INTERACTIONS WITH MATTER HIGH YIELD

Question 1

name this interaction:

photons pass through matter unaffected

Answer 1

penetrate

good for patient

Question 2

name this interaction:

transfer energy to matter

Answer 2

absorbed

bad for patient

Question 3

name this interaction:

change direction and possibly lose energy

Answer 3

scatter

bad for patient

Question 4

what are the types of interactions with matter and whether they are significant or not?

Answer 4

coherent scatter (5% insig)
pair production (not sig)
photodisintegration (not sig)
photoelectric absorption (sig)
compton scatter (sig)

Question 5

photoelectric absorption is dependent on _____?

Answer 5

atomic number, the lower and so the lower the K shell binding energy

Question 6

what KVP is photoelectric absorption significant?

Answer 6

KVP > 40, yields weak characteristic radiation

Question 7

what are the steps of the photoelectric absorption?

Answer 7

incident photon interacts w/inner orbital electrons

photons give energy to electron

electron ejected

vacancy of the inner orbit must be filled

outer orbital electron drops down into space

excess electron energy is given off as secondary photon

the atom becomes a positive ion because it is missing an outer shell electron

Question 8

3 products of photoelectric absorption?

Answer 8

photoelectron (the one ejected)

characteristic radiation (secondary photon given off when electron jumped down)

positive ion (missing an outer shell electron)

Question 9

the compton scatter is dependent on _____?

what does it reach in water?bone?

Answer 9

density

100% at 100 KeV, 50% around 26 KeV

80-90% at 100 KeV, 50% around 45 KeV

Question 10

what are the steps for compton scatter?

Answer 10

incident photon interacts w outer orbital electron

photon gives some of its energy to the electron

electron is ejected from orbit

photon continues on an altered path and scattered

Question 11

what are the two types of attentuation?

Answer 11

mono energetic attenuation

polyenergetic attenuation

Question 12

attenuation is affected by?

Answer 12

kVp, density, atomic number, electrons

Question 13

what happens if no attenuation?

Answer 13

x-ray film will be black