Convert centigray [cGy] to rad [rd] Online | Free radiation-absorbed-dose Converter

Centigray [cGy]: A Practical Unit in Radiation Therapy

The centigray (cGy) is a unit of absorbed radiation dose equal to 0.01 grays (Gy), or one-hundredth of a gray. It is widely used in clinical settings, especially in radiation therapy, where doses need to be both precise and clinically meaningful. One centigray equals 10 milligrays (mGy), making it a convenient unit for prescribing and documenting treatment doses.

In cancer treatment, therapeutic radiation is typically delivered in fractions, with each session often delivering 180–200 cGy (or 1.8–2.0 Gy) to the target area. Using centigrays allows healthcare professionals to express these fractions in whole numbers, simplifying treatment planning and communication. For example, a full course of radiation therapy might involve a total dose of 6000 cGy over several weeks.

Outside of therapy, the cGy is less commonly used, but it remains important in any context where mid-level radiation doses are applied or studied. Its use bridges the gap between small exposures (measured in mGy or µGy) and large, high-dose applications (measured in Gy), making the centigray a key unit in applied radiation science.

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.