Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
37 Cards in this Set
- Front
- Back
What is the advantage of fleuroscopy? |
|
|
When do the colors switch in a fluoroscopy? |
When recording |
|
How do the colors appear in a fleuroscopy? |
|
|
What are the eye sensors? |
|
|
How do the cones work? |
In daylight we can react to a wide range of light (strong light doesn't bother us) |
|
How do the rods work? |
Start to work in dark, pupil widens, we become sensitive to low levels of light |
|
What are the two main jobs of fluoroscopy? |
|
|
What type of radiation is used in fluoroscopes? |
xrays |
|
How do fluoroscope images appear? |
displayed on tv screen that shows several pictures/second (video), image as positive opposite of reality (bones show dark, lungs white) |
|
Because radiation is given over time, fluoroscopes must use ___ MA and ___ ___ ____. |
low, KV as needed |
|
Quality of fluoroscope images are ____ than xrays. |
worse (bc MA is low) |
|
What unit measures the light given off in fluoroscopes? |
lumens (.02 lumens we use rods, take a while to see) |
|
What type of screens are used in fluoroscopes? |
zinc cadium sulfide |
|
What is the mean source of exposure to staff in a fluoroscope? |
direct beam, NOT patient |
|
What is used to improve the light in fluoroscopes? |
image intensifiers |
|
What parts make up a fluoroscope? |
(from bottom up)
|
|
How does the image intensifier work in a fluoroscope? |
Made from glass vacuum tube, one part wider, has four parts:
|
|
In a fluoroscope, the photocathode produces e- based on the ___ of the ___ and not the ___ of the ___. |
power of the light, not the amount of photos (since MA is low) |
|
In fluoroscope, one xray may may ___ photo-electrons. |
50 |
|
In a fluoroscope, the ___ must be close to the ___. |
image intensifier, patient |
|
Adding light to a fluoroscope image is known as the _____ _______. |
brightness gain |
|
The brightness gain can be achieved in what two ways? |
|
|
What is the calculation for the flux gain? |
# photoelectrons/#xrays (=x50) |
|
What is the calculation for the minification (optic) gain? |
[diameter of input screen/diameter of output screen]squared (can be =x144, for ex.) |
|
How does magnification work in fluoroscopes? |
small FOV>magnified image large FOV>less magnified image (xrays come through pt first before hitting image intensifier) more magnification=more radiation to pt+darker image |
|
collimation - magnification ? |
collimation - magnification+ |
|
If the FOV is too big in relation to the output screen, only the e- in the center are read, and ____ occurs. |
distortion and darkness around edges |
|
What is 6" mode? |
magnification |
|
If not enough e- come to the image intensifier, the ___ kicks in. |
ABC automatic brightness control |
|
What happens when the ABC kicks in? |
When less radiation is received, ABC compensates by generating more x-rays (more more exposure) and making them more penetrating (reduces contrast) |
|
What is SNR? |
signal to noise ratio (measures noise. we want this to be high) |
|
If collimation is good: ? quality ? SNR ? radiation ? scatter |
If collimation is good: + quality + SNR - radiation - scatter |
|
What helps improve resolution in fluoroscopes? |
collimation, centering, image intensifier close to body |
|
What types of distortion occur in fluoroscopes |
(can reduce both by moving ii close to body) |
|
How can we improve the noise in a fluoroscope image? |
raise MA |
|
What is continuous fluoroscopy? |
giving radiation for a long time, uses MA .5-5 depending on size of organ and ability of system, will beep after 5 min |
|
What is pulsed fluoroscopy? |
Used to reduce radiation and improve resolution, can set how many pulses per second |