1. Rad Protection in Fluoro & INTRO RHB regsRT
Week 1,2 Wed

2. Regulatory Requirements
1. Regarding the operation of fluoroscopy units
2. Regarding personnel protection
3. Regarding patient protection
shielding for image intensifier
cumulative timer
dead-man switch

3. Fluoroscopic Positioning Previewing
Radiographers are trained in positioning
Unnecessary radiation exposure to patient is unethical
Fluoroscopic equipment should not be used to preview patient’s position

4. Patient Protection Tabletop exposure rate Maximum 10 R/min
Typically 1 – 3 R/min
Some books ave is 4 R/min **

5. Patient Protection Minimum source-to-skin distance
12” for mobile equipment
15” for stationary systems
Audible alarm at 5 mins.
Same rules for collimation

6. Patient Protection Typical exposure rates Cinefluorography Cassettes
7.2 R/min
Cassettes
30 mR/exposure
105 mm film
10 mR/exposure

7. Protection of Radiographer and Radiologist
Lead apron
0.25 mm Pb/eq
Highest energy scatter
90o angle to the incident beam
Same level as radiographer /radiologist’s gonads

8. Protection of Radiographer and Radiologist
Single step away from the table decreases exposure exponentially
Bucky slot cover
Lead rubber drape
Radiologist as shielding

11. ISOEXPOSURE CURVES

12. Protection of Others
Radiographer’s responsibility to inform others in the room to wear lead apron
Do not initiate fluoroscopy until all persons have complied

13. PUBLIC EXPOSURE 10 % OF OCCUPATIONAL NON MEDICAL EXPOSURE
.5 RAD OR 500 MRAD
UNDER AGE 18 AND STUDENT
.1 rem mSv

14. COLLIMATION (for X-ray TUBE Collimator)
The PATIENT’S SKIN SURFACE
SHOULD NOT BE CLOSER THAN
___________ CM BELOW THE COLLIMATOR?
____________ INCHES?
15 cm / 6.5 inches

15. The Patient & Scatter

16. Radiation Protection (recap)
Tube in never closer to the patient than 15” in stationary tubes and 12” with a C arm
As II moves away from the patient the tube is being brought closer
Bucky tray is connected to a lead shield called the Bucky slot cover. It must be 0.25 mm Pb
There should be a protective apron of at least 0.25 mm Pb that hangs down from the II
Every machine is required to have an audible timer that signals 5 minutes of fluoroscopy time
Exposure switch must be a “dead man” type 16

17. Regulations about the operation
Fluoroscopic tubes operate at currents that range from0.5 to 5 mA with 3 the most common
AEC rate controls: equipment built after 1974 with AEC shall not expose in excess of 10 R/min; equipment after 1974 without AEC shall not expose in excess of 5 R/min

18. Other regulations Must have a dead man switch
Must have audible 5 min. exposure timer
Must have an interlock to prevent exposure without II in place
Tube potential must be tested (monitored)weekly
Brightness/contrast must be tested annually
Beam alignment and resolution must be tested monthly
Leakage cannot exceed 100mR/hr/meter

19. Fluoroscopy exposure rate
For radiation protection purposes the fluroscopic table top exposure rate must not exceed 10 mR/min.
The table top intensity should not exceed 2.2 R/min for each mA of current at 80 kVp

20. Patient Protection
A 2 minute UGI results in an exposure of approximately 5 R!!
After 5 minutes of fluoro time the exposure is R
Use of pulsed fluoro is best (means no matter how long you are on pedal there is only a short burst of radiation)
ESE must not be more than 5 rads/min

21. Rad Protection
Always keep the II as close to the patient as possible to decrease dose
Highest patient exposure happens from the photoelectric effect (absorption)
Boost control increases tube current and tube potential above normal limits
Must have continuous audible warning
Must have continuous manual activation

22. ESE FOR FLUORO TLD PLACED AT SKIN ENTRACE POINT
1 – 5 R/MINUTE AVE IS 4 R/MIN
INTERGRAL DOSE –
100 ERGS OF TISSUE = 1 RAD EXPOSURE
OR 1 GM RAD = 100 ERGS

23. SSD – TUBE TO SKIN DISTANCE
FIXED UNITS
18” PREFERRED
15 “ MINIMUM
MOBILE UNITS ( C-ARMS)
12’ MINIMUM

24. PATIENT PROTECTION LIMIT SIZE OF BEAM BEAM ON TIME
DISTANCE OF SOURCE TO SKIN
PBL
FILTRATION (2.5 mm Al 70
SHEILDING
SCREEN/FILM COMBO

26. GONAD SHIELDING MUST BE . 5 MM OF LEAD
MUST BE USED WHEN GONADS WILL LIE WITHING 5 CM OF THE COLLIMATED AREA (RHB)
KUB. Lumbar Spine Pelvis
male vs female shielding

27. ♀ receive 3x more dose than ♂ for pelvic x-rays
Gonad shielding & dose
♀ receive 3x more dose than
♂ for pelvic x-rays
1 mm lead will reduce exposure (primary) by about 50% ♀
by about 90 – 95 % ♂

29. KEEP I.I. CLOSE TO PATIENT

30. Over vs under the table fluoro tubes

31. REDUCE DISTANCE OF IMAGE INTESIFIER
PATIENT EXPOSURE
REDUCE DISTANCE OF IMAGE INTESIFIER
INCREASE DISTANCE FROM THE TUBE

32. Patient entrance skin exposure (ESE) is higher when the fluoroscopic x-ray tube is too close to the tabletop.

33. PATIENT EXPOSURE
REDUCE SIZE OF
COLLIMATED BEAM
WHEN POSSIBLE

34. Framing and patient dose syll = Pg 31
The use of the available film area to control the image as seen from the output phosphor.
Underframing
Exact Framing, (58 % lost film surface)
Overframing,(part of image is lost)
Total overframing

35. EXPOSURE RATES FLUORO MA IS 0.5 MA TO 5 MA PER MIN
AVE DOSE IS 4 R / MIN
IF MACHINE OUTPUT IS 2 R/MA/MIN = WHAT IS PT DOSE AT 1.5 MA FOR 5 MIN STUDY?
15R

36. EXPOSURE RATES FOR FLUORO
CURRENT STANDARD
10 R/MIN (INTENSIFIED UNITS)
HLC: BOOST MODE 20 R/MIN
OLD (1974) NO ABC NON IMAGE INTES
5 R/MIN

37. DOSE REGULATIONS BEFORE 1974 - AT TABLETOP 5R/MIN (WITHOUT AEC)
5R/MIN (WITHOUT AEC) – BOOST MODE
After with AEC
10 R/MIN R/MIN BOOST

38. RADIATION PROTECTION The Patient is the largest scattering object
Lower at a 90 DEGREE ANGLE from the patient + PRIMARY BEAM
AT 1 METER DISTANCE -
1/1000 OF INTENSITY PRIMARY XRAY or 0.1%

39. BUCKY SLOT COVER
.25 MM LEAD

40. Bucky Slot Cover

41. ISOEXPOSURE CURVES

43. PERSONNEL PROTECTION SCATTER FROM THE PATIENT
TABLE TOP, COLLIMATOR, TUBE HOUSING, BUCKY
STRAY RADIATION – LEAKAGE OR SCATTER RADIATION

45. TOWER CURTAIN
.25 MM LEAD EQ

46. Lead curtain & dose reduction

47. Pulsed Fluoro
Some fluoroscopic equipment is designed for pulsed-mode operation. With the pulsed mode, it can be set to produce less than the conventional 25 or 30 images per second. This reduces the exposure rate.
Collimation of the X ray beam to the smallest practical size and keeping the distance between the patient and image receptor as short as possible contribute to good exposure management.

49. PERSONNEL PROTECTION
STANDING BEHIND A PROTECTIVE PRIMARY (1/16TH pb) BARRIER:
PRIMARY RADIATION EXPOSURE – 99.87% REDUCED
PORTABLE BARRIER = 99 % REDUCTION

50. PERSONNEL PROTECTION PROTECTIVE APRONS – 0.25 PB = 97% ↓ TO SCATTER
THYROID SHEILDS (0.25 & 0.5)
GLOVES (0.25 & 0.5)

51. PERSONNEL PROTECTION MONITORING
FILM BADGE
TLD
POSL
POCKET DOSIMETER
RING BADGE

52. PERSONNEL PROTECTION MONITORING
DOSE LIMITS
WHOLE BODY
EYES
EXTREMITIES (BELOW ELBOW/KNEES)

54. Report at least every quarter Preserved for a minimum of 3 years

55. RHB NOTIFICATION (EXP IN 24 HOURS) (RP Syllabus – pg 68)
IMMEDIATE reporting – WITHIN 24 HOURS
TOTAL DOSE OF 25 rems
Eye dose – 75 rem
Extremity – 250 RADS
OVEREXPOSURE – received w/in 24 hrs
Must be ReportedWITHIN 30 DAYS
TOTAL DOSE OF 5 rems
Eye dose – 15 rem
Extremity REMS

56. LICENSE RENEWAL WITHIN 30 DAYS OF EXPRIATION
NOTIFICATION OF CHANGE OF ADDRESS

57. HIGH RADIAITON AREA – RADIAITON AREA – 100 mRem ( 0.1 rem / (1 msV)
@ 30 cm from the source of radiaton
RADIAITON AREA –
RHB: 5 mRem ( rem / (.05 msV)
@ 30 cm from the source of radiation
PUBLIC 2 mrem per week* (STAT)

58. A “controlled area” is defined as one
that is occupied by people trained in radiologic safety
that is occupied by people who wear radiation monitors
whose occupancy factor is 1

59. RHB “RULES” RHB RP PG61 LICENTIATES OF THE HEALING ARTS
(MD, DO, DC, DPM)
MUST HAVE A
RADIOLOGY SUPERVISOR & OPERATORS PERMIT & CERTIFICATE
TO OPERATE OR SUPERVISE THE USE OF X-RAYS ON HUMANS
SUPEVISORS MUST POST THEIR LICENSES

60. RHB “RULES” RHB RP PG62 ALL XRAYS MUST BE ORDERED BY A PHYSICIAN
VERBAL OR WRITTEN PRESCRIPTION
See Section C – “Technologist Restrictions”

61. DOSE
CINE - 2mR per frame (60f/sec)
400 mr per “look”

62. WHATS WRONG?

63. Declared Pregnant Worker
Must declare pregnancy – 2 badges provided
1 worn at collar (Mother’s exposure)
1 worn inside apron at waist level
Under 5 rad – negligible risk
Risk increases above 15 rad
Recommend abortion (spontaneous) 25 rad
(“Baby exposure” approx 1/1000 of ESE)

64. Remote – over the table tube

65. Under table tube vs Over table tube (remote units) Need moving shield for Remote rooms

67. IsoExposure Curves Where is it SAFE??

68. Back to the Patient & Protection

72. RADIATION DOSE TO PATIENTS
ESE - ENTRACE SKIN EXPOSURE (MEASURED BY A TLD)
SKIN DOSE
GONADAL DOSE
BONE MARROW DOSE
(MEAN GLADULAR DOSE- MAMMO)
** SEE TABLE 1-5 PG 20 &
1-8 PG 21 (STAT)

75. ESE FOR FLUORO TLD PLACED AT SKIN ENTRACE POINT
1 – 5 R/MINUTE AVE IS 4 R/MIN
INTERGRAL DOSE –
100 ERGS OF TISSUE = 1 RAD EXPOSURE
OR 1 GM RAD = 100 ERGS

76. 1 rad (of ionizing radiation) deposits 100 ergs of energy per gram
1 RAD -100 ERGS – 1 GRAM
1 rad (of ionizing radiation) deposits 100 ergs of energy per gram

77. DOSE REGULATIONS BEFORE 1974 - AT TABLETOP 5R/MIN (WITHOUT AEC)
5R/MIN (WITHOUT AEC) – BOOST MODE
After with AEC
10 R/MIN R/MIN BOOST

79. SSD – TUBE TO SKIN DISTANCE
FIXED UNITS
18” PREFERRED
15 “ MINIMUM
MOBILE UNITS ( C-ARMS)
12’ MINIMUM

80. Conventional “FIXED” Fluoro

82. Mobile – C- arm fluoro

84. Pulsed Fluoro
Some fluoroscopic equipment is designed for pulsed-mode operation. With the pulsed mode, it can be set to produce less than the conventional 25 or 30 images per second. This reduces the exposure rate.
Collimation of the X ray beam to the smallest practical size and keeping the distance between the patient and image receptor as short as possible contribute to good exposure management.

86. Dose rate to patients

88. TUBE HOUSING 100MR / HR @ 1 METER
LEAKAGE RADIATION
TUBE HOUSING 100MR / 1 METER

90. STAT 8 & 9 Protecting Patients & Personnel
COMMUNICATE
COLLIMATE
SHIELD

91. IONIZATION CHAMBER- CUTIE PIE Q = t x תּ
Quantity of Radiation = time x pie (diameter of cylinder)

93. Mini c-arm

98. Some References
Physics of diagnostic radiology, Curry et al, Lea & Febiger, 1990
Imaging systems in medical diagnostics, Krestel ed., Siemens, 1990
The physics of diagnostic imaging, Dowsett et al, Chapman&Hall, 1998