Convert rad [rd] to hectogray [hGy] Online | Free radiation-absorbed-dose Converter

Rad [rd]: A Legacy Unit of Absorbed Radiation Dose

The rad (short for radiation absorbed dose) is a legacy unit used to measure the amount of ionizing radiation energy absorbed per unit mass of material. It was widely used before the adoption of the gray (Gy) in the International System of Units (SI).

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  1 rad = 0.01 gray (Gy)

  
  
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  This means that 1 rad corresponds to the absorption of 0.01 joules of radiation energy per kilogram of matter.

  
  

The rad was commonly used in medical, industrial, and scientific settings to quantify radiation doses. Although now largely replaced by the gray for consistency and international standardization, the rad is still sometimes referenced in older research, medical records, and certain fields.

The rad and its subunits (like the millirad) helped establish the groundwork for understanding radiation exposure and effects before the transition to the more precise and universally accepted gray unit.

Hectogray [hGy]: Measuring Extremely High Radiation Doses

The hectogray (hGy) is a unit of absorbed radiation dose equal to 100 grays (Gy). Since 1 gray corresponds to the absorption of 1 joule of ionizing radiation energy per kilogram of matter, a hectogray represents an extremely large energy dose—100 joules per kilogram. This unit is far above the levels used in medical or environmental contexts.

In radiation therapy, for example, cancer patients typically receive total doses of 60–70 Gy, delivered in small daily fractions. A dose of 100 Gy (or 1 hGy) to the human body would cause severe, often fatal radiation damage, and is not survivable if delivered systemically. Therefore, the hectogray is not used in clinical medicine.

However, the hectogray may be relevant in specialized industrial applications such as:

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  Radiation sterilization of medical equipment and food, where extremely high doses are used to eliminate all biological contaminants.

  
  
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  Radiation hardness testing of materials and electronics, particularly for aerospace or nuclear environments.

  
  
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  Experimental radiobiology, where specific tissues or small organisms are exposed to very high doses to study extreme effects.

  
  

Although rarely used in everyday practice, the hectogray is an important unit in high-dose radiation science and engineering, where understanding material and biological responses to extreme exposure is critical.