Chapter 3 Interactions with X-Ray production and matter

Question 1

What are some characteristics of X-ray?

Answer 1

invisible, travels in waves, no mass, no charge

Question 2

What are the three tissue interactions?

Answer 2

absorption/attenuated, scattered, pass through without interacting

Question 3

What is Absorbed Dose?

Answer 3

amount of energy absorbed per unit mass

Question 4

What is attenuation?

Answer 4

reduction in number of primary photons due to absorption and scatter as beam passes through the patient

Question 5

What is direct transmission?

Answer 5

photons with no interaction

Question 6

What is indirect transmission?

Answer 6

photons that interact with the patient, scattered or deflected with loss of energy

Question 7

What is an exit photon?

Answer 7

image formation photon/photons that strike the IR and have no interaction with the patient

Question 8

What is small angle scatter?

Answer 8

photon with a small degree of bending of its path/reached IR and degrades image covering up visibility of detail or radiographic fog

Question 9

What are attenuated photons?

Answer 9

interacted with biological tissue and have been scattered or absorbed

Question 10

What are the five different photon interactions?

Answer 10

Coherent Scatter
Photoelectric absorption
Compton Scatter
Pair Production
Photodisintegration

Question 11

What two photon interactions are most important in x-ray?

Answer 11

Photoelectric absorption and Compton scatter

Question 12

What are other names for coherent scatter?

Answer 12

classical elastic or unmodified scattering

Question 13

Define Coherent Scatter

Answer 13

low energy photon (less than 10 keV), transfers its energy by causing all or some electrons of the atom to vibrate momentarily

Question 14

Define Photoelectric Absorption

Answer 14

responsible for patient dose and contrast in images (23-150kVp), photon interaction with an inner shell electron K or L shell tightly bound electron is ejected and fill an open shell in a close atom

Question 15

Define Characteristic Photon

Answer 15

most common type, when an orbital electron of target atoms are removed from their shell and outer shell electrons fill inner shell vacancies, also called fluorescent radiation

Question 16

What is the Auger effect?

Answer 16

instead of characteristic photons, energy is liberated when this vacancy is filled transferred to another electron of atom ejecting it

Question 17

What is the atomic number of bone, calcium and soft tissue?

Answer 17

Bone 13.8
Calcium 20
Soft Tissue 7.4

Question 18

What effect does Positive contrast have?

Answer 18

leads to an increase in absorbed dose in body structures

Question 19

What are other names for Compton Scatter?

Answer 19

incoherent inelastic or modified scattering

Question 20

What is Compton Scatter?

Answer 20

responsible for technologist dose, interacts with outer shell electron knocks outer shell electron out called a recoil electron

Question 21

What is Pair Production?

Answer 21

energy of incident photon is at least 1.022 MeV, photon interacts with nucleus energy transformed into two particles ejecting a positron and negation, used in PET

Question 22

What is Photodisintegration

Answer 22

energies exceeding 10 MeV, used in high energy radiation therapy treatment