A PRIMER ON X-RAYS AND RADIATION

With the use of better and better sensors for our radiographic scans, we are now able to take a 3D Cone Beam Scan with less radiation exposure than we used to use for a panoramic film. Certainly, all radiation exposure is a concern and we continue to strive to provide the best care with a minimal exposure. There is however, a lot of debate and flawed information circling around regarding the appropriateness of dental x-rays and the risks associated with this. The bottom line is that, where needed as part of an oral surgery treatment, dental x-rays are appropriate and carry a minimal risk with a benefit that far exceeds that risk. In the following pages, I have put down a few definitions and details that may be of interest about x-rays and radiation as they relate to oral surgery.

X-Rays for Oral Surgery Patients in Milwaukee

Exposure to gamma radiation (x-rays) is part of everyday life. By far the largest exposure is by natural sources, especially Radon which is present in the earth and given off as a gas. Electronics such as televisions, microwaves, cell phones, etc., give off radiation. Again, these sources present a much greater risk than dental x-rays. Positioning one’s self too close to these appliances can be a concern.

Studies show that we are able to heal cell damage from x-ray sources and rid of many abnormal cells naturally. This helps with low level exposure and even periodic exposure such as with x-rays. The state of the science right now is still to approach all exposure with caution, but that the amount or dose at one time is much more important than the cumulative dose – which used to be thought of as more important. This again is because of the natural healing that can take place in our bodies to counter the harmful effects.

Medical and dental x-rays help us to diagnose and treat oral and facial disease and have contributed immensely to the science of oral surgery with great benefit at a low risk. The addition of Cone Beam Scanning has allowed us to easily see anatomy and pathology in three dimensions, greatly enhancing our ability to evaluate, treatment plan, reduce risk, and care for conditions and diseases of the oral/facial region. As you may know, digital x-ray units such as we use have significantly brought down the dose of radiation our patients receive.

Here are several important terms used to describe x-ray radiation:

DENTAL X-RAY DOSAGE

• Here are some typical x-ray studies and the average dose in millisieverts (mSv)

Dental x-ray (panoramic) 0.010 mSv

Dental x-ray (4 intraoral bitewings) 0.005 mSv

Dental CT 0.200 mSv

Medical brain CT (standard) 2.0 mSv

Medical chest CT (standard) 7.0 mSv

 

RADIATION

• Visible light is an example from a larger array of electromagnetic waves that we call radiation. Light, as well as other types of radiation, is made up of particles of different sizes and energies. These sizes and energies give the different types of radiation their characteristics. For instance, ultraviolet waves can cause sunburn. Infrared waves can cause a heat burn. Microwaves excite and disrupt water molecules which can cook our food. Radio, television and other types of microwaves can carry patterns of signals that can be transformed into sound, data, and light images. Visible light is absorbed in different ways by different objects giving us the sensation of color.

The spectrum of radiation is divided into parts and named based on the characteristics of the type of radiation. These include Black Body Radiation, extremely low frequency (ELF) radiation, very low frequency (VLF) radiation, radio waves, microwaves, infrared, visible light, ultraviolet light, cosmic radiation, and ionizing radiation. Ionizing radiation is dividing into x-ray and gamma radiation, alpha radiation, beta radiation, and neutron radiation.

IONIZING RADIATION

• Ionizing radiation is radiation composed of particles that individually carry enough kinetic energy to liberate an electron from an atom or molecule causing that atom or molecule to become ionized. X-rays/gamma radiation are a type of ionizing radiation. Although we cannot see these particles we can “read” the effects that these particles have on films and screens, thus allowing us to form x-ray (radiographic) images that we can see visually and interpret.

• We usually measure x-ray dose in sieverts (Sv).

SIEVERT

• A commonly used measurement used to define the effects of radiation from different sources. The sievert is a derived unit of ionizing radiation dose in the International System of Units. It is the unit of measurement used to assess the risks of low levels of ionizing radiation on the human body.

• One sievert of effective dose, which would be a massive dose, carries with it a 4 percent chance of developing a fatal cancer in an average adult, and a 0.8 percent chance of a hereditary defect in future offspring.

• When we talk about x-ray output from our machines, we are talking in millisieverts (1000^th) and microsieverts (1,000,000^th).

GRAY

• The gray is a derived unit of ionizing radiation dose in the International System of Units. It is a measure of the absorbed dose and is defined as the absorption of one joule of energy in the form of ionizing radiation by one kilogram of matter.

• An absorbed dose of one gray (Gy) by alpha particles will lead to an equivalent dose of twenty sieverts (Sv).

• Dose equivalent is expressed numerically in rems or sieverts (Sv).

RAD (Roentgen Absorbed Dose)

• The rad is a deprecated unit of absorbed radiation dose defined as 1 rad equals 0.01 Gy equals 0.01 J/kg. It was originally defined in CGS units in 1953, as causing 100 ergs of energy to be absorbed by one gram of matter. In talking about the radiation environment, the discussion is dominated by terms applying gamma or x-rays applied uniformly to the whole body. In this case, one rad of absorbed dose gives one rem of effective dose. One sievert is generally defined as the amount of radiation roughly equivalent in biological effectiveness to one gray (or 100 rads) of gamma radiation.

• The definition of these terms is very difficult because of the numbers of variables and the application of x-ray dose to a specific area rather than the whole body. For instance, certain parts of the body such as the gonads or eyes may be more susceptible or have a greater relative susceptibility than other parts of the body. The way the x-rays are applied, the energy of the dose, the amount, the focus of the beam, the density of the target tissue, location relative to the source, etc. all can have an effect. This has certainly been studied as it relates to various organ systems, but absolute data and absolute effects information does not exist and cannot be calculated for each case.

• Wilhelm Roentgen was a German physicist (1845-1923) who discovered x-rays or roentgen-rays for which he received the Nobel Prize for Physics in 1901.

REM (Roentgen Equivalent Man)

• The rem is a unit of effect absorbed dose of ionizing radiation on the human tissue equivalent to one roentgen of x-rays. This term was developed in the 1940s as an acronym for roentgen equivalent man.

• It is a unit of radiation dosage (such as from x-rays) applied to humans. The rem is now defined as the dosage in rads that will cause the same amount of biological injury as one rad of x-rays or gamma rays.

• Formerly poorly defined, the rem was redefined in 1962 to clarify the usage of the term relative biological effectiveness (RBE) in both radio biology and radiation protection.

• A rem is equivalent to 0.01 seiverts in the International System of Units (SI).

Experienced Oral Surgery Team for Milwaukee Residents

We are always excited to be able to keep on top of the latest in technology and technique when it comes to oral surgery. If you are ready to obtain innovative and patient-oriented oral surgery services, we can help. For a consultation, call Wagner Oral Surgery and Dental Implant Specialists at (262) 634-4646 today! Our oral surgery team is excited to help you achieve a happier, healthier smile.