Linear energy transfer

The linear energy transfer (LET, English linear energy transfer) is a term used in dosimetry and is a measure of the effect of radiation. He describes how much energy emits an ionizing particle per unit length of the penetrated material and is usually expressed in kilo-electron volts per micrometer. The linear energy transfer is an indirect measure of the number of ionizations per path length and particularly describes the effect of radiation on biological material.

Description

The linear energy transfer is closely related to the stopping power of a material. While the braking capacity describes the total energy loss of the particle per travel distance of the linear energy transfer, the energy that is output by the secondary electrons in the material. In contrast to the stopping power of the considered energy output is limited to the immediate vicinity of the particle track. Therefore, it includes secondary electrons whose energy is greater than a certain value Δ, since a greater energy and a greater range, and thus means a release of energy farther from the original particle track.

The linear energy transfer ( or the bounded linear electronic stopping power ) is therefore defined by

Where the energy loss by collisions with electrons is reduced by the kinetic energies of all secondary electrons with energy greater than Δ. When Δ goes to infinity, then there are no electrons with greater energy, and the linear energy transfer is identical to the linear electronic stopping power.

Based on the density of silicon correspond to an LET of about 100 MeV · cm2/mg a charge of about 1 pC / microns.

Mixed fields

In mixed radiation fields with particles of different kinetic energy and / or mass is considered depending on the problem the dose- weighted mean LET ( engl. dose- averaged LET) or the fluenzgewichteten average LET (English fluence - averaged LET).

In this case, and the energy dose or of Fluenzbeitrag all particles of the strain with the kinetic energy.