basic concepts of radiation

• Radiation


  - emission of energy through space
• Wave-Particle Duality


  concept that radiation can move as electromagnetic waves or subatomic particles
• Irradiated/ Exposed


  matter that intercept radiation is said to be:
• Non-Ionizing Radiation


  - type of radiation that does not remove electrons from atoms

  - radio waves, microwaves, infrared radiation, visible light
• Ionizing Radiation


  - type of radiation that removes electrons from atoms and molecules

  - alpha radiation, beta radiation, x-rays, gamma rays
• Sources of Ionizing Radiation

  natural environmental radiation &
• Natural Environmental Radiation


  - results in an annual radiation dose of approximately 3 millisieverts

  - cosmic rays, terrestrial radiation, internally deposited radionuclides, radon
• Cosmic Rays


  - originates in outer space through heavenly bodies such as sun and stars

  - source of natural background radiation

  - composed of particulate and electromagnetic radiation

  - the intensity increases with altitude and latitude
• Terrestrial Radiation


  - results from deposits of uranium, thorium, and other radionuclides in the earth

  - can be found all throughout nature such as in the soil, water, and vegetation

  - the intensity is highly dependent on the geology of the area
• Internally Deposited Radionuclides


  - found inside the human body through the water we drink or food we eat

  - have always been with us and contribute an equal dose to humans

  - eg: potassium-40 and carbon-14
• Radon


  - the largest source of natural environmental radiation.

  - radioactive gas produced by the natural radioactive decay of uranium

  - alpha emitter

  - contributes radiation dose only to the lungs

  - can be found in all earth-based materials
• Man-Made Radiation


  - results in an annual dose of 3.2 millisieverts

  - artificial

  - medical procedures, consumer items, & nuclear energy
• Medical Procedures


  * diagnostic x-rays

  * ct scan

  * fluoroscopy

  * PET imaging (Fluorine-18)

  * nuclear imaging (Iodine-132, Tc-99m, Co-60)
• Diagnostic X-Rays


  - largest man-made source of ionizing radiation

  - 3.2 mSv/yr
• Radiologic Technologist Responsibility


  to reduce unnecessary exposure of the patients and personnel
• Consumer Products


  * radium watch dials (radium & tritium)

  * smoking tobacco

  * road construction materials (radon)

  * electron tubes

  * exit signs

  * smoke detectors

  * camping lantern mantles (thorium)

  * airport x-ray systems
• Nuclear Energy


  - nuclear power plants

  * Chernobyl

  * Fukushima

  * Three Mile Island
• Two Groups that are Exposed to Man-made Radiation Source

  members of the public & occupationally exposed Individuals
• Members of The Public


  - any individual not working directly with radiation

  - exposed to consumer products, radiation from the nuclear fuel cycle, residual fallout from nuclear weapons and accidents
• Occupationally Exposed Individuals


  - individuals working directly with radiation

  - rad techs, flight attendants, nuclear reactor workers

  - exposed to a working environment such as in a radiology
• Dosimeter


  device used to monitor radiation exposure
• Directly Ionizing Radiation


  - includes charged particles that have enough energy to remove electrons or ionize molecules

  - can cause multiple ionization events
• Indirectly Ionizing Radiation


  - includes uncharged particles such as photons and neutrons

  - occurs from an ionization energy to produce multiple ionization events
• Particulate Radiation


  - charged subatomic particles (alpha & beta radiation)

  - subatomic particles carry energy and have mass

  - primarily produced during radioactivity of an unstable atom

  - must be in motion and possess sufficient kinetic energy to cause ionization
• Alpha Radiation


  - equivalent to a helium nucleus (consists of 2 protons and 2 neutrons)

  - atomic mass is approximately 4 amu

  - large and exerts great electrostatic force

  - emitted only from heavy elements
• Alpha Radiation


  - average kinetic energy = 4-7 MeV

  - ionizes approximately 40,000 atoms for every cm of travel through air

  - energy is lost quickly because of the amount of ionization

  - travels 5 cm in air; 100 um in soft tissue

  - safe if intercepted outside the body ( by layers of skin)

  - intense when intercepted inside the body (inhaled radon gas irradiates the lungs)
• Beta Radiation


  - differ in terms of mass and charge

  - carry a negative charge but differ in electrons by its origin (nucleus)

  - range is longer; 10-100 cm in air and 1-2 cm in soft tissue
• Electromagnetic Radiation


  - type of radiation that have both non-ionizing and ionizing capabilities

  - exists over a wide energy range called an energy continuum

  - has no mass, but has electrical and magnetic energy changing in sinusoidal fashion

  - travels in the form of photons
• Electromagnetic Radiation


  - its properties include: Frequency, Wavelength, Velocity, and Amplitude

  - travel at the speed of light

  * 3x108 m/s

  * 300,00 km/s

  * 186,000 miles