Fluoroscopy week 3 Flashcards by Melissa Trappen

Fluoro is what type of exam

Dynamic Radiographic

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Fluoro involves _ during the exam

active diagnosis

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Fluoro is primarily the domain of the

Radiologist

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Radiographers should perform fluoroscope only for _ examinations

static

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Fluoro was invention is credited to _ and when

Edison in 1896

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Fluoroscopic screen consists of a

specialized x-ray tube with an image receptor

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What was held by hand and put in front of the patient and x-ray tube (1st Fluoro)

a viewing hood

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when was image intensification tubes were developed in

1948

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what allow to view safely

digital monitoring system

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Fluoro is currently used only for studies that require

observation of dynamic physiological function
ex-. the flow of barium through the GI tract
ex.2- injection of a contrast medium into the heart

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what is the arm that supports the equipment suspended over the table

carriage

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the carriage includes an

image intensification tube

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what is the image intensifier

increases the brightness

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in order to gain access the the patient what can be done

the carriage can be disengaged and pushed away

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exposure cannot continue until the

the carriage is returned and locked into position

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Fluoroscopic x-ray tubes are very similar to what

Diagnostic tubes

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Fluoroscopic x-ray tubes are different from diagnostic tubes how

they are designed to operate for longer periods of time at much lower mA

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4 parts of a fluoro system

II
tube
carriage or gantry
monitor

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what is the Fluoroscopic mA range is

0.5-5.0 mA

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Fluoroscopic tubes are equipped with

electrically controlled shutters

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Fluoro tubes are equipped with electrically controlled shutters that permit _ both Fluoro and spot imaging

maintenance of close collimation from the Fluoro carriage

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Early Fluoroscopic screens were

very dim

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what is dark adaptation

a procedure in which light levels are reduced for a pd. of at least 10-15 min

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Dark adaptation, why are the light levels are reduced for a pd. of at least 10-15 min.

to permit the rods of the eye to become activated

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The brightness of the fluoro image was not raided to daylight levels until

image intensification technology was developed in 1948

an image intensification tube is designed to

electronically amplify the brightness of an image

modern image intensifiers are capable of increasing image brightness _ times

500-8,000

The primary x-ray beam exits the patient and strikes the

input screen of the II tube

what is the image intensifier tube

vacuum tube w.a cathode and an anode

fluorescent screen is an

input screen

The fluorescent screen absorbs

the x-ray photons and emits light photons

photocathode is a

cathode of the tube

the photocathode absorbs

the light photons and emits electrons

electrons are accelerated from the

cathode to anode

the same time the electron beam is focused onto the

output screen, which is much smaller than the input screen

what are electrostatic lenses used for

to accelerate and focus the electrons

The primaryBRIGHTNESS GAIN occurs from the

acceleration and focusing of the electron beam

The output screen absorbs the _ and emits

electrons | light photons

viewed on

video monitor

The input screen consists of

0.1 - 0.2 mm layer of sodium-activated cesium iodide (Csl) phosphors

For the input screen, the sodium-activated cesium (CsI) phosphors coated onto the

concave surface of the II tube

the surface of the II tube of the input screen may be made of _ and ranges from

``` glass titanium, steel aluminum 6" - 23" in diameter ```

the screen is

concave

The cesium iodide (CsL) phosphors are packed together very tightly so they absorb about _ of _ producing a good

66% of the incident beam | conversion efficiency or quantum yield

What is applied to the input screen to prevent a chemical interaction with the photocathode

extremely thin protective coating

the photo emissive materials absorb the light photons and emit electrons in a process called

photoemission

what are electrostatic lenses

series of charged electrodes located inside the glass envelope of the tube

the electrons are

negative

what reverses the image so the output screen image is reversed from the input screen image

focal point

The focal point reverses the image so the output screen image is

reversed from the input screen image

Image intensification tubes can be designed to magnify

the image electronically by changing the voltage on the electrostatic lenses

By changing the voltage on the electrostatic lenses they are know by these 4 types of intensifier fields

multi-field dual-field triple field quad-field

magnification image intensifiers are capable of _ magnification

1.5 -4x

The magnification image intensifiers are controlled at the

fluoro carriage

The mag factor is calculated as

Magnification= input screen diameter/ diameter if input screen used during magnification

The anode is _ charged and is normally supplied with about

+ | 25 kV

This charge causes a tremendous attraction of the

negative electrons from the photocathode

The anode is positioned inside the

glass envelope

electrons pass through the

anode field and onto the output screen

The output screen is also a _.

fluorescent screen

The output screen consists of

silver-activated zinc-cadmium sulfide phosphor

the electrons that strike the screen are converted into

green light photons that exit the tube

what transmit the image some distance without loss of resolution

fiber optics

what is a measurement of the increase in image intensity achieved by an image intensification tube

total Brightness Gain

The total brightness gain is determined by 2 factors

minification gain | flux gain

Minification gain occurs as a result of the

same number of electrons that were produced at the large input screen being compressed into the area of the sm. output screen

out put screens, most are how big

6" or 9"

typical output screens are

1" in diameter

Minification gains formula

Minification gain=input screen diameter2 | output screen diameter2

minification gain is simply an _ | not an improvement in the quality or # of photons making up the image

increase in brightness/intensity

Photocathode converts

photon to electrons

The Flux Gain is a measurement of the

increase in light photons due to the conversion efficiency of the output screen

Flux gain does not take into account the

conversion efficiency of the input screen

The flux Gain only deals with the _ and is accomplished by the

gain | electron to light conversion at the output screen

total brightness gain formula

brightness gain=minification gain x flux gain

Brightness gain deteriorates as much as _ per year because the

10% | input and output screen phosphors age