Dose Reduction in
Interventional
Radiology and Cardiology
Renato Padovani
ICTP, Trieste, Italy
The fact
 Interventional radiology &
cardiology are hospital fluoroscopy
guided practices with the highest
radiological workload
Cumulative Annual KAP
(Udine Hospital – 2010)
Annual workload
of fluoroscopy
guided practices
Neuro & Spinal surgery
1600
Urology
1000
Ortopaedics
1000
Gastroenterology
2400
Interventional radiology/neuroradiology
265000
Interventional cardiology
140000
0
100000
200000
KAP (Gycm2/year)
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology
300000
2
Instruments to monitor exposures and
practices
 Dose indexes:
 Patient doses (KAP, CK, PSK, …) related to:
 procedure
 and, complexity
 Staff doses (effective dose, over/under apron dose, hand/eye
dose) related to:
 Operator task
 No. procedure and type and complexity
 Procedure protocols
 Audits
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Variability in patient doses
 PTCA survey in a sample of European hospitals:
 FT: median values in a range from 5 to 13 (factor 2.5)
 KAP: median values in a range from 35 to 85 (factor 2.5)
Median
20.0
18.0
16.0
14.0
12.0
10.0
8.0
6.0
4.0
2.0
0.0
KAP (Gycm2)
FT (min)
Median
90.0
80.0
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
Great variability of KAP values,
not correlated with procedure complexity (fluoroscopy time)
SENTINEL project survey (2007)
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Variability in staff doses
20 hospitals in 15 countries: annual doses and individual workload (2010)
Interventional Cardiologists: Over apron and effective dose versus no. of IC
procedures performed in a year (triangle: staff in training)
Great variability, high doses and number of unrealistic zero values
ISEMIR (IAEA) project survey (2011)
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Optimisation of radiation protection in
interventional radiology
 From 1975, new technologies and materials for interventional devices
have been developed enabling new and complex procedures
 High doses can be delivered with reported:
 skin injuries to patients
 eye lens opacities of operators
 Optimisation of IR practices are mandatory to reduce un-necessary
exposures. Four central issues have been identified:
 Equipment
 Quality management
 Operator training
 Occupational radiation protection
D.L. Miller, Efforts to optimize radiation protection in interventional fluoroscopy. Health Phys, 2013 Nov; 105(5):435-44
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology
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Equipment for IR:
example of setups and performances
Entrance surface air kerma rate
In fluoroscopy modes
350
300
250
200
150
100
90.0
Low
80.0
Medium
70.0
Low
Medium
ESAK (mGy/min)
Entrance surface air kerma (uGyy/image)
Entrance surface air kerma rate
In image acquisition (cine) modes
High
60.0
50.0
40.0
30.0
20.0
50
0
10.0
0.0
Large variability in equipment set-up and performances:
- cine low: ratio max/min 4
- cine normal : ratio max/min 4
- fluoro low: up to 25 mGy/min (ratio max/min 7)
- fluoro medium: up to 50 mGy/min (max/min 5)
- fluoro high: up to 80 mGy/min (max/min 7)
SENTINEL project survey (2007)
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7
Equipment set up
 ICRP 120 (223) .... With digital imaging detectors, it is
possible to select a wide range of dose values to obtain the
required level of quality in the images.
 Cardiologists, radiographers, the medical physicist and the
industry engineer should set the fluoroscopic system doses
to achieve the appropriate balance between image quality
and dose.
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Example of reference levels for angiography
equipment dose rates
 SENTINEL proposed reference levels for entrance air kerma rates for
cardiac interventional procedures
Dose or dose analogue
Procedures
CA
PTCA
EFO
KAP (Gycm2)
45
85
35
CD at IRP (mGy)
650
1500
-
Fluoroscopy time (min)
6.5
15.5
21
No. of cine images
700
1000
Fluoroscopy low: 13 mGy/min
Entrance surface air kerma rate
Image acquisition: 100 Gy/frame
Recommendations to set-up equipment dose rates
for the different clinical tasks are necessary
SENTINEL project survey (2007)
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Quality management:
assess and use of DRLs in IR
 The concept of diagnostic reference level (DRL) refers to
“common examinations” done in a relatively standardized
manner.
 Extending this concept to fluoroscopically guided
interventions raises several problems:
 In addition to technical variables procedures are usually nonstandard for clinical reasons
 The complexity of a procedure is affected by the patient’s anatomy
and to the severity of the treated pathology.
Dose Management in Interventional Radiology
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Example of DRLs for IC
 DIMOND and SENTINEL projects proposed reference levels for dose
rates for cardiac procedures
Dose or dose analogue
Procedures
CA
PTCA
EFO
KAP (Gycm2)
45
85
35
CD at IRP (mGy)
650
1500
-
Fluoroscopy time (min)
6.5
15.5
21
No. of cine images
Entrance surface air kerma
rate
700
1000
Fluoroscopy low: 13 (mGy/min)
Image acquisition: 100 (Gy/frame)
 Other studies have been then undertaken to assess DRLs in cardiac
procedures with values in a range of a factor not more than 2
DIMOND & SENTINEL projects survey (2003 & 2007)
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DRLs for Interventional Radiology
Type of examination
Transjugular intrahepatic portosystemic shunt creation
Biliary drainage
Nephrostomy for obstruction
Nephrostomy for stone access
Pulmonary angiography
Inferior vena cava filter placement
Renal or visceral angioplasty without stent
Renal or visceral angioplasty with stent
Iliac angioplasty without stent
Iliac angioplasty with stent
Bronchial artery embolisation
Hepatic chemoembolisation
Uterine fibroid embolisation
Other tumor embolisation
Gastrointestinal hemorrhage localization and treatment
Embolisation in the head for AVM
Embolisation in the head for aneurysm
Embolisation in the head for tumor
Vertebroplasty
Pelvic artery embolisation for trauma or tumor
Embolisation in the spine for AVM or tumor
Reference levels
Fluoroscopy
Number of
time (min)
images
60
300
30
20
15
12
25
14
10
215
4
40
20
210
30
200
20
300
25
350
50
450
25
300
36
450
35
325
35
425
135
1,500
90
1,350
200
1,700
21
120
35
550
130
1,500
KAP
(Gy cm2)
525
100
40
60
110
60
200
250
250
300
240
400
450
390
520
550
360
550
120
550
950
DL. Miller, D. Kwon, GH. Bonavia. Reference levels for patient radiation doses in interventional radiology – Proposed initial values for
US practice. Radiology, 253: 3, 2009.
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… on DRLs in IR
 There is today a general consensus that DRLs :
 can be assessed and used in IR
 should be proposed as a set of parameters: fluoroscopy time, no.
images, KAP and CK at IRP
 can allow to identify non acceptable practices and to initiate an
optimisation process
 How to manage the complexity of procedures?
 How to manage the high skin doses delivered in nonoptimised, high dose and/or repeated procedures?
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DRLs vs complexity of PTCA procedures
IAEA study (2006)
•
Reference levels assessed as a
function of complexity
175
150
125
2
•
More 1000 PTCA procedures
analysed
Anathomical and pathology
determinants for complexity of
procedures identified
KAP (Gy cm )
•
PK,A (KAP) vs. Clinical Complexity for PTCA
100
mean
median
75%
75
50
25
0
Simple
Medium
Complexity Group
Complex
SB 0707
Anatomical and pathology data can be difficult to collect in the large sample of
procedures necessary to identify complexity factors
Dose Management in Interventional Radiology
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Complexity of IR procedures
 An alternative method not requiring complexity information
(NCRP 110):
 To collect dose data from every cases for a number of facilities to
compensate for the large variability in patient doses (ADS, Advisory
Data Set)
 This data set is compared with the Facility Data Set (FDS):
 Median (not mean) FDS is compared with DRL
 Also, the two distributions are compared
 Analysis should be performed in the presence of important
differences between the distributions (for high and low doses)
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Complexity of IR procedures
 Recommended investigations:
 Low doses: if the FDS median is below the 10th percentile (IAEA,
2009) or the 25th percentile (NCRP, 2010) of the ADS.
 Low radiation usage might be attributable to inadequate image quality,
mix of low clinical complexity, or superior dose management.
 High doses: presence of a higher percentage of high doses
compared to the ADS
 High doses might be attributable to a too high image quality, mix of high
clinical complexity, or poor dose management
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Management of tissue effects (skin burns)
 NCRP 168 defines a potentially high-dose procedure as
one where more than 5 % of cases result in CK exceeding
3 Gy or KAP exceeding 300 Gycm2
 The trigger level (TL) is proposed as a dose level aiming
to alert the interventionalist when skin dose can be
comparable to a threshold for tissue effects.
 Trigger levels are usually expressed in term of CK (or KAP), when
its relationship with the peak skin dose has been assessed.
 When skin dose maps are available on modern equipment, TL can
be expressed in term of peak skin dose (PSD)
 Clinical follow-up is recommended for patients exceeding
TL
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Quality management
 When dose reports from the angiographic equipment
(private or DICOM RDSR) and dose archives are available,
more detailed analysis are possible and easier to perform
like:
 Cumulative patient dose assessment
 Repeated procedures
 Peak skin dose assessment
 To address clinical follow-up
 Procedure protocol
 Operator behaviour
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Example of operator’s behavior
 3 interventionalists are working in the same hospital with
the same equipment on a similar mix of procedures
 average KAP for fluoro and cine modes IC-A/IC-B = 3
Average fluoroscopy time & KAP per IC procedure
60.0
KAP (Gycm2)
50.0
40.0
30.0
20.0
KAPcine
10.0
KAPflu…
0.0
A
Interventional Cardiologist
Fluoro…
B
D
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Quality management: dose tracking tools
 These necessary analysis require an easy collection of
procedure parameters and dose data
 IEC, DICOM and IHE have developed standards supporting
these needs (with AAPM and EFOMP)
 … today, patient dose tracking tools are becoming
available representing an
important step in the quality
management of the IR practice
 Reports should be easy
to read for all the IR staff,
they should not be a MP tool !
REGISTRATION
ARCHIVE
DISTRIBUTION
IHE Radiation Exposure Monitoring Profile (REM)
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Occupational radiation protection
20 hospitals in 15 countries: annual doses and individual workload (2010)
Interventional Cardiologists: Over apron and effective dose versus no. of IC
procedures performed in a year (triangle: staff in training)
Great variability, high doses and number of unrealistic zero values.
Do we know actual staff exposures in IR ?
ISEMIR (IAEA) project survey (2011)
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Occupational radiation protection
 The present poor situation of staff monitoring, mainly in IC,
is quite unexpected
 ... after 50 years of regulations, dosimetry techniques
developments, personal monitoring experience and training
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Personal monitoring habits
 Interventional cardiologists:
 76% claimed that they always used their dosimeter
 45% stated they always used 2 dosimeters
 50% in Healthcare Level I countries
 24% in other countries
Results from the survey probably give an over-optimistic picture
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Knowledge of doses
 Interventional cardiologists:
 64% said they knew their own personal doses
 38% knew both their own and patients’ doses
Results from the survey probably give an over-optimistic picture
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Regulatory requirements for monitoring in IC
 ~ 60% of RBs stated that they specify the number and
position of dosimeters
 20% specify 2 dosimeters
 1 above and 1 below the apron
 40% specify 1 dosimeter
 Most (~ 80%) above the apron
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Eye lens exposure of ICs
• Over apron Hp(0.07) is
frequently used to estimate
eye lens doses
• Sample of “good” quality
data are showing a great
fraction of ICs are receiving
doses over the recently
ICRP recommended limit.
First operator: mean value 50 µSv/procedure
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... summarising
 Staff exposure of IC staff:




Lack of knowledge of actual doses
Large variability of doses
Great number of unrealistic zero dose values
Individual high dose values are indicating existence of
high exposures in IC practice
 Probably, a large fraction of interventionalists have
annual eye doses well over 20 mSv/y
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Eye lens dose assessment in IR
 New dosimetry challenges are posed by the
2011 ICRP recommendation
 Several factors are influencing eye dose:




use of eye shields (suspended lead screen, lead glasses)
position of the operator
X-ray projection
dosimeter position:
 Above the eye on the side of the x-ray tube
 Alternative: dosimeter at the neck over the apron
 Uncertainty in dose assessment can be very high
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Optimisation in IR: staff exposure
 The need:
 To improve staff monitoring:
 Dosimetry: models to assess eye doses, computational
dosimetry
 Technologies:
 active dosimeters, electronic archives providing real time
information,
 integration of staff and patient exposures
 To improve dosimetry practices
 Inspection/audit
 to integrate national dose archives with personal data
(e.g. clinical tasks & workload)
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Reduce patient/staff exposure: training
 Training in RP should become an essential part of the IR
process
 The training should be theoretical and practical with:
 a curriculum appropriate to the practice
 a certification, or formal qualification
MEDRAPET
(2011)
(2014)
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EU BSS (2013)
 Formal recognition of E&T in RP is required by new BSS
 Art.18 - Education, information and training in the field of
medical exposure
1. Member States shall ensure that practitioners and the individuals
involved in the practical aspects of medical radiological procedures
have adequate education, information and theoretical and practical
training ... in radiation protection.
... Member States shall ensure that appropriate curricula are
established and shall recognise the corresponding diplomas,
certificates or formal qualifications.
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… training in IR for medical physicists
High dose X-ray procedures in Interventional Radiology
and Cardiology: establishment of a robust quality
assurance programme for patients and staff
Udine (Italy) 13–18 February 2016
Module leaders: E. Vano, A. Trianni
www.eutempe-rx.eu
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