1What is fluoroscopy?
real time/dynamic viewing of anatomic structures
2who invented fluoroscope
Thomas Edison in 1896
3What is the mA range of fluoroscopy?
0.5-5.0
4What is visual acuity?
the ability to see fine detail
5What is photopic vision?
daylight vision (cones)
6What is scotopic vision?
night vision (rods)
7What is the image intensifier?
Raises light level to photopic level (similar to radiograph)
8Where is visual acuity greatest at
fovea centralis
9what is visual integration
time to process image (.2 sec)
10What does the input phosphor do?
converts x-rays to light
11what does photocathode do
Converts visible light into electrons
12what does focusing lenses do?
acceleration/focusing of electrons
13What does the output phosphor do?
Convert electrons to light
14what is main advantage of image intensifier
increase image brightness
15what do electrons hit before output phosphor?
anode
16what is the correlation of number of light photons emitted to amount of xray photons exiting patient?
directly proportional
17how is input layer and output layer different
Output gets same image but minified and brighter
18what is the input layer/phosphor made of?
cesium iodide
19what is output layer/phosphor made of?
Zinc cadmium Sulfide
20what is photocathode made of?
cesium and antimony compounds
21What phosphor was used on the original fluoroscopic screen?
barium platinocyanide
22how much does 1 x-ray photon (input phosphor) equal to output phosphor?
5k-30k light photons
23What is brightness gain?
the ability of the image intensifier to increase the illumination level of the image. (5k-30k)
24what is the equation for brightness gain?
minification gain x flux gain
25What is minification gain?
The ratio of the diameter of the input phosphor (large) to diameter of the output phosphor (small)
26What is flux gain?
Ratio of the number of light photons at the output phosphor to the number of x-rays at the input phosphor
27How big is the input phosphor?
10-35 cm in diameter
28How big is the output phosphor?
2.5-5cm in diameter
29what happens when x-rays increase in input phosphor?
light intensity of output phosphor goes up
30what does viewing of fluoro image in magnification mode increase?
contrast resolution
spatial resolution
patient dose
31why does magnification mode increase contrast resolution?
increase of mA
32why does magnification mode increase spatial resolution?
more of center of input phosphor
33what is vignetting
reduction in brightness at the periphery of the image
34in fluoroscopy what is the relation of x-ray output/dose to mA used
directly proportional
35what will peak/optimal kV yield?
maximum differential absorption by the tissue.
results in good contrast resolution.
36kVp for BE(a.c) exams
80-90
39what is most widely used tv camera
vidicon
40what is the common indirect influencing factor
room lighting
41what is ABS or ABC
maintains brightness of an image over varying thickness parts and densities by varying technique