Principles of Radiation Physics Exam Questions and Answers With Verified
Solutions 2025
X-ray Production-What's needed - ✔✔1. Source of Free Electrons
2. Acceleration of Electrons
3. Focusing of Electrons
4. Deceleration of Electrons
Source of Free Electrons - ✔✔Thermionic Emission
-Electrons are released from the surface of one or two filament wires by a process called thermionic
emission
-While current passes through the wire, heat causes the separation of electrons that will be released
from the wire
Acceleration of Electrons - ✔✔Free electrons must be accelerated across the x-ray tube from cathode to
anode
kVp forces the electrons across the tube giving them kinetic energy; the higher the kVp the more energy
the electrons will have
Focusing of Electrons - ✔✔-Focusing cup houses the filament wire
-Cup holds the electrons around the wire in a cloud (space charge) until the exposure switch is activated;
when the kVp is applied, the electrons are focused into a narrow beam directed toward the anode
Deceleration of Electrons - ✔✔Electrons decelerate when they strike the anode.
Anode is a tungsten disk with a high atomic number and high melting point
Target Interaction - ✔✔-X-rays are produced by one of these methods when electrons interact with the
anode
-Bremsstrahlung
-Characteristic
Solutions 2025
X-ray Production-What's needed - ✔✔1. Source of Free Electrons
2. Acceleration of Electrons
3. Focusing of Electrons
4. Deceleration of Electrons
Source of Free Electrons - ✔✔Thermionic Emission
-Electrons are released from the surface of one or two filament wires by a process called thermionic
emission
-While current passes through the wire, heat causes the separation of electrons that will be released
from the wire
Acceleration of Electrons - ✔✔Free electrons must be accelerated across the x-ray tube from cathode to
anode
kVp forces the electrons across the tube giving them kinetic energy; the higher the kVp the more energy
the electrons will have
Focusing of Electrons - ✔✔-Focusing cup houses the filament wire
-Cup holds the electrons around the wire in a cloud (space charge) until the exposure switch is activated;
when the kVp is applied, the electrons are focused into a narrow beam directed toward the anode
Deceleration of Electrons - ✔✔Electrons decelerate when they strike the anode.
Anode is a tungsten disk with a high atomic number and high melting point
Target Interaction - ✔✔-X-rays are produced by one of these methods when electrons interact with the
anode
-Bremsstrahlung
-Characteristic
