Radiation Physics and Atomic Structure - Review Flashcards

Flashcards cover atomic structure, ionization, radiation, X-ray machine components, electricity basics, and interactions of X-rays with matter.

What is the fundamental unit of matter?

Atom—the fundamental unit of matter.

Which atom is the simplest?

Hydrogen—the simplest atom.

What is the nucleus composed of?

Protons and neutrons.

What charge do protons carry?

Positive.

What charge do neutrons carry?

No charge (neutral).

What charge and mass do electrons have?

Electrons carry a negative charge and have very little mass.

How do electrons travel around the nucleus?

They orbit the nucleus in well-defined paths called orbits or shells.

Where is most of the atom located?

In empty space; most of the atom is empty space.

What is a molecule?

Two or more atoms joined by chemical bonds; the smallest unit that possesses a substance’s properties.

How are molecules formed?

By transfer or sharing of electrons between atoms.

What is ionization?

Gain or loss of electrons by an atom, making it electrically unbalanced (an ion).

What is radiation?

The emission and propagation of energy through space or a substance as waves or particles.

What is radioactivity?

Spontaneous disintegration/decay of unstable atoms to attain a more balanced nuclear state.

What is ionizing radiation?

Radiation capable of producing ions by removing or adding electrons to atoms; includes particulate and electromagnetic radiation.

What are the two groups of ionizing radiation?

Particulate radiation and electromagnetic radiation.

Name the four types of particulate radiation.

Electrons, alpha particles, protons, neutrons.

What is electromagnetic radiation?

Propagation of wavelike energy through space or matter, without mass.

What are the three characteristics used to describe electromagnetic waves?

Velocity, wavelength, and frequency.

What is X-radiation?

High-energy, ionizing electromagnetic radiation; photons travel as energy bundles at the speed of light and can ionize matter.

What are the main parts of an X-ray machine?

Control panel, extension arm, and tube head.

What is the purpose of insulating oil in the X-ray tube head?

To prevent overheating of the tube head.

What is the cathode and its purpose in the X-ray tube?

The cathode is a negative electrode with a tungsten filament; it supplies electrons necessary to generate X-rays.

What is the anode and its purpose?

The anode is a positive electrode with a tungsten target; it converts electrons into X-ray photons and dissipates heat via the copper stem.

What is the function of the tungsten filament?

Heats to produce electrons used to form X-rays.

What is the focal spot in an X-ray tube?

The tungsten target on the anode where electrons are converted into X-rays.

What is the role of the copper stem?

Dissipates heat away from the tungsten target.

What is the purpose of the X-ray tube head?

Houses the X-ray tube and its cooling system; directs X-rays.

What is electricity?

The energy used to make X-rays.

What is electrical current?

Flow of electrons through a conductor.

What is direct current (DC)?

Electrons flow in one direction.

What is alternating current (AC)?

Electrons flow in two opposite directions.

What is rectification?

Conversion of alternating current to direct current.

What is amperage?

Measurement of the number of electrons moving through a conductor.

In what units is current measured?

Amperes (A) or milliamperes (mA).

What is voltage?

Electrical force that causes electrons to move; measured in volts (V) or kilovolts (kV).

What does kilovoltage peak (kVp) control?

The voltage driving electrons from the cathode to the anode in the high-voltage circuit.

What does milliamperage adjustment (mA) control?

The number of electrons passing through the cathode filament.

What is the filament circuit?

Provides 3–5 volts to the filament; controlled by mA settings.

What is the high-voltage circuit?

Provides 65,000–100,000 volts; controls the voltage to generate X-rays; controlled by kV settings.

What is a circuit?

A path of electrical current.

What are the two main circuits in an X-ray system?

Filament circuit and high-voltage circuit.

What is primary radiation?

The penetrating X-ray beam produced at the anode target.

What is secondary radiation?

X-radiation created when the primary beam interacts with matter.

What is scatter radiation?

A form of secondary radiation from deflection of the primary beam; harmful to the patient and operator.

What are the four interaction types of X-ray photons with matter and their approximate percentages?

No interaction; absorption (photoelectric effect) ~30%; Compton scatter ~62%; coherent scatter ~8%.