Radiation Safety

At Overlake we regularly review patient radiation dosage data in an effort to continually improve patient safety. Members of the Overlake Patient Dose Review Committee — which includes physicists, radiologists, technologists and administrators — meet regularly to re-examine the protocols and establish optimal radiation levels for patients. Our tools for Radiation Awareness and Community Education program (TRACE) is one of the first to address radiation safety in the region. We are accredited by the American College of Radiology in computed tomography (CT), magnetic resonance imaging (MRI), nuclear medicine and ultrasound.

What is a Dose of Radiation?

Radiation isn't measured simply by quantity. Instead, it is measured more like sunlight exposure because radiation dose is corresponds to the length and intensity of exposure. In medical imaging, the amount of radiation received depends on such factors as the type of diagnostic test being performed, the size of the patient and the part of the body being examined.

How is Radiation Dose Measured?

For patients, the most important way to measure radiation dose is termed "effective dose." This measures patient risk by assessing the long-term effects of radiation on body organs and tissue. Effective dose is most often expressed in milliSieverts (mSv).

Ionizing radiation is used daily in hospitals and clinics as part of X-ray, nuclear medicine, and computed tomography (CT) diagnostic imaging procedures. These imaging procedures provide important information to your doctor about your health and help ensure that you receive appropriate care. Physicians and technologists performing these procedures are trained to use the minimal amount of radiation necessary. 

What Does Radiation Risk Mean?

Risk level means the approximate lifetime risk of fatal cancer for an adult as the result of radiation exposure. Risk level is further defined as follows:

• Negligible: <1 in 1,000,000
• Minimal: 1 in 1,000,000 to 1 in 100,000
• Very Low: 1 in 100,000 to 1 in 10,000
• Low: 1 in 10,000 to 1 in 1,000
• Moderate: 1 in 1,000 to 1 in 500 

How is Radiation Risk Calculated? 

Radiation risk is calculated by comparing the radiation from a diagnostic test to everyday background radiation we receive from the environment, or by comparing diagnostic radiation to the radiation we receive when flying in a plane.

We are constantly being exposed to natural radiation from the environment and space. For example, you receive the same amount of radiation exposure in a four-hour airplane flight as you receive when a X-ray is taken of your chest. In addition, this is the same amount of radiation you would be exposed to naturally in the environment over a period of 10 days living in the Seattle area or in only four days living in a higher elevation city such as Denver, Colorado. 

Does Radiation Risk Depend on Age?

Children are more susceptible to the effects of radiation because their cells are still growing and developing. However, radiation dose is dependent upon the size of the patient. A greater dose of radiation is needed to penetrate larger amounts of tissue and bone. As a result, for similar imaging procedures a child will usually be exposed to much less radiation than an adult.

How Will I Know How Much Radiation I've Received?

We are committed to helping our patients track their diagnostic radiation exposure. We will track, record, and report radiation dose for each exam, and when this is not possible, we will estimate the radiation dose received based on normal exam levels. This information will be recorded on your imaging examination report and provided to your referring physician. Also, an estimate of the amount of radiation you are expected to receive will be provided to you upon registration.

When considering the very small risk of harm from a medical imaging procedure the first question to ask is this: Will the benefits of the imaging procedure greatly outweigh the risks? The answer is almost always "yes."