Absorbed Dose
Convert between different units of absorbed radiation dose used in medical physics, nuclear safety, and radiation protection
Absorbed Dose Converter
Convert between different units of absorbed radiation dose used in medical physics, nuclear safety, and radiation protection
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About Absorbed Dose
Explore absorbed dose units from medical physics, nuclear safety, and radiation protection
Historical Context
The concept of absorbed dose emerged in the early 20th century as scientists began to understand the energy deposition of ionizing radiation in matter. Following the discovery of X-rays by Wilhelm Röntgen in 1895 and radioactivity by Henri Becquerel in 1896, researchers needed ways to quantify radiation exposure. The rad (radiation absorbed dose) was introduced in the 1950s as a unit to measure energy absorption in tissue. One rad represents 100 ergs of energy absorbed per gram of matter. As the International System of Units (SI) was developed, the gray (Gy) was introduced in 1975, named after British physicist Louis Harold Gray, a pioneer in radiation biology. One gray represents one joule of energy absorbed per kilogram of matter.
Modern Standards
Today, the gray (Gy) is the standard SI unit for absorbed dose, representing one joule of radiation energy absorbed per kilogram of matter. While the scientific and international communities have widely adopted the gray, the traditional unit rad (radiation absorbed dose) remains in common use in the United States, particularly in the nuclear industry and medical fields. The conversion between these units is straightforward: 1 Gy equals 100 rad. In radiation therapy for cancer treatment, absorbed doses are typically specified in gray, with treatments often delivering 20-80 Gy to tumors over multiple sessions. For radiation protection and safety monitoring, smaller units like milligray (mGy) are commonly used, especially in diagnostic radiology where a typical chest X-ray delivers about 0.1 mGy.
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Conversion Reference
Quick reference for common absorbed dose conversions