Radiation Safety Lecture 1

electromagnetic energy

energy traveling through space with a combination of an electric and magnetic field, used in x-ray, includes x-rays, gamma rays, radiowaves, microwaves, UV, etc.

exposed/irradiated matter

matter that intercepts/absorbs radiation

types of natural environment radiation

cosmic rays, terrestrial radiation, internally deposited radionuclides, radon

what modality has the highest % as a source of ionizing radiation

CT & PET

when did the first fatality by x-ray occur and who was it?

1904 - Clarence Daley (Thomas Edison's friend)

matter

anything that occupies space

mass

quantity of matter, measured in kilograms; described by its energy equivalent

weight

force exerted on a body under the influence of gravity

kinetic energy

energy of motion possessed by all matter

potential energy

ability to do work by virtue of position

radiation

energy emitted and transferred through space (transfer of energy)

ionizing radiation

any radiation capable of removing an orbital electron from the atom which it interacts

ion pair

separated orbital electron (negative ion) and remaining atom (positive ion)

largest source of natural environmental radiation

radon gas, produced by natural radioactive decay of uranium

discovery of x-rays

November 8, 1895 by Wilhem Roentgen

3 general types of x-ray examinations

radiography, fluoroscopy, and computed tomography (CT)

ALARA

as low as reasonably achievable

3 basic principles of radiation protection

time, distance, shielding

air kerma

kinetic energy released per unit mass, measured in grays (Gya)

measures total energy of ions in air

absorbed dose

radiation energy absorbed per unit mass, measured in grays (Gyt), short term effects

effective dose

measured occupational exposure and effective dose, with the SI unit being sievert (Sv), long term effects

radioactivity

quantity of radioactive material, measured in Becquerel (Bqa), not related to x-rays

rem to sievert conversion

100 rem = 1 Sv

what is radiation safety/protection and why is it important in our field?

reduces unnecessary radiation exposure with a goal to minimize the harmful effects of ionizing radiation

energy

ability to do work; measured in joules (J)

chemical energy

energy released by a chemical reaction

electrical energy

work that occurs when an e-moves through an electric potential difference

thermal energy

energy of motion at molecular level; the faster molecules vibrate the more thermal energy the substance has & higher temp

nuclear energy

energy that is contained within the nucleus of an atom

filtration

removing low-energy x-rays before they reach thepatient (metal filters usually aluminum or copper)

intensifying screens

radiation to light conversion within the imaging device (shortens exposure time and reduces patient dose)

collimation (field of view)

use collimators to limit exposed areas