Deck 9: X-ray Interaction with Matter

Question 1

The two primary forms of x-ray interaction in the diagnostic range are _____.

A) Compton scattering and photoelectric absorption
B) Compton scattering and pair production
C) photoelectric absorption and coherent scattering
D) coherent scattering and Thompson scattering

Answer 1

Compton scattering and photoelectric absorption

Question 2

Differential absorption is dependent on (the)_____.

A) kVp of the exposure
B) atomic number of the absorber
C) mass density of the absorber
D) all of the above

Answer 2

all of the above

Question 3

Only at energies above 10 MeV can _____ take place.

A) photodisintegration
B) pair production
C) Compton scatter
D) photoelectric absorption

Answer 3

photodisintegration

Question 4

_____ occurs only at the very high energies used in radiation therapy and in nuclear medicine P.E.T. imaging.

A) Coherent scatter
B) Compton scatter
C) Photoelectric absorption
D) Pair production

Question 5

Which x-ray interaction involves the ejection of the K-shell electron?

A) coherent scattering
B) Compton interaction
C) pair production
D) photoelectric absorption

Question 6

The use of contrast agents increases the amount of _____.

A) differential absorption
B) Compton scatter
C) photoelectric absorption
D) all of the above

Question 7

An incident x-ray interacts with an atom without ionization during _____.

A) photoelectric absorption
B) Compton scattering
C) coherent scattering
D) pair production

Question 8

Attenuation is caused by _____.

A) absorption
B) scattering
C) transmission
D) both A and B

Question 9

An outer-shell electron is ejected and the atom is ionized during _____.

A) photoelectric interactions
B) Compton interactions
C) coherent scattering
D) pair production

Question 10

K-shell binding energy increases with increasing _____.

A) mass density
B) kVp
C) atomic number
D) mAs

Question 11

Compton scatter is directed at _____ angle from the incident beam.

A) a 180°
B) a 90°
C) a 0°
D) any

Question 12

As kVp _____,the probability of photoelectric absorption _____.

A) increases, remains the same
B) increases, decreases
C) decreases, decreases
D) decreases, remains the same

Question 13

In _____,there is complete absorption of the incident x-ray photon

A) photoelectric interaction
B) Compton interaction
C) pair production
D) coherent scatter

Question 14

The scattered x-ray from a Compton interaction usually retains _____ of the energy of the incident photon.

A) none
B) little
C) most
D) all

Question 15

A negative contrast agent is _____.

A) air
B) iodine
C) barium
D) water

Question 16

Barium is a good contrast agent because of its _____.

A) low atomic number
B) high atomic number
C) light color
D) low density

Question 17

Which has the greatest mass density?

A) fat
B) soft tissue
C) bone
D) air

Question 18

Because of differential absorption,about _____% of the incident beam from the x-ray tube contributes to the finished image.

A) 0.5
B) 10
C) 50
D) 95

Question 19

Differential absorption in diagnostic imaging is primarily caused by _____.

A) photoelectric absorption
B) Compton scatter
C) pair production
D) all of the above

Question 20

When the mass density of the absorber is _____,it results in _____ Compton scatter.

A) decreased, increased
B) increased, increased
C) increased, decreased
D) decreased, decreased

Question 21

High kVp techniques reduce _____.

A) patient dose
B) differential absorption
C) image fog
D) all of the above

Question 22

Compton interactions,photoelectric absorption,and transmitted x-rays all contribute to _____.

A) image fog
B) differential absorption
C) patient dose
D) attenuation

Question 23

X-rays transmitted without interaction contribute to _____.

A) photoelectric absorption
B) the radiographic image
C) the image fog
D) beam attenuation

Question 24

At energies below 40 keV,the predominant x-ray interaction in soft tissue and bone is _____.

A) coherent scatter
B) Compton scatter
C) photoelectric absorption
D) photodisintegration

Question 25

If 5% of an incident beam is transmitted through a body part,then 95% of that beam was _____.

A) scattered
B) attenuated
C) absorbed
D) back-scattered