (sqm)
EF
(%)
1
2
3
diseased vessels (%)
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Comparison of Philips H 3000 and Innova 2000 in PCI
-- Characteristics of procedures & lesions (1)
70
65.9
60
H 3000
56.5
Innova
50
%
40
30
22.9
25.5
20
15.3
14.8
11.3
10.2
10
6.1
6.6
3.6
2.6
3.2
2.9
0
on
e si
l
1
mu
s
s
e
1v
n
sio
e
l
lt i
Radiation Protection in Cardiology
2-3
v
els
s
s
e
++
Ca
+
++
a
C
n
sio
u
l
c
oc
Lecture 9: Optimization of Radiation Protection in Cardiology
0d
>3
d
n
sio
u
l
c
oc
17
d
un
et.
IAEA
Comparison of Philips H 3000 and Innova 2000 in PCI
-- Characteristics of procedures & lesions (2)
40
37.2
H 3000
Innova
35
30
29
25
20
18.1
16.1
15
12.8
10
6.2
5
4.8
4.7
3.6
3.3
Radiation Protection in Cardiology
ab
l.
ity
m
)
vt
se
Lecture 9: Optimization of Radiation Protection in Cardiology
ot
Ar
DC
or
t
uo
s
2m
bi
fu
rc
.(
>
os
ti a
l
C
0
B2
%
22.2 22.3
18
IAEA
Comparison of Philips H 3000 and Innova 2000 in PCI
-- Performance & complexity index
H 3000
2
70
84
1,8
59
60
Innova
1,6
1,4
48
50
1,47
1,37
1,2
40
1
1
40
0,93
0,8
30
24,1
0,6
21,6
20
11,6
0.30
0,4
0,2
11,5
0.29
0.34
0.26
r (with fluoro time)
0
10
0
Fluoro T
proced. T
Radiation Protection in Cardiology
(m’)
room occ.
contrast (dl)
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Comparison of Philips H 3000 and Innova 2000 in
diagnostic procedures
-- Characteristics of patients & procedures
120
H 3000: 1401 pts, 92% of tot.
studied in the year 2002
99 98
100
Innova: 702 pt, 69% of tot.
studied between Jan-Oct 2003
80
72 74
71 69
67 67
60
40
24
20 20
19
18
20
12
9
9
1.9 1.9
AB
G
C
ot
he
r
r.
rt
og
ao
ca
t.
R
LV
co
ro
es
ex
m
al
m
)
(s
q
A
BS
ag
e(
y)
0
(%)
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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Comparison of Philips H 3000 and Innova 2000 in
diagnostic procedures
measured
-- performance indexes and exposure parameters
60
H 3000
50
54 54
calculated
Innova
45.88
40
35.32
31.06
30
28
27.05
24
20.39
20
1,3
18.83
15.6 15.8
10.67
10
4.2 4.4
0
Radiation Protection in Cardiology
m’
Lecture 9: Optimization of Radiation Protection in Cardiology
Gy *
21
cm2
IAEA
Entrance surface dose: H3000 and Innova 2000
Entrance surface dose rates, FOV=17 cm, PMMA=20 cm
70
60
50
Entrance dose 40
rate
30
(mGy/min)
H3000
Innova2000
20
10
0
Low
Normal
High
Image quality
Entrance surface dose rates in Fluoro LOW for Innova is 30% less
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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Why the anticipated 30% per-frame dose
reduction of digital flat panel technology
does not translate into an effective dose
reduction to patients
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Differences in operating conditions of the two
systems
H 3000
Innova
• field of view (cm)
• field of view (cm)
20/17/15/12
23/18/14
• cine mode
• cine mode
15/30 fps
pref 1/pref 2 (lower dose)
12,5/25 fps
• fluoro mode
• fluoro mode
low/medium/high
• filter
automatic
Radiation Protection in Cardiology
low/normal
• filter
manual
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Detectors area are similar
20 cm
400 cm2
375 cm2
H3000
Radiation Protection in Cardiology
Innova200
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Using similar nominal field of view (FOV) sizes
corresponds to very different area of the two X ray beams
17 cm
290 cm2
230 cm2
H3000
Innova200
area +26% пѓ DAP +26% !!!!
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Other possibilities……
пѓ� patients may not be the same
пѓ� procedures may not be the same
� operators’ behavior
пѓј filters/collimation
 use of “difficult” projections (fluoro/cine)
пѓј focus-detector mean distances
� ………
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Collimators use in INNOVA to reduce exposure
FOV 15
dose reduction
25%
Radiation Protection in Cardiology
[still]
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Collimators use in INNOVA to reduce exposure
FOV 20
Radiation Protection in Cardiology
[still]
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
H 3000
improper filtering causes image
deterioration
proper filtering
Filtering prevents image saturation in
low absorption areas
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
INNOVA
improper filtering does not cause
image deterioration
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Skin exposure variation in exposure rate (DAP
rate) with projection
anthropomorphic phantom (average-sized) measurements
Projection
Fluoroscopy
entrance dose rate
(mGy/min)
Cine
entrance dose rate
(mGy/min)
AP
31
388
RAO 30В°
19
203
LAO 40В°
20
216
LAO 40В°, Cran 30В°
80
991
LAO 40В°, Cran 40В°
99
1236
LAO 40В°, Caud 20В°
29
341
Cusma JACC 1999
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Distance between patient and detector
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
The inverse square law
Source
Because the same energy is spread
over a surface 4 times larger at a
doubled distance, the same object
will receive only a fourth of the
dose when moved away from “d”
to “2d”
d
2d
Doubling the distance from
the source divides the dose
by a factor of 4
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
The inverse square law
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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Collimation
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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Anti-scatter grid
Increase DAP and skin dose x 2 times
Improve image quality
To be removed for pediatric patients !!
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
37
IAEA
Coronary Angiography optimization DIMOND Quality
Criteria
Aspects of an optimized angiographic technique
1. Use of the wedge filter on bright peripheral areas
2. 2-3 sequences (except for difficult anatomic details)
3. 12.5-15 frames/s (25-30 only if heart rate exceeds
90-100 bpm or in paediatric patients)
4. 60 images per sequence at average (12.5-15 fr/s)
except if collaterals have to be imaged or in case of
slow flow
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Innova 2000. Changes in exposure parameters over time
-- diagnostic procedures Jul 2003 - Feb 2004
Fluoro T
(m')
5
4
Tot DAP
(Gy*cm2)
34
33
32
31
3
30
29
2
28
27
1
26
25
0
JulAug
Se ptOct
NovDe c
Radiation Protection in Cardiology
JanFe b
Jul-Aug
Se ptOct
Lecture 9: Optimization of Radiation Protection in Cardiology
NovDe c
Jan-Fe b
39
IAEA
IAEA
International Atomic Energy Agency
Optimization Process
Optimization requires……….
• Knowledge of factors contributing to patient and
staff radiation dose
patient factors
procedural factors
equipment (machine) factors
• Knowledge of dose reduction capabilities of our X
ray system
• Periodic update of our clinical and technical working
protocols
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Optimization process involves ............
• Data collection
• procedures, DAP, fluoro time
• Data analysis
• reliability of data
• Discussion & processes review
• collimators/filters use, FOV, projections
• Implementation of changes
• more precise data collection, collimators/filters use, FOV 17 whenever
possible, avoiding LAO projections
• Data verification
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Reference levels
Reference levels: an instrument to help operators to conduct optimized
procedures with reference to patient exposure
3rd level
“Patient risk”
Required by international (IAEA) and national regulations
For complex procedures
reference levels should
include:
• more parameters
• and, must take into
account the protection
from stochastic and
deterministic risks
2nd level
“Clinical protocol”
Level 2 + DAP
1st level
+ Maximum Skin Dose (MSD)
“Equipment performance”
Level 1
+ No. images + fluoroscopy time
Dose rate and dose/image
(BSS, CDRH, AAPM)
(Dimond)
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
• Modern X ray systems display dosimetric
indications directly on the console in the control
room and inside the catheterization laboratory,
allowing cardiologists to know the level of
radiological risk during the procedure.
• Typically Dose Area Product and Cumulative Dose
(*) are displayed.
(*) Cumulative Dose (CD) is the air kerma accumulated for a procedure at a
specific point in space relative to the fluoroscopic gantry for a procedure (it
does not include tissue backscatter). It can give an indication of the skin dose.
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
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IAEA
Example of the data included in the study report (Siemens)
FIXED Coro ND 1k
1 CARD
A 81kV 744mA 6.0ms 200CL small 0.3Cu 17cm
7s 15F/s 15-Jan-03 09:16:21
211.4ВµGymВІ 36.2mGy 0LAO 0CRA 105F
FIXED Coro ND 1k
2 CARD
A 86kV 734mA 6.0ms 600CL small 0.2Cu 17cm
6s 15F/s 15-Jan-03 09:17:01
376.9ВµGymВІ 63.8mGy 29RAO 0CRA 94F
FIXED Coro ND 1k
3 CARD
A 124kV 553mA 8.0ms ****** small 0.2Cu 17cm
5s 15F/s 15-Jan-03 09:17:43
490.3ВµGymВІ 94.1mGy 48RAO 22CRA 75F
FIXED Coro ND 1k
4 CARD
A 115kV 591mA 8.0ms ****** small 0.2Cu 17cm
6s 15F/s 15-Jan-03 09:18:16
460.4ВµGymВІ 97.8mGy 48RAO 22CRA 84F
FIXED Coro ND 1k
5 CARD
A 96kV 714mA 8.0ms ****** small 0.2Cu 17cm
***** 15F/s 15-Jan-03 09:19:05
9.3ВµGymВІ 1.9mGy 15RAO 30CRA 2F
FIXED Coro ND 1k
6 CARD
A 102kV 666mA 8.0ms ****** small 0.2Cu 17cm
***** 15F/s 15-Jan-03 09:19:07
17.2ВµGymВІ 3.5mGy 15RAO 30CRA 3F
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
45
IAEA
The proposed reference levels for Coronary
Angiography and PTCA were DAP 45 Gy•cm2 and 75
Gy•cm2; fluoroscopy time 7.5 min and 17 min and
number of frames 1250 and 1300, respectively.
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
46
IAEA
Procedure optimization in the cath. lab.
patients and staff share a lot……
(patient)
•
•
•
•
•
•
•
•
correct indications
fluoro time reduction
frame rate reduction (25
12,5/sec)
collimation/filtering
LAO cranial projection limitation
distance from X ray source
lead apron and thyroid protection
protective glasses and suspended screen
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
(staff)
47
IAEA
• Optimization is especially important in more
complex PTCA procedures
chronic total occlusion
bifurcation lesion
degenerated saphenous
vein graft lesion
lesion in severely
tortuous vessel
ostial lesion
Radiation Protection in Cardiology
Lecture 9: Optimization of Radiation Protection in Cardiology
48
IAEA
Procedure optimization
Cardiologia & Fisica Sanitaria - Udine
annual hand dose (cardiologist)
1994-1998
60
- 71%
mSv
50
40
30
n. procedurex10
dose mSv
+ 2%
- 27%
20
- 49%
10
- 23%
0
1994
Radiation Protection in Cardiology
1995
1996
1997
1998
Lecture 9: Optimization of Radiation Protection in Cardiology
49
IAEA
Procedure optimization
DAP measurements at Udine Hospital (all procedures)
70
60
Gy*cm2
50
DAP cine
DAP fluoro
DAP total
40
30
20
10
0
1998
Radiation Protection in Cardiology
1999
2000
2001
2002
Lecture 9: Optimization of Radiation Protection in Cardiology
50
IAEA
Scatter
radiation
X-Ray
Radiation Protection in Cardiology
Measures taken to reduce radiation
exposure to patient will also benefit
the operator/cath. lab. staff
Lecture 9: Optimization of Radiation Protection in Cardiology
51
IAEA
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