Minus Related Pages. Units of Measure Most scientists in the international community measure radiation using the System Internationale SI , a uniform system of weights and measures that evolved from the metric system. Measuring Emitted Radiation When the amount of radiation being emitted or given off is discussed, the unit of measure used is the conventional unit Ci or the SI unit Bq.
Measuring Radiation Dose When a person is exposed to radiation, energy is deposited in the tissues of the body. The rem has been replaced by the Sv. One Sv is equal to rem. Abbreviations for Radiation Measurements When the amounts of radiation being measured are less than 1, prefixes are attached to the unit of measure as a type of shorthand.
Abbreviation Example atto- 1 X 10 Abbreviation Example kilo- 1 X 10 3 k kCi mega- 1 X 10 6 1,, M MCi giga- 1 X 10 9 ,, G GBq tera- 1 X 10 12 ,,, T TBq peta- 1 X 10 15 ,,,, P PBq exa- 1 X 10 18 ,,,,, E EBq Common Radiation Exposures People are exposed to radiation daily from different sources, such as naturally occurring radioactive materials in the soil and cosmic rays from outer space of which we receive more when we fly in an airplane. To receive email updates about this page, enter your email address: Email Address.
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Cancel Continue. Manufacturers of imaging technology continue to make improvements towards reducing radiation exposure while maintaining image quality. Note for pediatric patients : Pediatric patients vary in size. Doses given to pediatric patients will vary significantly from those given to adults. Please note that this chart attempts to simplify a very complex topic.
The actual dose can vary substantially, depending on a person's size, the reason for imaging, and differences in imaging practices.
The International Commission on Radiological Protection ICRP Report states: "The use of effective dose for assessing the exposure of patients has severe limitations that must be considered when quantifying medical exposure," and "The assessment and interpretation of effective dose from medical exposure of patients is very problematic when organs and tissues receive only partial exposure or a very heterogeneous exposure which is the case especially with x-ray diagnostics.
It can vary based on a person's height and weight, how the procedure is performed, and the body area being exposed to radiation. The risk associated with medical imaging procedures refers to possible long-term or short-term side effects. Most imaging procedures have a relatively low risk. This means they make every effort to decrease radiation risk.
It is important to remember that a person is at risk if the doctor cannot accurately diagnose an illness or injury.
Therefore, it could be said that the benefit from medical imaging, which is an accurate diagnosis, is greater than the small risk that comes with using it. Talk to your doctor or radiologist about any concerns you may have about the risks of a given procedure. For more discussions about benefit versus risk, see the Benefits and Risks section. The Image Gently Alliance: imagegently. Please type your comment or suggestion into the text box below.
Note: we are unable to answer specific questions or offer individual medical advice or opinions. Some imaging tests and treatments have special pediatric considerations. The teddy bear denotes child-specific content. Please contact your physician with specific medical questions or for a referral to a radiologist or other physician. To locate a medical imaging or radiation oncology provider in your community, you can search the ACR-accredited facilities database.
This website does not provide cost information. The costs for specific medical imaging tests, treatments and procedures may vary by geographic region. Web page review process: This Web page is reviewed regularly by a physician with expertise in the medical area presented and is further reviewed by committees from the Radiological Society of North America RSNA and the American College of Radiology ACR , comprising physicians with expertise in several radiologic areas.
This particular resource used the following sources:. Skip to main content. Nuclear Chemistry. Search for:. Measuring Radiation Exposure. Learning Objective Define the terms used to define radiation exposure, the gray Gy and sievert Sv.
Key Points Radiation dosimetry is the measurement and calculation of the absorbed dose in matter and tissue resulting from exposure to indirect and direct ionizing radiation. Dose is reported in gray Gy for matter or sieverts Sv for biological tissue.
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