week 3: xray production

Question 1

the stators of the anode induction motor are (inside/outside) the glass enveloped

Answer 1

outside

Question 2

what are the three conditions necessary for xray production?

Answer 2

1. source
2. acceleration
3. stoppage of e-

Question 3

Explain the two most common ways an x-ray tube assembly is orientated

Answer 3

?

Question 4

X-rays not in the controlled beam that escape through the protective housing surrounding the x-ray tube

Answer 4

leakage radiation

Question 5

what is the purpose of the lead lining?

Answer 5

radiation protection

Question 6

what is the window in the glass envelope?

Answer 6

a thinned/shaved area for xray photons to exit

Question 7

what is the function of the glass envelope?

Answer 7

allows air to be completely evacuated from xray tube, insulation of electrical shock, dissipates heat

Question 8

function of oil in the tube

Answer 8

dissipates heat, insulation from electrical shock

Question 9

true/false: tungsten filament has a charge at normal state

Answer 9

false; it does not have a charge. Tungsten will release electrons when heated

Question 10

what is the function of the focusing cup?

Answer 10

because the focusing cup is negative, it repels electrons and helps focus stream of electrons from filament toward anode target

Question 11

what is the charge of the focusing cup? what is it made out of?

Answer 11

negative charge; nickel

Question 12

the formed cloud around the filament during thermionic emission

Answer 12

space charge

Question 13

refers to the tendency of the space charge to prevent more electrons to be boiled off

Answer 13

the space charge effect

Question 14

the high temp where the filament is not “boiling off” electrons

Answer 14

saturation current

Question 15

the flow of e- from cathode to anode

Answer 15

tube current

Question 16

what is tube current measured in?

Answer 16

milliamperes

Question 17

why is tungsten used as the metal of choice for cathode filament?

Answer 17

high heat capacity d/t high atomic number

Question 18

what are the three basic functions of the anode?

Answer 18

1. electrical conductor
2. thermal dissipater
3. mechanical support

Question 19

what is the name of the motor in the anode?

Answer 19

induction motor

Question 20

what are the consequences of the line focus principle?

Answer 20

heat capacity increased d/t increased surface area while creating a smaller beam so image quality is sharpened

Question 21

what is the difference between the effective and the actual focal spot?

Answer 21

effective = xray photon (exiting)
actual = the literal/actual place the e- are hitting the anode and turning into xray photons

Question 22

what’s another word for actual focal spot size?

Answer 22

real (Graham’s)

Question 23

what’s another word for effective focal spot size?

Answer 23

apparent (Graham’s)

Question 24

what is the most common angle degree? (from powerpoint?)

Answer 24

12 degrees

Question 25

what is the range of the beveled angle?

Answer 25

5-20 degrees

Question 26

intensity of beam is (more/less) on the anode side. what is this due to?

Answer 26

less; anode heel effect

Question 27

anode heel effect would lead you to want the “head of the patient” on the (anode/cathode) side

Answer 27

anode

Question 28

% range for anode - CR - cathode due to the anode heel effect

Answer 28

75–100–120

Question 29

total filtration is the combination of what?

Answer 29

inherent filtration + added filtration

Question 30

What is the leakage radiation maximum?

Answer 30

100 mR/h or 1mGy/h measured at 1 meter from the tube