Fluoroscopy Exam Questions

What is fluoroscopy?

A specialized radiographic equipment used to visualize the motion of internal structures and fluids

What is fluoro referred to as?

Dynamic (moving)

What is plain radiography referred to as?

Static

Who invented the first fluoroscope and what year?

Thomas Edison in 1896

What ten things make up a fluoro unit?

1. fluoroscopic x-ray tube and image receptor

2. arm

3. intage intensification (II) tube

4. control panel

5. spot imaging or other imaging capability

6. foot exposure switch (deadman’s type)

7. television monitor

8. protective curtain

9. bucky slot cover

10. timer

Fluoroscopic x-ray tube and image receptor

Will be mounted on a C-arm to maintain their alignment at all times

What are the two types of fluoroscopic x-ray tubes?

1. Under-table unit

2. Over table unit

What is the arm that supports the equiptment over the table called?

Carriage

What in included in the control panel of the fluoro unit?

Power drive, shutters, image selection, etc

The timer on the fluoro machine makes an audible sound at what time?

5 minutes

What must be engaged for fluoro to work?

Carriage

Fluoroscopic x-ray tubes are very similar to diagnostic tubes except they are what?

Designed to operate for longer periods of time at a much lower mA

Diagnostic tubes operate at _____ mA

50-1200 mA

Fluorocopic tube range is _____ mA

.5-5 mA

Why is patient dose higher for fluoro?

Due to the decreased SOD

UGI is approximately _____ mR

700

BE is approximately _____ mR

1300

Can you use fluoro as a positioning aid?

No

What is the kVp range for barium studies (UGI, BE, etc)?

High kVp (90-120).

What is the kVp range for iodine studies (gallbladder, angiography, orthopedics, etc)?

Low kVp (60-80)

What are the two types of technology being used for fluoro today?

1. conventional

2. digital conversion

Conventional fluoroscopy

In the old days, radiologists used to look directly at the fluoroscopic screen and it caused a lot of exposure to the radiologist

What was used after people realized the damange convertional fluoroscopy had on the radiologist?

A mirror-optic system transmitted the optical image to the viewer

What year were image intensification tubes developed?

1948

With image intensification tubes, where does the image go?

To a TV monitor, spot film device, or cine camera

What does conventional fluoroscopy use to produce an analog (visible) image?

An x-ray tube, image intensifier (II), and a television system

The radiologist can obtain a permanent image with little interruption of the study by using ______ (or DR now)

Spot film device

When using a photospot camera, what is the mm film?

105

Image intensification

Utilizes the radiation that passes through the patient and enhances the image by electronically making the image 1000 to 6000 times brighter

For the maximum detail to be visible, the image brightness must be ______

High

What is the main reason that image intensifiers were created?

For increased image brightness

What are the units for illumination (brightness)?

Lumen per square meter or lux

Radiographs are visualized under illumination levels of ____-____ lux, fluoroscopy is performed at similar levels

100-1000

Before II, conventional fluoroscopy fluoroscopic screens used what phosphor?

Zinc cadmium sulfide (ZnCdS)

The image intensifier tube receives the _____ x-ray beam, converts it into _____, and _____ the light intensity

Remnant, light, increases

What is the process of image intensification?

• vacuum tube with glass enelope

• x-rays pass through the glass envelope and hit the input phosphor

What is the input phosphor made out of?

Cesium iodide (CsI)

What does the input phosphor do?

Converts x-rays to visible light

For image intensification, the light strikes the ________

Photocathode

What is the photocathode connected to?

The input phosphor by an adhesive layer

The photocathode is a thin metal layer made up of _____ and ______

Cesium (Cs) and antimony (Sb)

What absorbs the light energy recieved from input phosphor and emits electrons?

Photocathode

What is the process of photoemission?

When the photocathode turns light energy into electrons

The number of electrons emitted through photoemission is _____ proportional to the intensity of the light reaching it

Directly

A potential difference between the photocathode and the anode of about _______ volts is applied

25,000

Anode

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

What do electrostatic focusing lenses do?

Focus the electrons to keep them going in the right direction

When electrons strike the ________ (located just after the anode) light is produced

Output phosphor

What is the output phosphor made out of?

Zinc cadmium sulfide (ZnCdS) crystals

What is the light (image) directed to after it is created?

A monitoring system (TV monitor, spot-film camera, etc)

What are the several occasions where information is transferred within the II?

• from the x-ray beam to the input screen,

• from the input to the photocathode,

• from the photocathode to the electron beam,

• from the electrons to the output screen,

• from the output to the human eye

Each photoelectron that hits the output phosphor produces ___-___ times as many light photons

50-75

The gain in brightness achieved by the II is a result of the ___________ and __________

Electron acceleration, image minification

A typical II has a flux gain of about _____

50

What is flux gain?

The ratio of the number of light photons at the output phosphor to the number of x-rays at the input phosphor

What is the equation for flux gain?

number of light photons output/ number of x-ray photons input

The image produced on the input screen is reproduced as a ______ image on the output screen because the output screen is so much smaller than the input screen

Minified

What is minification gain?

The increase in brightness caused by the electrons being focused into a small area

What is the equation for minification gain?

(input screen diameter/output screen diameter)²

The ____ increases the illumination level- “brightness gain”

II

Brightness gain=

minification gain x flux gain

THe brightness gain of most IIs is _____ to _____-this decreases with tube age

5,000-30,000

As your tube gets older, patient dose ______ to maintain brightness

Increases

Input phosphors (screens) range from ____” (15 cm) to ____” (30 cm) in diameter

6, 12

A typical output phosphor has a diameter of ___” (2.5 cm)

1

Most image intensifiers are of the multifield type, what can they be called?

• dual-focus image intensification

• dual-field inage intensification

• tri-focus image intensification

• tri-field image intensification

What is the most common design for multi-field image intensification?

10/7” (25/17) dual focus

On a 6” mode for multi-field image intensification, the voltage of the focusing lenses is increased and only the inner ____ inches of the input phosphor is used

6

The electron focal point is moved further from the output phosphor, causing what?

Magnification

Using the 6” mode reduces the field of view and thereby ______ the image

Magnifies (mag mode)

On a 9/6 II, the ^” mode is ______ times larger than the 9” mode

1.5

Mag mode will _____ magnification, ______ resolution (spatial and contrast), minification gain is _____ (less brightness), and mA will need to ______

Increase, increase, reduced, increase

The area of the input phosphor not used is still hit with x-rays, this creates a loss of brightness at the periphery of the image called?

Vignetting

For fluoroscopic control, what does ABC stand for?

Automatic Brightness Control

For fluoroscopic control, what does ABS stand for?

Automatic Brightness Stabilization

What does Automatic Brightness Control or Automatic Brightness Stabilization do?

Maintains the brightness of the image by automatically adjusting the exposure factors (mA and kVp) according to the density and contrast of the subject

What are the two types of digital fluoroscopy being used today?

1. charged coupled device (CCD)

2. flat panel

What is the advantages of digital fluoroscopy over conventional fluoroscopy?

• no cassettes are required

• requires less dose

• speed of image acquisition and the ability to post process

In digital fluoro, the image-intensifier output screen image is coupled via?

Charged-coupled device

What does a CCD do?

Converts visible light to an electrical charge that is sent to the ADC for processing

The CCD’s rapid discharge time virtually eliminates image _____ and is particularly useful in high-speed imaging procedures such as cardiac catheterizations

Lag

CCD camera have replaced what?

Analog cameras

CCDs are more sensitive to light emitted by the output phosphor and are associated with less ______

Noise

CCD still uses an II, and uses a layer of ______ silicon

Crystalline

CCD is mounted where?

On the output phosphor of the II

Flat panels are ______ and _____ than the II and CCD for easier manipulation

Smaller and lighter

What are flat panels composed of?

Cesium iodide

For image monitoring and recording, what are the systems?

• optical monitoring (mirrors)

• cinefluoroscopy

• spot filming

• television (video) monitoring

• video recording

Optical (mirror-optics) system

• system of lenses and mirrors

• magnifies the image from the output phosphor onto a viewing glass

• the field of view is small

• only one person can use it at a time

• a significant amount of light is lost

Cinefluoroscopy (cinecamera)

• a movie camera records the images on film

• primarily used in cardiac catheterization

• patient dose is very high

• image quality is high

What mm film cameras are used for cinefluoroscopy?

16 or 35 mm film cameras

35 mm cameras in cinefluoroscopy has _______ quality and ______ dose than 16 mm

Higher

Cine cameras are driven by _________ motors (60 Hz)

Synchronous

What are the framing frequencies in cinefluoroscopy?

7.5, 15, 30, 60, and 90 frames per second

Cine cameras are different from a roll film photospot camera; the major difference are that the film is smaller (35 mm wide) and longer (400 ft on a roll) and that the camera is capable of operating at up to _______ images per second

90

Increased framing frequency will _______ patient dose

Increase

Spot filming

• uses the same technology as conventional screen-film radiography

• a cassette with regular radiographic film/CR is positioned between the patient and II

• when fluoro is on, the cassette is positioned away from the II

Spot film devices usually allow _____ than one image to be obtained on a single film

More

Spot film devices produce ______ patient dose

High

What is a disadvantage of conventional spot film devices?

The delay involved in moving the cassette into position for exposure