physics 3

Question 1

what is an x-ray?

Answer 1

• defined as weightless packages of pure energy
• without electrical charge
• travel in waves along a straight line
• specific frequency and speed

Question 2

properties of x-rays

Answer 2

• v short wavelength
• have no mass
• unaffected by electric/magnetic fields
• travel in speed of light in vacuum
• travels in straight lines
• causes ionisation

Question 3

what are the 2 types of events that can lead to x-ray production?

Answer 3

An electron travelling at high speed may experience a sudden change in direction or motion

An electron in an atom may undergo a transition from a high energy state to a low energy state

Question 4

which type of event is more common? where?

Answer 4

first, in x-ray production in tube

Question 5

what is the production process in x-rays?

Answer 5

• negative cathode produces electrons
• positive anode is electron target

there is energy conversion
- potential type
- kinetic type
- kinective energy proportional to potential difference

Question 6

what are the types of energy conversion in production process of x-rays?

Answer 6

there is energy conversion
- potential type
- kinetic type
- kinective energy proportional to potential difference

Question 7

what happens when the exposure button is depressed?

Answer 7

• cathode becomes strongly neg
• anode strongly pos

electrons emitted from filament exist within strong electric field

large measure of pd potential energy

• potential energy changed into kinetic energy until electrons reach anode, accelerating very high speed

Question 8

what does slide 7 graph show?

Answer 8

radiation intensity in relation to energy, and the noticeable characteristic radiation ‘peaks’ as they have higher intensity than brems.

Question 9

label the graph

Answer 9

you got this bro!!!

Question 10

What is bremsstrahlung radiation step by step

Answer 10

1. incident e- from cathode hits target anode
2. e- passes close to nucleus of tungsten atom
3. • charge from photon in nucleus attracts e- changing direction of e-
4. causes deceleration releasing energy in form of x-ray

Question 11

what is more blue or red in bremsstrahlung photon energy?

Answer 11

red is more common

Question 12

explain bremsstrahlung photon energies

Answer 12

two electrons from filament

blue: close to nucleus, deviate and convert some kinetic energy to x-ray photon
- photon has more energy (shorter wavelength)

Question 13

yo y

Answer 13

yo

Question 14

yo

Question 15

explain bremsstrahlung photon energy ranges

Answer 15

diagnostic energy range 30-120kVp (more bremsstrahlung)

below 70kVp, tungsten target, 100% bremsstrahlung

above 70kVp - then its 85% bremsstrahlung

Question 16

what is the continuous spectrum? and graph look at on ur own!

Answer 16

• represents the intensity of x-rays being distributed in a continuous fashion over the range of wavelengths present.
• short wavelength limit
• photons of minimum wavelength have maximum energy

Question 17

what is the graph on slide 11?

Answer 17

unfiltered Bremsstrahlung spectrum shows a ramp-shaped relationship between the number and energy of the x-rays produced, with the highest x-ray energy determined by the peak voltage (kVp) applied across the tube

A typical filtered Bremsstrahlung spectrum shows no x-ray output below around 10keV

Question 18

what is characteristic radiation protection?

Answer 18

• filament e- collides with e- within an atom of the target
• if filament e- energy greater than binding energy of e- in the shell, it will eject the e-
• this causes release of energy in the form of a photon
• outer shell e- will move to fill vacancy, releasing lower energy photons

Question 19

compare bremsstrahlung and characteristic interactions

Answer 19

• no diference, simply produced by different processes
• majority of interactions produced at diagnostic voltages are bremsstrahlung

Question 20

what is characteristic cascade? where is it?

Answer 20

in characteristic radiation protection

When vacancies on the shell are filled

will trigger a characteristic cascade when electrons ‘cascade’ from the outer shells to the innermost shells until all vacancies are filled.

Question 21

bremstrahllung and characteristic have what?

Answer 21

discrete energies that are confined to that element

Question 22

tungsten sum characteristic x-ray energy

Answer 22

EK-shell – EL-shell

= 69.5keV – 10.2keV

= 59.3keV

Question 23

explain graph on slide 15th: Filtered Bremsstrahlung & Characteristic Radiation of Tungsten

Answer 23

seeee!!!