Radiation for dummies

Meet Helga and Zohar, the dummies destined for a pioneering lunar flyby to help protect space travelers from cosmic rays and energetic solar storms.

Photonic radiation sensors survive huge doses undamaged

Researchers at the National Institute of Standards and Technology (NIST) have published landmark test results that suggest a promising class of sensors can be used in high-radiation environments and to advance important medical, ...

New measurements to guide radiation therapy

When ionizing radiation passes through living tissue, it interacts with molecules present in the cells, stripping away electrons and producing charged species known as ions. Ionizing radiation used for cancer treatment includes ...

Lightning produces afterglow of gamma radiation

Lightning can produce X-rays and gamma radiation. In the past, researchers thought that this phenomenon only lasted for a very short time, about one ten-thousandth of a second. However, the ionizing radiation of lightning ...

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Absorbed dose

Absorbed dose (also known as total ionizing dose, TID) is a measure of the energy deposited in a medium by ionizing radiation. It is equal to the energy deposited per unit mass of medium, and so has the unit J/kg, which is given the special name Gray (Gy).

Note that the absorbed dose is not a good indicator of the likely biological effect. 1 Gy of alpha radiation would be much more biologically damaging than 1 Gy of photon radiation for example. Appropriate weighting factors can be applied reflecting the different relative biological effects to find the equivalent dose.

The risk of stochastic effects due to radiation exposure can be quantified using the effective dose, which is a weighted average of the equivalent dose to each organ depending upon its radiosensitivity.

When ionising radiation is used to treat cancer, the doctor will usually prescribe the radiotherapy treatment in Gy. When risk from ionising radiation is being discussed, a related unit, the sievert is used.

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