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R. Padovani, AOSMM Udine
Quality Assurance in Interventional Cardiology, Lodz 2005
Radiation Protection in Medicine Past, Present and Future Challenges
Quality Assurance in Interventional Cardiology
Renato PadovaniOspedale S. Maria della Misericordia, Udine
26th October 2005, Lodz, Poland
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 2
Interventional cardiology
PTCACase: bifurcation lesion
AP, 38 CR
LAD-D1
LAO 50, 38 CR
D1
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 3
Case 1 bifurcation lesion
A
stent and balloon inflation
B
balloon angioplasty (PTCA)technique
PTCA & stentingtechnique
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 4
EHJ 2001, 2003
PTCA in European countries
0
20000
40000
60000
80000
100000
120000
140000
160000
GER FRA GB ITA OLA SPA
No
./m
illi
on 1994
19961999
1200 2081
825 1443
242 484
239 763
800 818267 858
No.million
PTCA in some European Countries
45,469
40,584
34,723
31,29026,993
23,010
20,14618,54515,009
12,35910,4337,717
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
45,000
50,000
93 94 95 96 97 98 99 00 01 02 03 04
E.Vano 2005
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 5
Patient dose rangein angiographic procedures (UNSCEAR 2000)
AngiographicProcedure
Technique Fluoro time (min)
KAP (Gy.cm2)
Effective dose (mSv)
Coronary Cine film 3.6 – 9.8 16.1 - 98 2 – 15.8
Digital cine 5.7 47.7 9.4
Cerebral DSA/conventional 1.2 – 36 12 – 120 2.7 – 23.4
Abdominal Hepatic (DSA) 2.3 – 28.6 28 – 279 4 – 48
Renal DSA 5.5 - 21 41 - 186 6 - 34
Renal angiogr. 0.5 – 9.3 17 – 327 2.8 – 11.5
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 6
Patient dose range in interventional procedures (UNSCEAR 2000)
Interventionalprocedures
Localized dose
to skin (Gy)
Fluoro time (min)
KAP (Gy.cm2)
Effective dose (mSv)
PTCA 0.05 - 5 3 - 92 20 - 402 7.5 - 57
PTA 0.4 5 – 68 5 – 338 10 – 12.5
TIPS 0.4 – 5 9 – 115 7 - 1131 2 - 181
RF ablation 0.1 – 8.4 3 - 195 7 – 532 17 – 25
Embolization 0.2 – 0.5 1 – 90 7 – 918 6 – 43
ICRP recognise as ‘high dose’ procedures, giving potentially high skin doses:- Embolisation: aneurysm and arteriovenous malformation- Angioplasty (cardiac = PTCA)- Radiofrequency ablation- Transjugular intrahepatic porto-systemic shunt (TIPS)
R. Padovani, AOSMM Udine
Quality Assurance in Interventional Cardiology, Lodz 2005
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 7
ICRP report 85 (2001): Avoidance of Radiation Injuriesfrom Interventional Procedures
Photograph of the patient's back 21 months after a coronary angiographyand two angioplasty procedures within three days; the assessed cumulative dose was 15 - 20 Gy (Photograph courtesy of F. Mettler).
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 8
Cataract in eye of interventionalistafter repeated use of old x ray systems and improper working conditions related to high levels of scattered radiation. (Photograph courtesy of E Vano).
ICRP report 85 (2001): Avoidance of Radiation Injuriesfrom Interventional Procedures
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 9
In 12/29 hosp. 50% of studies had deficencies
6 of these are techinghosp.
Percentage of inadequate studies by differenthospitals (Leape, Am Heart J 2000;139:106-13)
technical deficiencies in 308 cineangiograms
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 10
Quality Assurance in InterventionalCardiology
Image quality and procedure protocolAngiography equipment specification and performancePatient dosimetry
Dose quantitiesReference levels and role of complexity
Skin injuries preventionDosimetry and follow up protocol
Staff dosimetryOperator training
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 11
Quality Assurance in InterventionalCardiology
Image quality and procedure protocolAngiography equipment specification and performancePatient dosimetry
Dose quantitiesReference levels and role of complexity
Skin injuries preventionDosimetry and follow up protocol
Staff dosimetryOperator training
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 12
Image quality of cardiac procedures
Objective: cardiac cine-angiographic images should allow to evaluate the anatomic (and sometimes functional) details which are relevant for clinical decision makingVariables
technical performance of the imaging systempatient cooperationangiographic techniqueoperator skill
R. Padovani, AOSMM Udine
Quality Assurance in Interventional Cardiology, Lodz 2005
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 13
Image quality evaluation: objective/subjective methods
Based on measurement of some physical parameters
Detective quantum efficiency (DQE): MTF and NPSSNR (signal to noise ratio)they are rather complex and rarely applied to constancy QC test
Based on subjective evaluation of test object images
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 14
A guideline for the evaluation of image quality in
– Left Ventriculography– Left Coronary Angiography– Right Coronary Angiography– Angiography of Venous Graft or Arterial Free Graft– Angiography of Left Mammary Artery ‘In Situ’
ModelEuropean guidelines on quality criteria for diagnostic radiographic images (EUR 16260 EN)
Image quality evaluation: subjective methodQuality criteria for CA images (Dimond)
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 15
1) Visually sharp reproduction of the origin, proximal, mid (especially the crux region) and distal portion in at least two orthogonal views, with minimal foreshortening and overlap
2) Visually sharp reproduction of side branches ≥ 1.5 mm in at least two orthogonal views, with minimal foreshortening and overlap. The origin should be seen in at least one projection
3) Visually sharp reproduction of lesions in vessels ≥ 1.5 mm in at least two orthogonal views, with minimal foreshortening and overlap
4) Visualization of collateral circulation when present
Clinical criteriafor Right Coronary Angiography projections
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 16
1) Simultaneous and full opacification of the vessel lumen at least until the first flow-limiting lesion (in general ~ 90-95% by visual estimation)
2) Performed at full inspiration if necessary to avoid diaphragmsuperimposition or to change anatomic relationship (in apnoea in any case)
3) Arms should be raised clear of the angiographic field4) Panning should be limited. If necessary, pan in steps rather than
continuously, or make subsequent cine runs to record remote structures
5) When clinical criteria 1-4 have been fulfilled, avoid extra projections (mainly LAO semi-axial)
Technical criteria for Right CoronaryAngiography projections
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 17
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
Aspects of an optimised technique for Right Coronary Angiography projections
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 18
European survey: Image quality for coronaryangiography in some European centers (Dimond survey)
Dimond Survey - Quality of CA procedures
0
0.10.2
0.3
0.40.5
0.6
0.7
0.8
0.9
1
Procedure no.
CA
Qua
lity
Scor
e (S
.D.)
Dimond III, WP 5.2: Quality Criteria for cardica images (www.dimond3.org)
R. Padovani, AOSMM Udine
Quality Assurance in Interventional Cardiology, Lodz 2005
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 19
European survey: Mean fluoroscopy time, frame numberand dose-area product (DAP) for coronary angiographyin some European centers
8034174.84.152.739.6Finland
5855804.43.237.533.3Ireland
6105704.23.033.528.2England
6105704.23.033.528.2Italy
15969039.46.439.427.8Spain
196016207.15.546.738.6Greece
meanmedianmeanmedianmeanmedian
No. of framesFT (min)DAP (Gy×cm2)Country
+ 41% + 113%
+ 390%
Neofotistou, Eur.Jou.Radiol. 2003
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 20
05
1015
2025
3035
4045
50
%
Dublin % Leuven % Athens % Madrid %
LEFT-CR (+,+)
LEFT-CAU (+,-)RIGHT-CR (-,+)
RIGHT-CAU (-,-)
projections’ distribution11,5
9,27,5
15,413,8
12,4
0,0
2,0
4,0
6,0
8,0
10,0
12,0
14,0
16,0
18,0
Udine Dublin Leuven Greece Treviso Spain
Seri
es
1000,4
1045,1
982,4
950,0960,0970,0980,0990,0
1000,01010,01020,01030,01040,01050,0
Dublin Greece Spain
SIID
(cm
)
focus-detector mean distances
European survey: Technical factors: mean number of series, SIID, projection type
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 21
Quality Assurance in InterventionalCardiology
Image quality and procedure protocolAngiography equipment specification and performancePatient dosimetry
Dose quantitiesReference levels and role of complexity
Skin injuries preventionDosimetry and follow up protocol
Staff dosimetryOperator training
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 22
IEC Standard 2000
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 23
Equipment performance: quality control programme
Extensive acceptance test Frequent simple constancy tests (Dimond protocol):
Image quality, patient doserates, x-ray beam collimation on clinical used modalities (frequency: 3-6 months) On all modalities + DAP calibration (frequency: yearly)
Fluoroscopy modes. Innova 2000, FOV 17 cm
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
14 16 18 20 22 24 26 28 30
PMMA thickness (cm)
Entr
ance
Sur
face
Dos
e (m
Gy/
min
)
Fluoro Low
Fluoro Normal
Fluoroscopy modes, GE Advantx, FOV 22 cm
0.0
20.0
40.0
60.0
80.0
100.0
120.0
14 16 18 20 22 24 26 28 30
PMMA thickness (cm)
En
tran
ce s
urf
ace
do
se r
ate
(miG
y/m
in)
Fluoro Low
Fluoro Medium
Fluoro High
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 24
Quality Assurance in InterventionalCardiology
Image quality and procedure protocolAngiography equipment specification and performancePatient dosimetry
Dose quantitiesReference levels and role of complexity
Skin injuries preventionDosimetry and follow up protocol
Staff dosimetryOperator training
R. Padovani, AOSMM Udine
Quality Assurance in Interventional Cardiology, Lodz 2005
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 25
Patient dosimetry in IR
The EC Directive on Medical Exposure and D.Lgs. 187/2000 request patient dose monitoring in interventional radiology (art. 9: Special practices)
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 26
Patient dosimetry in IR
Dosimetry for stochastic risk evaluationdose equivalent to selected organseffective dose
Dosimetry for quality assuranceAir kerma area product (KAP, PKA)
Dosimetry to prevent deterministic effects of radiation (maximum skin dose assessment)
Maximum entrance surface air kerma (MESAK or Ke,max)
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 27
1. Dosimetry for stochastic risk evaluation: organ doses and effective dose
NRPB, GSF or STUK Monte Carlo simulations:
Conversion coefficients from ESAK or KAP for a selection of projections
FDA ‘Handbook of Selected Doses for Fluoroscopic and CineangiographicExamination of the Coronary Arteries (HHS Publication FDA 95-8289:
Monte Carlo simulations for typical cardiac projections
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 28
2. Patient dosimetry for QA
Dosimetric quantities:Air kerma-area product (KAP) (PKA)
Total KAP, fluoro KAP and cine/fluorography KAPCumulative entrance surface air kerma (Ke) at a reference point (Interventional Reference Point - IRP)
Other important quantities:Fluoroscopy timeNumber of imagesAir kerma rate at the entrance of imaging detectorSurface air kerma rate at the entrance of the patient
(in red the new ICRU symbols)
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 29
Air kerma-area product (KAP)
KAP:Measured (ionisation chamber) Calculated
Calibration:With an ionisation chamber (with a valid calibration) free in air (without backscatter)With patient tabletop and mattress included in the beam (most of projections include the tabletop)
Attention: influence on calibration factor of automatic added filtration and transparent filters
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 30
Interventional Radiology Point (IRP)
Cumulative ESAK to Interventional Reference Point (IRP)measured with a flat ion chamber or calculated by the system and displayed in the angio room
15 cm
Isocenter
IRP
15 cm
Isocenter
IRP
R. Padovani, AOSMM Udine
Quality Assurance in Interventional Cardiology, Lodz 2005
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 31
3. Patient dosimetry to prevent deterministic effects (skin injuries)
Dosimetric quantity:Maximum entrance surface air kerma at the patient skin (MESAK)
Evaluated by on/off line methods:Direct measurement/evaluation of MESAK
Point or area detectors Cumulative dose at IRP (interventional radiology point)Calculation from technical data
Indirect methodsFrom fluoroscopy time and no. of imagesFrom KAP measurement From type of procedure, technical parameters and complexity
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 32
MESAK evaluation: radiochromic film
Example: Radiochromic films type Gafchromic XR R 14”x17”• usefull dose range: 0.1-15 Gy• minimal photon energy dependence (60 - 120 keV)• acquisition with a flatbed scanner:b/w image, 12-16 bit/pixel
or, measure of OD measurement with a reflection densitometer
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 33
Reference levels
Entrance Surface Dose Rate (mGy/min)
--180-100High
-658839/6825Normal
ECAAPMCDRHFDA
CRCPDBSS(IAEA)Mode:
Dose reference levels or limits available for fluoroscopy (only) modalities:
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 34
13551270No. of frames
166Fluoroscopy time (min)
9457KAP (Gycm2)
PTCACAProcedures:
Reference levels in interventional cardiology
DIMOND EU project. E.Neofotistou, E.Vano, R.Padovani & others, Preliminary reference levels in interventional cardiology, J.Eur.Radiol, 2003
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 35
Reference dose vs. complexity of PTCA
0
20
40
60
80
100
120
140
Simple Medium Complex
KA
P (G
ycm
2)
0
200
400
600
800
1000
1200
1400
1600
Simple Medium Complex
Fluo
roso
cpy
time
(s)
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 36
Quality Assurance in InterventionalCardiology
Image quality and procedure protocolAngiography equipment specification and performancePatient dosimetry
Dose quantitiesReference levels and role of complexity
Skin injuries preventionDosimetry and follow up protocol
Staff dosimetryOperator training
R. Padovani, AOSMM Udine
Quality Assurance in Interventional Cardiology, Lodz 2005
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 37
12Delayed skin necrosis
7Permanent epilation
2Cataracts
2Erythema
Dose(Gy)
Acute radiation doses (in single or closely spaced
procedures)
5.5(> 3 months)
4(< 3 months)Cataracts
Dose(Gy)
Protracted exposures to eyes
Prevention of deterministic injuries
Dose thresholds for deterministic injuries to skin and lens
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 38
100 cm80 cm
Dose rate: 20 – 40 mGyt/min
Non optimised practice:
• thick patients and oblique views
100 cm
50 cm
Dose rate: ~250
mGyt/min
40 cm
5
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 39
Non optimised practice:overlapping fields (bad collimation)
Courtesy of Steve Balter, Ph.D.
18
GRANEL F, BARBAUD A, GILLETGRANEL F, BARBAUD A, GILLET--TERVER M N, REICHERT S, WEBER M, TERVER M N, REICHERT S, WEBER M, DANCHIN N, SCHMUTZ JDANCHIN N, SCHMUTZ J--L. L. RADIODERMITES CHRONIQUES APRÈS RADIODERMITES CHRONIQUES APRÈS CATHÉTÉRISME INTERVENTIONNEL CATHÉTÉRISME INTERVENTIONNEL CARDIAQUE CARDIAQUE QuatreQuatre observationsobservationsAnn Ann DermatolDermatol VenereolVenereol 1998; 125: 4051998; 125: 405--77
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 40
91429411381949401967No. of patients
>77654321No. of procedures per patient
87 (2.6%)No. of patients with KAP>300Gycm2
50.6 Gycm2Median KAP
78.6 Gycm2Mean KAP
3332No. of patients
0
100
200
300
400
500
600
0 100 200 300 400 500 600 700
Gy cm^2
Freq
uenc
y
Retrospective evaluation of skin injuries on patients at Udine cardiac centreFrequencies of repeated procedures and cumulative dose
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 41
Sample of patients extracted for the follow-up study
Maximum local skin dose evaluated for the 79 patients
02468
1012141618
1,5 2 2,5 3 3,5 4 4,5 5 5,5 6 6,5 7Maximum Local Skin Dose (Gy)
No.
of p
atie
nts
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 42
Follow-up results
56 patients received medical examination with particular focus on the more exposed skin area.
None of patients presented skin lesions
The result assures cardiologists and medical physicists that, if proper quality assurance and radiation protection programme is established, the frequency of skin injuries can be very low also when repeated procedures are taken into account
R. Padovani, AOSMM Udine
Quality Assurance in Interventional Cardiology, Lodz 2005
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 43
Quality Assurance in InterventionalCardiology
Image quality and procedure protocolAngiography equipment specification and performancePatient dosimetry
Dose quantitiesReference levels and role of complexity
Skin injuries preventionDosimetry and follow up protocol
Staff dosimetryOperator training
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 44
Staff exposure in fluoroscopy guided procedures:Isodose map
Several variables influenceoperator exposure:
Type of equipment and performanceDistance from the patientX-ray beam projection and beam areaUse of protective screen (additionaly to personal protective devices) Procedure type and protocolOperator experienceOperator trianing in radiationprotection
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 45
The effective dose per procedure is highly variable:All relevant factors inflencing patient dose should be monitored
0
5
10
15
20
Eff
ec
tiv
e d
os
e/p
roc
ed
ure
(u
Sv
/pro
c)
Wu et al., 1991Renaud, 1992Li et al., 1995Steffenino et al., 1996Folkerts et al., 1997Watson et al., 1997Zorzetto et al., 1997Vañó et al., 1998Padovani et al., 1998DIMOND – 1999 SpainDIMOND – 1999 ItalyDIMOND – 1999 Greece
Staff exposure in cardiac procedures
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 46
Optimisaton of staff exposure
Staff protection requires:Use of dedicated equipment for IR Proper protection devicesOptimised technique (kV, contrast curve, image quality in fluoroscopy and fluorography, grid, filters)Optimised procedure (no. of frames, frame rate, fluoroscopy time, magnification, beam orientation, field size)Training in radiological imaging and radiation protectionFrequent reassessment of the practice
Optimisation is more difficult when non-radiologistsperform IR.
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 47
Quality Assurance in InterventionalCardiology
Image quality and procedure protocolAngiography equipment specification and performancePatient dosimetry
Dose quantitiesReference levels and role of complexity
Skin injuries preventionDosimetry and follow up protocol
Staff dosimetryOperator training
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 48
Training: operator must know the factors affecting patient dose
Technical factorsImage quality level, electronic magnificationGeometric magnificationPerformance of the X ray equipmentAvailable dose reduction tools Patient size
Procedure factorsPulse frequency in fluoroscopy and acquisition frequencyProjectionsNumber of series and total number of imagesFluoroscopy time Operator training and experience
R. Padovani, AOSMM Udine
Quality Assurance in Interventional Cardiology, Lodz 2005
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 49
Importance of training
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 50
… training
In large and teaching hospitals there is a need for frequent training sessions
It is possible to use a training multimedia tool:MARTIR on CD-ROM, (EC publication no. 119)
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 51
Conclusions (I)
The positive trend in the health care activity due to IC requires some radiation protection actions, because:
a larger arena of clinicians and support personnel are using x-ray equipmentsome procedures require high patient and staff exposurecomplications during complex procedures, or repeated complex procedures, can constitute a potential risk of high exposure dose, over the threshold of deterministic effects of ionising radiation
R. Padovani. Quality Assurance in Interventional Cardiology, Lodz 2005 52
Conclusions (II)
It is difficult to separate the protection of the patient from the protection of the staff: the optimisation process should be balanced between patient and operator protection Design and use of reference levels for optimised proceduresTools for initial and continuous trainingImprovement of x-ray system and room design