Convert milligray [mGy] to hectogray [hGy] Online | Free radiation-absorbed-dose Converter

Milligray [mGy]: A Common Unit in Radiation Dosimetry

The milligray (mGy) is a unit of absorbed radiation dose equal to 10⁻³ grays (Gy), or one-thousandth of a gray. It is widely used in medical, environmental, and industrial applications where moderate levels of ionizing radiation are involved. In medical imaging, such as X-rays, CT scans, and fluoroscopy, radiation doses are often measured in milligrays. For example, a typical chest X-ray may deliver a dose of around 0.1 mGy, while a CT scan can range from 2 to 20 mGy depending on the body part and procedure. The mGy is also used in radiation therapy planning to define exposure to surrounding healthy tissues that must be minimized. In environmental and occupational safety, monitoring radiation exposure in milligrays helps ensure that workers and the public remain within safe limits set by regulatory bodies. The unit is practical because it provides a manageable scale between very small doses (like microgray) and larger therapeutic doses (measured in grays). Understanding and using the milligray is essential for balancing diagnostic or industrial effectiveness with radiation protection and patient or worker safety.

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.