Bragg–Gray cavity theory relates the radiation dose in a cavity volume of material to the dose that would exist in a surrounding medium in the absence of the cavity volume. It was developed in 1936 by British scientists
Louis Harold Gray,
William Henry Bragg, and
William Lawrence Bragg.
Most often, material is assumed to be a gas, however Bragg–Gray cavity theory applies to any cavity volume (gas, liquid, or solid) that meets the following Bragg-Gray conditions.
The dimensions of the cavity containing is small with respect to the range of charged particles striking the cavity so that the cavity does not perturb the charged particle field. That is, the cavity does not change the number, energy, or direction of the charged particles that would exist in in the absence of the cavity.
The absorbed dose in the cavity containing is deposited entirely by charged particles crossing it.
is the ratio of the mass-electronic stopping powers (also known as mass-collision stopping powers) of and averaged over the charged particle fluence crossing the cavity.
In an ionization chamber, the dose to material (typically a gas) is
where
is the ionization per unit volume produced in the (SI unit
Coulomb)
Bragg–Gray cavity theory relates the radiation dose in a cavity volume of material to the dose that would exist in a surrounding medium in the absence of the cavity volume. It was developed in 1936 by British scientists
Louis Harold Gray,
William Henry Bragg, and
William Lawrence Bragg.
Most often, material is assumed to be a gas, however Bragg–Gray cavity theory applies to any cavity volume (gas, liquid, or solid) that meets the following Bragg-Gray conditions.
The dimensions of the cavity containing is small with respect to the range of charged particles striking the cavity so that the cavity does not perturb the charged particle field. That is, the cavity does not change the number, energy, or direction of the charged particles that would exist in in the absence of the cavity.
The absorbed dose in the cavity containing is deposited entirely by charged particles crossing it.
is the ratio of the mass-electronic stopping powers (also known as mass-collision stopping powers) of and averaged over the charged particle fluence crossing the cavity.
In an ionization chamber, the dose to material (typically a gas) is
where
is the ionization per unit volume produced in the (SI unit
Coulomb)