Dose Reduction in Interventional Radiology and Cardiology

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

2. The fact Annual workload of fluoroscopy guided practices Interventional radiology & cardiology are hospital fluoroscopy guided practices with the highest radiological workload 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 • 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)

5. Variability in staff doses 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) 20 hospitals in 15 countries: annual doses and individual workload (2010) R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

6. Optimisation of radiation protection in interventional radiology D.L. Miller, Efforts to optimize radiation protection in interventional fluoroscopy. Health Phys, 2013 Nov; 105(5):435-44 • 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 R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

7. 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 • - fluorolow: 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

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 • 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

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 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 allowto 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 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

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

21. Occupational radiation protection 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) 20 hospitals in 15 countries: annual doses and individual workload (2010) 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 Results from the survey probably give an over-optimistic picture • 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 R.Padovani _ Dose Reduction in Interventional Radiology & Cardiology

24. 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 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 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 MEDRAPET (2011) (2014) • 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 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 www.eutempe-rx.eu 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