What is radiation dose? Radiation dose is a measure of the energy deposited in a medium (i.e. tissue) by ionizing radiation per unit mass. The equivalent radiation dose often in units of rems or sieverts accounts for the different biological damage potential of different types of ionizing radiation on different organs.
Small amounts of radioactive materials can be found in our bodies, in products we use daily, in the ground, in building materials, and in outer space. They are a natural part of our everyday life. We commonly find radiation devices such as x-ray machines in a hospital or at the airport. We use radiation mainly for its beneficial purposes such as in medicine to diagnose disease, in industry to generate electricity, and in smoke detectors to make our homes safer. Radiation dose equivalent is measured in millirem (mrem). The average dose per person in the US from all sources (excluding occupational doses) is approximately 620 mrem per year. For those who work with and around radioactive material or x-rays, the national regulations allow doses as much as 5,000 mrem per year from occupational exposures.
| Common Sources of Radiation | Est. annual dose |
| Where you live | |
| Cosmic → at sea level | 26 mrem |
| Terrestrial → States that border the Gulf or Atlantic coast | 16 mrem |
| Terrestrial → Colorado Plateau area | 63 mrem |
| Terrestrial → Elsewhere in the continental US | 30 mrem |
| Live within 50 miles of a nuclear power plant | 0.01 mrem |
| Live within 50 miles of a coal-fired power plant | 0.03 mrem |
| Consumer Products and Air Travel | |
| Jet plane travel hours: (in air) | 0.5 mrem/hr |
| X-ray inspection at the airport | 0.002 mrem |
| View a TV or computer screen which uses CRT technology |
1 mrem |
| Smoke 1/2 pack of cigarettes every day of the year | 18 mrem |
|
Medical Diagnostic Test |
|
| X-Ray - Dental Bitewing/Image | 0.5 mrem |
| X-Ray - Extremity (hand/foot) | 0.5 mrem |
| X-Ray – Chest or Skull | 10 mrem |
| X-Ray - Mammogram | 42 mrem |
| CT Scans - Head | 200 mrem |
| CT Scans - Chest |
700 mrem |
| CT Scans - Angiography (head) | 500 mrem |
|
At UTHSC-H |
|
| Typical occupational doses are less than 50 mrem annually | 50 mrem |
For more information about estimating your various sources, see the American Nuclear Society’s Radiation Dose Chart at http://www.new.ans.org/pi/resources/dosechart/. For answers to questions about radiation and you, see the Health Physic Society’s radiation answers website http://www.radiationanswers.org/ or their Ask the Experts section at http://hps.org/publicinformation/ate/. For information on how to request a radiation dosimeter or to request your radiation dose record if you already have a radiation dosimeter, call the Radiation Safety Program of Environmental Health & Safety at 713-500-5840.