Unit 4

Fluoroscopy

what is fluoroscopy?

an imaging technique that uses x-rays to create real-time, moving images of the internal structures of the body

what is fluoroscopy also known as?

Dynamic Images

What do dynamic images permit?

the visualization and evaluation of not only the structure, but the function of the anatomy as well

what are some of the exams done under fluoroscopy?

• GI studies 

• urinary studies 

• arthrograms 

• orthopedic surgery 

• cardiovascular cases

when was fluoroscopy first invented?

in 1896

who invented fluoroscopy

thomas edison

what did the first fluoroscopy unit require?

the viewer need to look directly at the glowing screen in line with the x-ray source

Later in time, systems did not require looking directly into the source but….

only one person could view the image at a time

T/F: images could not be saved at first- diagnosis solely based off radiologist’s report 

true 

early fluoroscopy was _____ intensity fluorescent screen that x-ray anatomy was projected on 

low 

what was the screen made out of on thomas edison’s fluoroscope?

calcium tungsten (fluoresced (glowed) when exposed to x-rays)

what was the disadvantage of early fluoroscopic systems besides radiation dose?

the lake of brightness of the image

due to the lake of brightness in the images for early fluoroscopic, what had to be done?

procedures needed to be done in the dark, so radiologist needed to adapt their eyes to the dark room 

what are the two types of cells in the eye that are responsible for vision?

rods and cones 

what are rods?

sensitive to low light

what is the responsibility of rods?

for night vision

what are cones?

detect color and fine detail

what do cones do?

function best in bright light

early fluoro exams were performed under conditions that….

resulted in very poor visual acuity (sharpness)

T/F: conventional R/F rooms can perform both radiographic and fluoroscopic images

true

conventional rooms are convenient for…

static after pictures so the patient doesn’t need to move 

conventional rooms include?

ceiling mounted x-ray tube and wall bucky

why is the tube in the table for fluoro rooms?

under the table to make it easier for the operator to reposition the image receptor

Components in the table: TUBE?

generates a continuous or pulsed x-ray beam

Components in the table: Collimator?

radiologist can decrease the field size to improve image quality and decrease patient exposure

Components in the table: Filtration 

filters out low energy x-rays 

Components in the table: Tabletop

in fixed systems table usually moves by button push

what is the Image intensifier?

makes low mA image brighter

• some systems have a flat panel detector 

what is a anti-scatter grid?

systems with an image intensifiers have a physical one attached to the image intensifier housing 

• systems with a flat panel detector might have a built in grid

what is the video camera or charge-coupled device? (on systems with an image intensifier)

it is what takes the intensified image and sends to the analog to digital converter (ADC)

• then the adc sends the image to the monitor where it is displayed 

in flat panel detector systems, the image is sent to directly to the Analog to digital converter meaning…

no intensification needed

the fluoro tube is….

radiolucent 

what two ways can fluoro be initiated?

a hand switch on the carriage or a foot pedal (controlled by radiologist and both are called dead mean style)

where is the fluoro tube attached to?

the back of the table and coupled to the table

what will happen if the fluoro tube is not fixed into place over the table?

the tube will not produce x-rays

the patient should be supine and looking at what on the c-arm 

a smiley face

what is high-level fluoroscopy referred to as

“ a boost”

what does high level fluoroscopy do

allow for increased radiation output to improve image quality

Info card: interventional fluoroscopy

in larger hospitals it can be found in its own modality

in smaller hospitals the technologists may be expected to perform some interventional procedures 

who should be operating the c-arm

technologist or physicians (doctors) only

T/F: nurses or OR staff can operate the c-arm

false

why are c-arms used

they produce less radiation, and should only be used for larger parts 

T/F: bumping into the table is best practice

false

the closer the patient is to the source…..

the higher their dose will be

what does the remote hand switch do?

allows technologist to initiate exposure- dead man style

what does the monitor display system do?

displays real-time live images

• has capability to also show saved or reference images

every step away form the patient does what to the occupational dose 

decreases it

what are the components of the c-arm imaging unit 

the x-ray tube and either an image intensifier or a flat panel detector

what are the components of the c-arm free space

where the body part being imaged needs to go

what are the components of the c-arm

attaches tube to the image intensifier

• handles for moving 

• measurements for positioning 

what is the foot pedal?

allows doctor to initiate exposure

what are the components of the c-arm: rotational joint

allows c-arm to rotate or obliques or tolt or cranial/caudal imaging

what are the components of the c-arm: control panel

adjusts imaging settings

• collimation 

• pulse settings 

• low dose 

• magnification mode

• resets timer

T/F: pulsed per second can be adjusted in system settings

true

the SID for a c-arm is

fixed

T/F: the closer we move the source to the patient to move the image receptor is moved away from the patient with a c-arm

true 

fluoroscopy uses an _____ exposure time

increase

what two ways can fluoroscopy exposure time be in

pulsed or continuous

what is focal point

just the location where the e-stream is the most tightly focused

what is the input phosphor do

converts the x-ray photons to light photons

what is the input phosphor made of

cesium iodide

why is the input phosphor made of cesium iodide

• structured type of phosphor crystal

  • better for spatial resolution 

1 photon can produce ______ light photons in the input phosphor

1000

what is the photocathode layer do?

converts light photons into electrons

how do we help lower patient dose

we use a lower mA, results in reduced brightness

what is the primary function of the image intensifier?

to brighten the image to improve visual acuity

what is visual acuity

the ability to visualize small details and small changed in density (visualize low contrast)

why was the image intensifier developed

to overcome the dim images

because we use an image intensifier, it allows us to use a lower…

mA, which results in lower patient dose 

what are all the image intensifier components encased in ?

a metal housing, which protects the glass or metal envelope that maintains a vacuum around the structures

how does the image get to the viewing monitor?

from the video camera (or charged coupled device) then to a analog to digital converter

the photocathode is ____ bonded to the input phosphor

directly, which help maintain spatial resolution

where is the accelerating anode?

on the opposite end of the image intensifier

what kind of charge does the accelerating anode have

a positive charge; with a hole in the middle

T/F: the accelerating anode in the image intensifier does not spin like the anode in the x-ray tube

true

what does the anode’’ positive charge attract?

the negatively charged electrons; moving towards the anode 

what does the hole in the middle of the accelerating anode do?

allows electrons to pass through and strike the output phosphor

what is flux gain

the kinetic energy gained during acceleration from photocathode to output phosphor

what does acceleration mean in “accelerating anode”

it means the speeding up of electrons, so they increase in kinetic energy

what happens when electrons gain kinetic energy?

they can produce more light photons at the output phosphor; which will intensify the signal, making an increase in image brightness 

what do the electrostatic focusing lenses do

the negatively charged electrostatic focusing lenses line in the inside of the image intensifier so the electrons can make it through the hole of the anode; like the focusing cup, funnels the electrons into a concentrated stream 

what does the output phosphor do

takes the electrons and converts them back into light photons 

the output phosphor is the phosphor that..

the electrons strike after they pass through the anode is much smaller than the input phosphor 

what is the difference between input and output phosphors

the electron stream is condensed for the output phosphor so they all can strike it

acceleration and condensing of the electrons causes what the image

more/another intensification

• takes the electrons and multiplies them by 50-75 times more

info: the light photons from the output phosphor strike a CCD or video camera which then takes the light photons and converts them into a electronic signal and collect that signal

the collected signal is then sent to an analog to digital converter 

what does the analog to digital converter do

takes the electronic signal and converts it to a digital signal

why are there so many steps?

each step intensifies the signal, making the final image bright enough for the monitor

T/F: light photons and electrons can be focused, x-rays cannot

true

T/F: intensifying the image allows for lower x-ray doses, protecting patients and staff

true

what does an anti-scatter grid do

reduced scatter reaching the image receptor 

what does an anti-scatter grid increase

image quality, image contrast, and patient dose

where is the anti-scatter grid located

within the outer housing and is placed in front of the input phosphor

what is stationary fluoro grid

usually a linear/focused grid

what is interventional fluoro grid 

uses crossed grids because of the higher beam in time and mA use 

why are higher grid ratios not needed in fluoroscopy

because a low mA is used in fluoro

T/F; fluoro grids are similar to radiography but usually lower

true

T/F: Grids SHOULD be used in pediatric fluoroscopy

false

T/F: the higher image intensifier efficiency, the less radiation to produce a quality image

true 

what is the flux gain equation 

#of photons output phosphor produced/ #of x-ray photons striking the input phosphor