1. Interventional Radiology Radiation Safety
Radiation Safety in IR

2. Radiation Risk from X-Rays
Even small doses of radiation can damage DNA.
Large doses of radiation can cause health effects.
Ulceration
Dentist’s Finger (1980) Angioplasty (1994) CT Perfusion Scan
Radiation Safety in IR

3. Who is at risk from radiation?
PRIMARY BEAM:
Patient: mSv/procedure
SCATTER RADIATION:
Physician Operator: mSv/yr
Technologist: mSv/yr
Anesthesiologist: mSv/yr
Nurse: mSv/yr
*Above are Effective Doses (1 mSv = 100 mrem)
Radiation Safety in IR

4. Scatter Radiation from X-Rays
The patient is the main source of scatter
radiation during x-rays.
Scatter radiation dose is approximately
0.001 x Patient Dose 1m)
Radiation Safety in IR

5. X-Rays Scatter from Patient to You:
Scatter 1m is ~0.001 of patient dose
40 mSv/min
3 ft
40 uSv/min
Radiation Safety in IR

6. Personnel Dose is Proportional to Patient Dose:
Scatter radiation dose is approximately
0.001 x Patient Dose 1m)
Patient dose depends on:
patient thickness
# of DSA images
minutes of fluoro/cine
Radiation Safety in IR

7. Minimizing Radiation Dose to Personnel - Minimize TIME
Surgeon / Radiologist / Cardiologist:
Minimize fluoro/cine beam-on time
Minimize # of CR/DR/DSA images
Personnel in X-Ray Room:
Minimize time NEAR patient during
x-ray on.
Radiation Safety in IR

8. Minimizing Radiation Dose to Personnel - Maximize DISTANCE
Scatter radiation decreases as
1 / (Distance)2
During x-ray exposures, ancillary personnel should stand at least 6 ft. from the patient, whenever possible.
Radiation Safety in IR

9. Scatter Dose Decreases with Distance
Scatter Dose falls off as 1/(distance)2
3 ft
3 ft
40 uSv/min
10 uSv/min
Radiation Safety in IR

10. Minimizing Radiation Dose to Personnel - Use SHIELDING
Lead aprons attenuate > 90% of scattered radiation
Lead should be between you and patient
Radiation Safety in IR

11. Lead Shield Care Hang aprons and shields on racks.
Do not bend or fold lead aprons or shields.
Folding can cause cracks and tears in
the protective material.
Inspect all shields for lead integrity at least
annually.
Radiation Safety in IR

12. Minimizing Radiation Dose to Personnel - Use SHIELDING
Use tableside lead drapes
Use rolling & pull down head shields
Radiation Safety in IR

13. Minimizing Radiation Dose to Personnel - Positioning
Good Geometry
Poor Geometry
Radiation Safety in IR

14. Minimizing Radiation Dose to Personnel - Positioning
Poor Geometry
Good Geometry
Radiation Safety in IR

15. Worker Occupational Doses:
Whole Body Limit: mrem/qtr
(12.5 mSv/qtr)
Investigational Limit: mrem/qtr
(1.25 mSv/qtr)
Typical dose to ancillary staff in room:
<50 mrem / quarter
<200 mrem / year
Radiation Safety in IR

16. How Much Radiation do You Get?
Only your radiation badge reading can give a reliable estimate.
… and only if you wear
it and return it!
Radiation Safety in IR

17. Radiation Badges Wear the badge flat against your body. Do
not wear badges on a chain (allows badge to turn at various angles as you work.
Wear the badge outside of any lead apron at
the collar.
Radiation Safety in IR

18. Remember to: Wear it only at this hospital
Wear only your own badge
Wear it only at this hospital
Do not expose to other sources of radiation.
Do not wear the badge for personal x-ray or nuclear medicine exams.
Turn in your badge for processing in a timely manner.
Radiation Safety in IR

19. Pregnant Workers Declared Pregnant Workers must be limited to
50 mrem (0.5 mSv) / month to the fetus.
Should formally Declare Pregnancy
Extra radiation badges to wear at the waist
are available to pregnant radiation workers.
Historically rare for ancillary staff to get
50 mrem/month.
Radiation Safety in IR

20. Radiation Risk Skin Effects Cataracts Cancer Fetal Effects
Four concerns in IR:
Skin Effects
Cataracts
Cancer
Fetal Effects
Radiation Safety in IR

21. Radiation Risk: Skin Effects
Deterministic Threshold ~2 Gy (2000mGy)
This is for a single study
Threshold increases for cumulative dose from multiple studies on different days
>2 Gy 0%
HIGH %
Radiation Safety in IR

22. Absorbed Dose: Gy, mGy
Absorbed Dose = Energy deposited by ionizing radiation per unit mass of material.
Units (gray or Gy):
1 Gy = 1 joule / kg
1 Gy = 1000 mGy
1 Gy = 100 rads
Used for organ dose in estimating risk.

23. Absorbed Dose (mGy) Organ Dose (mGy) DAP (cGy-cm2) DAP (mGy-cm2)
Skin Dose (mGy)
ESAK (mGy/min)

24. Fluoro systems display Reference Point Dose:
Dose at 15 cm from isocenter
Approximates skin surface dose if patient is 30 cm thick
15 cm

25. Philips Ref Pt Dose Display:
Reference Point is 15 cm below isocenter – ESTIMATES Air Kerma, ie Entrance Skin Dose
Useful for predicting risk of skin injury

26. GE Ref Point Dose Display:
Reference Point is 15 cm below isocenter – ESTIMATES Air Kerma, ie Entrance Skin Dose
Useful for predicting risk of skin injury

27. Siemens Ref Pt Dose Display:
Reference Point is 15 cm below isocenter – ESTIMATES Air Kerma, ie Entrance Skin Dose
Useful for predicting risk of skin injury

28. Dose Distribution to Patient:
Total ESAK displayed = 7.5 Gy
Total displayed ESAK is not usually all to the same skin area.

29. Radiation Induced SKIN Injuries:
If dose is above specific threshold levels, repair mechanisms become overloaded and cell death and tissue breakdown can occur.
Note x-ray doses above these thresholds cause no sensation during irradiation.
Effects are not observable until hours to weeks after irradiation.

30. Potential Skin Effects from Fluoroscopy:
Effect Single-dose Onset Peak
Early transient erythema 2 Gy hours ~24 hr
Main erythema 6 Gy ~10 d ~2 wk
Temporary epilation 3 Gy ~3 wk
Permanent epilation 7 Gy ~3 wk
Dry desquamation 10 Gy ~4 wk ~5 wk
Moist desquamation 15 Gy ~4 wk ~5 wk
Secondary ulceration 20 Gy >6 wk
Late erythema 15 Gy ~6-10 wk
Dermal necrosis 18 Gy >10 wk

31. Typical Skin Dose in IR Procedures (50th percentile):
Procedure Skin Dose
Neuroembolization (head) Gy
Neuroembolization (spine) Gy
TIPS Gy
Hepatic Embolization Gy
Uterine Fibroid Embolization 2.0 Gy
GI Bleed Gy
NCRP No. 168; p77

32. Fluoro Dose & Dose Rates:
Entrance Skin Dose can range from:
< 10 mGy/min to > 500 mGy/min
30 minutes of fluoro on-time could result in:
0.3 Gy Gy
to patient skin.
0.3 Gy will produce no acute effect while Gy can cause severe radiation burns.

33. Fluoroscopy induced wound at 2 months after angioplasty
Coronary angiography, angioplasty, 2nd coronary angiography, coronary artery bypass graft all on same day.
Fluoro time estimated > 120 min

34. Fluoroscopy induced wound at 5 months after angioplasty
Appearance of healed burn with small ulcerated lesion near center

35. Fluoroscopy induced wound at 20 months after angioplasty
Skin breakdown with progressive necrosis.
Eventually required a skin graft.

36. EP Catheter Ablation: Injury at 6.5 months after procedure
Fluoro time estimated only 20 min
Dose estimated > 2500 rad (25 Gy)
Arm was hanging against x-ray collimator
BONE

37. Radiation Injuries to Patients: TJC SENTINEL EVENT
> 15 Gy
~200,000 cGy-cm2 (13 cm FOV)

38. Radiation Injuries to Patients: TJC SENTINEL EVENT
> 15 Gy cumulative over months to same area
Radiologist requires knowledge of patient’s radiation exposure history to minimize harm to patient

39. Radiation Injuries to Patients: TJC SENTINEL EVENT
> 15 Gy cumulative over months to same area
Detailed radiation exposure history must be available in patient record.

40. Radiation Risk Skin Effects Cataracts Cancer Fetal Effects
Four concerns in IR:
Skin Effects
Cataracts
Cancer
Fetal Effects
Radiation Safety in IR

41. Radiation Induced Cataracts:
Threshold for acute dose now ~ 0.5 Gy
Threshold for chronic dose much higher
ICRP limit for radiation workers of 150 mSv/yr now being lowered to 20 mSv/yr.
NCRP and SIR now recommend leaded glasses for IR procedures.

42. Radiation Risk Skin Effects Cataracts Cancer Fetal Effects
Four concerns in IR:
Skin Effects
Cataracts
Cancer
Fetal Effects
Radiation Safety in IR

43. Radiation Risk: Cancer
EFFECTIVE DOSE (mSv) is better correlated with probability of cancer induction than Entrance Skin Dose (mGy)
Effective Dose takes into account the dose to all organs and the radiation sensitivity of each organ.
Effective Dose = ∑ Organ Dose * Tissue Weighting Factor
Radiation Safety in IR

44. EFFECTIVE Dose
Effective Dose (mSv)
DAP (cGy-cm2)

45. Radiation Risk: Cancer
Effective Dose can be compared to the natural background radiation to which everyone is exposed
Radiation Safety in IR

46. Background Radiation Total ~ 3.0 mSv/year NYC ~ 4.5 mSv/year CO
Radiation Safety in IR

47. Radiation Risk: Cancer
NO dose threshold
Probability of radiation induced cancer low
0.1%/10 mSv
10 mSv (1 body CT) increases cancer risk from normal 42% to 42.1% (1 CT)
(BEIR VII)
10 mSv
42%
42.1%
Radiation Safety in IR

48. Cancer Risk: CT
Radiology 2008; p255
Radiation Safety in IR

49. Cancer Risk: IR
Radiology 2008; p255
Radiation Safety in IR

50. Cancer Risk: NIR AVM: 100-200 mSv (BJR 2000; p747)
Head Estimate from Skin Air Kerma:
mSv = ESAK(mGy) * ~0.02
Radiation Safety in IR

51. Radiation Induced Cancer:
Probability adds for multiple exams, ie to patients
Probability adds for chronic exposure, ie radiation workers.
Probability is age dependent
Children at least 2x more sensitive.

52. Radiation Induced Cancer is Age Dependent:
(1 sievert = 1 gray for x-rays)
Radiation Safety in IR

53. Radiation Risk Skin Effects Cataracts Cancer Fetal Effects
Four concerns in IR:
Skin Effects
Cataracts
Cancer
Fetal Effects
Radiation Safety in IR

54. Fetal Radiation Risk: Childhood Cancer
NO dose threshold
Small increased risk entire gestation period
0.4%/10 mSv
Radiation Worker: 0.5 mSv/month for 9 months = 5 mSv to fetus increases risk above normal 0.3%
5 mSv
0.3%
0.5%
Radiation Safety in IR

55. Fetal Radiation Risk: Birth Defects
Dose Threshold of ~50 mSv
Radiation Worker: 0.5 mSv/month for 9 months = 5 mSv to fetus does not increase risk.
5 mSv 5% 5%
Radiation Safety in IR

56. Fetal Radiation Risk: Birth Defects
Above 50 mSv threshold: 1% increased risk per additional 10 mSv to fetus if 2-15 weeks postconception
1% per 10 mSv
Additional 10 mSv increases birth defect risk from normal 5% to 6%
10 mSv 5% 6%
Radiation Safety in IR

57. ALARA As Low As Reasonably Achievable
Using good safety practices each day,
every study, to keep your and your
patient’s radiation dose as low as
feasible.
Radiation Safety in IR

58. APPENDIX 1 Procedure & Post-Procedure Protocols for Dose Management
NCRP No. 168

59. Expected Skin Reactions:
Balter, et al, Radiology: Volume254: Number 2- Feb 2010:

60. Notification of Angiographer:
CD = Cumulative Dose = Reference Point Dose

61. Post-Procedure Action:

62. Patient Follow-Up:
Balter, et al, Radiology: Volume254: Number 2- Feb 2010:

63. Patient Follow-Up: Patient handout Advises where to look and for what
Says Department will follow-up with phone call “next month”
Steele et al, RadioGraphics 2012;32:

64. Review: Minimizing Skin Injury
Maximize distance between x-ray focal spot and patient.
Skin spacer cones which touch the patient or couch, or the need to remove
cone are indications this recommendation is not being followed.
2. Bring image receptor as close as possible to patient.
For fixed SID c-arms, this means c-arm as low and table as high as feasible.

65. Good Geometry:
Typical Dose Rate:
30 mGy/min
SSD = maximum

66. Poor Geometry:
Typical Dose Rate:
90 mGy/min
SSD = minimum

67. Unacceptable Geometry:
Typical Dose Rate:
190 mGy/min !
Spacer removed

68. Review: Minimizing Skin Injury
3. Use magnification judiciously.
Higher mag (smaller FOV) modes use more radiation/image.
4. Use Low Dose settings for fluoro, cine, and DSA.
20 mGy/min
30 mGy/min
40 mGy/min
Low Dose
Med Dose
High Dose

69. Review: Minimizing Skin Injury
5. Use as low a Frame Rate as feasible in fluoro, cine, DSA.
6. Collimate to region of interest.
Better contrast + Lower risk

70. Review: Minimizing Skin Injury
7. Minimize fluoroscopy time.
5 min x 30 mGy/min = mGy
30 min x 30 mGy/min = mGy
60 min x 30 mGy/min = 1,800 mGy
8. Minimize length and number of Cine/DSA runs.
2 frames/sec x 10 sec x 2 mGy/fr = mGy
8 frames/sec x 10 sec x 2 mGy/fr = 160 mGy
15 frames/sec x 10 sec x 2 mGy/fr = 300 mGy
Also FLUORO SAVE can often be substituted for DA/DSA/Spot Film
FLUORO SAVE image = 0 mGy!

71. ALARA As Low As Reasonably Achievable
Using good safety practices each day,
every study, to keep your and your
patient’s radiation dose as low as
feasible.
Radiation Safety in IR