Essential Concepts of Radiologic Science (CH 1)

Vocabulary-style flashcards covering the fundamental concepts of radiologic science, forms of energy, ionizing radiation, and standard radiologic units based on Chapter 1.

Matter

Anything that occupies space and has mass; the material substance of which physical objects are composed.

Mass

The quantity of matter contained in any physical object, described by its energy equivalence and measured in kilograms ($kg$).

Weight

The force exerted on a body under the influence of gravity.

Energy

The ability to do work, measured in the SI unit joule ($J$) or the radiologic unit electron volt ($eV$).

Potential Energy

The ability to do work by virtue of position, such as a guillotine blade held aloft or a rollercoaster at the top of an incline.

Kinetic Energy

The energy of motion, possessed by all matter in motion.

Chemical Energy

The energy released by a chemical reaction, such as the energy provided to the body through food or the explosion of dynamite.

Electrical Energy

The work that can be done when an electron moves through an electric potential difference ($\text{voltage}$).

Thermal Energy

Also known as heat, it is the energy of motion at the molecular level and is closely related to temperature.

Nuclear Energy

The energy that is contained within the nucleus of an atom.

Electromagnetic Energy

Energy traveling through space that is a combination of electric and magnetic fields; it includes x-rays, gamma rays, radio waves, and visible light.

Radiation

The transfer of energy emitted through space.

Ionizing Radiation

Any type of radiation capable of removing an orbital electron from the atom with which it interacts.

Ionization

The removal of an electron from an atom.

Ion Pair

The combination of an ejected orbital electron (negative ion) and the remaining atom (positive ion) resulting from ionization.

Ubiquitous Background Radiation

Natural environmental radiation consisting of cosmic rays, terrestrial radiation, internally deposited radionuclides, and radon.

Radon

A radioactive gas produced by the natural decay of uranium that emits alpha particles; it is the largest source of ubiquitous background radiation.

Crookes Tube

A partially evacuated glass tube used in late 19th-century physics laboratories; it was the forerunner of modern x-ray tubes.

Wilhelm Roentgen

The physicist who discovered x-rays on November 8, 1895, at Würzburg University in Germany.

Fluorescence

The emission of visible light by a material, such as barium platinocyanide, when stimulated by radiation.

Kilovolt peak ($kVp$)

The unit used to measure x-ray voltage, where $1000$ volts ($V$) equals $1$ kilovolt ($kV$).

Milliampere ($mA$)

The unit used to measure x-ray current, where milli stands for $1/1000$ ($0.001$).

Coolidge Tube

A hot-cathode vacuum tube unveiled in 1913 that allowed x-ray intensity and energy to be selected separately and accurately.

Snook Transformer

An interrupterless high-voltage power supply introduced in 1907 that, combined with the Coolidge tube, paved the way for modern radiography.

ALARA

A primary radiation protection philosophy meaning "As Low As Reasonably Achievable."

Filtration

The insertion of metal filters (usually aluminum or copper) into the x-ray tube housing to absorb low-energy x-rays.

Collimation

The restriction of the useful x-ray beam to the part of the body being imaged to spare adjacent tissue.

Air Kerma ($Gy_a$)

The SI unit of radiation exposure ($\text{Kinetic Energy Released in Matter}$), measured in grays ($Gy$) where $1\text{ J/kg} = 1\text{ Gy}$.

Absorbed Dose ($Gy_t$)

The radiation energy absorbed per unit mass; the SI unit is the gray ($Gy$).

Effective Dose ($Sv$)

The unit (sievert) used to express radiation received by workers and populations, accounting for biological effectiveness and partial-body irradiation.

Becquerel ($Bq$)

The SI unit of radioactivity, representing the quantity of material in which a nucleus disintegrates every second ($1\text{ d/s} = 1\text{ Bq}$).