Ch. 12 X-Ray Interactions

Question 1

When an x-ray photon passes through matter, it undergoes a process called:

Answer 1

Attenuation

Question 2

During the process of attenuation, x-ray photons in the beam:

Answer 2

• Reduce in number
• Lose energy
• Interact

Question 3

During the process of attenuation, the x-ray photon may interact with:

Answer 3

• The nucleus
• The entire atom
• An orbital electron

Question 4

Which atomic shell possesses the highest binding energy?

Answer 4

The K shell.

Question 5

In which element are the inner-shell electrons more tightly bound to the nucleus?

a. Mercury (Z#=80)
b. Tungsten (Z#=74)
c. Lead (Z#=82)
d. Chromium (Z#=24)

Answer 5

c. Lead (Z#=82)

- highest atomic number out of the choices

Question 6

Which energy-level electrons possess the highest total energy?

a. K
b. L
c. M
d. N

Answer 6

d. N

Question 7

As the electron shells move farther from the nucleus, total electron energies ____ and binding energies ____.

Answer 7

Increase; decrease

Question 8

When x-ray interacts with matter and scatters, the photon:

Answer 8

Exits with less energy

Question 9

When x-ray photons interact with matter and change direction, the process is called:

Answer 9

Scatter

Question 10

When an x-ray photon with a slightly greater energy than the biding energy of the inner-shell electron interacts with that inner-shell electron, the following interaction results:

Answer 10

Photoelectric absorption

Question 11

During photoelectric absorption, a/an ____ shell electron is ejected.

Answer 11

Inner

Question 12

During photoelectric absorption, the ejected electron is called:

Answer 12

A photoelectron

Question 13

A photoelectron:

Answer 13

• Is matter and possesses energy
• Typically travels 1-2 mm in soft tissue
• Capable of creating biological changes

Question 14

When an electron from an outer shell fills a vacancy in an inner shell,

Answer 14

A photon is released.

Question 15

During the photoelectric interaction, as an electron transfers from an outer shell to a vacant inner shell, energy is released in the form of:

Answer 15

A characteristic photon

Question 16

Secondary radiation energies are highest for which element?

a. Hydrogen
b. Carbon
c. Barium
d. Oxygen

Answer 16

c. Barium

Question 17

An interaction that occurs between very low energy x-ray photons and matter is called _____ scatter.

Answer 17

• Coherent
• Classical
• Unmodified

Question 18

During coherent scattering, the scattered photon possesses ______ as the incident photon.

Answer 18

The same energy, the same frequency, and the same wavelength

Question 19

Compton scattering occurs when an incident x-ray photon interacts with a ____ electron.

Answer 19

Loosely bound outer-shell

Question 20

The electron dislodged during Compton scattering is called the:

Answer 20

Recoil electron

Question 21

The photon that exits the atom after a Compton scattering is called the ______.

Answer 21

Compton scattered electron.

Question 22

During Compton scattering, the incident photon energy is divided between the:

Answer 22

Recoil electron and the scattered photon

Question 23

As the angle of deflection is increased from 0 degrees to 180 degrees:

Answer 23

Greater energy is imparted to the recoil electron

Question 24

Unwanted radiographic image densities caused predominantly by scattered photons is called:

Answer 24

Radiation fog

Question 25

During which interaction with matter is the x-ray photon converted to matter in the form of two electrons?

Answer 25

Pair production

Question 26

In which process is matter converted back to energy?

Answer 26

Annihilation reaction

Question 27

What interactions has a significant impact on the x-ray image?

Answer 27

Photoelectric absorption and Compton scattering

Question 28

In the human body, ____ is the predominant interaction through most of the diagnostic x-ray range.

Answer 28

Compton scattering

Question 29

What interaction with matter results in a radiograph with a loss of radiographic image contrast?

Answer 29

Compton scattering

Question 30

Which interaction with matter results in an image with higher contrast?

Answer 30

Photoelectric interaction

Question 31

In an effort to decrease the mAs of an exposure, the 15% rule of kVp change may be considered. Changing the original kVp of 84 using the 15% rule will have what impact?

Answer 31

Greater Compton scatter interactions

Question 32

The incidence of the photoelectric effect increases with:

Answer 32

Increasing atomic number of the absorber

Question 33

In diagnostic radiology, radiographic image contrast is principally due to the predominance of:

Answer 33

Photoelectric interactions

Question 34

An incident photon with 35 keV is most likely to interact with the K-shell electron of what atom?

Answer 34

Iodine