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Fluoroscopy Intro to EQUIPMENT

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Conventional I I system. IMAGE INTENSIFIER. The anode of the II ... Used for barium swallows. Image Quality - Review. Terms that are necessary to know: ... – PowerPoint PPT presentation

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Title: Fluoroscopy Intro to EQUIPMENT


1
Fluoroscopy Intro to EQUIPMENT
  • RT 244
  • FALL 2008
  • Week 1
  • Wed- CONTINUED

Ref Fluoroscopy Bushongs Ch. 24
2
Basic Componets of old Fluoroscopy Imaging
Chain
Primary Radiation
EXIT Radiation
Fluoro TUBE
PATIENT
105 Photospot
Fiber Optics OR
Image Intensifier
ABC
LENS SPLIT
Cassette
Image Recording Devices
CINE
CONTROL UNIT
VIDICON Camera Tube
TV
3
Conventional I I system
4
IMAGE INTENSIFIER
5
The anode of the II
  • The anode is about 20 away from these electrons
    so what will help move the Es?
  • Electrostatic lenses have a negative charge to
    repel the negative electrons and push them to the
    anode and focus them to a narrow beam
  • Anode has a hole in the middle of it allowing
    electrons to pass through and hit the output
    phosphor made of zinc cadmium sulfide
  • The electrons are carrying the latent image and
    when they hit the output phosphor they are turned
    into light again

6
Anode and Output Screen
  • Anode
  • Positively charged
  • 25 kVp
  • Hole in center allows electrons to pass through
    to output screen
  • OUTPUT SCREEN
  • Usually 1 inch in diameter
  • Zinc cadnium sulfide coating
  • Changes electrons back to LIGHT

7
1ST STOPPING PLACE FOR DAY 1
8
Image IntensifierPROPERTIES Image Quality
  • Contrast
  • Resolution
  • Distortion
  • Quantum mottle

9
Contrast
  • Controlled by amplitude of video signal
  • Affected by
  • Scattered ionizing radiation
  • Penumbral light scatter

10
Veiling glare
  • Scatter in the form of x-rays, light electrons
    can
  • reduce contrast of an image intensifier tube.

11
Resolution
  • Video viewing
  • Limited by 525 line raster pattern of monitor
  • Newer digital monitors 1024 - better
    resolution
  • MORE ON THIS LATER IN THE LECTURE

12
Image distortion
PINCUSHION EFFECT
13
Shape Distortion
  • Geometric problems in shape of input screen
  • Concave shape helps reduce shape distortion, but
    does not remove it all
  • Vignetting or pin cushion effect
  • Vignetting
  • FALL-OFF OF BRIGHTNESS AT PERIPHERY (EDGES)
    OF THE IMAGE

14
VIGNETTING.
  • Darkness on edges (falloff of brightness)

15
Size Distortion
  • Affected by same parameters as static radiography
  • Primarily OID
  • Can be combated by bringing image intensifier as
    close to patient as possible

16
  • 2ND STOPPING PLACE FOR THE FIRST DAY LECTURE?

17
ABC
18
Basic Componets of old Fluoroscopy Imaging
Chain
Primary Radiation
EXIT Radiation
Fluoro TUBE
PATIENT
105 Photospot
Fiber Optics OR
Image Intensifier
ABC
LENS SPLIT
Cassette
Image Recording Devices
CINE
CONTROL UNIT
VIDICON Camera Tube
TV
19
Brightness Control
  • Automatic brightness stabilization
  • Automatic adjustments made to exposure factors by
    equipment
  • Automatic gain control
  • Amplifies video signal rather than adjusting
    exposure factors

20
BRIGHTNESS CONTROL
  • ABC ABS AEC ADC
  • MAINTAINS THE BRIGHTNESS OF THE IMAGE BY
    AUTOMATICALLY ADJUSTING THE EXPSOURE FACTORS (KVP
    /OR MAS) FOR THICKER PARTS
  • SLOW RESPONSE TIME - IMAGE LAG

21
ABC
  • Automatic brightness control allows Radiologist
    to select brightness level on screen by ? kVp
    or ? mAs
  • Automatic dose control
  • Located just beyond the Output Phosphor
  • Will adjust according to pt thickness

22
Automatic Brightness Control
  • Monitoring Image Brightness
  • Photocell viewing (portion of) output phosphor
  • TV signal (voltage proportional to brightness)
  • Brightness Control Generator feedback loop
  • kVp variable
  • mA variable/kV override
  • kVmA variable
  • Pulse width variable (cine and pulsed fluoro)

23
Quantum Mottle
  • Blotchy, grainy appearance
  • Caused by too little exposure
  • Most commonly remedied by increasing Ma
  • Controlled by the ABC
  • Affected by too little technique
  • size of patient
  • distance of II to patient
  • size of collimation

24
Fluoroscopic Noise (Quantum Mottle)
  • Fluoroscopic image noise can only be reduced
    by using more x-ray photons to produce image.
    Accomplished in 3 ways
  • Increase radiation dose (bad for patient dose)
  • Frame-averaging
  • creates image using a longer effective time
  • Can cause image lag (but modern methods good)
  • Improve Absorption Efficiency of the input
    phosphor

25
KEEP I.I. CLOSE TO PATIENTreduces beam on time
26
(No Transcript)
27
Units of measurement
  • INPUT PHOSPHOR IS MEASURED IN
    _________________________________
  • OUTPUT PHOSPHOR IS MEASURED IN
  • ______________________________

28
Units of measurement
  • INPUT PHOSPHOR IS MEASURED IN
  • Milliroentgens mR
  • OUTPUT PHOSPHOR IS MEASURED IN
  • CANDELAS (LIGHT)
  • VIEWBOXES ARE MEASURED IN lamberts (light)

29
Fluoroscopic Imaging
30
Coupling I.I. to TV Monitor
  • 2 Methods
  • Fiber optics directly to T.V. camera.
  • Lens system which utilizes auxiliary imaging
    devices.

31
(No Transcript)
32
Directly to T.V.
  • Only cassettes can be used.

33
Beam splitting mirror
34
Basic Componets of old Fluoroscopy Imaging
Chain
Primary Radiation
EXIT Radiation
Fluoro TUBE
PATIENT
105 Photospot
Fiber Optics OR
Image Intensifier
ABC
LENS SPLIT
Cassette
Image Recording Devices
CINE
CONTROL UNIT
VIDICON Camera Tube
TV
35
(No Transcript)
36
Beam splitting mirror
  • Often a beam splitting mirror is interposed
    between the two lenses.
  • The purpose of this mirror is to reflect part of
    the light produced by the image intensifier onto
    a 100 mm camera or cine camera.
  • Typically, the mirror will reflect 90 of the
    incident light to other RECORDING DEVICES
  • and transmit 10 onto the television camera.
  • TV MONITOR is the weakest link (low resolution)

37
Viewing Fluoroscopic Images
38
(No Transcript)
39
Lenses / Mirrors
  • Used to direct image to recording devices
  • Several mirrors in a series and angled - the
    last mirror is outside the II for the operator to
    view
  • Image decreases as it is projected from 1 mirror
    to the next
  • Only 1 person can view image

40
RECORDING THE IMAGE
  • STATIC IMAGES
  • DYNAMIC IMAGES

41
Basic Componets of old Fluoroscopy Imaging
Chain
Primary Radiation
EXIT Radiation
Fluoro TUBE
PATIENT
105 Photospot
Fiber Optics OR
Image Intensifier
ABC
LENS SPLIT
Cassette
Image Recording Devices
CINE
CONTROL UNIT
VIDICON Camera Tube
TV
42
Recording the Fluoroscopic Image
  • STATIC IMAGES
  • Cassettes
  • 105 mm chip film 12 frames per second
  • Digital fluoroscopy
  • DYNAMIC VIEWING
  • Cine film
  • Videotape

43
Recording Fluoroscopic Images
44
IMAGE RECORDING
  • OLD II - ONLY FIBER OPTICS NO LENS SPLITTER TO
    OTHER RECORDING DEVICES
  • ONLY RECORED IMAGE ON SPOT CASSETTES (9X9 ONLY)
  • NEWER - TAKES CASSETTES or uses /105 PHOTOSPOT /
    VIDEO/ CINE
  • NEWEST USES DIGITAL !!!!!!!!!
  • (but the tests still have all of it!)

45
Basic Componets of old Fluoroscopy Imaging
Chain
Primary Radiation
EXIT Radiation
Fluoro TUBE
PATIENT
105 Photospot
Image Intensifier
Fiber Optics
ABC
LENS SPLIT
Cassette
Image Recording Devices
CINE
CONTROL UNIT
VIDICON Camera Tube
TV
46
Fluoroscopy mA
  • Low, continuous exposures .05 5 ma
  • (usually ave 1 2 ma)
  • Radiographic Exposure
  • for cassette spot films
  • mA increased to 100 200 mA

47
RECORDING IMAGES
  • OLD (Smaller) II with fiber optic
  • ONLY RECORDING WAS CASSETTE
  • CASSETTE SPOT IMAGES
  • TAKEN DURING FLUORO PROCEDURE
  • VERY OLD 9X9 inch cassettes
  • Later could take up to 14 x 14 inches

48
Cassettes
  • Standard size - 9 x 9 (old)
  • NOW CAN TAKE UP TO 14X14
  • Stored in lead-lined compartment until ready for
    exposure
  • When exposure is made, mA is raised to
    radiographic level
  • Multiple image formats

49
(No Transcript)
50
(No Transcript)
51
Image recording
  • Cassette loaded spot film
  • Where is the tube?
  • How should you put the IR into the II slot?
  • You can format the image,
  • 2 on 1, 4 on 1 or 1 on 1
  • Cassette loaded spot film increases patient dose

52
(No Transcript)
53
Basic Componets of old Fluoroscopy Imaging
Chain
Primary Radiation
EXIT Radiation
Fluoro TUBE
PATIENT
105 Photospot
Fiber Optics OR
Image Intensifier
ABC
LENS SPLIT
Cassette
Image Recording Devices
CINE
CONTROL UNIT
VIDICON Camera Tube
TV
54
(No Transcript)
55
70 105 PHOTOSPOT (CAMERA)
  • Photo spot camera will take the image right off
    the output phosphor
  • This requires less patient dose
  • 70 105 mm roll film

56
CASSETTE SPOT FILMINGvs PHOTOSPOT FILMING
  • First type of recording used
  • 9x9 cassettes then later up to 14x 14
  • 9 on 1, 4 on 1, 2 on 1
  • Delay while filming (anatomy still moving)
  • Radiographic mA - must boost up to
  • 100 200 mA for filming
  • And moving cassettes around inside tower
  • Higher patient dose
  • Replaced by Photospot (f/sec) filming

57
(No Transcript)
58
CASSETTE SPOT FILMINGvs PHOTOSPOT FILMING
  • Photospot (f/sec) filming
  • Set at control panel from 1 f/sec 12 f/sec
  • Used for rapid sequence
  • Upper Esophogram
  • Voiding Cystourethrograms (Peds)
  • Lower patient dose

59
Recording the Fluoroscopic Image
  • Dynamic systems
  • Cine film systems
  • Videotape recording
  • Static spot filming systems

60
TV camera and video signal Recording the image
  • The output phosphor of the image intensifier is
    optically coupled to a television camera system.
  • Beam splitter is a partially reflective mirror.
  • A pair of lenses focuses the output image onto
    the input surface of the television camera.
  • Often a beam splitting mirror is interposed
    between the two lenses.
  • The purpose of this mirror is to reflect part of
    the light produced by the image intensifier onto
    a 105 mm PHOTOSPOT camera or cine camera.

61
CINE - USED FOR CARDIAC CATH
62
Cine Film Systems
  • Movie camera intercepts image
  • 16 mm and 35 mm formats
  • Record series of static exposures at high speed
  • 30 60 frames per second
  • Offer increased resolution
  • At the cost of increased patient dose

63
Cinefluorgraphy aka CINE
  • 35 or 16 mm roll film (movie film)
  • 35 mm ? patient dose / 16 mm
  • higher quality images produced
  • 30 f/sec in US (60 frames / sec)
  • THIS MODALITY HIGHEST PATIENT DOSE (10X
    greater than fluoro)
  • (VS SINGLE EX DOSE IS ?)

64
Cine
  • Cinefluorography is used most often in cardiology
    and neuroradiology.
  • The procedure uses a movie camera to record the
    image from the image intensifier.
  • These units cause the greatest patient doses of
    all diagnostic radiographic procedures, although
    they provide very high image quality.
  • The high patient dose results from the length of
    the procedure and relatively high inherent dose
    rate.
  • For this reason special care must be taken to
    ensure that patients are exposed at minimum
    acceptable levels.
  • Patient exposure can be minimized in a number of
    ways. The most obvious means of limiting exposure
    is to limit the time the beam is on.
  • CINE - 2mR per frame (60f/sec)
  • 400 mr per look

65
More on Cine
  • Synchronization
  • Framing frequency
  • F-number of the optical system
  • Framing and patient dose

66
Synchronization
  • Camera shutters and x-ray pulsed fluoro happen at
    the same time
  • Only exposes pt when shutter is open to record
    image
  • Patient radiation dose ? as /f/sec ?
  • (filming a TV show pattern seen)

67
F-number of the optical system
  • Speed of any given camera system
  • The amount of light made available to the lens

68
Framing and patient dosesyll 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

69
OVERFRAMING vs Exact Framing
Also related to Radiation Safety
70
Framing frequency
  • Number of frames per second
  • Cine division of 60 (7.5, 15,30,90,120)
  • Organ if interest determines f/s rate
  • Patient exposu

71
More on Safety later.
72
RECORDING DEVICESRESOLUTION P 542 (3rd ed)
  • OPTICAL MIRROR BEST BUT NOT
    PERMANENT RECORDING MEDIUM
  • SPOT FILM CASSETTES 6LP/MM
  • PHOTO SPOT 105 / 70
  • CINE 35 MM / 16 MM
  • DIGITAL (?) (VS FILM)
  • VIDEO VIEWING REALTIME
  • VIDEO TAPE - PLAYBACK

73
(No Transcript)
74
Line pair gauges
75
Line pair gauges
  • GOOD RESOLUTION POOR RESOLUTION

76
Video disc
  • This technique is referred to as electronic
    radiography.
  • Fluoroscopic radiation continues only long enough
    to build up a useful image on the display
    monitor.
  • The image is stored as a single television frame
    on the video disc recorder.
  • There is about a 95 reduction in patient dose.

77
Video tape
  • Utilizes VHS or high-resolution tapes.
  • Patients exposure to radiation is not increased.
  • Used for barium swallows.

78
Image Quality - Review
  • Terms that are necessary to know
  • Vignetting is the loss of brightness at the
    periphery of the II due to the concave surface
  • Pincushion effect is the drop off at the edges of
    the II due to the curved surface
  • Quantum mottle is the grainy appearance on the
    image due to statistical fluctuations
  • The center of the II will always have the best
    resolution.
  • Lag is the blurry image from moving the II too
    fast

79
OVERFRAMING vs Exact Framing
80
Monitoring
  • The output phosphor of the II is connected
    directly to a TV camera tube when the viewing is
    done through a television monitor.
  • The most commonly used camera tube - vidicon
  • Inside the glass envelope that surrounds the TV
    camera tube is a cathode, an electron gun, grids
    and a target.
  • Past the target is a signal plate that sends the
    signal from the camera tube to the external video
    device

81
VIDEO/CAMERA TUBE
  • PLUMICON, VIDICON, ORTHOCON
  • VIDICON MOST COMMOM
  • ORTHOCON VERY
  • PLUMICON BETTER RESOLUTION
  • TRANSFERS IMAGE FROM OUTPUT PHOSPHOR TO TV
    MONITOR
  • CONNECTED BY FIBER OPTICS

82
VIDEO/CAMERA TUBE
  • PLUMICON, VIDICON, ORTHOCON, CCDs
  • TRANSFERS IMAGE FROM OUTPUT PHOSPHOR TO TV
    MONITOR
  • CONNECTED BY FIBER OPTICS or Optical Lens
  • VIDICON- MOST COMMOM
  • PLUMICON BETTER RESOLUTION
  • CCD Charged Coupling Devices
  • ORTHOCON VERY

83
VIDEO/CAMERA TUBE
  • VIDICON MOST COMMOM
  • good resolution with moderate lag ok for
    organs
  • Uses ANTIMONY TRISULFATE
  • PLUMICON (a modification of Vidicon)
  • BETTER RESOLUTION / (? dose)
  • Better for moving part like the heart faster
    response time
  • High performance, lag may improve, but ?quantum
    mottle
  • Uses LEAD OZIDE
  • ORTHOCON VERY - Larger (Not used) BEST
    RESOLUTION WITH NO LAG
  • Functions as both II and pick up tube
  • CCD smaller longer life, very little image
    lag

84
Type of TV camera
  • VIDICON TV camera
  • improvement of contrast
  • improvement of signal to noise ratio
  • high image lag
  • PLUMBICON TV camera (suitable for cardiology)
  • lower image lag (follow up of organ motions)
  • higher quantum noise level
  • CCD TV camera (digital fluoroscopy)
  • digital fluoroscopy spot films are limited in
    resolution, since they depend on the TV camera
    (no better than about 2 lp/mm) for a 1000 line TV
    system

85
TV camera and video signal (II)
  • Older fluoroscopy equipment will have a
    television system using a camera tube.
  • The camera tube has a glass envelope containing a
    thin conductive layer coated onto the inside
    surface of the glass envelope.
  • In a PLUMBICON tube, this material is made out of
    lead oxide, whereas antimony trisulphide is used
    in a VIDICON tube.

86
Vidicon (tube) TV Camera
87
(No Transcript)
88
camera tube have a diameter of approximately 1
inch and a length of 6 inches.
89
(No Transcript)
90
Parts of the camera tube
  • Glass envelope
  • Electron gun (Cathode)
  • Control grid
  • Electrostatic grids
  • Target

91
Camera Tube steps
  • Light is received by the camera tube.
  • The light from the II is received at the face
    plate of the target assembly.
  • Electrons are formed into an electron beam (by
    the control grid) at the electron gun.
  • Electrons are burned off by thermionic emission
    then focused and accelerated to the target.
    (made of antimony trisulfide)

92
Target of the Camera Tube
93
  • The electrons scan the signal plate similar to
    reading a page.
  • Starting in the upper left across to the right,
    then back to the left to right.
  • This is called an active trace.
  • The movement of the electron beam produces a
    RASTER pattern.
  • The same pattern occurs in the TV monitor.

94
  • The signal plate sends the electrical video
    signal to the control unit which amplifies the
    signal and synchronizes the pulses between the
    camera tube and the TV monitor.
  • This synchronization

95
Vidicon Target Assembly
96
Viewing Systems
  • Video camera charge-coupled device (CCD)
  • Video monitor
  • Digital

97
Video Viewing System
  • Closed circuit television
  • Video camera coupled to output screen and monitor
  • Video cameras
  • Vidicon or Plumbicon tube
  • CCD

98
Synchronization (Sync Signals)
99
TV camera and video signal (V)
  • On most fluoroscopy units, the resolution of the
    system is governed by the number of lines of the
    television system.
  • Thus, it is possible to improve the high contrast
    resolution by increasing the number of television
    lines.
  • Some systems have 1,000 lines and prototype
    systems with 2,000 lines are being developed.

100
TV Monitor
101
TV MONITOR
  • CRT Cathode Ray Tube
  • Much larger than camera tube but similar
    function
  • The electrons are synchronized by the control
    unit so they are of the same intensity and
    location as the electrons generated by the pick
    up (camera) tube.

102
TV Monitor
  • The TV monitor contains the picture tube called
    cathode ray tube (CRT).
  • It works like the camera tube.
  • With an electron gun and control grids the
    electron beam is fired toward the anode.
  • The TV screen contains small fluorescent crystals

103
Video Field Interlacing
104
Different types of scanning
11
1
INTERLACED SCANNING
12
13
2
3
15
14
5
625 lines in 40 ms i.e. 25 frames/s
4
17
16
7
6
19
18
8
9
20
21
10
1
2
3
4
5
6
7
PROGRESSIVE SCANNING
8
9
10
11
12
13
14
15
16
17
18
105
Line pair gauges
  • GOOD RESOLUTION POOR RESOLUTION

6 LP/MM AT SPOT CASSETTE 2
LP/MM AT TV
106
  • Two fields a frame (525 lines)
  • It take 1/30 of a second.
  • To prevent flicker, two fields are interlaced to
    form on television frame.
  • There are 60 fields and 30 frames per second.
  • The eye cannot detect flickering above 20
    frames/sec.

107
(No Transcript)
108
RASTER Pattern
  • The electron beam moves in the same raster
    pattern as in the camera tube.
  • The signal consists of many individual pulses
    corresponding to the individual location on the
    camera tube target.
  • The varying voltage pulses are later reassembled
    into a visible in by the TV monitor.

109
TV RESOLUTION-Vertical
  • Conventional TV 525 TV lines to represent entire
    image. Example 9 intensifier (9 FOV)
  • 9 229 mm
  • 525 TV lines/229 mm 2.3 lines/mm
  • Need 2 TV lines per test pattern line-pair
  • (2.3 lines/mm) /2 lines/line-pair 1.15 lp/mm
  • Actual resolution less because test pattern bars
    dont line up with TV lines. Effective resolution
    obtained by applying a Kell Factor of 0.7.
  • Example 1.15 x 0.7 Kell Factor 0.8 lp/mm

110
Kell Factor
  • The ability to resolve objects spaced apart in a
    vertical direction.
  • More dots more scan lines more/better
    resolution
  • Kell factor for 525 line system is 0.7

111
KELL FACTOR
  • VERTICAL RESOLUTION
  • ABILITY TO RESOLVE OBJECTS SPACED APART IN A
    VERTICAL DIRECTION
  • MORE DOTS(GLOBULES) MORE SCAN LINES
    MORE/BETTER RESOLUTION
  • RATIO OF VERTICAL RESOLUITON
  • OF SCAN LINES
  • KELL FACTOR FOR 525 LINE SYSTEM
  • IS 0.7

112
TV RESOLUTION-Horizontal
  • Along a TV line, resolution is limited by how
    fast the camera electronic signal and monitors
    electron beam intensity can change from minimum
    to maximum.
  • This is bandwidth. For similar horiz and vertical
    resolution, need 525 changes (262 full cycles)
    per line. Example (at 30 frames/second)
  • 262 cycles/line x 525 lines/frame x 30
    frames/second
  • 4.2 million cycles/second or 4.2 Megahertz (MHz)

113
Bandpass/Horizantal Resolution
  • Horizontal resolution is determined by the
    bandpass.
  • Bandpass is expressed in frequency (Hz) and
    describes the number of times per second the
    electron beam can be modulated.
  • The higher the bandpass, the better the resolution

114
TV SYSTEMS
  • Images are displayed on the monitor as individual
    frames which tricks the eye into thinking the
    image is in motion (motion integration)
  • 15 f/sec eye can still see previous image
  • Weakest Link - 2 lp /mm resolution
  • Real Time

115
(No Transcript)
116
Final Image
  • The result of hundreds of thousands of tiny dots
    of varying degrees of brightness.
  • These dots are arranged in a specific patterns
    along horizontal scan lines.
  • Usually 525 scan lines.
  • The electron gun within the picture tube scans
    from top to bottom in 1/60 of a second, (262 1/2
    lines) called a field.

117
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118
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119
TABLE MOVEMENThorizonatal to upright 30 sec
120
Digital Fluoro
121
DIGITAL FLUORO
122
(No Transcript)
123
DIGITAL Fluoro System
124
ADC
  • ANALOG TO DIGITAL CONVERTER
  • TAKE THE ANALOG ELECTRIC SIGNAL CHANGES IT TO A
    DIGITAL SIGNAL
  • TO MONITOR
  • BETTER RESOLUTION WITH DIGITAL UNITS

125
Digital Fluoroscopy
  • Use CCD to generate electronic signal
  • Signal is sent to ADC
  • Allows for post processing and electronic storage
    and distribution

126
Video Camera Charged Coupled Devices (CCD)
  • Operate at lower voltages than video tubes
  • More durable than video tubes
  • Semiconducting device
  • Emits electrons in proportion to amount of light
    striking photoelectric cathode
  • Fast discharge eliminates lag

127
CCDs
128
Modern Digital Fluoro Systemunder table tubes
129
Remote over the table tube
130
Remote over the table tube
131
Newer Digital Fluoroscopy
  • Image intensifier output screen coupled to TFTs
  • TFT photodiodes are connected to each pixel
    element
  • Resolution limited in favor of radiation exposure
    concerns

132
Digital CCD using cesium iodide
  • Exit x-rays interact with CsI scintillation
    phosphor to produce light
  • The light interact with the a-Si to produce a
    signal
  • The TFT stores the signal until readout, one
    pixel at a time

133
CsI phosphor light detected by the AMA of silicon
photodiodes
134
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135
(No Transcript)
136
Digital Uses Progressive Scan
  • 1024 x 1024
  • Higher spatial resolution
  • As compared to 525
  • 8 images/sec
  • (compared to 30 in 525 system)

137
DSA POSTPROCESSING
138
DSA
139
(No Transcript)
140
Mobile C-arm Fluoroscopy
141
(No Transcript)
142
Fluoro Rad Protection INTRO RHB
143
Regulatory Requirements
  • 1. Regarding the operation of fluoroscopy units
  • 2. Regarding personnel protection
  • 3. Regarding patient protection

144
Fluoroscopic Positioning Previewing
  • Radiographers are trained in positioning
  • Unnecessary radiation exposure to patient is
    unethical
  • Fluoroscopic equipment should not be used to
    preview patients position

145
Patient Protection
  • Tabletop exposure rate
  • Maximum 10 R/min
  • Typically 1 3 R/min
  • Some books ave is 4 R/min

146
Patient Protection
  • Minimum source-to-skin distance
  • 12 for mobile equipment
  • 15 for stationary systems
  • Audible alarm at 5 mins.
  • Same rules for collimation

147
Patient Protection
  • Typical exposure rates
  • Cinefluorography
  • 7.2 R/min
  • Cassettes
  • 30 mR/exposure
  • 105 mm film
  • 10 mR/exposure

148
Protection of Radiographer and Radiologist
  • Single step away from the table decreases
    exposure exponentially
  • Bucky slot cover
  • Lead rubber drape
  • Radiologist as shielding

149
Protection of Others
  • Radiographers responsibility to inform others in
    the room to wear lead apron
  • Do not initiate fluoroscopy until all persons
    have complied

150
PUBLIC EXPOSURE
  • 10 OF OCCUPATIONAL
  • NON MEDICAL EXPOSURE
  • .5 RAD OR 500 MRAD
  • UNDER AGE 18 AND STUDENT
  • .1 rem 1 mSv

151
COLLIMATION
  • The PATIENTS SKIN SURFACE
  • SHOULD NOT BE CLOSER THAN
  • ___________ CM BELOW THE COLLIMATOR?
  • ____________ INCHES?

15 cm / 6.5 inches
152
Protection
  • Lots to remember in the summer, for right now
  • 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

153
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

154
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

155
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

156
Patient Protection
  • A 2 minute UGI results in an exposure of
    approximately 5 R!!
  • After 5 minutes of fluoro time the exposure is
    10-30 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

157
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

158
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159
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

160
SSD TUBE TO SKIN DISTANCE
  • FIXED UNITS
  • 18 PREFERRED
  • 15 MINIMUM
  • MOBILE UNITS ( C-ARMS)
  • 12 MINIMUM

161
PATIENT PROTECTION
  • LIMIT SIZE OF BEAM
  • BEAM ON TIME
  • DISTANCE OF SOURCE TO SKIN
  • PBL
  • FILTRATION (2.5 mm Al eq) _at_ 70
  • SHEILDING
  • SCREEN/FILM COMBO

162
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163
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

164
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 ?

165
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166
KEEP I.I. CLOSE TO PATIENT
167
Over vs under the table fluoro tubes
168
Framing and patient dosesyll 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

169
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

170
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

171
DOSE REGULATIONS
  • BEFORE 1974 - AT TABLETOP
  • 5R/MIN (WITHOUT AEC)
  • 5R/MIN (WITHOUT AEC) BOOST MODE
  • After 1974 with AEC
  • 10 R/MIN 20R/MIN BOOST

172
RADIATION PROTECTIONThe 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

173
BUCKY SLOT COVER
  • .25 MM LEAD

174
Bucky Slot Cover
175
ISOEXPOSURE CURVES
176
PERSONNEL PROTECTION
  • SCATTER FROM THE PATIENT
  • TABLE TOP, COLLIMATOR, TUBE HOUSING, BUCKY
  • STRAY RADIATION LEAKAGE OR SCATTER RADIATION

177
TOWER CURTAIN
  • .25 MM LEAD EQ

178
Lead curtain dose reduction
179
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.

180
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181
PERSONNEL PROTECTION
  • STANDING BEHIND A PROTECTIVE PRIMARY (1/16TH pb)
    BARRIER
  • PRIMARY RADIATION EXPOSURE 99.87 REDUCED
  • PORTABLE BARRIER 99 REDUCTION

182
PERSONNEL PROTECTION
  • PROTECTIVE APRONS
  • 0.25 PB 97 ? TO SCATTER
  • 0.5 PB 99.9 ? TO SCATTER
  • THYROID SHEILDS (0.25 0.5)
  • GLOVES (0.25 0.5)

183
PERSONNEL PROTECTIONMONITORING
  • FILM BADGE
  • TLD
  • POSL
  • POCKET DOSIMETER
  • RING BADGE

184
PERSONNEL PROTECTIONMONITORING
  • DOSE LIMITS
  • WHOLE BODY
  • EYES
  • EXTREMITIES (BELOW ELBOW/KNEES)

185
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186
Report at least every quarterPreserved for a
minimum of 3 years
187
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 - 50 REMS

188
LICENSE RENEWAL
  • WITHIN 30 DAYS OF EXPRIATION
  • NOTIFICATION OF CHANGE OF ADDRESS

189
HIGH RADIAITON AREA
  • 100 mRem ( 0.1 rem / (1 msV)
  • _at_ 30 cm from the source of radiaton
  • RADIAITON AREA
  • RHB 5 mRem ( 0.005 rem / (.05 msV)
  • _at_ 30 cm from the source of radiation
  • PUBLIC 2 mrem per week (STAT)

190
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

191
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

192
RHB RULES RHB RP PG62
  • ALL XRAYS MUST BE ORDERED BY A PHYSICIAN
  • VERBAL OR WRITTEN PRESCRIPTION
  • See Section C Technologist Restrictions

193
DOSE
  • CINE - 2mR per frame (60f/sec)
  • 400 mr per look

194
Declared Pregnant Worker
  • Must declare pregnancy 2 badges provided
  • 1 worn at collar (Mothers 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)
  • www.ntc.gov/NRC/RG/08/08-013.html

195
FLUOROSCOPYEnd of wk 1RT 244 2008
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