week 6: tissue interactions

Question 1

differential absorption: a process whereby some of the x-ray beam is ___________ and some _____________ anatomic part

Answer 1

absorbed in the tissue; passes through (transmits)

Question 2

beam name as it leaves the x-ray tube

Answer 2

primary radiation

Question 3

beam name as it leaves the patient

Answer 3

remnant radiation (also known as exit radiation)

Question 4

what is exit radiation composed of?

Answer 4

transmitted and scattered radiation

Question 5

what is exit radiation?

Answer 5

when the attenuated x-ray beam leaves the patient

Question 6

When an x-ray photon enters into biological tissue what three basic “things” can happen?

Answer 6

1. the photons pass through the body unaffected
2. absorption of photons occurs
3. change of direction of photons

Question 7

the reduction in the intensity or number of photons in the primary x-ray beam

Answer 7

attenuation

Question 8

why does attenuation occur?

Answer 8

it is a result of the photon interaction with the atomic structures that comprise the tissues

Question 8

what are the two processes the occur during beam attenuation?

Answer 8

absorption and scattering

Question 9

What does it mean for an x-ray photon to pass through biological tissue (transmission)?

Answer 9

most common “interaction”
Here, the photon does not interact with tissue and photon has no loss of intensity

Question 9

What are the five interaction in matter?

Answer 9

1. Coherent
2. Photoelectric
3. Compton
4. Pair production
5. Photodisintegration

Question 10

which interaction is the one is below diagnostic range?

Answer 10

Coherent scattering

Question 11

which interaction is at the diagnostic range?

Answer 11

photoelectric, compton

Question 12

which interaction is above the diagnostic range?

Answer 12

pair production, photodisintegration

Question 13

what is to note regarding the probability of a photoelectric interaction?

Answer 13

probability concerns (1) energy of incoming x-ray photon (kVp) and (2) atomic number of anatomic tissue)

Question 14

what is to note regarding the probability of a Compton scattering?

Answer 14

probability is kVp dependent only

Question 15

Compton scattering interacts with which type of electron shell: inner or outer?

Answer 15

outer

Question 16

Photoelectric interactions interacts with which type of electron shell: inner or outer?

Answer 16

inner

Question 17

what are the 4 factors that affect beam attenuation?

Answer 17

1. Tissue thickness
2. Type of Tissue
3. X-ray beam quality
4. Transmission

Question 18

what contributes to patient dose?

Answer 18

the photoelectric effect

Question 19

what contributes to occupational dose?

Answer 19

Compton scattering radiation

Question 20

how is beam attenuation impacted by an increase/decrease in tissue thickness?

Answer 20

increase in tissue thickness = increase attenuation
decrease: decrease attenuation

Question 21

how is beam attenuation impacted by an increase/decrease in types of tissue?

Answer 21

increase in tissue atomic number/tissue density = attenuation increase
decrease: attenuation decrease

Question 22

how is beam attenuation impacted by an increase/decrease in x-ray beam quality?

Answer 22

increase in x-ray beam quality = less attenuation
decrease: increase attenuation

Question 23

exit radiation interacts with an IR to create a non-visible image which is a ____________

Answer 23

latent image

Question 24

processed latent image, now a visible image is a _______

Answer 24

manifest image

Question 25

block radiation rather than allowing it to pass through

Answer 25

radiopaque

Question 26

allows radiation to pass through

Answer 26

radiolucent

Question 27

radiopaque vs. radiolucent: which is bright/which is dark?

Answer 27

radiopaque = bright
radiolucent = dark

Question 28

positive contrast agent is _________

Answer 28

radiopaque

Question 29

negative contrast agent is _________

Answer 29

radiolucent (example: air when inspiring)

Question 30

what are the two broad forms of pathology?

Answer 30

additive, destructive

Question 31

additive pathology _________, and is (harder/easier) to penetrate, is more (radiopaque/radiolucent)

Answer 31

adds to tissue density, harder, radiopaque

Question 32

destructive pathology _________, and is (harder/easier) to penetrate, is more (radiopaque/radiolucent)

Answer 32

takes away from tissue density, easier, radiolucent

Question 33

the fraction of x-rays removed from a beam per unity thickness of the attenuating medium

Answer 33

linear attenuation coefficient

Question 34

the fraction of the x-rays removed from a beam of unity cross-sectional area by unit mass of the medium

Answer 34

total mass attenuation coefficient

Question 35

photon and electron in/out for the photoelectric effect

Answer 35

photon in, (photo)electron out

Question 36

photon and electron in/out for Compton scattering

Answer 36

photon in, electron out and photon out