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Rad Conversion Table
This comprehensive rad conversion table shows how various units relate to rad, a unit of absorbed radiation dose. Use this reference for quick conversions between rad and other radiation dose units.
| Conversion | To Unit | Multiplier |
|---|---|---|
| Rad to gray | Gray | 0.01 |
This rad conversion reference table provides accurate conversion factors for radiation dose units. All values are based on internationally recognized standards for maximum precision in scientific and medical applications.
What is a Rad?
The rad (radiation absorbed dose) is a unit of absorbed radiation dose, defined as 0.01 gray (Gy) or 0.01 joules of energy deposited per kilogram of matter. It was originally defined in CGS units as 100 ergs per gram. The rad is still widely used in the United States for radiation safety and medical applications, despite the gray being the SI unit.
Our rad conversion tool helps you easily convert between rad and other radiation dose units. For example, 100 rad equals 1 gray, which is the SI unit for absorbed radiation dose.
What is the SI Unit for Radiation Dose?
The gray (Gy) is the SI unit for absorbed radiation dose, defined as one joule of energy absorbed per kilogram of matter. The rad is a non-SI unit that is still commonly used in the United States:
- 1 rad = 0.01 gray
- 1 gray = 100 rad
What are Rads Used For?
Rads are used in a wide range of applications in medicine, research, and radiation protection:
Medical Radiation Therapy
Radiation doses for cancer treatment are often specified in rads or grays. For example, a typical radiation therapy session might deliver 180-200 rads (1.8-2.0 Gy) to a tumor.
Radiation Safety
Occupational exposure limits for radiation workers in the US are often expressed in rads. For example, the annual whole-body dose limit is 5,000 millirads (5 rad or 0.05 Gy).
Medical Imaging
Radiation doses from diagnostic imaging procedures like X-rays and CT scans are sometimes reported in rads. For example, a chest X-ray typically delivers about 0.1 millirad (0.0001 rad or 1 µGy) to the chest.
Research Applications
Scientific studies involving radiation exposure often use rads to quantify absorbed doses in experimental subjects or materials. For example, research on radiation effects might use doses ranging from 100 rads (1 Gy) to 10,000 rads (100 Gy).
Etymology and History
The term "rad" is an acronym for "radiation absorbed dose." It was introduced in the 1950s as part of the CGS (centimeter-gram-second) system of units. The rad was defined as the absorption of 100 ergs of energy per gram of matter.
With the adoption of the International System of Units (SI) in the 1970s, the gray (Gy) became the official SI unit for absorbed radiation dose, defined as one joule per kilogram. However, the rad remains in common use in the United States, particularly in medicine and radiation protection.
Frequently Asked Questions
What is the difference between rad and gray?
The rad and gray are both units of absorbed radiation dose, but the gray is the SI unit. One gray equals 100 rad. The gray is defined as one joule of energy absorbed per kilogram of matter, while the rad was historically defined as 100 ergs per gram.
Why is rad still used in the US?
Despite the gray being the official SI unit, the rad remains widely used in the United States in medical and radiation protection contexts due to historical precedent and familiarity. Many regulations, equipment specifications, and professional practices in the US continue to reference rads.
How do I convert rad to gray?
To convert rad to gray, divide by 100. For example, 500 rad equals 5 gray. Our rad conversion calculator above makes this easy - just enter your value and select gray as the target unit.
What are typical radiation doses in rads?
Common radiation doses in rads include: a chest X-ray (0.0001 rad), a dental X-ray (0.005 rad), a CT scan (1-10 rad), natural background radiation per year (0.2-0.3 rad), and radiation therapy sessions (180-200 rad).
Is rad a measure of radiation exposure or absorption?
The rad measures absorbed dose, which is the amount of energy deposited in matter by ionizing radiation. It specifically quantifies the energy absorbed per unit mass of material, making it a measure of the biological effect of radiation rather than just exposure.
How accurate are rad conversions?
Rad conversions to other radiation dose units like gray are highly accurate since they use the defined relationship (1 Gy = 100 rad). Our conversion tool provides precise results suitable for scientific, medical, and safety applications.