Microsoft PowerPoint - Interventional_Cardiology_ Padovani

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


Case 1 bifurcation lesion

A

stent and balloon inflation

B

balloon angioplasty (PTCA)technique

PTCA & stentingtechnique


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


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


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)




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).


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


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


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








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




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


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)


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


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


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


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)




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


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








IEC Standard 2000


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










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)


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)


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


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)


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


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




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


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


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:


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


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)










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


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


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


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


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


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










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


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


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.








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




Importance of training


… 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)


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


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

Microsoft PowerPoint - Interventional_Cardiology_ Padovani

Documents

Transcript of Microsoft PowerPoint - Interventional_Cardiology_ Padovani