Radiation Physics and Radiobiology Review Notes

Vocabulary flashcards based on radiation physics and radiobiology concepts.

Thermionic Emissions

The release of electrons in response to heat in an x-ray tube.

Bremsstrahlung

A German term meaning 'braking radiation', referring to the interaction where fast-moving electrons slow down by approaching a positive nucleus, emitting energy as x-ray photons.

Characteristic Interaction

An x-ray process where an electron collides with an inner shell electron, creating a vacancy and resulting in the emission of a characteristic x-ray photon.

mA

Milliamperage, a measurement that reflects the flow of electrons in the x-ray tube; increasing mA creates more x-rays.

Kilovoltage Peak (kVp)

The maximum voltage difference between the cathode and anode in an x-ray tube; higher kVp leads to increased energy and quantity of x-rays.

Photoelectric Absorption

An interaction where an x-ray photon is completely absorbed by an inner shell electron, causing ionization and resulting in a photoelectron.

Compton Scatter

An interaction where an x-ray photon is partially absorbed by an outer shell electron, leading to ionization and the emission of a scattered photon.

Coherent Scattering

A type of scattering where an x-ray photon is temporarily absorbed by an atom and then re-emitted without energy loss.

Attenuation

The reduction in x-ray beam intensity as a result of absorption and scatter in matter.

Radiosensitivity

The degree to which cells, tissues, or organs are susceptible to the damaging effects of radiation.

Absorbed Dose (Gy)

The amount of radiation energy absorbed per unit mass, measured in Grays.

Dose Equivalent (Sv)

A measure that compares the biological effect of different types of radiation, calculated by absorbed dose times weighting factor.

Effective Dose (Sv)

A measure used to assess the impact of radiation on the risk of adverse effects, factoring in the type of radiation and tissues exposed.

Linear Energy Transfer (LET)

The average energy deposited per unit length of tissue by ionizing radiation, expressed in keV/μm.

Oxygen Enhancement Ratio (OER)

The increased biological effectiveness of radiation in oxygenated conditions compared to hypoxic conditions.

Acute Radiation Syndrome (ARS)

A serious illness caused by significant exposure to radiation in a short period, characterized by specific syndrome phases.

^LD50/60

The lethal dose of radiation that will kill 50% of the population within 60 days without medical intervention; typically around 3-4 Gy for humans.

Cumulative Timer

A device used in fluoroscopy that signals every 5 minutes to monitor the duration of exposure.

Automatic Exposure Control (AEC)

A system that automatically adjusts exposure time to maintain consistent receptor exposure during radiographic procedures.

Filtration

The process of removing low-energy photons from the x-ray beam to minimize patient dose.

Grid Ratio

The ratio of the height of the lead strips to the distance between them, impacting scatter radiation absorption.