image intensifier

glass envelope

the outer casing that maintains a vacuum, allowing the electrons to move freely

encloses and protects the internal elements

x-rays (remnant beam)

enter the image intensifier after passing through the patient

what is the input phosphor made of

cesium iodide

what does the input phosphor do

absorbs incoming x-rays and converts then into visible light photons

what is the photocathode made of

cesium antimony

what is the purpose of the photocathode

converts the visible light produces by the input phosphor into electrons (photoemission)

electron beam

released by the photocathode

accelerated and focused through the tube, resulting in a brighter and clearer image due to their increased energy and number

electrostatic lenses

focus and direct the flow of electrons from the photocathode to the output phosphor

(negative charge)

minification

what the electrostatic lenses do to make the electron beam smaller in order to fit through the output phosphor

focal point

where the electrons from each side of the beam meet

anode

positively charged portion that attracts the electrons and directs them towards the output phosphor

has a hole in the center to allow electrons to pass through

what is the output phosphor made of

zinc cadmium sulfide

what is the output phosphor

site where accelerated electrons interact and produce visible light, resulting in increased image brightness

power supply

supplies electricity to the camera tube, providing energy for thermionic emission, and potential difference (voltage)

control grid

forms and accelerates the electron beam towards the anode

electron gun

a heated filament that supplies a constant electron current to be aimed at the target assembly

accelerator grids

accelerates and focuses the electron beam

steering coils

focus and steer the electron beam towards the anode

target assembly

consists if three layers: the window, the signal plate, and the target plate

at the anode end

what is the target plate made of

antimony trisulfide

what is the purpose of the target plate

a photoconductive layer that transmits electrons to the signal plate in the presence of light

signal plate

a thin layer of metal or graphite that transmits light from the image intensifier and electrons from the target plate

window

the outside layer and the thin part of the glass envelope that allows light from the image intensifier to come in

video signal

produced by the signal plate

amplified and then transmitted by cable where it is transformed into a visible image

tv picture tube (CRT)

receives video signal from the TV camera tube

focusing coil

focuses the electron beam

control grid

modulates (controls) the intensity of the electron beam

aluminum reflector

transmits the electron beam, but reflects any scattered light that does not belong

phosphor

receives electrons and converts them into light

what is the phosphor of the CRT made of

linear crystals that are aligned perpendicularly to the glass envelope to reduce lateral dispersion

light

produced by the electron beam striking the phosphor