Production of X rays Part 2

Question 1

what is eelctricity

Answer 1

flow of electrons through an electrical conductor

Question 2

what is current

Answer 2

amount of electrons flowing through a conductor per second

Question 3

what is a circuit

Answer 3

path of electrical current

Question 4

what is voltage

Answer 4

difference in electrical potential energy between two points in an electrical circuit

Question 5

what does the rectifier do

Answer 5

-changes alternating current into direct current
- full waive rectification, high frequency power supply
- constant potential between anode and cathode
- higher mean energy of beam compared to AC

Question 6

what does constant potential and direct current cause

Answer 6

• shorter exposure times
• more consistent beam intensity
• higher mean energy of beam
• decreased radiation dose

Question 7

how are x rays produced

Answer 7

whenever high speed electrons are suddenly decelerated or brought to a stop when they pass close to the nuclei of a high Z # absorbing material

Question 8

what are the 2 mechanisms for x ray formation

Answer 8

-bremsstrahlung
- characteristic

Question 9

describe bremsstrahlung radiation

Answer 9

electron to nucleus interaction
- the fast moving electrons either slow down or stop when they come close to the nucleus of the atoms and part of their energy is transferred as X rays

Question 10

describe characteristic radiation

Answer 10

• electron to electron interaction
• a few electrons interact with tungsten target orbital electrons, imparting enough energy to ionize the tungsten target
• electrons collide with inner orbital electron of tungsten atom and removes it from orbit. atom is ionized and unstable. the hole left by the electron is filled by an electron from an outer shell and energy is emitted from this electron in the form of x radiation characteristic of tungsten

Question 11

do all electrons have the same velocity in brensstrahlung radiation

Answer 11

no

Question 12

the higher the velocity the greater the:

Answer 12

KE of electrons

Question 13

Bremsstrahlung radiation increases with increasing:

Answer 13

voltage (kV) and atomic number of the target (Z#)

Question 14

what are the 2 things that could happen in bremsstrahlung radiation

Answer 14

• electron is deflected and decelerated. KE lost is emitted as an XR photon
• head on collision with nucleus: electron produces a maximum energy photon

Question 15

bremsstrahlung radiation has a wide distribution of:

Answer 15

wavelengths

Question 16

the energy emitted in characterisitc radiation is equivalent to the difference i:

Answer 16

the binding energies of the two shells/ orbits

Question 17

what percentage of x rays are from characterisitc radiation

Answer 17

30%