What are the types of radiation?

The most common kinds of ionizing radiation are X-rays, gamma rays, alpha, beta particles and neutrons.

X-rays are the most common sources of radiation exposure for the general public, since they are commonly used in medicine. Moving at the speed of light, X-rays are a penetrating form of radiation, which means they travel through material easily.

Exposure to X-rays is measured in units of radiation absorbed dose (rad) – the amount of radiation absorbed per unit mass of material. Rads are often converted to units of rem by multiplication with quality factors to account for biological damage produced by different forms of radiation.

Who should be monitored?

Background radiation is naturally and inevitably present in our environment. A lot of our natural exposure is due to radon, a gas which seeps from the earth’s crust and is present in the air we breathe, the food we eat and the solar system on the whole.

The average person in the United States receives about 360 mrem whole body equivalent dose every year. This is mostly from natural sources of radiation, such as radon.

According to the US Nuclear Regulatory Commission, radiation monitoring should be considered for those who work in occupations where risks may be prevalent due to exposures from X-ray equipment. Even in environments where exposure risks may be minimal, such as in a dental practice, it is good policy to take the proper precautions in order to monitor exposure over time, ensuring healthy productive lives with no long-term effects.

Why is radiation dangerous?

Ionizing radiation cannot be seen, heard, tasted, smelt or felt in any way. Therefore it is important that those working in an environment where the equipment being used emits ionized radiation be monitored on a regular basis. Essentially, ionized radiation disrupts some of the atoms in its path causing them to separate into electrically charged (+ and -) components called ions.

The atoms in our bodies become biologically useless if divided into ions. According to FDA CDRH 2001, of the trillions of atoms that exist in our bodies, small ionization may potentially cause no real harm; however, large doses of ionizing radiation can potentially cause sickness, cancer and birth defects.

The radiation from X-rays, depending on the dose, can reduce cell division, damage genetic material and harm unborn children. Cells that divide quickly are very sensitive to X-ray exposure.

When is it considered dangerous?

Annual Radiation Exposure Limits – based on US Nuclear Regulatory Commission’s Regulation CFR Title 10, Part 20:

Radiation workers adhere to the concept of ALARA that means, “As Low As Reasonably Achievable”. We have adopted an ALARA limit of 2000 mrem/year for any client. Should a client’s dose exceed 200 mrem for a particular wear period; we undertake a dose investigation involving getting in touch with the concerned employee. The Deep Dose Equivalent (Whole Body) limit is 5,000 mrem/year according to the USNRC. Anybody who can potentially receive a dose of 100 mrem/year should wear a dosimeter.

Where can you be exposed?

In many occupations, radiation can be encountered as a natural part of their jobs. Some of these occupations include doctors, nurses, radiographers, X-ray technicians, astronauts, dental hygienists, researchers, pharmacists, welders and airline and jet crews.

The doses received can be up to several rem of exposure over the course of a year.

How can you minimize the risk according to the US NRC?

For most practical purposes it is sufficient to detect the presence of radiation by the use of small devices called dosimeters. A dosimeter measures the exposure of radiation the user wearing the badge is exposed to.

For employees who work in a radiation environment, be it a nuclear power plant, a hospital or a dentist’s office, the wearing of dosimetry measurement devices on a daily basis is a sound radiation safety practice, and in many cases, it may be mandatory.

It is important to know whether you have been exposed. The timely return of your dosimeter will allow you to know if exposure levels are within safety limits or if necessary action needs to be taken.

The only way to know your real exposure level is to wear a dosimeter every day and to check your exposure reports regularly.

If you have employees who are pregnant and working where exposure is possible, you should consider any necessary work restrictions and request a fetal badge in addition to the normal body badge. Even those who are of childbearing age should be aware of the dangers of radiation exposure and its potential affects on the unborn child.
Depending on the dose, x-rays could potentially harm an unborn child. The FDA (FDA CDRH 2001) stated that:

“There is scientific disagreement about whether the small amounts of radiation used in diagnostic radiology can actually harm the unborn child, but it is known that the unborn child is very sensitive to the effects of things like radiation, certain drugs, excess alcohol, and infection. This is true, in part, because the cells are rapidly dividing and growing into specialized cells and tissues. If radiation or other agents were to cause changes in these cells, there could be a slightly increased chance of birth defects or certain illnesses, such as leukemia, later in life.”

A fetal badge should be worn over the fetal area, along with the normal monitoring device. It is recommended that a fetal badge be worn under the lead apron when one is used.

References

1.Nuclear Regulatory Commission 10 CFR 20 – 10 CFR 71
2.Occupational Safety and Health Administration Department of Labor 29 CFR Ch XVII (7-1-03 Edition)
3.Health Physics Society – Personnel Dosimetry Performance Criteria for Testing ANSI/HPS N13.11.2001