Question

Find LET1 keV for 10-MeV protons in (a) soft tissue, (b) bone of density 1.93 g cm–3

Answer 1

The term “linear energy transfer (LET)” is used to indicate the average amount of energy that is lost per unit path-length as a charged particle travels through a given material. The LET for electrons is traditionally expressed in units of MeV/cm, or, when divided by the mass density, in units of MeV-cm^2/g. Values of the LET for electrons have been tabulated for many materials and for a wide range of energies of the incident electrons.

The average amount of energy deposited in a thin sample, per electron, can be estimated by multiplying the LET by the sample thickness, t. Similarly, the total energy deposited per gram of a specimen, following an exposure of N electrons/area, is

E=LET⋅Nρ

where ρ is the mass density of the specimen material.