X-Ray Production

Front 1

X-rays were discovered by ____ in the year ____

Back 1

Roentgen 1895 involving cathode rays and photographic film

Front 2

the amount of energy required to move an electron (or ionisation energy) is measured in...

Back 2

electron volts (eV)

Front 3

What an electron drops from a higher level (excited) to a lower level...

Back 3

a photon is emitted
(can be light or other wavelength)

Front 4

The difference in energy between the ground and excited states of an electron correspond to...

Back 4

the energy of the photon emitted

Front 5

Plank's Constant (h) is used to describe the relationship between what two variables?

Back 5

Energy (of a photon) and the frquency of the electromagnetic wave.
E=hv or E=hc/λ

Front 6

If an atom (electron) absorbs a photon

Back 6

The low-energy electron will be excited to a higher level proportional to the energy absorbed

Front 7

Name several properties of X-rays [6]

Back 7

high-energy photons, blacken photographic film, highly penetratin in tissue, absorbed by high-density material, produce fluorescence, can cause ionisation in air and tissue (damage)

Front 8

In simple terms, X-rays are produced by...

Back 8

accelerating electrons through very high voltages and allowing them to strike a metal target

Front 9

The filament heated up with voltage to produce X-rays is known as

Back 9

a cathode

Front 10

The number of electrons produced at the cathode depends on....(directly proportional)

Back 10

the filament (cathode) temperature

Front 11

Thermionic emission

Back 11

the process of heating the cathode filament to accelerate electrons to high kinetic energies

Front 12

Typical voltages for producing X-rays

Back 12

20-200kV (kilo volts)

Front 13

Tube voltage

Back 13

the voltage between the cathode and the anode [which determines the energy of the produced X-rays]

Front 14

Anode filament

Back 14

also known as the target; what the electrons strike to produce the x-rays

Front 15

Intensity of the x-ray beam is determined by

Back 15

the anode material [once the electrons have hit the anode]

Front 16

A lower atomic number (z) of the anode material...

Back 16

the less efficient the production of x-rays

Front 17

In the context of x-rays, intensity refers to

Back 17

the number of x-rays produced in the beam, not the level of energy

Front 18

Proton effeciency

Back 18

refers to how much of the energy put into the cathode will produce an X-ray beam [usually less than 1%]

Front 19

Most of the energy released from the cathode is in the form of...[why is this significant?]

Back 19

Heat (roughly 99%) which necessitates that the anode have a high melting point

Front 20

Two methods of reducing thermal damage to anodes

Back 20

Rotate the anode and use an angled anode [increases surface/contact area]

Front 21

Evacuated Glass Tube

Back 21

because air molecules slow down accelerated electrons, a vacuum tube eliminates the repulsion (Coulomb Repulsion) and deceleration caused by air

Front 22

Name 2 mechanisms which converts the electron energy into X-rays

Back 22

Bremsstrahlung X-Rays
Characteristic X-Rays

Front 23

Bremsstrahlung X-rays (photons) are produced

Back 23

when an electron decelerates (by couloumb repulsion forces). The amount of deceleration will determine the energy of the photon

Front 24

Couloumb repulsion forces which decelerate electrons (to produce X-rays) occur where?

Back 24

At the large atoms of the anode (heavy metal)

Front 25

Bremstrahlung X-rays translates to

Back 25

Braking radiation - since the anode target atoms slow down or "brake" the electron acceleration

Front 26

The range of energies for Bremsstrahlung X-rays are said to be ____ because...

Back 26

wide because the electrons can be decelerated by different amounts of atoms (or different rates)

Front 27

Characteristic X-rays

Back 27

when an incident electron strikes a ground state electron of a anode atom and frees the electron from the atom producing a vacant electron gap which is filled by a higher energy electron thud emitting a photon

Front 28

Characteristic X-rays are said to have _____ values because...

Back 28

Very specific values for the X-rays produced because the photon emitted corresponds exactly to the constant energy difference between the orbitals

Front 29

Characteristic X-rays are named this because

Back 29

the x-rays produced are specific or characetristic of the chosen anode material

Front 30

Kα and Kβ x-rays refer to

Back 30

the electron transition from n=2 to n=1 (α) or from n=3 to n=1 (β) [precise energy differences]

Front 31

Characteristic X-rays are particularly used for what medical purpose?

Back 31

Mammography

Front 32

The two components visible in a spectrum of produced x-rays

Back 32

broad smooth curve of Bremsstrahlung x-rays and sharp spikes at precise frequencies from characteristic x-rays