1. Dose Reduction in Interventional Radiology and Cardiology
Renato Padovani
ICTP, Trieste, Italy

2. The fact
Interventional radiology & cardiology are hospital fluoroscopy guided practices with the highest radiological workload
Annual workload of fluoroscopy guided practices
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

3. 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
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

4. Variability in patient doses
R. Padovani, Dose Management in Interventional Radiology
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)
Great variability of KAP values, not correlated with procedure complexity (fluoroscopy time)
SENTINEL project survey (2007)
IAEA Training Course, March 2009, Udine (Italy)

5. 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)
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

6. 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

7. Equipment for IR: example of setups and performances
R. Padovani, Dose Management in Interventional Radiology
Equipment for IR: example of setups and performances
Entrance surface air kerma rate
In image acquisition (cine) modes
Entrance surface air kerma rate
In fluoroscopy modes
- 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)
Large variability in equipment set-up and performances:
- cine low: ratio max/min 4
cine normal : ratio max/min 4
SENTINEL project survey (2007) 7
IAEA Training Course, March 2009, Udine (Italy)

8. 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.
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

9. Example of reference levels for angiography equipment dose rates
SENTINEL proposed reference levels for entrance air kerma rates for cardiac interventional procedures
Recommendations to set-up equipment dose rates for the different clinical tasks are necessary
SENTINEL project survey (2007)

10. Quality management: assess and use of DRLs in IR
R. Padovani, Dose Management in Interventional Radiology
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 non-standard 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
IAEA Training Course, March 2009, Udine (Italy)

11. Example of DRLs for IC
DIMOND and SENTINEL projects proposed reference levels for dose rates for cardiac procedures
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)

12. DRLs for Interventional Radiology
Type of examination
Reference levels
Fluoroscopy time (min)
Number of images
KAP
(Gy cm2)
Transjugular intrahepatic portosystemic shunt creation 60
300
525
Biliary drainage 30 20
100
Nephrostomy for obstruction 15 12 40
Nephrostomy for stone access 25 14
Pulmonary angiography 10
215
110
Inferior vena cava filter placement 4
Renal or visceral angioplasty without stent
210
200
Renal or visceral angioplasty with stent
250
Iliac angioplasty without stent
Iliac angioplasty with stent
350
Bronchial artery embolisation 50
450
240
Hepatic chemoembolisation
400
Uterine fibroid embolisation 36
Other tumor embolisation 35
325
390
Gastrointestinal hemorrhage localization and treatment
425
520
Embolisation in the head for AVM
135
1,500
550
Embolisation in the head for aneurysm 90
1,350
360
Embolisation in the head for tumor
1,700
Vertebroplasty 21
120
Pelvic artery embolisation for trauma or tumor
Embolisation in the spine for AVM or tumor
130
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.
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

13. … 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 non-optimised, high dose and/or repeated procedures?
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

14. DRLs vs complexity of PTCA procedures
R. Padovani, Dose Management in Interventional Radiology
DRLs vs complexity of PTCA procedures
IAEA study (2006)
More 1000 PTCA procedures analysed
Anathomical and pathology determinants for complexity of procedures identified
Reference levels assessed as a function of complexity
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
IAEA Training Course, March 2009, Udine (Italy)

15. 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)
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

16. 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
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

17. 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
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

18. 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
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

19. 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
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

20. 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
DISTRIBUTION
ARCHIVE
IHE Radiation Exposure Monitoring Profile (REM)
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

21. 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)
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

22. 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
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

23. 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
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

24. Results from the survey probably give an over-optimistic picture
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
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

25. 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
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

26. 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
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

27. ... 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
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

28. Eye lens dose assessment in IR
New dosimetry challenges are posed by the 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
Brow (fronte)
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

29. 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)

30. 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)
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

31. 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
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.
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

32. … 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
R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology