kim review

Question 1

list image intensifier components in order:

Answer 1

input phosphor
photocathode
accelerating anode
electrostatic focusing lenses
output phosphor

Question 2

what is the potential difference applied between the cathode and anode of the input phosphor in kv and v?

Answer 2

25 kv

25000 V

Question 3

what is the input phosphor made of?

Answer 3

cesium iodide

Question 4

why is the input phosphor curved?

Answer 4

so that all photoelectrons travel the same distance to the output phosphor

Question 5

define flux gain, minification gain and total brightness gain and what is the formula?

Answer 5

flux-measurement of the increase of light photons

minification- increase in the brightness intensity due to reduction in size of the output phosphor

total brightness gain- measurement of the increase in image intensity due to image intensifier

flux x minification = total brightness gain

Question 6

what happens to the image and pt dose when the image intensifier is magnified:

Answer 6

pt dose increases
resolution increases
the size of the input phosphor is reduced
the increase in dose is equal to the ratio of the area of the input phosphor being used

Question 7

what are the two systems for image monitoring in the image intensifier?

Answer 7

1. automatic gain control: radiation level is constant for all part sizes
2. automatic brightness control: radiation output varies (mA and KV) between 1-5 mA, pt dose decreases

Question 8

define the heat units formula for single phase, 3 phase 6 pulse and 12 pulse:

Answer 8

single phase: HU = kvp x mA x sec

3 phase (6 pulse): HU = 1.35 x kvp x mA x sec

3 phase (12 pulse): HU = 1.41 x kvp x mA x sec

Question 9

define ohms law and state the equation:

Answer 9

the voltage across the total circuit or any portion of the circuit is equal to the current times the resistance

V=IR
R=V/I
I=V/R

Question 10

What is the n-p junction?

Answer 10

the interface between semiconductors on the solid state rectifier

Question 11

distinguish between an electromagnet and a solenoid:

Answer 11

electromagnet: coil or wire wrapped around an iron core that intensifies the magnetic died
solenoid: helical winding of current carrying wire that produces a magnetic field

Question 12

which parts of the X-ray circuitry control the amount of current sent to the X-ray tube?

Answer 12

• exposure timer and switch
• mA selector
• rheostat

Question 13

what is a capacitor?

Answer 13

storage tank for electrons (voltage)