FLUOROSCOPY

Question 1

Provide real-time dynamic viewing of anatomic structures.

Uses contrast media to highlight the anatomy

● Continuous image of the internal structure while the x-ray tube is energized.

is used for examination of moving internal structures and fluids.

● is actually a rather routine type of x-ray examination except for its application in the visualization of vessels, called angiography

Answer 1

FLUOROSCOPY

Question 2

invented the fluoroscope in 1896

Answer 2

Thomas A. Edison

Question 3

are examinations that show the motion of circulation or the motion of internal structures.

Answer 3

Dynamic studies

Question 4

Direct Fluoroscopy: is

Main source staff exposure is NOT the patient but ?

Answer 4

obsolete

direct beam

Question 5

During fluoroscopy, the x-ray tube is operated at

Answer 5

less than 5 mA

Question 6

The principal advantage of image-intensified fluoroscopy over earlier types of fluoroscopy is ?

Answer 6

increased image brightness.

Question 7

Illumination levels are measured in units of ? or ?
● Radiographs are visualized under illumination levels of ? to ?

Answer 7

lumen per square meter or lux.

100 to 1000 lux

Question 8

○ structures in the eye that are responsible for the sensation of vision

More than ? of them are found per square millimeter of retina.

Answer 8

Rods and Cones

100,000

Question 9

⚫ Transparent protective covering ⚫ Light incident on the eye must first pass through this part of the eye where the light is focused onto the retina

Answer 9

Cornea

Question 10

○ Between the cornea and the lens ○ Controls the amount of light that is admitted to the eye ○ Contracts and allows only a small amount of light to enter in the presence of bright light
○ Dilates (i.e., it opens up) and allows more light to enter during low-light conditions, such as in a dimly lit digital radiography reading area, the

Answer 10

Iris

Question 11

, are most numerous on the periphery of the retina ○ No rods are found at the fovea centralis.
○ Sensitive to low light levels
○ Stimulated during dim light situations.

essentially color blind.

Answer 11

Rods

Question 12

The threshold for rod vision is approximately? lux. ○ Used for night vision, called ?

Answer 12

2

scotopic vision.

Question 13

○ Concentrated at the center of the retina in an area called the fovea centralis.
○ have better visual acuity and contrast perception that rods

perceive color

are sensitive to a wide range of wavelengths of light.

○ Capable of responding to intense light levels, rods cannot
○ are used primarily for daylight

Answer 13

Cones

Question 14

CONES Less sensitive to light; their threshold is only approximately ?

daylight○ Vision, called ?

Answer 14

100 lux

photopic vision

Question 15

?– ability to perceive small objects in fine detail.

●?– ability to detect differences in brightness levels.

Answer 15

Visual acuity

Contrast perception

Question 16

Under scotopic conditions, the sensitivity of the eye is greatest in the? part of the spectrum at about ?.

Answer 16

green

555 nm

Question 17

The? was developed principally to replace the conventional fluorescent screen, which had to be viewed in a darkened room and then only after ?s of dark adaptation

● it raises illumination into the cone vision region, where visual acuity is greatest.

Complex electronic device that receives the image-forming x-ray beam and converts it into a visible-light image of high intensity

○ Components are contained within a glass or metal envelope that provides structural support but more importantly maintains a vacuum

Answer 17

image intensifier

15 minute

Question 19

Input phosphor
material:
length:
diameter:

Answer 19

Cesium iodide (CsI)
300 μm length
○ 5 μm in diameter.

Question 20

X-ray energy is converted into visible light ○ Similar to the effect of radiographic intensifying screens

Answer 20

input phosphor

Question 21

fkux gain of image intensifier

Answer 21

3000

Question 22

○ Usually composed of cesium and antimony compounds that
○ Respond to stimulation of input phosphor light by the emission of electrons
○ emits electrons when illuminated by the input
phosphor.

Answer 22

Photocathode

Question 23

Photocathode
○ Usually composed of ? and ?compounds

?- electron emission that follows light stimulation.

It takes many light photons to cause the emission of one electron.

● The number of electrons emitted by the photocathode is directly proportional to the intensity of light that reaches it.

● Consequently, the number of electrons emitted is proportional to the intensity of the incident image-forming x-ray beam.

Answer 23

cesium and antimony

Photoemission

Question 24

tube is approximately? long.

● A potential difference of about ? is maintained across the tube between photocathode and anode

Answer 24

50 cm

25,000 V

Question 25

is a circular plate with a hole in the middle through which electrons pass to the output phosphor

Answer 25

anode

Question 26

○ Usually made of ? ○ The site where electrons interact and produce light.

Answer 26

Output phosphor zinc cadmium sulfide.

Question 27

? : Maintaining proper electron travel ● ?: Directs the path of electrons towards the anode

Answer 27

Electron optics Electrostatic focusing lenses

Question 28

Each photoelectron that arrives at the output phosphor produces ? to ? times as many light photons as were necessary to create it. ● This ratio of the number of light photons at the output phosphor to the number of x-rays at the input phosphor is the ?

Answer 28

50 to 75 flux gain.

Question 29

flux gain =

Answer 29

# OF OUTPUT LIGHT / # OF INPUT XRAY PHOTONS

Question 30

○ The increased illumination attributable to the multiplication of light photons at the output phosphor compared with x-rays at the input phosphor and the image minification from input phosphor to output phosphor

Answer 30

Minification gain

Question 31

Minification gain=

Answer 31

(di/do)2

Question 32

Output phosphor size is fairly standard at ? to ?Input phosphor size varies from ? to ? and is used to identify image intensifier tubes.

Answer 32

2.5 or 5 cm. 10 to 40 cm

Question 33

○ The ability of the image intensifier to increase the illumination level of the image Now defined as the ratio of the illumination intensity at the output phosphor, measured in candela per meter squared (cd/m2 ) to the radiation intensity incident on the input phosphor, measured in milligray per second (mGy a /s)

Answer 33

Brightness gain

Question 34

○ The brightness gain of most image intensifiers is ? to ?, and it decreases with tube age and use. ○ As tube ages, patient dose ?

Answer 34

5000 to 30,000 increases

Question 35

brightness gain is simply the product of the ? & ?

Answer 35

minification gain and the flux gain.

Question 37

Brightness gain ○ Now defined as the ratio of the illumination intensity at the output phosphor, measured in ? to the radiation intensity incident on the input phosphor, measured in milligray per second (mGy a /s)

Answer 37

candela per meter squared (cd/m2 )

Question 38

proper quantity for expressing image intensification. ■ approximately? times the brightness gain

Answer 38

0.01

Question 39

Image intensifiers have conversion factors of ? to ? ○ These correspond to brightness gains of ? to ?

Answer 39

50 to 300. 5000 to 30,000.

Question 40

conversion factor=

Answer 40

Output phosphor illumination/ input exposure rate

Question 41

The spot-film camera ○?-mm film ○ ?-mm film

Answer 41

90 105

Question 42

○ used almost exclusively in cardiac catheterization, but that use has been largely replaced by digital imaging.

Answer 42

cineradiography camera

Question 43

○ Reduction in image contrast caused by internal scattering of radiation in the form of x-rays, electrons, and particularly light ○ Signal is produced behind a lead disc that is positioned on the input phosphor

Answer 43

Veiling glare

Question 44

Trifield tubes: most popular is ?/?/? cm. ○ numeric dimensions refer to the diameter of the input phosphor of the image-intensifier tube

Answer 44

25/17/12

Question 45

?-cm mode: ○ Photoelectrons from the entire input phosphor are accelerated to the output phosphor.

Answer 45

25

Question 46

?-cm mode: ○ The voltage on the electrostatic focusing lenses increases; this causes the electron focal point to move farther from the output phosphor. ○ Consequently, only electrons from the center 17-cm diameter of the input phosphor are incident on the output phosphor. ○ The principal result of this change in focal point is to reduce the FOV ○ The image now appears magnified because it still fills the entire screen on the monitor.

Answer 46

17

Question 47

?-cm mode produces an image that is 25/? = 2.1 times larger than the image produced in the 25-cm mode.

Answer 47

12

Question 48

○ Minification gain is reduced ○ Fewer photoelectrons are incident on the output phosphor ○ A dimmer image results

Answer 48

Magnification

Question 49

Magnification results in

Answer 49

better spatial resolution better contrast resolution higher patient dose

Question 50

To improve?: ○ Patient radiation dose increases ○ The patient radiation dose is higher because more x-rays per unit area are required to form the image. ○ This results in lower noise

Answer 50

contrast resolution

Question 51

○ Reduction in brightness at the periphery of the image ○ The portion of any image that results from the periphery of the input phosphor is inherently unfocused

Answer 51

Vignetting

Question 52

Because only the central region of the input phosphor is used in the magnification mode,? is also improved.

Answer 52

spatial resolution

Question 53

25-cm mode:? -mm objects (? lp/mm) 10-cm mode: ? mm (? lp/mm)

Answer 53

0.125-mm objects (4 lp/mm) 0.08 mm (6 lp/mm)

Question 54

The output phosphor of the image-intensifier tube is coupled directly to a ? ●? also allows for storage of the image in its electronic form for later playback and image manipulation.

Answer 54

television camera tube Television monitoring

Question 55

○ Converts the light image from the output phosphor of the image intensifier into an electrical signal that is sent to the television monitor, where it is reconstructed as an image on the television screen. Contains electromagnetic coils that are used to properly steer the electron beam inside the tube

Answer 55

Television Camera

Question 56

To convert light photons from the output phosphor of the II into an image on the television, two methods can be used

Answer 56

■ Thermionic television camera tube ■ Solid state charge-coupled device (CCD)

Question 57

Television Camera ?mm in diameter ○ ? cm in length

Answer 57

15 25

Question 58

○ A number of such television camera tubes are available for television fluoroscopy, but the? and its modified version, the ?, are used most often.

Answer 58

Vidicon Plumbicon

Question 59

○ Television camera tube that is most often used in television fluoroscopy. ○ Has a sensitive input surface that is the same size as the output phosphor of the image-intensifier tube ● A television camera tube or CCD converts the light signal from the output phosphor to an electronic signal.

Answer 59

Vidicon

Question 60

○ Maintain a vacuum and provide mechanical support for the internal elements. ■ Cathode, its electron gun, assorted electrostatic grids, and a target assembly that serves as an anode.

Answer 60

Glass envelope

Question 61

○ A heated filament that supplies a constant electron current by thermionic emission ○ The electrons are formed into an electron beam by the control grid, which also helps to accelerate the electrons to the anode

Answer 61

Electron gun

Question 62

The electron beam is further accelerated and focused by additional ? The size of the electron beam and its position are controlled by external electromagnetic coils known as ?(3:

Answer 62

electrostatic grids deflection coils, focusing coils, and alignment coils

Question 63

○ The outside layer is the, the thin part of the glass envelope.

Answer 63

Window

Question 64

? ○ Coated on the inside of the window ○ Thin layer of ? or ? ○ Is thin enough to transmit light yet thick enough to efficiently conduct electricity ○ Conducts the video signal out of the tube into the external video circuit

Answer 64

Signal plate metal or graphite

Question 65

? ○ Is swept by the electron beam ○ A photoconductive layer of ?applied to the inside of the signal plate ○ is photoconductive because, when illuminated, it conducts electrons; when dark, it behaves as an insulator

Answer 65

Target antimony trisulfide

Question 66

If that area of the target is ?, no video signal is produced ● The magnitude of the video signal is proportional to the intensity of?

Answer 66

dark light

Question 67

Two methods are commonly used to couple the television camera tube to the image-intensifier tube

Answer 67

1. Fiberoptics 2. Lens coupling

Question 68

○ The simplest method of coupling ○ Bundle is only a few millimeters thick ○ Contains thousands of glass fibers per square millimeter of cross section Compact assembly, ○ Easy move the image-intensifier tower. ○ rugged and can withstand relatively rough handlin Cannot accommodate the additional optics required for devices such as cine or photospot cameras.

Answer 68

Fiberoptics

Question 70

○ coupling that Results in a much larger assembly ○ Should be handled with care ○ Absolutely essential that the lenses and the mirror remain precisely adjusted because malposition results in a blurred image

Answer 70

Lens coupling

Question 72

? Accepts light from the output phosphor & Converts it into a parallel beam. ? Interrupts the beam ○ Portion is transmitted to the television camera; the remainder is reflected to a film camera.

Answer 72

Objective lens Beam-splitting mirror

Question 73

○ The video signal is amplified and is transmitted by cable to the television monitor, where it is transformed back into a visible image. ○ The ? forms one end of a closed-circuit television system. The other end is the ? or ?

Answer 73

Television Monitor television camera tube or CCD.

Question 74

Two differences between closed-circuit television fluoroscopy and home television are immediately obvious: ? ○ Usually, the radiologic technologist manipulates only two controls: ? & ?

Answer 74

no audio and no channel selection contrast and brightness

Question 75

○ Cathode ray tube ○ Heart of the television monitor ○ Similar to the television camera tube in many ways: ■ Has glass envelope, electron gun, and external coils ○ Much larger and its anode assembly consists of a fluorescent screen and a graphite lining

Answer 75

Television picture tube

Question 76

The video signal received by the television picture tube is ?, that is, its magnitude is directly proportional to the light intensity received by the television camera tube a change in a quantity or signal in response to another quantity or signal and is widely used in medical imaging.

Answer 76

modulated

Question 77

○ Modulates intensity of the electron beam ○ Attached to the electron gun ○ Electron beam is focused onto the output fluorescent screen by the external coils ○ Electrons interact with an output phosphor and produce a burst of light

Answer 77

Control grid

Question 78

The ? is composed of linear crystals that are aligned perpendicularly to the glass envelope to reduce lateral dispersion. It is usually backed by a thin layer of ?, which transmits the electron beam but reflects the light.

Answer 78

phosphor aluminum

Question 79

Both electron beams are finely focused pencil beams that are precisely and synchronously directed by the? of each tube

Answer 79

external electromagnetic coils

Question 80

The movement of these electron beams produces a? pattern on the screen of a television picture tube ● The electron beam begins in the upper left corner of the screen and moves to the upper right corner, creating a line of varying intensity of light as it moves. This is called an ?

Answer 80

raster active trace

Question 81

The electron beam then is blanked, or turned off, and it returns to the left side of the screen. This is the ? ● A series of active traces then is followed by horizontal retraces until the electron beam is at the bottom of the screen

Answer 81

horizontal retrace

Question 82

The electron beam is blanked again and undergoes a ? retrace to the top of the screen ● The electron beam now describes a second television field, which is the same as the first except that each active trace lies between two adjacent active traces of the first field ● This movement of the electron beam is called ?, and two interlaced television fields form a single television ?

Answer 82

vertical interlace frame

Question 83

Flickering is not detectable by the human eye at rates above approximately ? frames per second ● At a frame rate of 30 per second, each frame is ? ms long ● Video monitoring uses a rate of ? frames per second.

Answer 83

20 33 30

Question 84

In the television camera tube, as the electron beam reads the optical signal, the signal is erased ● In the television picture tube, as the electron beam creates the television optical signal, it immediately fades, hence the term ? ● Therefore, each new television frame represents ? ms of new information.

Answer 84

fluorescent screen. 33

Question 85

Actually, only about ? lines are used per frame because of the time required for retracing. ● ? or ? lines per frame for better spatial resolution (important for digital fluoroscopy)

Answer 85

480 875 or 1024

Question 86

525-line TV system: spatial resolution of approximately ? lp/mm ○ 1024-line system provides spatial resolution of ?lp/mm

Answer 86

1 lp/mm 2 lp/mm

Question 87

?resolution - determined by the number of scan lines ●? resolution - is determined by bandpass ○ Expressed in ?and describes the number of times per second that the electron beam can be modulated ○ A 1-MHz bandpass would indicate that the electron beam intensity could be changed a million times each second.

Answer 87

Vertical Horizontal frequency (Hz)

Question 88

higher the bandpass, the better is the ? ○ Commercial television ■ Bandpass of about? MHz ○ Fluoroscopy television ■ ? MHz ○ 1000-line high-resolution systems ■ ?MHz

Answer 88

horizontal resolution 3.5 MHz 4.5 MHz 20 MHz

Question 89

Entrance skin dose (ESD) ○ For an adult averages ?mGy t /min (?to ?R/min) ○ Skin dose of ? mGyt (? rad) is common but should be avoided if possible ○ ESD rate shall not exceed ?mGyt/min (? R/min).

Answer 89

30 to 50 (3 to 5 R/min) 1000 mGyt (100 rad) i 100 mGyt/min (10 R/min).

Question 90

Unlimited exposure rates are permitted for recorded fluoroscopy, such as ? ● Measurements are made with a calibrated ?

Answer 90

cineradiography radiation dosimeter

Question 91

?(4)filters are used to determine the adequacy of any automatic brightness stabilization (ABS) system

Answer 91

Lucite, aluminum, copper, and lead

Question 92

○ Use less film ○ Require less personnel interaction ○ Images produced with a lower patient radiation dose ○ Recorded on film from the output phosphor of an image-intensifier tube ○ Depends on characteristics of the image intensifier, particularly the diameter of the input phosphor

Answer 92

Photofluorospot

Question 93

As the active area of the input phosphor of the image intensifier tube is increased, the patient dose is ? in approximate proportion to the change in diameter of the input phosphor. ○ Use of a grid during photofluorospot imaging approximately ? the ESD

Answer 93

reduced doubles

Question 94

Input exposure rate to the image-intensifier tube is measured and should be in the range of ?

Answer 94

0.1 to 0.4 μGya/s (10–40 μR/s)7

Question 95

? has better spatial resolution and faster frame rate but ? has lower Patient ESD

Answer 95

Casette Spot Photospot

Question 96

The higher the Kvp the ? than ESD

Answer 96

lower