RAD 205 Ch. 3 Review

Which of the following is an interaction between x-radiation and matter?

• Photoelectric absorption

• Pair production

• Compton scattering

• All of the above

Answer explanation

All of the options listed—photoelectric absorption, pair production, and Compton scattering—are recognized interactions between x-radiation and matter, making 'All of the above' the correct choice.

Which interaction is most likely to occur when x-rays pass through a high atomic number material?

• Compton scattering

• Photoelectric absorption

• Pair production

• Rayleigh scattering

Answer explanation

Photoelectric absorption is the dominant interaction for x-rays in high atomic number materials, as the probability of absorption increases with atomic number, leading to the complete absorption of the x-ray photon.

At what energy level does pair production become a significant interaction for x-rays?

• Below 1 MeV

• 1.02 MeV

• Above 10 MeV

• Between 0.1 and 0.5 MeV

Answer explanation

Pair production occurs when photon energy exceeds 1.02 MeV, the threshold needed to create an electron-positron pair. Thus, at 1.02 MeV, pair production becomes a significant interaction for x-rays.

Which interaction results in complete absorption of the incident photon?

• Coherent scattering

• Compton scattering

• Photoelectric absorption

• Pair production

Answer explanation

Photoelectric absorption occurs when an incident photon is completely absorbed by an atom, resulting in the ejection of an electron. This interaction contrasts with others like Compton scattering, where the photon is only partially absorbed.

This is the reduction of energy of the primary beam as it passes through various anatomic tissues.

• Absorption

• Scattering

• Attenuation

• Transmission

Answer explanation

Attenuation refers to the reduction of energy of the primary beam as it passes through various anatomic tissues, encompassing both absorption and scattering effects.

Remnant or exit radiation is composed of _______ photons.

• Absorbed and transmitted

• Transmitted and scattered

• Absorbed and scattered

• Absorbed, Transmitted and Scattered

Answer explanation

Remnant or exit radiation consists of photons that have passed through the material (transmitted) and those that have interacted with it (scattered). Thus, the correct answer is 'Transmitted and scattered'.

The probability of photoelectric interaction increases with:

• Lower atomic number

• Higher photon energy

• Higher atomic number

• Lower mass density

Answer explanation

The probability of photoelectric interaction increases with higher atomic number because heavier elements have more electrons, enhancing the likelihood of photon interactions.

What is the energy range where Compton scattering dominates?

• 0-10 keV

• 20-40 keV

• 60-90 keV

• 100 keV and above

Answer explanation

Compton scattering is most significant in the energy range of 60-90 keV, where the interaction between photons and electrons is maximized, leading to a higher probability of scattering events compared to lower or higher energy ranges.

In Compton interaction, the scattered electron is known as:

• Auger electron

• Photoelectron

• Secondary photon

• Recoil electron

Answer explanation

In Compton interaction, the electron that is ejected due to the collision with a photon is referred to as the recoil electron. This term specifically describes the electron that gains energy and is scattered.

Compton scatter contributes to occupational dose.

• True

• False

Answer explanation

True. Compton scatter is a significant interaction of X-rays and gamma rays with matter, contributing to the radiation dose received by occupational workers in fields like radiology and nuclear medicine.