Fluoroscopy (Meaghan Peretti) Flashcards by Madison moss

C-arm is considered:

Mobile Fluoroscopy

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Fluoroscopy room is considered:

Stationary Fluoroscopy

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The fluoroscopic x-ray tube is located:

under the fluoroscopic table

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The C-arm x-ray source is located:

under the patient and/or surgical table

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The Image Intensifier (II) is located:

over the patient

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The Image Intensifier Job (II):

works similar to the Imaging plate by collecting the remnant or exit radiation after passing through the patient to create the radiographic image. The image is displayed on the monitor.

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Fluoroscopy uses a technology referred to as:

Automatic Brightness Control (ABC) to control the kVp and mA

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Purpose of ABC:

regulates the kVp and mA for fluoroscopy depending on the part being examined.
It will adjust as the radiologist moves the II over different areas of the body, as well as areas with or without contrast.

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The maximum mA station for fluoroscopy is:

5 mA
(This will also control the brightness of the image)

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kVp will vary by:

body part, thickness of body part, and type of contrast. This also may vary per equipment type/manufacturer.

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Barium work kVp range:

100 range

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Air Contrast kVp range:

90 range

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Water soluble contrast kVp range:

70-80 range

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Automatic Brightness Stabilization (ABS):

maintains image brightness

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Automatic Exposure Rate Control (AERC):

maintains the radiation dose per frame at a predetermined level.

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Automatic Brightness Control (ABC) controls:

kVp and mA

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For a fluoroscopy of an arthrogram what do you do with technical factors?

nothing, do not set them.

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What is the role of the Input phosphor?*

takes remnant beam and converts x-ray photons into light photons

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What is the Input Phosphor made of?

Cesium Iodide

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Photocathode purpose?

takes the light photons and converts them into electrons

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Photoemission:

emitting electrons from light source

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What is the photocathode made of?

Antimony compounds and cesium

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The purpose of the electrostatic lenses:

focuses the electrons toward the anode

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What is the anode in fluoroscopy made of?

Tungsten

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What is the purpose of the output screen?

converts electrons into light photons

What is the output screen made of?

zinc cadmium sulfide

Put the image intensifier in order:

1. Input phosphor (cesium iodide crystal) a. x-rays to light 2. Photocathode -light photons into electrons 3. Electrostatic lenses -focuses electrons 4. Anode -accelerates electrons 5. Output -converts electrons into light photons 6. CCD -converts light back to electrical signal 7. ADC -converts to digital signal 8. Monitor -see the image on the monitor screen

The ratio of light photons at the output phosphor divided by the number of input x-ray photons is the:

Flux Gain

total number of light photons produced by each electron

Flux Gain

a ratio of the size of the input phosphor compared to the size of the output phosphor.

Minification Gain

The output phosphor is _________ than the output, _________ brightness.

smaller, increasing

The ability of the image intensifier to increase the illumination level of the image is called the:

Brightness Gain

The brightness gain is simply the product of the:

minification gain x the flux gain

Total brightness gain ranges from:

5,000-20,000 and decreases as the tube ages

What does Flux Gain Compare:

of light photons (output)/# of x-rays (input)

Minification gain compares:

(input phosphor diameter/output phosphor diameter)^2

Brightness Gain=

minification gain x flux gain

A Radiologist needs to magnify up:

results in a smaller field of view decreased input phosphor size Increased Spatial Resolution Increases Contrast Resolution Increases Patient Dose

Smaller input phosphor size=

increased dose

Which input phosphor size would increase dose the most?

15 cm phosphor size=increased dose (smaller input phosphor size means magnification is more present)

As magnification increases:

the focal point moves forward the size of the input phosphor decreases The FOV decreases Patient Dose Increases (use it only when they need it)

If the patient is standing for a PA chest against the wall bucky:

decrease OID, decrease magnification of the heart

The patient is on the OR table what would you do?

Increase the SID, move the patient away from the x-ray source, closer to the II reduces dose.

Reducing magnification in flouroscopy:

decrease OID bring the II closer to the patient

Newer C-arms are a:

FPD model

FPD improvements:

improve image quality reduce patient dose less cumbersome to move reduces sterile field contamination

FPD=indirect conversion steps:

X-rays exit the patient, cesium iodide scintillator converts x-rays to light, amorphous silicon photodiode converts light to electrons. TFT collects electrical signal

Smaller DEL's=

increased spatial resolution

For pediatric fluoroscopy __________ is recommended

removal of the grid

Fluoroscopic grids tend to be _____________ ratio grids due to the ________ mA values used in flouro imaging.

lower, low

the reduction of an image's brightness or saturation toward the periphery compared to the image center.

Vignetting

image in a fluoroscopic system to distort with an "S" shape

S Shape Distortion

The loss of shape at the edges of the fluoro image

Pincushion Artifact

The exposure switch type in flouroscopy:

Dead Man Switch

X-rays are only generated when the operator actively pressed the switch (Button or Foot Pedal).

Dead Man Switch

Remote switch- mobile

2 meters

When fluoroscopy is stopped, an image continues to be displayed on the monitor.

Last Image Hold (LIH)

The last image hold/save grab feature:

allows the image to be saved, thus reducing the need for another exposure

The last image is digitally "frozen" on the monitor after x-ray exposure is terminated

Last Image Hold

The presence of a grid:

increases contrast, increases image quality, increase the dose to the patient

In pediatric cases, removal of the grid has resulted in dose reduction of up to:

1/3 to 1/2 with little or no loss in contrast and image quality

overlays a collimator blade on the last image hold so that one can adjust field dimensions without exposing the patient

Electronic Collimation

eye +

Boost

eye

Fluoro

Low dose reduces exposure by:

50%

Pulse reduces exposure by:

75-90%

Beam is emitted as a series of short pulses

Pulse Setting

there is a constant beam on time

Continuous Fluoro

Stepping on and off the foot pedal (dead man switch), usually for filling bladder

Intermittent Fluoroscopy

***Mobile Fluoroscopy (c-arm) SSD:

12" or 30 cm (hint: take a lunch at 12:3- in the OR)

the distance between the tube and the patient during fluoroscopy

Source to Skin Distance (SSD)

***Stationary Fluoroscopy (flouro room) SSD:

14" or 38 cm

The largest amount of scatter produced on a c-arm is located:

where the x-ray beam enters the patient

In Fluoroscopy keep the _______ minimized when possible.

OID

The least scatter location is _______ to the patient where the II is placed over them.

90 degrees

The highest operator exposure is:

on the x-ray tube side

As patient size increases:

scatter radiation increases

The increase in scatter radiation will impact:

the radiographer and the patient

If you are doing a lateral C-arm examination, where should you be standing?

Behind the C-arm with an increased distance and use your remote and step back.

If the surgeon or radiologist is using flouro and not looking at the screen. Communication with the patient will improve efficiency of the exam.

Time

Move back from the flouro table or C-arm

Distance

Dosimeter placed outside the lead shield

Shielding

Lead apron and Thyroid shield minimum required:

.25 mm Pb

For fluoroscopy the minimum shield required:

.50 mm lead (Pb)

Bucky slot cover minimum:

.25 mm pb

Lead Curtain minimimum:

.25 mm pb

For fluoroscopy the exposure timer should be:

under 5 minutes

light must turn on to alert of exposure

radiation light

Keep the II Distance closer to the patient:

reduces scatter