Convert petagray [PGy] to millirad [mrd] Online | Free radiation-absorbed-dose Converter

Petagray [PGy]: An Unimaginably High Radiation Dose

The petagray (PGy) is a unit of absorbed radiation dose equal to 1,000 trillion grays (10¹⁵ Gy)—that’s one quadrillion grays. This is an extraordinarily vast amount of radiation energy absorbed per kilogram of matter, far beyond any natural or engineered radiation exposure known to humanity.

The petagray is purely theoretical and only relevant in extreme astrophysical phenomena or fundamental physics simulations, such as:

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  Modeling the intense radiation environments near supermassive black holes or during the most energetic cosmic events.

  
  
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  Exploring theoretical limits of matter-radiation interactions at cosmic or quantum scales.

  
  
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  Simulating conditions immediately following high-energy particle collisions or gamma-ray bursts.

  
  

At doses this high, all conventional matter would be utterly destroyed or transformed, and the concept of dose loses practical meaning.

The petagray highlights the vast scope of radiation measurement, showing how the gray unit can be scaled to express energy absorption at levels far beyond any earthly or practical scenario, emphasizing its role as a universal scientific measure across all scales.

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Though the rad and its subunits like the millirad have largely been replaced by the gray and its subunits (milligray, microgray, etc.), they may still be encountered in older literature or certain regions.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