1. Radiation Safety Michael Shortsleeve, MD Thomas Osborne, MD MAH

2. Radiation Safety outline 1. Background radiation to the general public 2. X ray production and terms 3. X ray interaction 4. The Fluoroscopy machine -And specific related exposure concerns 5. Radiation Biology 6. Tips to decrease patient and operator exposure

3. Michael Shortsleeve, MD & Thomas Osborne, MD -U.S. Nuclear Regulatory Commission

4. Background X-ray Production An electrically heated filament within the X-ray tube generates electrons Electrons are then accelerated from the filament to hit a tungsten target –This is done with a high voltage potential in the tube Michael Shortsleeve, MD & Thomas Osborne, MD antonine-education.co.uk

5. Background X-ray Production The quantity of electron flow, is the current –Described in units of milliamperes (mA) The maximum kinetic energy of the accelerated electrons –Is defined in terms of kilovolts peak potential (kVp) Michael Shortsleeve, MD & Thomas Osborne, MD Energy = kVp Amount = ma

6. Background X-ray Production Higher mA values = more electrons =more X-rays – The relationship is directly proportional Increasing kVp = an increase in the energy of the X-ray –However, this relationship is not directly proportional The total number of X-rays produced at a set kVp depends directly on the product of the mA and exposure time and is described in terms of mA-s Michael Shortsleeve, MD & Thomas Osborne, MD Energy = kVp Amount = ma Total xrays = mAs

7. Background Description of Radiation Exposure Terms X-ray machine output is described in terms of Entrance Skin Exposure (ESE) "table-top dose." –Amount of radiation delivered to the skin –Units of ESE are Roentgens per minute (R/min) Michael Shortsleeve, MD & Thomas Osborne, MD Wilhelm Conrad Röentgen

8. Background Description of Radiation Exposure Terms Patient radiation exposure is described in terms of radiation dose Radiation dose is: –The energy imparted per unit mass of tissue –And has the units of Rad –Rad is an acronym for Radiation Absorbed Dose –Immediate biological effects are described in terms of Rad Michael Shortsleeve, MD & Thomas Osborne, MD

9. Background Description of Radiation Exposure Terms Occupational radiation exposure is also described in terms of radiation dose –However, the unit used is called the Rem –R oentgen E quivalent M an –Rems are synonymous with risk of latent Health effects –Dose equivalent was developed in an effort to incorporate biology into the physics of radiation exposure For discussion: 1 Rad = 1 Rem Michael Shortsleeve, MD & Thomas Osborne, MD 1 chest X-ray = about 6 mrem 1 CAT Scan = about 110 mrem 1 rem = 1,000 mrem

10. X ray interaction X-rays have several fates: No interaction: X-ray passes completely through tissue –To the image recording device Complete absorption: X-ray energy is completely absorbed –No imaging information results Partial absorption with scatter: Scattering involves a partial transfer of energy to tissue, a different trajectory –Degrade image quality –Primary source of radiation exposure to operator and staff Michael Shortsleeve, MD & Thomas Osborne, MD

11. X ray interaction Probability of radiation interaction is a function of: –Tissue electron density –Tissue thickness –X-ray energy (kVp) Dense material attenuates more –Bone, barium, iodine The differential rate of attenuation provides the contrast necessary to form an image Michael Shortsleeve, MD & Thomas Osborne, MD

12. X ray interaction Exposure The primary beam X-rays travel in straight but divergent directions as they exit the X-ray machine The degree of divergence increases with distance away from the X-ray origin (tungsten target) Michael Shortsleeve, MD & Thomas Osborne, MD 1 chest X-ray = about 6 mrem 1 CAT Scan = about 110 mrem

13. Consequently, the number of X-rays traveling through a unit area decreases with increasing distance Therefore, radiation exposure decreases with increasing distance –Exposure is directly proportional to the # of X-rays/unit area –The inverse square law Michael Shortsleeve, MD & Thomas Osborne, MD 1 chest X-ray = about 6 mrem 1 CAT Scan = about 110 mrem X ray interaction Exposure

14. Exposure The Inverse Square Law X A = the radiation exposure rate at distance D A X B = the radiation exposure rate at distance D B Therefore doubling the distance from a radiation source decreases radiation exposure by a fourth Michael Shortsleeve, MD & Thomas Osborne, MD 1 chest X-ray = about 6 mrem 1 CAT Scan = about 110 mrem

15. Example The Inverse Square Law An operator normally stands 1 meter away –If the exposure rate at this point is 15 mrem/min –And if the total time is 2 min (= 30 mrem) What is the reduction at 1.2 meters away? Michael Shortsleeve, MD & Thomas Osborne, MD 1 chest X-ray = about 6 mrem 1 CAT Scan = about 110 mrem

16. Example The Inverse Square Law An operator normally stands 1 meter away. –The exposure rate at this point is 15 mrem/min –Total time is 2 min. (= 30 mrem) What is the reduction at 1.2 meters away? Michael Shortsleeve, MD & Thomas Osborne, MD A 31% percent reduction in radiation exposure is achieved in this example. 1 chest X-ray = about 6 mrem 1 CAT Scan = about 110 mrem

17. Fluoroscopy X-ray tube (under table) X-rays, captured by an Image Intensifier (above table) –Which converts the X-ray energy into light. –Light output is then distributed to a closed- circuit video –Output can also be distributed to a spot film or cine. Although the output must be greater 10 – 20 x greater with cine “Last Image Hold” option Michael Shortsleeve, MD & Thomas Osborne, MD Saint Luke’s Health System Fluoroscopy Users Manual

18. Fluoroscopy Scatter Radiation is scattered in all directions –However, radiation levels are significantly lower above the table than below because of tissue attenuation in the forward direction Michael Shortsleeve, MD & Thomas Osborne, MD

19. The scatter radiation profile tilts with the X-ray tube Less exposure on the II side of the table when oblique angles are being imaged –tissue attenuation Michael Shortsleeve, MD & Thomas Osborne, MD Fluoroscopy Scatter

20. Larger field = more tissue irradiated Larger field = increased scatter radiation –Some of this scatter will degrade the resulting image –Some of this extra scatter will enter you Therefore, cone down the image Michael Shortsleeve, MD & Thomas Osborne, MD Fluoroscopy Field Size and Collimators

21. Fluoroscopy Automatic Brightness Control (ABC) ABC mode was developed to provide a consistent image quality during dynamic imaging With ABC, output is adjusted automatically to bring the brightness to a constant, proper level –Ex: when there is too much dark, the mA, kVp, or both, increase –The ABC compensates brightness loss caused by decreased xray reception by generating more X-rays –Therefore, a bigger patient or more dense material = more exposure Michael Shortsleeve, MD & Thomas Osborne, MD

22. Fluoroscopy Magnification Modes Magnification by electronically manipulating a smaller radiation II input area over the same II output area The ABC system compensates for the lower output brightness by increasing radiation production and subsequent exposure to patient and staff Michael Shortsleeve, MD & Thomas Osborne, MD (Field-Of-View)ESE (R/min)Increase Factor Normal (9 inch)1.21.0 Mag 1 (6 inch)2.92.4 Mag 2 (4.5 inch)5.24.3 Saint Luke’s Health System Fluoroscopy Users Manual

23. Fluoroscopy Magnification Modes Michael Shortsleeve, MD & Thomas Osborne, MDSaint Luke’s Health System Fluoroscopy Users Manual

24. Radiation Biology Stochastic Effects Carcinogenesis A non-threshold linear response to the dose-effect relationship 1 rem to 1 million persons would result in an increase in cancer deaths from 190,000 to 190,400 –increase of 0.2 % Michael Shortsleeve, MD & Thomas Osborne, MD National Council on Radiation Protection and Measurements. Recommendations on limits for exposure to ionizing radiation, NCRP Report No. 91, Bethesda, MD,1987.

25. Effects that appear only above a threshold dose The threshold may vary from person to person The severity of these effects increases with increasing dose above the threshold Most of these deterministic effects are seen within days or weeks after the exposure, but cataracts may appear a few years after exposure Michael Shortsleeve, MD & Thomas Osborne, MD Radiation Biology Deterministic Effects

26. Michael Shortsleeve, MD & Thomas Osborne, MD EffectThreshold Hours of Fluoro Hours of Cineeffect (rad)5 R/min30 R/min Transient Erythema2000.70.124 hr Epilation30010.23 wk Erythema60020.310 day Pericarditis8002.70.4>10 wk Dermal Necrosis180061>10 wk Saint Luke’s Health System Fluoroscopy Users Manual

27. Symptomatic Skin Reactions Two case reports –Unfortunately, many more in the literature Michael Shortsleeve, MD & Thomas Osborne, MD

28. Symptomatic Skin Reactions On March 29, 1990, a 40-year-old male underwent coronary angiography, coronary angioplasty… –And a second angiography procedure (due to complications) followed by a coronary artery by-pass graft. Total fluoroscopy time estimated to be > 120 min Michael Shortsleeve, MD & Thomas Osborne, MD Case Report #1: Thomas B. Shope, Ph.DScientific Exhibit 060PH at the 81st Scientific Asssembly and Annual Meeting of the Society of North America, November 26 - December 1, 1995. Radiology Vol. 197(P) Supplement, P449

29. Symptomatic Skin Reactions 7 w following the procedures Michael Shortsleeve, MD & Thomas Osborne, MD Case Report #1: Thomas B. Shope, Ph.DScientific Exhibit 060PH at the 81st Scientific Asssembly and Annual Meeting of the Society of North America, November 26 - December 1, 1995. Radiology Vol. 197(P) Supplement, P449

30. Symptomatic Skin Reactions 21 M following the procedures Michael Shortsleeve, MD & Thomas Osborne, MD Case Report #1: Thomas B. Shope, Ph.DScientific Exhibit 060PH at the 81st Scientific Asssembly and Annual Meeting of the Society of North America, November 26 - December 1, 1995. Radiology Vol. 197(P) Supplement, P449

31. Symptomatic Skin Reactions Following skin grafting procedure Michael Shortsleeve, MD & Thomas Osborne, MD Case Report #1: Thomas B. Shope, Ph.DScientific Exhibit 060PH at the 81st Scientific Asssembly and Annual Meeting of the Society of North America, November 26 - December 1, 1995. Radiology Vol. 197(P) Supplement, P449

32. Symptomatic Skin Reactions Pt had a 20 min cardiac catheter ablation –Prior to the procedure the separator cones were removed so that the fluoroscopic c-arms could be easily rotated around the patient –The separator cone is a spacer attached to the tube housing designed to keep the patient at a reasonable distance from the x-ray source –This is done specifically to avoid the high skin-dose rates that can be encountered near the tube port Michael Shortsleeve, MD & Thomas Osborne, MD Case Report #2: Benjamin R. Archer Louis K. Wagner Protecting patients by training physicians in fluoroscopic radiation management, Journal of Applied Clinical Medical Physics, Vol.1, No.,1, Winter, 2000.

33. Symptomatic Skin Reactions During the procedure, the right arm moved into the field However, personnel were not aware of this change because sterile covers were draped over the patient Michael Shortsleeve, MD & Thomas Osborne, MD Case Report #2: Benjamin R. Archer Louis K. Wagner Protecting patients by training physicians in fluoroscopic radiation management, Journal of Applied Clinical Medical Physics, Vol.1, No.,1, Winter, 2000.

34. Symptomatic Skin Reactions 3 w s/p the procedure –Bright erythema Michael Shortsleeve, MD & Thomas Osborne, MD Case Report #2: Benjamin R. Archer Louis K. Wagner Protecting patients by training physicians in fluoroscopic radiation management, Journal of Applied Clinical Medical Physics, Vol.1, No.,1, Winter, 2000.

35. Symptomatic Skin Reactions 3 w s/p the procedure –Bright erythema 5 m s/p procedure –A large ulcer the size of the collimated x-ray port Michael Shortsleeve, MD & Thomas Osborne, MD Case Report #2: Benjamin R. Archer Louis K. Wagner Protecting patients by training physicians in fluoroscopic radiation management, Journal of Applied Clinical Medical Physics, Vol.1, No.,1, Winter, 2000.

36. Symptomatic Skin Reactions 3 w s/p the procedure –Bright erythema 5 m s/p procedure –A large ulcer the size of the collimated x-ray port 8 m, s/p procedure –Debridement Michael Shortsleeve, MD & Thomas Osborne, MD Case Report #2: Benjamin R. Archer Louis K. Wagner Protecting patients by training physicians in fluoroscopic radiation management, Journal of Applied Clinical Medical Physics, Vol.1, No.,1, Winter, 2000.

37. Symptomatic Skin Reactions 3 w s/p the procedure –Bright erythema 5 m s/p procedure –A large ulcer the size of the collimated x-ray port. 8 m, s/p procedure –Debridement and a surgical flap Michael Shortsleeve, MD & Thomas Osborne, MD Case Report #2: Benjamin R. Archer Louis K. Wagner Protecting patients by training physicians in fluoroscopic radiation management, Journal of Applied Clinical Medical Physics, Vol.1, No.,1, Winter, 2000.

38. How to decrease overall exposure ALARA concept –i.e. As Low As Reasonably Achievable Michael Shortsleeve, MD & Thomas Osborne, MD

39. Caution modifying equipment Decrease fluoro time Last image hold Pulsed fluoro Decrease II – patient gap Cone down image (lead shutters) Avoid mag views Avoid cine run Michael Shortsleeve, MD & Thomas Osborne, MD Decrease patient exposure

40. Decrease personnel exposure Decrease patient exposure Increase distance Avoid x-ray tube side of table Shield Lead Aprons, gloves, glasses Fluoro on! Michael Shortsleeve, MD & Thomas Osborne, MD

41. Decrease complications History of prior radiation therapy 10 day rule for women of childbearing age Michael Shortsleeve, MD & Thomas Osborne, MD

42. Conclusion The risk of adverse radiation effects originating from a medically necessary procedure is almost always offset by the benefit received by the patient However, inadequate training can produce patient and staff doses that lead to serious consequences

43. Conclusion In this talk we covered: 1. Background radiation to the general public 2. X ray production and terms 3. X ray interaction 4. The Fluoroscopy machine -And specific related exposure concerns 5. Radiation Biology 6. Tips to decrease patient and operator exposure

44. Michael Shortsleeve, MD & Thomas Osborne, MD Radiation Safety The End Thank You

45. Decrease personnel exposure Decrease patient exposure Increase distance Avoid x-ray tube side of table Shield Lead Aprons, gloves, glasses Fluoro on! Michael Shortsleeve, MD & Thomas Osborne, MD Caution modifying equipment Decrease fluoro time Last image hold Pulsed fluoro Decrease II – patient gap Cone down image (lead shutters) Avoid mag views Avoid cine run Decrease patient exposure