Interactions with matter

Xrays interactions with matter depend on

the energy of the photon

Low energy photons interact with

the entire atom

moderate energy photons interact with

shell electrons

What is excitation 

energy of the photon is enough to cause outer shell electrons to break away from pull of nucleus and move to other shell , but not completely 

Ionization

energy of the photon is enough to eject an electron from the atom and changing the charge 

Classical scattering, also known as 

Coherent and Thompson scattering 

At what XR energy does classical scattering occur

10 keV

How can classical scattering be observed on film

causes small amount of film fog

How does an xray photon interact with an atom in classical scattering

atom gets excited, releases excited energy as scattered xray

Which TWO interactions are of significance in the diagnostic field!

Photoelectric and Compton

Compton Effect/Scattering, also known as

incoherent and modified scattering

Compton scattering exists at any keV level

True

How does compton scattering occur

XR photon knocks/ ejects out outer shell electron, causing it to zoom off in different direction(with less energy)

Compton scatter poses the most risk to the 

radiographic technologist

The probability of the Compton scatter is ___
proportional to the energy of the x-ray photon

Inversely

Compton scatter probability is ___ proportional to the mass density and part thickness

directly

Photoelectric absorption exists between

50 to 150 keV range

In photoelectric absorption, the XR photon

interacts with inner k shell electron

In photoelectric absorption, the XR photon is ____ totally absorbed into the atom

totally

The most important effect for producing useful images is 

photoelectric absorption

Photoelectric absorption contributes the most to 

patient dose 

The probability of the photoelectric effect is____
proportional to the third power of the energy of the x-ray
photon(1/E)3

INVERSELY

The probability of the photoelectric effect is ___ to the
third power (Z3)proportional to the atomic number of the
absorbing material.

directly

The two types of interactions with matter that are not in the diagnostic field are 

Pair production and Photodisintegration

In order for pair production to take place, there must be

at least 1.022 million e- volts (meV)

Incident xray pair production has enough energy to what

bypass all electron shells

The ejected positron is a form of

antimatter

Though pair production cannot be used in diagnostic range , it is useful in 

PET-positron emission tomography

The negatron is pair production will

eventually recombine with any atom that needs another elctron

Photodisintegration interactions occur at

above 10 mEv

Photodisintegration can be found in

high energy radiation therapy treatment machines

High energy photons in photodisintegration

collide with atomic nucleus and gets all their energy absorbed