ARRT Radiation Physics and Radiobiology 3

Question 1

Characteristic radiation is produced when an outer-shell electron fills a vacancy in which shell?

Accepted Answer

An inner electron shell

Answer

Characteristic radiation is emitted when an outer-shell electron transitions to fill a vacancy in an inner shell, releasing a photon with energy equal to the difference between the two shells.

Question 2

The relative biologic effectiveness (RBE) of alpha particles compared to x-rays is approximately:

Accepted Answer

20

Answer

Alpha particles have an RBE of approximately 20, meaning they are 20 times more biologically effective than x-rays at causing the same level of damage.

Question 3

During which phase of the cell cycle are cells MOST radiosensitive?

Accepted Answer

M phase (mitosis)

Answer

Cells are most radiosensitive during M phase because chromosomes are condensed and the mitotic spindle is vulnerable to radiation-induced disruption.

Question 4

What is bremsstrahlung radiation?

Accepted Answer

X-rays produced when electrons decelerate near a nucleus

Answer

Bremsstrahlung ('braking radiation') is produced when high-speed electrons lose kinetic energy by decelerating in the Coulomb field of a nucleus, emitting photons with a continuous energy spectrum.

Question 5

Which statement about the photoelectric effect is correct?

Accepted Answer

The ejected electron carries away all of the photon's energy minus binding energy

Answer

In the photoelectric effect, the incident photon is completely absorbed and a photoelectron is ejected with kinetic energy equal to the photon energy minus the electron's binding energy.

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT Radiation Physics and Radiobiology 3