Convert gray [Gy] to millirad [mrd] Online | Free radiation-absorbed-dose Converter

Gray [Gy]: The Standard Unit of Absorbed Radiation Dose

The gray (Gy) is the International System of Units (SI) measurement for absorbed radiation dose, defined as the absorption of one joule of ionizing radiation energy per kilogram of matter. It quantifies how much energy from radiation is deposited in a given mass, typically biological tissue or materials. The gray is widely used in medicine, radiation protection, and scientific research.

In clinical settings, the gray is essential for measuring and controlling doses in radiation therapy for cancer, where precise amounts of radiation are delivered to destroy tumor cells while minimizing damage to healthy tissue. For example, a typical therapeutic dose might be in the range of 1–2 Gy per treatment session.

Beyond medicine, the gray is also used in radiation safety to assess exposure levels, in nuclear industry applications, and in research involving radiation effects on materials.

The gray replaced the older unit “rad” (where 1 Gy = 100 rad) and provides a universal, standardized way to quantify radiation energy absorption, allowing for consistency across disciplines and countries. It is fundamental to understanding radiation interactions and their biological or physical consequences.

Millirad [mrd]: A Subunit of Radiation Absorbed Dose

The millirad (mrd) is a unit of absorbed radiation dose equal to one-thousandth of a rad. The rad (radiation absorbed dose) is an older, non-SI unit that was commonly used before the gray (Gy) became the standard.

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  1 rad = 0.01 gray (Gy)

  
  
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  Therefore, 1 millirad = 0.001 rad = 0.00001 Gy (10⁻⁵ Gy)

  
  

The millirad was used to measure the amount of energy absorbed from ionizing radiation per unit mass, primarily in radiation protection and medical contexts.

Though the rad and its subunits like the millirad have largely been replaced by the gray and its subunits (milligray, microgray, etc.), they may still be encountered in older literature or certain regions.

In summary, the millirad is a very small dose unit equal to one-thousandth of a rad, useful historically for quantifying low-level radiation exposures before the universal adoption of the gray.