TEST 2 - Fluoroscopy REVIEW 💕

What is the formula for magnification?

Input diameter
Diameter of input screen used

What is total brightness gain? What is the formula?

Measure of the increased image intensity (increased brightness) achieved by an image intensifier tube (II tube)

Minification gai
Flux gain

Never use fluoroscopy to?

Previewing, positioning

The cones of eyes control what type of visual acuity?

Photopic (Daylight)

What lies between the input screen and photocathode? What is its
purpose?

• Thin protective coating

• Prevents chemical reactions between input screen and cathode

Describe the function of the photocathode?

Absorbs light photons and emits electrons

What does the output screen do?

Absorbs electrons and emits light photons

A single incident photon can potentially produce how many light photons at the input screen?

Over 1,500 light photons

What happens when greater voltage is applied to the electrostatic lenses?

Accelerates electrons and moves the focal point closer to input screen

During fluoroscopy, what degree from the patient/primary beam produces the highest energy scatter?

90 degrees

What does photoemissive materials do?

Absorb light photons and emit electrons

What is the name of edge distortion in image intensification tubes?

Vignetting

TFT technology for fluoroscopy allows for what type of contrast detectability?

Low-contrast

What is the mathematical formula for minification gain?

minification gain focal point diameter of input

output screen

Identify the steps in the processing of an image in an intensifying tube?

1. x-ray

2. light 

3. electrons

4. light

Define vinetting?

Edge distortion

Why is fluoro the domain of the radiologists?

Involves active diagnosis dynamic

What invention enabled the brightness to be enhanced?

Image iintensifier

Identify the rad tech responsibilities during fluoro?

• Post- fluoroscopic radiograph

• Assist radiologist

• Static exams

What does flux gain do to image quality?

Decreases quality

What are the mA ranges for both fluoro & diagnostic?

Fluoro:
0.5 – 5 mA

Diagnostic:
50 – 1,200 mA

Cumulative timers sound after ____ minutes of fluoroscopy time?

5 minutes

What is the minimum source to skin distance for mobile fluoro?

12 inches

The minimum source to skin distance for stationary fluoro equipment is

15 inches

What does CsI (phosphors) stand for, and what % of the incident beam
do they absorb?

Cesium iodide phosphers, 66%

List the components of the image intensification tube?

• Input screen

• Photocathode

• Electrostatic lenses

• Anode

• Output screen

The fluoro skirt has ___ mm Pb/eq?

0.25 mm

How do you reduce patient dose when utilizing the mag factor?

Collimate

Digital fluoro resolution cannot be as high as radiography because the fluoro pixels are ___ lp/mm and radiography is ___ lp/mm.

Fluoro:
1-2 lp/mm

Radiography:
100-150 lp/mm

Digital fluoro reduces patient exposures up to ___%?

90%

After the x-ray photon leaves the patient, what does it strike next?

Input screen

What is the purpose of electrostatic lens?

• Accelerates and focus electrons

• Intensifies the image

What is ABC and how does it function?

• Automatic Brightness Control'

• Automatically adjusts the exposure

What is the output screen made of?

Silver activated zinc-calcium sulfide phosphors

The photocathode is comprised of what material?

photoemissive metals

What reduces quantum mottle?

Increasing the mA

List some dynamic studies?

• Barium studies

• Gastrointestinal

• Swallows

List two types of c-arm arrangements (fluoro machines)

• Under-table unit

• Over table unit

True or False:

In fluoroscopy, the focal point reverses the image so the output screen is reversed from the input screen

True

What is the purpose of the concaved shape of the Input Screen?

To maintain an equal distance to the output screen

Over-table units operate with a minimum tabletop exposure rate not to exceed _____? Most units operate around _______?

Table-top
10 R/min

Average is
1 to 3 R/min