1. Fluoroscopy Notes
Rad Tech 290

2. Fluoroscopy Notes Ch 1
Approximately 5% of the US population has a fluoro procedure each year
The average number of fluoro exams per person is 1.3
The average number of spot films is 4.6

3. The MC exam is a GI tract at 53%
A 2 minute UGI exam can produce an exposure ranging from 5-15 rads, comparatively a KUB is between mrads.
Fluoro is defined as a rad exam utilizing fluorescence for the observation of the transient image.

4. Fluoro was first used as a dynamic procedure
Fluoro was first used as a dynamic procedure. Second as a means of positioning for spot films.
Medical exposure accounts for about 20% of the total radiation people receive.
Even though the percentage is small, for medical exposure, it is the only exposure that is controllable.
FLUOROSCOPY TO POSITION PATIENTS IS PROHIBITED.

5. Notes Chapter 2 Factors Directly Affect ExposuremA
kVp
Collimation
Filtration
Exposure time
Total fluoro time
Target to panel distance (TPD)
Patient to II distance
Sensitivity of the image receptor
Essentially speed RSV

6. The following will reduce exposure
Collimating
Last frame hold
Shortest possible patient to II distance
Highest possible kVp
Pulsed fluoroscopy
Using the largest II mode with collimation

7. Factors indirectly influencing exposure
Room illumination
Image receptor quality
Absorption of the table top

8. mA
0.5 – 5 mA
Usually 1 – 3 mA
Spot films
100 mA or higher
Output and dose are directly proportional to mA

9. kVp Maximum photon energy Beam quality Penetrability of the beam
Tube potential

10. collimation Required by law
Image quality improves as the beam is collimated

11. Collimation Collimate tightly to the area of interest.
Reduces the patient’s total entrance skin exposure.
Improves image contrast.
Scatter radiation to the operator will also decrease.

12. Factor affecting staff doses
FIELD SIZE DEPENDENCE
Scattered dose rate is higher when field size increases
11x11 cm
17x17 cm
17x17 cm
100 kV
0.8 mGy/h
1.3 mGy/h
1 mA
0.6 mGy/h
1.1 mGy/h
0.3 mGy/h
0.7 mGy/h
1m patient distance
Patient
thickness 18 cm

13. filtration
If the tube is operated above 125 kVp, 3 mm Al eq is required.
Filtration reduces patient dose

14. Source to table top target to panel distance
Cannot be less than 12” and should be 18”
Mobiles are required to be at least 12”
Fixed units, 15”

15. Patient to II distance The closer the II, the lower the dose
This is more pronounced with fixed units.
Decreases the SID

16. Tabletop
Less than 1 mm Al eq at 100 kVp
Exposure switch
Dead man type

17. Primary protective barrier
The II is the primary barrier and must have 2 mm Pb eq for systems operating above 125 kVp
The II has to be in place for the tube to energize

18. Protective Actions Bucky Slot Cover Protective curtains
Automatically covered, 0.25 mm Pb eq
Protective curtains
0.25 mm Pb eq
Not required on c-arms
Scatter at 1 foot can reach 500 mrad/hr

19. Allowable exposure rates
Cannot exceed 5 rad/minutes
Unless, ABC or image recording
Cumulative timer
Cannot exceed 5 minutes
Illumination

20. II Considerations Purpose Brightness Gain
The basic purpose of the II is to make the fluoro image brighter
When the image is brighter it is easier to visualize structures
Brightness Gain
Minification gain multiplied by electronic (flux) gain

21. II Facts Input phosphor, cesium iodide Photcathode, danium antimony
Output phosphor, zinc cadnium sulfide

22. Image Quality Issues Quantum Mottle Contrast Resolution
Caused by too few photons
Contrast
Subject
Detector
Image
Resolution

23. The first step in obtaining optimum contrast in an x-ray image is to adjust the x-ray beam spectrum for the specific anatomy and clinical purpose. The penetration and the resulting contrast of a specific object or structure in the body generally depends on the photon energy spectrum.
Contrast is not the only thing that must be considered in selecting the spectrum for a specific procedure.  The spectrum also affects the penetration through the body section being imaged.  This has a significant effect on the radiation dose to the patient.  Also, as the penetration through a body section is reduced, the amount of radiation required from the x-ray tube is increased with a resulting increase in x-ray tube heating. 
Effect of X ray Beam Penetration on Contrast, Body Penetration, and Dose t

24. Dose vs. Noise
15 µR per frame
24 µR per frame
2 µR per frame

25. Magnification tubes, Multi-mode
Distortion
Size, shape, pincushion
Lag
Vignetting
Less bright at the edges than center of image
Magnification tubes, Multi-mode
Variable FoV

26. Closed Circuit TV Systems
Camera
MC is the vidicon
Camera control unit
Video amplifier
Monitor
CRT, etc.

27. Cinefluoroscopy Synchronization Framing frequency F-number
Record with the x-ray pulses
Framing frequency
Division of 60
The higher the rate the higher the dose
F-number
Video disk recording (electronic radiography)
Exposure ends when image is formed
Basically fluoro phototiming
95% dose reduction

28. Video tape Spot films Instant playback and no additional dose
Conventional cassettes
Photospot cameras
½ to 1/3 dose of convent. Cass.
Lower image quality

29. Accessories Gonadal shields Grids Cassettes Cine film
Required when possible
Grids
Fluoro uses low ratio grids
Cassettes
Cine film
Per frame basis 10 x the dose than fluoro

30. Factors affecting an Increase in Scatter
High kVp
Large field size
Thick body part

31. Advantages of 3 phase and medium/high frequency generators
Relatively high mA
Higher effective kVp
Near constant potential
Less ripple

32. Notes for Chapter 3 Fluoro Image Production
Fluoro units have 2 basic components
X-ray tube
Image intensifier

33. Fluoro X-ray Tube Regular rotating anode x-ray tube Runs at a lower mA
Less than 5 mA
Small focal spot
Possible because of the low mA

34. II
The primary purpose is to increase the brightness of the fluoro image
Components
Glass envelope that provides a vacuum
Input layer
Converts x-ray photons to electrons
Electronic (electostatic) lens
Output layer

35. Input layer Converts x-ray photons to light photons
Light photons then strike the photocathode and convert into electrons
Electrons are then accelerated across the II
Electrons strike the output phosphor and are converted back into light photons

36. The image intensifier (I.I.)
I.I. Input Screen
Electrode E1
Electrode E2
Electrode E3
Electrons Path
I.I.Output Screen
Photocathode +

37. Image intensifier component
Input screen: conversion of incident X Rays into light photons (CsI)
1 X Ray photon creates  3,000 light photons
Photocathode: conversion of light photons into electrons
only 10 to 20% of light photons are converted into photoelectrons
Electrodes : focalization of electrons onto the output screen
electrodes provide the electronic magnification
Output screen: conversion of accelerated electrons into light photons

38. Image Intensifier Magnification Modes
Same area
Output phosphor
Input Phosphor
9 inch field
6.5 inch field

39. RELATIVE PATIENT ENTRANCE DOSE RATE
FOR SOME UNITS
IMAGE INTENSIFIER
Active Field-of-View (FOV)
12" (32 cm) 100
9" (22 cm)
6" (16 cm) 300
4.5" (11 cm) 400

40. Brightness Gain
BG is the product of minification gain and flux(electronic) gain
Minification Gain
Input phosphor dia.2/output phosphor dia2
Making the image smaller will make it brighter.
The same number of photons are contained in a smaller area
In most IIs the output phosphor is 1 inch.

41. Flux Gain
Caused by the conversion efficiency of the output phosphor and the acceleration of the electrons across the II
As the electrons accelerate they gain kinetic energy
Flux gain is usually between 50 and 150.

42. Measuring Brightness Gain
The actual measurement is done by calculating the conversion factor
Intensity of output phosphor (candelas)/mrads/sec
Brightness gain will deteriorate 10% annually.
This will ultimately decrease image contrast

43. Beam Splitter Mirror
10% of the output light goes to the vidicon (video camera) the remainder goes to the photospot device.
NOTE: not all units have a beam splitter

44. Vignetting and Pincushion Distortion
The loss of shape at the edges of the fluoro image
Vignetting
Loss of brightness at the edge of the image

45. Veiling Glare
Occurs when the light from the output phosphor ‘reflects’ back into the II.
Remember, the photocathode is stimulated by light, so light ‘reflecting’ from the output phosphor would also trigger electron production.
Decreased contrast results

46. Keeps light output of the II constant.
Automatic Brightness Stabilization (ABS) Automatic Brightness Control (ABC)
Keeps light output of the II constant.
Brightness of the image varies with changes to kVp and mA.
Increase mA increase brightness; direct relationship
Increase kVp 10% double brightness

47. Brightness Sensing II photocathode current
Television camera signal sensing
Lens coupled phototube sensing

48. Types of ABS Variable mA, preset kVp Variable mA with kVp following
Set the kVp and the unit adjusts mA
Variable mA with kVp following
If the mA range is exceeded the unit will automatically adjust the kVp to compensate
Variable kVp, preset mA
Set the mA and the unit adjusts kVp
Variable kVp, variable mA

49. Closed Circuit TV Systems
Camera
Camera control unit
Power supply and video amplifier
Monitor

50. Cameras Vidicon MC, inexpensive, lag, 525 raster lines Plumbicon
Cardiac cath labs
Fixed gain (better contrast) and low lag
Increased quantum mottle
Image orthicon
Not widely used
CCD
Solid state semiconductor
Small, low power consumption, low price, long life

51. Photoconductive camera tube
Focussing optical lens
Input plate
Steering coils
Deviation coil
Alignement coil
Accelarator grids
Control grid
Electron beam
Video Signal
Signal electrode
Field grid
Electrode
Electron gun
Iris
Photoconductive layer

52. Schematic structure of a charged couple device (CCD)

53. Monitor 525 lines 30 times per second
Combined with the video camera improves image contrast

54. TV Image Quality Horizontal resolution Vertical resolution Contrast
Brightness
Lag

55. Horizontal resolution
Bandwidth or bandpass
Increase frequency bandwidth increase horizontal resolution
Vertical resolution
Determined by number of scan lines
Kell factor
Ratio of vertical resolution and scan lines

56. Contrast Brightness Lag Adjust contrast first and brightness after
Occurs when the II is moved rapidly.

57. Dynamic Image Recording
Video Tape
2 advantages
Instant replay
No additional patient exposure
Disadvantages
Poor image quality, fixed frame rate,

58. Cinefluoroscopy 16 or 35 mm (MC high patient dose, better image)
Synchronization
Camera shutters open at the same rate as x-ray pulses
Framing rate
F-number
The lower the number the more light hitting the camera the lower the patient dose; however, more distortion at the edges

59. Framing Underframing should be avoided
Exact framing, diameter of the II fits in the shortest dimension of the film
Overframing, diameter of the II fits the largest dimension of the film. Part of the image is lost
Total overframing, diameter of the II is equal to the diagonal of the film

60. Static Image Recording
Video disk
Last image freeze (hold) (sticky fluoroscopy)
Electronic radiography, similar to AEC x-ray only until image is made.
Decrease dose up to 95%
1 to 30 frames per second
Spot film
Conventional cassettes

61. Spot film Photospot Cassette spots
Image is taken from the II output phosphor
Dose 20 – 50 X higher per frame than fluoro because of higher mA
Currently, 70 mm roll, 105 roll, 100 mm chip
105 mm roll ½ the dose of cassette spots
Cassette spots
Slower ‘frame’ rate
Higher dose and better spatial resolution

62. Digital Fluoroscopy
Digital image is obtained from the output phosphor.
A vidicon then a digital image processor
Or, digital video camera
Digital photospot
Instant playback, possible image enlargement

63. Pulsed Fluoroscopy
Variable frame rates are possible with a corresponding decrease in patient dose

64. High level (boost) fluoroscopy
Higher tube currents than normal
10-20 mA usual 40 mA potentially
Increase patient dose 2-10 times reg. Fluoro
10-50 rads per minute
Limited to 20 rad/minute unless recording the image
Key points
Special activation required, audible signal, dose rate limited to 20 rad.minute

67. Notes from Chapter 4 Conducting the Fluoro Exam
Operator dose is directly proportional to patient dose
Image brightness is directly proportional to dose rate at input phosphor

68. Technical factors which directly influence dose rate at the table topmA
kVp
Collimation
Filtration
Exposure time
Target panel distance

69. Technical factors which indirectly influence dose by affecting technical factors
Room lighting
Image receptor quality
tabletop

70. Collimation
A border needs to be visible when the II is 14 inches above the tabletop and the collimator is fully opened
With an automatic collimator, a border should always be visible
Image is not brighter with a less collimation (bigger field size)

71. Filtration Total filtration
2.5 mm Al eq < 125 kVp
3.0 mm Al eq at 125 kVp and above
Total filtration includes inherent and added
Exposure rate should be less than 2.2 rads/min at 80 kVp
HVL

72. Allowable exposure rates
Limited to 5 rads per minute
If the unit has ABC/ABS then 10 rads/minute is allowed
However, if the unit has ‘boost’ then the limit is 5rads/minute
ABC/ABS units have to be checked by a physicist annually
Also have to have weekly fluoro checks of mA and kVp
No ABS 3 year check by physicist

73. TPD TPD increases from 12 to 18 inches
Pt. Dose decreases by 30%
II as close as possible to the patient

74. Room Lighting Affects visual acuity
Photopic acuity is 10 X better than scotopic acuity
Day versus night vision
Normal viewing distance is 12 – 15 inches
Image recognition in 0.2 seconds

75. Gonadal Shields 0.5 mm Pb eq
97% effective at 100 kVp and 3 mm Al filtration

76. Notes from Chapter 5 Basic Operational Procedures
Minimize exposure time by utilizing short looks
Use the cumulative timer
Use the highest applicable kVp
Collimate
Use mag and boost only when necessary
Use last image hold

77. Use a photospot instead of cassettes
Use video tape
Use II with good contrast
Monitor the TV monitor for brightness and contrast
Minimize the pt. II distance
Position the II prior to exposure

78. Prevent pt. Motion with instructions
Use gonadal shielding when possible
Use compression devices

79. Factor affecting staff doses
ANGLE DEPENDENCE
Scattered dose rate is higher near the area into which the X-ray beam enters the patient
100 kV
0.9 mGy/h
1 mA
0.6 mGy/h
11x11 cm
0.3 mGy/h
1m patient distance
patient thickness 18 cm

80. Factor affecting staff doses
DISTANCE VARIATION
mGy/h at 0.5m
mGy/h at 1m
Scattered dose rate is lower when distance to the patient increases
100 kV
1 mA
11x11 cm

81. Factor affecting staff doses
Tube undercouch position reduces, in general, high dose rates to the specialist’s eye lens
X-Ray tube
mGy/h
100 kV
2.2 (100%)
1 m
2.0 (91%)
20x20 cm
1.3 (59%)
mGy/h
1 Gy/h
(17mGy/min)
1.2 (55%)
1.2 (55%)
1.2 (55%)
1 Gy/h
1m patient distance
(17 mGy/min)
1.3 (59%)
20x20 cm
2.2 (100%)
100 kV
1 m
1m patient distance
X-Ray tube

82. Mobile Concerns Audible indicator
Cumulative timer visible on the monitor
Video storage
Last frame hold
Longest possible TPD

83. Notes for Chapter 6 Pediatric Fluoroscopy
Motion
Sedation
Mechanical devices
Personnel and Parental Protection
Everyone in the room needs lead
Gonadal shielding
Artifacts

84. Photospots instead of cassette spots if possible
ABS/ABC
Watch putting the II directly over large concentrations of contrast
Distance
Collimation
Photospots instead of cassette spots if possible

85. Notes for Chapter 7 Mobile Fluoroscopic Equipment
Primary beam is intercepted by the II
If the II is used routinely in a single location it needs to have secondary shielding
SSD has to be at least 12 inches
Must have an II
Collimation has to be used or unit will not energize
Unit cannot energize unless the II is in the primary beam

86. Maximum dose rate of 5 rads/minute
Personnel monitoring in required for all persons operating fluoro equipment
Protective aprons are required if exposed to more than 5mrads/hour
Boost mode should only be used after areas of interest have been localized

87. Notes for Chapter 8 Responsibilities of X-ray Supervisor
Chief Radiologist or designees are responsible
Licentiates who can use and supervise fluoro
Radiology supervisor and Operator
Fluoro supervisor and Operator
Techs with Fluoro permits can only use fluoro when supervised by above

88. Specific requirements
Establish a fluoro procedures manual
Annual review of manual
Assure that techs don’t practice medicine
Observe tech performance
Assure techs are offered training
Assure equipment monitoring is adhered to

89. Personnel Protection Operator is adequately protected from scatter
Individuals in the room need to wear aprons and film badges
Use protective devices as applicable

90. Protection Devices
SCREEN AND GOGGLES
CURTAIN
THYROID

91. Restrictions
Techs can only use fluoro equip. under the supervision of a supervisor operator
Techs cannot interpret films
Techs cannot use a title implying the right to practice medicine

92. Notification Requirements
Immediate notification (prompt phone call and timely letter)
Total dose 25 rems
Eye dose 75 rems
Skin or extremity dose of 250 rems
24 hour notification ( call within 24 hours and a letter follow-up)
Total dose 5 rems
Eye dose 15 rems
Skin or extremity 50 rems

93. Notes on Chapter 9 Supervision of Techs w/Fluoro permits
Clear the room of unnecessary personnel
Collimate
Use shields
Use correct technical factors
Position the patient correctly
Avoid patient motion

94. Direct supervision Indirect supervision Use equipment only as trained
Spot filming and video taping

95. Notes on Chapter 10 Health Effects of Low Level Radiation dose
Somatic dose indicators
Injuries to superficial tissue
Induction of cancer
Cataracts, fertility issues, life-span shortening
Injuries to developing fetus
Based on dose at specific locations or points

96. Genetic dose indicators
High marrow dose exams
BE, UGI, abdominal angio
Genetic dose indicators
50 rads temp male sterility
30 rads temp female sterility
Genetically significiant dose
Number of future kids
X-ray exam rate
Mean gonadal dose/exam

97. Notes on Chapter 11 Biological Effects and Significance of Dose
Effects appear to follow a linear non-threshold dose curve
Dose rate to tissue
Total dose
Type of cell exposed

98. Radiobiological injury
Cellular amplification
Gross cellular effects
MC effect is the cessation of cell division
Latent Period
Short term, weeks or less
Immediate or early effects
Long term, years or longer
Delayed or late effects

99. Dose relationship curves
Non-threshold
linear
Threshold
Non-linear
Regulations are based on non-threshold linear curves

100. Variations in Cell Sensitivity
Bergonie and Tribondeau
Number of undifferentiated cells
Degree of mitotic activity
Duration of active proliferation
Radiation induced mitotic delay is usually reversable

101. Cell Sensitivity Lymphocytes or white blood cells RBCs Epithelial
Endothelial
Connective tissue cells
Bone
Nerve
Brain
Muscle

102. Short Term Effects
25 rads or less demonstrate no effects

103. Long Term Effects
No specific effect associated with radiation exposure
Somatic damage
Increased incidence of cancer
Embryological effects
Cataracts
Life span shortening
Genetic mutations

104. Carcinogenic Effects Human evidence Early radiologists and dentists
Radium dial painters
Uranium miners
Survivors of Hiroshima and Nagasaki

105. Radiation Induced Cancers
Female breast
Thyroid
Hemopoitic tissue
Lungs
GI tract
Bones

106. Embryological Effects
As little as 10 rads demonstrates effects in animal models
50 rads can cause spontaneous abortion

107. Notes on Chapter 12 Personnel Radiation Protection
ALARA
Basis for radiation protection requirements
Stochastic effects
Probability of an event occurring, ie cancer
Non-stochastic effects (deterministic)
Severity of the effects varies with exposure

108. Operator Exposure Distance Apparel Aprons, 0.25 mm Pb 97% effective
Should be placed on hangers when not in use
Aprons cover 80% of the bone marrow

109. Notes on Chapter 13 Personnel Monitoring
Record exposure
Measure accumulated exposure
Indicate type of exposure
Provide a record of exposure

110. Types Film badge TLD Others 10 mrad to 700 rads +/- 25% accuracy
Lithium fluoride
+/- 9%, cannot be reread
Others
Pocket dosimeter
Audible device

111. Maximum Permissible Dose For adults over 18 y/o
Whole body - head, trunk, arms above the elbow, and legs above the knee
5 Rem
Skin and extremities
50 rem
Lens
15 Rem
Occupational dose for people under 18 y/o 10% of adult dose

112. Occupational Exposure Limit
Whole Body – 5rem/year
Extremities – 50rem/year
Eye – 15rem/year
Pregnant workers – 0.5rem/gestation period
General public
Limited to 0.1 rem/year (Addition to the background radiation)
0.002 Rem (2 mrem) per hour

113. Who must be monitored? Persons in high radiation area
0.1 Rem per hour at 30 cm
Fluoro rooms
Persons operating mobile x-ray equipment
Radiation Area
0.005 Rem per hour at 30 cm

114. Typical Exposures mrem/yr X-Ray Tech Pain Mgnt. MPD Cardio. 5000 4000
3000
2000
1000
X-Ray
Tech
Pain
Mgnt.
MPD
Cardio.