1. patient skin dose in IR, the worrying gap between best practice and clinical practice
Lee O’Hora BSc, MSc
Radiation Safety Officer
Mater Misericordiae University Hospital
Dublin
Danish Council of Radiographers
Annual Conference
Copenhagen
June 2017

2. ACKNOWLEDGEMENTS
Irish Institute Radiographers and Radiation Therapist University College Dublin (Dr. Louise Rainford, Dr. Marie Louise Butler) Mater Misericordiae University Hospital, Dublin

3. OVERVIEW
Part of on-going PHD research into clinical practice surrounding the management of potential tissue reactions (deterministic effects) across total of 136 large IR centers in 7 countries internationally.

4. STAFF AND TRAINING
IR SPECIALITY/PROCEDURE NUMBERS
EQUIPMENT AND DOSE METRICS
IR CONSENT
TISSUE REACTION IDENTIFICATION
PATIENT FOLLOW-UP
TISSUE REACTION MANAGMENT 18 11 4 3 3 91
A total of 136 questionnaires were completed from 7 countries.
Country Respondent Numbers
Italy 91
England 18
Ireland 11
Singapore 6
The Netherlands 4
Belgium 3
Portugal 3 6

5. ‘BEST PRACTICE’ Routine pre procedure consent
Use of ‘substantial radiation dose level’
Patient information and follow up once this has been reached

6. CONSENT
In 2011 (updated in 2014 and 2016), the ACR and the Society of Interventional Radiology (SIR) collaborated on the development of consent for image-guided procedures guidelines (ACR-SIR 2016). These clearly put responsibility for acquisition and recording of informed consent (of invasive diagnostic or therapeutic procedures) in the hands of the ‘physician or health care provider performing the procedure’ and add that and the consent process requires ‘face-to-face discussion…. of the anticipated benefits and potential risks of the procedure, as well as reasonable alternatives to the procedure’ where the patient has an opportunity to ask questions and discuss the procedure . It specifically elaborates on the notion of ‘image-guided procedures that may be associated with higher levels of radiation’ and suggests an explanation of the likelihood and characteristics of tissue reactions prior to the procedure.

7. CONSENT
All guidance and literature is clear in the need for pre-procedure planning and informed consent to include radiation effects, particularly tissue reactions in IR (NCRP 2010)(CRCPD 2010)(ACR–AAPM 2013)(Doudenkova and Bélisle Pipon 2015) The whole concept of consent in IR relating to tissue reactions is summated perfectly by Professor Stephen Balter “…Deterministic effects should never be a post procedure surprise.”(CRCPD 2010) Consent is the first domino in this important process, without which the process is flawed!

8. DOSE IN INTERVENTIONAL RADIOLOGY
Dose considerations are unique
Only area in diagnostic radiography where we must consider the stochastic effects (B) and tissue reactions (A) of radiation for both the staff and patient

9. Measuring patient dose
MEASURING PATIENT DOSE - IR
Dose quantities in fluoroscopy fall into two categories. One that relates to stochastic risks (mostly cancer) and another to tissue reactions (deterministic risks) like skin injury.
Stochastic Effect
Cancer
DAP/KAP(Pka)
Gy.cm²
Tissue Reaction
Skin Injury
PSD
mGy
Really important concepts for radiographers to grasp and be able to explain to staff if necessary.
IR is the only area where we also must consider tissue effects or deterministic effects (skin redness generally, known as erythema), as well as stochastic effects (Increased chances of cancer)
Pka is the same as DAP which is the same as KAP, we use this for general radiography also as a way of quantifying patient dose/stochastic effects.
In IR we need to ALSO consider the maximum dose to the skin (Peak skin dose).

10. PATIENT SKIN DOSE IN INTERVENTIONAL RADIOLOGY
In IR, the tissue of concern is the skin because it is the area where radiation enters the body and thus receives the highest radiation dose. Reports of tissue reactions have been demonstrated across a range of interventional radiological procedures (Miller, Balter et al. 2003)(Wunderle and Gill 2015). Current thinking suggests that, while they occur, they are relatively uncommon (Balter and Miller 2014). Skin damage may be caused by a cumulative effect of multiple procedures (Imanishi, Fukui et al. 2005) but may also be a side effect of a single IR procedure (Balter and Miller 2014).

11. PATIENT SKIN DOSE IN INTERVENTIONAL RADIOLOGY
What we must remember is there is a THRESHOLD dose below which these will not occur, generally accepted as 2 Gy (Valentin 2000). An essential part of avoiding these is measuring or estimating Peak Skin Dose in Real time!

12. QUANTIFYING SKIN DOSE IN INTERVENTIONAL RADIOLOGY
Peak Skin Dose (PSD) Peak Skin Dose has been described as the highest dose at any portion of a patient’s skin during a procedure. Peak skin dose includes contributions from both the primary x-ray beam and from scatter. Peak skin dose is measured in Grays (to soft tissue) (Miller, Balter et al. 2010)

13. QUANTIFICATION OF SKIN DOSE
Direct measurement of PSD
PSD can be directly measured using radio chromic films or a matrix of thermo luminescent dosimeters (TLDs).
‘Skin dose mapping’ can be used as a direct, real time indicator of PSD when exposure and geometric factors are available for pairing with an anatomical patient models. (Johnson, Borrego et al )

14. DIRECT PSD – PROBLEMS!
FILMS/TLDs - labour intensive and do not give real time dose readings. More suitable for research purposes on a small sample of patients. (Padovani and Quai 2006) Skin dose mapping facilities - not widely available and, therefore ‘absent in routine practice’. (Struelens, Bacher et al. 2014)

15. QUANTIFICATION OF SKIN DOSE
Indirect measurement of PSD
PSD can be indirectly measured using other dose metrics;
Fluoroscopic Time (FT)
Pka (Dose/Kerma Area Product)
Kar (Air Kerma at a Reference point)
The official notation for kerma area product recommended in ICRU report 74 is PKA.
ICRU, International Commission on Radiation Units and Measurements, Patient Dosimetry for X Rays used in Medical Imaging, ICRU Report 74, Oxford University Press, Oxford, UK, Vol. 5, N° 2, 2005.
International Electrotechnical Commission. Medical electrical equipment: part particular requirements for the safety of x-ray equipment for interventional procedures. Report nd ed. Geneva, Switzerland: International Electrotechnical Commission, 2010

16. INDIRECT PSD – PROBLEMS!
FT - Non-dosimetric quantity BUT readily available . Should not be relied on as the sole dose metric for complex IR procedures as it is an extremely poor indicator of the risk of skin injury. (Balter, Hopewell et al. 2010) DAP – DAP (Pka) is a good surrogate for the amount of energy delivered to the patient and is generally used as a predictor of the risk of stochastic effects in IR. (NCRP 2010)

17. PATIENT DOSE IN INTERVENTIONAL RADIOLOGY
We must keep Pka dose (stochastic effects) ALARA
We must to attempt to eliminate the possibility of tissue reactions (avoid exposing any area of skin to 2 Gy)

18. SUBSTANTIAL RADIATION DOSE LEVELS
The NCRP, CRCPD and ACR and AAPM have suggested identical, unambiguous indirect dose parameter ‘trigger values’ or ‘substantial radiation dose levels (SRDLs)’ for the routine identification of and follow up of potential tissue reactions post interventional radiological procedures.

19. Parameter
Threshold
PSD
3000 mGy
Kar
5000 mGy
Pka
500 Gy.cm2 FT
60 min

20. PATIENT INFORMATION AND FOLLOW UP ONCE SRDL IS REACHED
Balter and Miller (2014) summate the accepted patient management after a SRDL or trigger value has been reached as; 1. Record rationale for Dose in patient notes (interventionist) 2. Advise patient/caregivers of possible tissue effects and follow-up procedures. 3. Advise patient of radiation dose and possible sequelae (appearance and position) 4. Instruct patient to perform self-examination 4 weeks after the procedure (A minor skin reaction will have disappeared by 4 weeks after the procedure but is of no clinical consequence and does not require further follow-up) 5. Telephone follow-up is sufficient if the patient reports no evidence of a tissue reaction 6. Follow-up in the interventionalist’s office is necessary if the patient has observed any abnormality (When a tissue effect is suspected, the patient should be referred to a physician experienced in managing radiation injuries. A radiation oncologist can usually identify an appropriate physician.)

21. RESULTS
Consent Out of 125 respondents, 35.2% (n=44) indicated that routine IR procedure consent included radiation effects, 16 of these included stochastic effects only, omitting tissue reactions. As a result 77.6% (n=97) of facilities surveyed did not routinely include tissue reactions in IR procedure consent.
“All guidance and literature in IR is clear in the need for pre-procedure planning and informed consent to include radiation effects”

22. RESULTS
Of 108 respondents, 23.1% (n=25) use a SRDL to identify patients who may have a potential tissue reaction. Of this group, 19 gave further information on the local SRDL used. A total of 29 SRDLs were quoted, some facilities quoting a range of different dose metrics as a SRDL.

23. RESULTS
PSD
Kar
Pka FT
Total
Total responses 7 4 12 6 29
SRDL VALUE and UNIT supplied 9 5 25
In accordance with best practise SRDLs 2 3
Of the 29 SRDLs quoted, 25 gave sufficient information (SRDL value and unit) to enable comparison with internationally suggested SRDL values. 5 of these were in line with internationally suggested SRDL values.
Questions regarding;
Appropriate use of a single/group of SRDL
Incorrect v. Locally determined SRDL (more research required)

24. RESULTS
Patient Information and Follow Up
Of 108 respondents, 23.1% (n=25) use a SRDL to identify patients who may have a potential tissue reaction. Of the facilities which professed to use SRDL, 11 give information regarding the potential tissue reaction to the patient and 6 routinely follow up with the patient.

25. SUMMARY
Interventional radiological procedures may cause patient tissue reactions (previously deterministic effects)
Large interventional facilities were surveyed regarding practice surrounding potential tissue reactions
22.4% routinely include tissue reactions in patient consent
23.1% attempt to identify potential tissue reactions
10.2% give patient information and 5.6% follow up patients (post SRDL)

26. THANK YOU….

27. REFERENCES
ACR-SIR. Practice parameter on informed consent for image guided procedures [cited ];
MILLER, D. L., BALTER, S., SCHUELER, B. A., WAGNER, L. K., STRAUSS, K. J. & VAÑÓ, E Clinical radiation management for fluoroscopically guided interventional procedures. Radiology, 257,
JOHNSON, P. B., BORREGO, D., BALTER, S., JOHNSON, K., SIRAGUSA, D. & BOLCH, W. E Skin dose mapping for fluoroscopically guided interventions. Medical Physics, 38,
PADOVANI, R. & QUAI, E Patient dosimetry approaches in interventional cardiology and literature dose data review. Radiation Protection Dosimetry, 117,
STRUELENS, L., BACHER, K., BOSMANS, H., BLEESER, F., HOORNAERT, M. T., MALCHAIR, F. & BALTER, S Establishment of trigger levels to steer the follow-up of radiation effects in patients undergoing fluoroscopically-guided interventional procedures in Belgium. Physica Medica, 30,
Miller, D.L., et al., Radiation doses in interventional radiology procedures: The RAD-IR study. Part II: Skin dose. Journal of Vascular and Interventional Radiology, (8): p
Wunderle, K. and A.S. Gill, Radiation-related injuries and their management: An update. Seminars in Interventional Radiology, (2): p
ICRU, International Commission on Radiation Units and Measurements, Patient Dosimetry for X Rays used in Medical Imaging, ICRU Report 74, Oxford University Press, Oxford, UK, Vol. 5, N° 2, 2005.
International Electro technical Commission. Medical electrical equipment: part particular requirements for the safety of x-ray equipment for interventional procedures. Report nd ed. Geneva, Switzerland: International Electro technical Commission, 2000
BALTER, S., HOPEWELL, J. W., MILLER, D. L., WAGNER, L. K. & ZELEFSKY, M. J Fluoroscopically guided interventional procedures: A review of radiation effects on patients' skin and hair. Radiology, 254,
NCRP NCRP Report 168. Radiation dose management for fluoroscopically-guided interventional medical procedures.
MILLER, D. L., BALTER, S., COLE, P. E., LU, H. T., SCHUELER, B. A., GEISINGER, M., BERENSTEIN, A., ALBERT, R., GEORGIA, J. D., NOONAN, P. T., CARDELLA, J. F., ST. GEORGE, J., RUSSELL, E. J., MALISCH, T. W., VOGELZANG, R. L., MILLER III, G. L. & ANDERSON, J Radiation doses in interventional radiology procedures: The RAD-IR study part I: Overall measures of dose. Journal of Vascular and Interventional Radiology, 14,
CHAMBERS, C. E., FETTERLY, K. A., HOLZER, R., LIN, P. J. P., BLANKENSHIP, J. C., BALTER, S. & LASKEY, W. K Radiation safety program for the cardiac catheterization laboratory.
FDA Performance standards for ionizing radiation emitting products. Code of Federal Regulations, Part 1020.
CRCPD, Technical White Paper: Monitoring and Tracking of Fluoroscopic Dose.
ACR–AAPM, TECHNICAL STANDARD FOR MANAGEMENT OF THE USE OF RADIATION IN FLUOROSCOPIC PROCEDURES.
ICRP Statement on Tissue Reactions / Early and Late Effects of Radiation in Normal Tissues and Organs – Threshold Doses for Tissue Reactions in a Radiation Protection Context. ICRP Publication 118. Ann. ICRP 41(1/2), 2012
COUNCIL DIRECTIVE 2013/59/EURATOM. Available at; Accessed

28. STAFF DOSE IN INTERVENTIONAL RADIOLOGY
Chest dosimeter worn under apron, estimating risk of stachastic effects (Cancer) Eye dosimeter worn to approximate/estimate lens dose and risk of tissue reaction (Radiation induced cataracts)

29. STAFF EYE DOSE IN INTERVENTIONAL RADIOLOGY
Threshold revised by the ICRP in 2012 and compounded by BSS in 2013 for national transposition by February Evidence for cataract development in medical occupationally exposed populations 20 mSv per year, averaged over defined periods of 5 years, with no single year exceeding 50 mSv.
ICRP Statement on Tissue Reactions / Early and Late Effects of Radiation in Normal Tissues and Organs – Threshold Doses for Tissue Reactions in a Radiation Protection Context
ICRP Publication 118
Ann. ICRP 41(1/2), 2012
COUNCIL DIRECTIVE 2013/59/EURATOM

30. PATIENT DOSE IN INTERVENTIONAL RADIOLOGY
Dose/Kerma area product (Pka, DAP, KAP) used to produce a procedure effective dose. Effective dose is more of a risk metric per se and can be used for inter-modality comparison and risk assessment (large patient cohorts, routine procedures). This can subsequently be related to a ‘lifetime risk’ , Usually expressed as odds (1 in x chance) or a percentage (x%) and sometimes as increased number of cancer cases per 100/1,000/100,000/1,000,000 people exposed to that quantity of radiation. Used for development of local, national and international DRLs and should be kept ALARA