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International Atomic Energy AgencyIAEA
Optimization of Radiation Optimization of Radiation Protection in CardiologyProtection in Cardiology
L 9
Lecture 9: Optimization of Radiation Protection in Cardiology 2 IAEARadiation Protection in Cardiology IAEA
Educational ObjectivesEducational 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
Lecture 9: Optimization of Radiation Protection in Cardiology 3 IAEARadiation Protection in Cardiology IAEA
Is this statement “True” or “False”?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.
Lecture 9: Optimization of Radiation Protection in Cardiology 4 IAEARadiation Protection in Cardiology IAEA
In room dosimetric indications
Have you ever paid attention to this?
Lecture 9: Optimization of Radiation Protection in Cardiology 5 IAEARadiation Protection in Cardiology IAEA
Do you know how to interpret these data?Do you know how to interpret these data?
Lecture 9: Optimization of Radiation Protection in Cardiology 6 IAEARadiation Protection in Cardiology IAEA
Reality check……Reality check…… Dose Information and Dose Reports 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”?
Lecture 9: Optimization of Radiation Protection in Cardiology 7 IAEARadiation Protection in Cardiology IAEA
Reality check……Reality check…… Knowing your X ray machine 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?
Lecture 9: Optimization of Radiation Protection in Cardiology 8 IAEARadiation Protection in Cardiology IAEA
Siemens Axiom ArtisCine normal mode
20 cm PMMA177 Gy/fr (entrance PMMA)
Siemens Axiom Artis, Fluoro low dose
20 cm PMMA13 Gy/fr (entrance PMMA)
Lecture 9: Optimization of Radiation Protection in Cardiology 9 IAEARadiation Protection in Cardiology IAEA
Optimization means ...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.
Lecture 9: Optimization of Radiation Protection in Cardiology 10 IAEARadiation Protection in Cardiology IAEA
Optimization of Radiation ProtectionOptimization 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!
International Atomic Energy AgencyIAEA
One of the center's experience with One of the center's experience with new angiographic machine having new angiographic machine having
flat panel detectorflat panel detector
Lecture 9: Optimization of Radiation Protection in Cardiology 12 IAEARadiation Protection in Cardiology IAEA
Motorized Iris
Video Camera
Image Intensifier
DE
TE
CT
OR
DE
TE
CT
OR
Photons
Cesium Iodide (CsI)
Light
Amorphous Silicon Panel(Photodiode/Transistor Array)
Digital DataDigital Data
Electrons
Read Out Electronics
Photons
Cesium Iodide (CsI)
Light
Photo-cathode
Video SignalVideo Signal
Electrons
Output screen
Light
CCD or PUT
Electrons
Readout Electronics
1
3,000
400
400,000
2,400
Particles #
ImageIntensifier
Flat-panel
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Anticipated per-frame dose Anticipated per-frame dose reduction with Digital Flat reduction with Digital Flat Panel technology is 30%Panel technology is 30%
Lecture 9: Optimization of Radiation Protection in Cardiology 14 IAEARadiation Protection in Cardiology IAEA
Coronary Angiography and AngioplastyCoronary Angiography and AngioplastyUdine,Udine, years 1990-2002years 1990-2002
0
500
1000
1500
2000
'90 '91 '92 '93 '94 '95 '96 '97 '98 '99 '00 '01 '02 '03
diagnosticPCI
Philips OM 200 (1983)
Philips Integris 3000 (1995)
performed by 3 interventionalists except in 1998
Lecture 9: Optimization of Radiation Protection in Cardiology 15 IAEARadiation Protection in Cardiology IAEA
GE Innova 2000 (angiographic machine with GE Innova 2000 (angiographic machine with digital flat panel technology) at Udine Centerdigital flat panel technology) at Udine Center
• Activity started
04/12/2002
• Jan - Oct 2003
1421 procedures (79% of total)
• 1019 diagnostic coronary angiography
• 402 percutaneous coronary angioplasty
Lecture 9: Optimization of Radiation Protection in Cardiology 16 IAEARadiation Protection in Cardiology IAEA
66
77
1.9
56
31.233.4
35.4
66
78
1.9
53
30.8
38.5
30.8
0
10
20
30
40
50
60
70
80
90
age (y) male sex (%) BSA (sqm) EF (%)
1 2 3
Comparison of Philips H 3000 and Innova 2000 in PCI
-- -- Characteristics of patientsCharacteristics of patients
diseased vessels (%)
H 3000: 588 pts, 90% of tot. treated in the year 2002
Innova: 274 pts, 67% of tot. treated between Jan-Oct 2003
Lecture 9: Optimization of Radiation Protection in Cardiology 17 IAEARadiation Protection in Cardiology IAEA
65.9
22.9
11.314.8
6.12.6 3.2
56.5
25.5
15.3
10.2
3.6 2.96.6
0
10
20
30
40
50
60
70
H 3000
Innova
Comparison of Philips H 3000 and Innova 2000 in PCI
-- Characteristics of procedures & lesions (1)Characteristics of procedures & lesions (1)
%
Lecture 9: Optimization of Radiation Protection in Cardiology 18 IAEARadiation Protection in Cardiology IAEA
29
22.2
6.2
18.1
4.8
12.8
37.2
22.3
4.7
16.1
3.6 3.3
0
5
10
15
20
25
30
35
40
H 3000Innova
Comparison of Philips H 3000 and Innova 2000 in PCI
-- Characteristics of procedures & lesions (2)Characteristics of procedures & lesions (2)
%
Lecture 9: Optimization of Radiation Protection in Cardiology 19 IAEARadiation Protection in Cardiology IAEA
0
10
20
30
40
50
60
70
Fluoro T proced. T room occ. contrast (dl)
(m’)
Comparison of Philips H 3000 and Innova 2000 in PCI
-- Performance & complexity indexPerformance & complexity index
1,37
1
1,47
0,93
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
Comp.
Inde
x
GIS
E Inde
x
r (with fluoro time)
0.30 0.29 0.34 0.26
11,6
11,5
40
48
59
84
24,1 21,
6
H 3000
Innova
Lecture 9: Optimization of Radiation Protection in Cardiology 20 IAEARadiation Protection in Cardiology IAEA
67
1.9
72
99
71
20 1812
9
67
1.9
74
98
69
2024
19
9
0
20
40
60
80
100
120
Comparison of Philips H 3000 and Innova 2000 in Comparison of Philips H 3000 and Innova 2000 in diagnostic proceduresdiagnostic procedures
-- -- Characteristics of patients & proceduresCharacteristics of patients & procedures
(%)
H 3000: 1401 pts, 92% of tot. studied in the year 2002
Innova: 702 pt, 69% of tot. studied between Jan-Oct 2003
Lecture 9: Optimization of Radiation Protection in Cardiology 21 IAEARadiation Protection in Cardiology IAEAm’ Gy * cm2
measured
Comparison of Philips H 3000 and Innova 2000 in diagnostic procedures
-- performance indexes and exposure parametersperformance indexes and exposure parameters
calculated
4.2
24
54
15.6
20.39
10.67
31.06
4.4
28
54
15.8
27.05
18.83
45.88
35.32
0
10
20
30
40
50
60
Fluoro T
proced. T
room occ.
contrast (dl)
cine DAP
fluoro DAP
tot. DAP
1,3
H 3000
Innova
Lecture 9: Optimization of Radiation Protection in Cardiology 22 IAEARadiation Protection in Cardiology IAEA
Entrance surface dose: H3000 and Innova 2000Entrance surface dose: H3000 and Innova 2000
0
10
20
30
40
50
60
70
Entrance dose rate
(mGy/min)
Low Normal High
Image quality
Entrance surface dose rates, FOV=17 cm, PMMA=20 cm
H3000
Innova2000
Entrance surface dose rates in Fluoro LOW for Innova is 30% less
Lecture 9: Optimization of Radiation Protection in Cardiology 23 IAEARadiation Protection in Cardiology IAEA
Why Why the anticipated 30% per-frame dose the anticipated 30% per-frame dose reduction of digital flat panel technology reduction of digital flat panel technology does not translate into an effective dose does not translate into an effective dose
reduction to patientsreduction to patients
Lecture 9: Optimization of Radiation Protection in Cardiology 24 IAEARadiation Protection in Cardiology IAEA
Differences in operating conditions of the two Differences in operating conditions of the two systemssystems
H 3000• field of view (cm)
23/18/14
• cine mode12,5/25 fps
• fluoro modelow/medium/high
• filterautomatic
Innova• field of view (cm)
20/17/15/12
• cine mode15/30 fps
pref 1/pref 2 (lower dose)
• fluoro modelow/normal
• filtermanual
Lecture 9: Optimization of Radiation Protection in Cardiology 25 IAEARadiation Protection in Cardiology IAEA
20 cm23
cm 400 cm2
375 cm2
Detectors area are similar
H3000 Innova200
Lecture 9: Optimization of Radiation Protection in Cardiology 26 IAEARadiation Protection in Cardiology IAEA
17 cm18
cm 290 cm2
230 cm2
area +26% DAP +26% !!!!
Using similar nominal field of view (FOV) sizes corresponds to very different area of the two X ray beams
H3000 Innova200
Lecture 9: Optimization of Radiation Protection in Cardiology 27 IAEARadiation Protection in Cardiology IAEA
Other possibilities……Other possibilities……
patients may not be the same procedures may not be the same operators’ behavior
filters/collimation use of “difficult” projections (fluoro/cine) focus-detector mean distances
………
Lecture 9: Optimization of Radiation Protection in Cardiology 28 IAEARadiation Protection in Cardiology IAEA
Collimators use in INNOVA to reduce exposure
FOV 15
dose reduction 25%
[still]
Lecture 9: Optimization of Radiation Protection in Cardiology 29 IAEARadiation Protection in Cardiology IAEA
FOV 20
Collimators use in INNOVA to reduce exposure
[still]
Lecture 9: Optimization of Radiation Protection in Cardiology 30 IAEARadiation Protection in Cardiology IAEA
proper filtering
improper filtering causes image deterioration
H 3000
Filtering prevents image saturation in low absorption areas
Lecture 9: Optimization of Radiation Protection in Cardiology 31 IAEARadiation Protection in Cardiology IAEA
improper filtering does not cause image deterioration
INNOVAINNOVA
Lecture 9: Optimization of Radiation Protection in Cardiology 32 IAEARadiation Protection in Cardiology IAEA
Skin exposure variation in exposure rate (DAP rate) with projectionanthropomorphic phantom (average-sized) measurements
Cusma JACC 1999
Projection Fluoroscopy entrance dose rate
(mGy/min)
Cine
entrance dose rate
(mGy/min)
AP 31 388
RAO 30° 19 203
LAO 40° 20 216
LAO 40°, Cran 30° 80 991
LAO 40°, Cran 40° 99 1236
LAO 40°, Caud 20° 29 341
Lecture 9: Optimization of Radiation Protection in Cardiology 33 IAEARadiation Protection in Cardiology IAEA
Distance between patient and detector
Lecture 9: Optimization of Radiation Protection in Cardiology 34 IAEARadiation Protection in Cardiology IAEA
d
2d
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”
Source
Doubling the distance from the source divides the dose by a factor of 4
The inverse square law
Lecture 9: Optimization of Radiation Protection in Cardiology 35 IAEARadiation Protection in Cardiology IAEA
The inverse square law
Lecture 9: Optimization of Radiation Protection in Cardiology 36 IAEARadiation Protection in Cardiology IAEA
Collimation
Lecture 9: Optimization of Radiation Protection in Cardiology 37 IAEARadiation Protection in Cardiology IAEA
Anti-scatter grid
Increase DAP and skin dose x 2 timesImprove image qualityTo be removed for pediatric patients !!
Lecture 9: Optimization of Radiation Protection in Cardiology 38 IAEARadiation Protection in Cardiology IAEA
Coronary Angiography optimization DIMOND Quality Coronary Angiography optimization DIMOND Quality CriteriaCriteria
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
AAspects of an optimized angiographic techniquespects of an optimized angiographic technique
Lecture 9: Optimization of Radiation Protection in Cardiology 39 IAEARadiation Protection in Cardiology IAEA
Innova 2000. Changes in exposure parameters over time
---- diagnostic procedures Jul 2003 - Feb 2004diagnostic procedures Jul 2003 - Feb 2004
0
1
2
3
4
5
Jul-Aug
Sept-Oct
Nov-Dec
Jan-Feb
Fluoro T (m')
25
26
27
28
29
30
31
32
33
34
Jul-Aug Sept-Oct
Nov-Dec
Jan-Feb
Tot DAP(Gy*cm2)
International Atomic Energy AgencyIAEA
Optimization ProcessOptimization Process
Lecture 9: Optimization of Radiation Protection in Cardiology 41 IAEARadiation Protection in Cardiology IAEA
Optimization requires……….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
Lecture 9: Optimization of Radiation Protection in Cardiology 42 IAEARadiation Protection in Cardiology IAEA
Optimization process involves ............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
Lecture 9: Optimization of Radiation Protection in Cardiology 43 IAEARadiation Protection in Cardiology IAEA
Reference levels Reference levels
3rd level “Patient risk”
2nd level “Clinical protocol”
1st level“Equipment performance”
Dose rate and dose/image
(BSS, CDRH, AAPM)
Level 1 + No. images + fluoroscopy time
Level 2 + DAP + Maximum Skin Dose (MSD)
Reference levels: an instrument to help operators to conduct optimized procedures with reference to patient exposure
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
(Dimond)
Lecture 9: Optimization of Radiation Protection in Cardiology 44 IAEARadiation Protection in Cardiology 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.
Lecture 9: Optimization of Radiation Protection in Cardiology 45 IAEARadiation Protection in Cardiology IAEA
1 CARD FIXED Coro ND 1k 7s 15F/s 15-Jan-03 09:16:21A 81kV 744mA 6.0ms 200CL small 0.3Cu 17cm 211.4µGym² 36.2mGy 0LAO 0CRA 105F
2 CARD FIXED Coro ND 1k 6s 15F/s 15-Jan-03 09:17:01A 86kV 734mA 6.0ms 600CL small 0.2Cu 17cm 376.9µGym² 63.8mGy 29RAO 0CRA 94F
3 CARD FIXED Coro ND 1k 5s 15F/s 15-Jan-03 09:17:43A 124kV 553mA 8.0ms ****** small 0.2Cu 17cm 490.3µGym² 94.1mGy 48RAO 22CRA 75F
4 CARD FIXED Coro ND 1k 6s 15F/s 15-Jan-03 09:18:16A 115kV 591mA 8.0ms ****** small 0.2Cu 17cm 460.4µGym² 97.8mGy 48RAO 22CRA 84F
5 CARD FIXED Coro ND 1k ***** 15F/s 15-Jan-03 09:19:05A 96kV 714mA 8.0ms ****** small 0.2Cu 17cm 9.3µGym² 1.9mGy 15RAO 30CRA 2F
6 CARD FIXED Coro ND 1k ***** 15F/s 15-Jan-03 09:19:07A 102kV 666mA 8.0ms ****** small 0.2Cu 17cm 17.2µGym² 3.5mGy 15RAO 30CRA 3F
Example of the data included in the study report (Siemens)
Lecture 9: Optimization of Radiation Protection in Cardiology 46 IAEARadiation Protection in Cardiology 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.
Lecture 9: Optimization of Radiation Protection in Cardiology 47 IAEARadiation Protection in Cardiology IAEA
Procedure optimization in the cath. lab.Procedure optimization in the cath. lab.patients and staff share a lot……patients and staff share a lot……
• 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
(staff)
(patient)
Lecture 9: Optimization of Radiation Protection in Cardiology 48 IAEARadiation Protection in Cardiology 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
Lecture 9: Optimization of Radiation Protection in Cardiology 49 IAEARadiation Protection in Cardiology IAEA
Procedure optimizationProcedure optimizationannual hand dose (cardiologist)annual hand dose (cardiologist)
0
10
20
30
40
50
60
1994 1995 1996 1997 1998
n. procedurex10dose mSv
- 27%
+ 2%
- 49% - 23%
Cardiologia & Fisica Sanitaria - Udinem
Sv
1994-1998 - 71%
Lecture 9: Optimization of Radiation Protection in Cardiology 50 IAEARadiation Protection in Cardiology IAEA
0
10
20
30
40
50
60
70
1998 1999 2000 2001 2002
DAP cineDAP fluoroDAP totalG
y*cm
2Procedure optimization Procedure optimization DAP measurements at Udine Hospital (aDAP measurements at Udine Hospital (all proceduresll procedures))
Lecture 9: Optimization of Radiation Protection in Cardiology 51 IAEARadiation Protection in Cardiology IAEA
X-Ray
Scatterradiation
Measures taken to reduce radiation exposure to patient will also benefit the operator/cath. lab. staff