X-Ray Production

Question 1

When are X-Rays produced?

Answer 1

When fast moving electrons are rapidly decelerated

Question 2

What is an electron?

Answer 2

• charged particle in an atom

Question 3

Function of Xray machine tubehead

Answer 3

Contains Xray tube

Question 4

Function of Xray control panel

Answer 4

Allows you to chose the right exposure for the radiographic image

Question 5

What is the filament (cathode) made of?

Answer 5

Tungsten

-ve

Question 6

Why can the filament be used over again? (2)

Answer 6

• Has a high MP which means we can use it again and again and it wont degrade or melt
• It will maintain its integrity

Question 7

What is processing?

Answer 7

Conversion of latent image to permanent visible image by computer technology or chemical

Question 8

What happens when a low voltage current passed through a filament circuit? (2)

Answer 8

Filament heats up

Electrons form a cloud around filament

Question 9

What should our equipment operate within the range of?

Answer 9

60-70kV

Question 10

What interactions does the target anode cause?

Answer 10

Heat 99%

Only produces X rays <1%

Question 11

What happens when an incoming electron reaches the target anode?

Answer 11

Incoming electron deflected by cloud of outer shell tungsten electrons

OR

Collides with an outer shell electron, displacing it

Small loss of energy (E)
Loss of energy in form of HEAT

Question 12

What is target surround made of?

Answer 12

Copper

Effective heat conductor

Question 13

List the target interactions for continuous spectrum (4)

Answer 13

1. Incoming e- passes close to nucleus of a target atom
2. e- rapidly decelerated + deflected
3. e- loss in form of electromagnetic radiation as a continuous spectrum of energies
4. Maximum E is applied kv

Question 14

What are the mechanisms for producing X-Rays? (2)

Answer 14

1. Continuous Spectrum

2. Characteristic Spectrum

Question 15

List the target interactions for characteristic spectrum (5)

Answer 15

1. Incoming e- collides with an inner shell (orbit) target e
2. Target e- displaced to an outer shell or completely lost from atom
3. Target atom unstable
4. Orbiting e-s rearranged to fill vacant orbital slots to return atom to neutral state
5. Difference in E between orbits is released as characteristic radiation of known E values

Question 16

Characteristic radiation of tungsten values (3)

Answer 16

1. 8kV - L shell
2. 58kV - K shell
3. 68kV - K shell

Question 17

Function of the glass envelope

Answer 17

Prevents e’s interacting with air atoms prior to meeting target

Question 18

Function of shielding

Answer 18

To ensure dose rate stays in the vicinity (no more than 7.5)

Question 19

Function of filtration

Answer 19

Getting rid of the low energy xrays we dont want

Done by using aluminium

Question 20

Function of the collimator

Answer 20

Controls the shape of the XRay beam

Question 21

What are the 2 types of beams a collimator produces?

Answer 21

Circular diaphragm
Rectangular diaphragm

Orientation lined up with image receptor

Question 22

What Xrays is the rectangular collimator beam used for?

Answer 22

Bitewings
Periapicals
Occlusal

Question 23

Max beam diameter for collimator

Answer 23

No greater than 60mm at patient end of spacer cone

Question 24

Function of a spacer cone (2)

Answer 24

Controls focus-skin distance

100mm=<60kV
200mm=>60kV