RADI1130 - Outcome 1

Question 1

What type of interaction occurs when an electron is added or removed from an atom?

Answer 1

Ionization

Question 2

What type of frequency and wavelength does high energy electromagnetic radiation possess?

Answer 2

High frequency; short wavelength

Question 3

What is the purpose of a generator?

Answer 3

To convert mechanical energy into electrical energy (A/C)

Question 4

What are the 2 circuits in a x-ray system?

Answer 4

Main circuit; filament circuit

Question 5

Which circuit uses a step-up transformer to increase voltage?

Answer 5

Main circuit

Question 6

Which circuit uses a step-down transformer to decrease voltage? Why do we want to decrease voltage?

Answer 6

Filament circuit
To increase amperage

Question 7

What component of the main circuit converts A/C current to D/C current needed for x-ray production?

Answer 7

Rectifier

Question 8

If more coils are selected on the autotransformer in the main circuit, how does that affect voltage?

Answer 8

Increases voltage

Question 9

What part of the tube ‘boil’s off electrons via thermionic emission?

Answer 9

Filament (current heats up the filament and electrons ‘boil’ off)

Question 10

What part of the tube is the target for electrons, and the site of x-ray production?

Answer 10

Anode

Question 11

Where do x-ray photons exit the glass envelope?

Answer 11

The window

Question 12

What components of the tube rotate the anode?

Answer 12

Rotor (inside glass envelope) is powered by the stator (electromagnetic; outside glass envelope)

Question 13

List some heat dissipating qualities of the x-ray tube components.

Answer 13

1) Expandable gasket and dielectric oil within tube housing
2) Glass envelope made of pyrex
3) Space charge effect of filament limits mA ranges
4) Rotating anode made of tungsten (high atomic number, high melting point, heat conducting; stress relieved in DR)

Question 14

What information does the anode cooling chart provide?

Answer 14

1) How many times consecutive exposures can be made before reaching the tube limit (in HU)
2) How long you need to wait to make another exposure

Question 15

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

Answer 15

Actual FS - spot on focal track/anode where x-rays produced
Effective FS - area of focal spot projected out of the tube towards the patient/object being x-rayed

Question 16

What principle tells us that we get increased resolution of detail when the effective focal spot area is smaller than the actual focal spot?

Answer 16

Line-focus principle

Question 17

What is the anode heel effect?

Answer 17

Radiation is more intense at the cathode end of the tube vs. the anode end (at the anode end, x-ray photons get absorbed by the anode)

Question 18

What component of the x-ray tube absorbs unwanted photons?

Answer 18

Tube housing/protective housing

Question 19

What are the 2 target interactions that produce x-ray photons at the anode?

Answer 19

Bremsstrahlung and Characteristic interactions