Radiologic Physics Practice Flashcards

Flashcards covering the fundamentals of radiologic physics, including matter, energy, radioactivity, electromagnetism, and X-ray production.

Matter

Anything that has mass and takes up space.

Atom

Smallest unit of matter.

Nucleus

The part of the atom containing Protons and Neutrons.

Proton (+)

The particle that identifies the element, similar to a person’s name.

Neutron (0)

The particle in the nucleus that adds to the atomic mass.

Electron (-)

Particles orbiting the nucleus in shells.

Meter (m)

The unit of measurement for length, representing the distance from one point to another.

Kilogram (kg)

The unit of measurement for mass, representing the amount of matter in an object.

Second (s)

The unit of measurement for time, representing the duration of an event.

Force (N)

A derived unit calculated as $\text{Mass} \times \text{Acceleration}$.

Work (Joules)

A derived unit calculated as $\text{Force} \times \text{Distance}$.

Power (Watt)

A derived unit calculated as $\text{Work} \div \text{Time}$.

Kinetic Energy

Energy in motion, calculated by the formula $0.5 \times \text{Mass} \times \text{Velocity}^2$.

Potential Energy

Stored energy, calculated by the formula $\text{Mass} \times \text{Gravity} \times \text{Height}$.

Gamma Ray interaction level

The interaction of electromagnetic radiation at the Nucleus level.

X-ray interaction level

The interaction of electromagnetic radiation at the Electron shells level.

Radiation

Energy transfer through space.

Ionization

The removal or addition of electrons in an atom.

Ionizing Radiation

Radiation capable of knocking out electrons, such as X-rays and Gamma rays.

Inertia

Newton's first law stating an object at rest or motion stays that way unless acted on.

Radioactive Decay

The process of unstable atoms releasing energy.

Half-life

The time required to reduce radioactive activity by half.

Becquerel (Bq)

A unit of radioactivity representing $1$ decay/sec.

Gray (Gy)

The unit for absorbed dose.

Sievert (Sv)

The unit for biological effect or effective dose.

Alpha Decay

A process that releases $2$ protons and $2$ neutrons; it is heavy and dangerous.

Beta Plus Decay

A process where a proton changes to a neutron, emitting a positron and neutrino; used in PET Scans.

K-Capture

An interaction where an electron is absorbed by the nucleus, resulting in the release of Characteristic X-rays.

Voltage (V)

Electrical pressure.

Current (I)

The flow of electrons, measured in Amperes.

Resistance (R)

Opposition to electrical flow, measured in Ohms.

Ohm’s Law

The formula expressed as $V = I \times R$.

Electromagnetism

Magnetism created by moving electrons.

Faraday’s Law

The principle that moving magnets near wires creates electricity.

Lenz’s Law

The law stating induced current opposes the change causing it.

Anode (+)

The Tungsten target in an X-ray tube that rotates to spread heat.

Cathode (-)

The part of the X-ray tube that heats to emit electrons.

Thermionic Emission

The process of heating a filament to release electrons.

Bremsstrahlung

Radiation produced when an electron slows near a nucleus, emitting an X-ray.

Characteristic X-ray

Radiation produced when an electron hits the K-shell, releasing a specific X-ray.

Filtration

The process of removing weak X-rays to reduce patient dose.

Coherent Scattering

An interaction below $10\,keV$ involving no ionization and only a direction change.

Compton Scattering

An interaction between $30\text{--}150\,keV$ involving ionization and scatter.

Photoelectric Effect

An interaction between $30\text{--}150\,keV$ involving total absorption and ionization.

Pair Production

An interaction requiring over $1.02\,MeV$ that creates a positron and an electron.

Photodisintegration

An interaction above $10\,MeV$ where the nucleus absorbs energy and breaks.

Transformer

A device that changes voltage; Step-Up increases it, Step-Down decreases it.

Heat Units (HU)

Calculated as $kVp \times mA \times \text{time} \times \text{correction factor}$.

Leakage limit

X-ray tube safety standard that must not exceed $1\,mGy/hr$ at $1$ meter.

Quantum Shell Formula

Formula for maximum electrons per shell: $2n^2$, where $n$ is the shell number.