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Ionizing and Non-Ionizing Radiation Study Guide
Radiation - Energy emitted from a body or source that is transmitted through an intervening medium or space and absorbed by another body. Transmission is in the form of waves but wave/particle duality under quantum physics.
Radiation is classified as being either non-ionizing or ionizing. Non-ionizing radiation is longer wavelength/lower frequency lower energy. While ionizing radiation is short wavelength/high frequency higher energy.
Ionizing Radiation has sufficient energy to produce ions in matter at the molecular level. If that matter is a human significant damage can result including damage to DNA and denaturation of proteins. This is not to say that non-ionizing radiation can’t cause injury to humans but the injury is generally limited to thermal damage i.e. burns.
There is a great deal of information on the above chart. One of the most interesting things is that the visible spectrum is essentially the divide between ionizing and non-ionizing radiation. This makes sense clinically when we think of UV radiation causing skin cancer.
Types of Non-Ionizing Radiation and Their Clinical Effects-
Referring again to the chart above we can see that Non-Ionizing radiation comes in the forms of:
- ELF (extremely low frequency)
- Radio Frequencies
- Microwave Frequencies
- Lasers
- Infrared
- Visible Spectrum
- Ultraviolet
This list is in order of lowest to highest frequency.
1. ELF
Power plant or line workers
Inconclusive evidence of leukemia link
2. 3. Radiofrequency and Microwave Frequency Exposures-
Occupational Exposures-
Radar and communications equipment, industrial and commercial ovens
Other Exposures
Cell Phones
Clinical Effects-
There is a great deal of controversy regarding potential cancer risks, particularly with cell phone use. We know that exposure to radio and microwave frequency sources can cause burns and clinically this is what you are most likely to see.
4. LASER (Light Amplification by Stimulated Emission of Radiation)
Beams of coherent light with single wavelength and frequency
May be in the IR, Visible or UV spectrum
Eye is most sensitive to injury from LASER
Types of Ionizing Radiation and Their Clinical Effects-
Ionizing radiation is emitted from radioactive atomic structures as high energy electromagnetic waves (gamma and x-rays) or as actual particles (alpha, beta, neutrons)
- Gamma Rays
- X-Rays
- Alpha Particles
- Beta Particles
- Neutrons
Penetration of Radiation
Gamma Rays, Xrays and Neutrons Penetrate Body Easily, Need lead to shield for gamma and x-rays, massive shielding for Neutrons
Alpha and Beta Particles are essentially blocked by the skin with Beta Particles penetrating more deeply with the potential to cause burns. Alpha particles can be stopped by paper, Beta by plastic
Alpha Particles can cause significant damage if taken internally, see former Soviet Spy
Radiation Measurement
Roentgen (R)- Describes a radiation field in terms of the amount of ionizations produced in air, not in common use today
Rad - Conventional unit of absorbed dose of radiation per unit mass.
Gray (Gy) – 1 Gray=100 Rads
Rem - Absorption measure to whole body or specified organ, takes into account radiation quality, Rem=rads x quality factor, each type of ionizing radiation has a different quality factor
Sievert (Sv)- 1SV=100 Rem
Ionizing Radiation Exposure Limits
Occupational- National Council on Radiation Protection (NCRP) annual exposure 5 rem
Background Exposure for a US resident is 360mrem
Common Occupational Exposures -
- Medicine- Radionuclides, X-Ray
- Nuclear Power Industry
- Document Dating
- Food Preservation
- Airplane/Space Flight
- Transportation of Radioactive Material
Four Ionizing Radiation Exposure Categories-
- Radioactive Contaminates on Intact Skin
- Local Radiation Injuries
- Whole Body Exposure
- Internal Deposition
Acute Radiation Syndrome
Over 100 rad in a single exposure or within 24-48 hours, progressive predictable series of signs and symptoms developing over a period ranging between a few hours to several weeks
Clinical response and prognosis generally depends on damage sustained by hematopoietic system.
Lethal dose for 50% of healthy humans is 350 to 450 rad (3.5 to 4.5 Gy)
Prodromal Period - 1 to 6 hours after exposure
Anorexia, Nausea, Vomiting, Diarrhea
Initial Symptoms subside after a few hours to two days
Ominous signs include diarrhea, skin erythema, lymphocyte count less than 1000, short or no latent period
Latent Period- Variable in duration hours to 30 days
Manifest Illness
Fatigue, GI symptoms, desquamation, deep ulcerations, bone marrow depression, Stomatitis, hemorrhagic phenomena
Death or Recovery
CBC normalizes in six months to a few years, Clinical recovery within 6 months, persistent fatigue
Long Term Effects
