An analytical equation of electron beams percentage depth ionization curve along the central axis

An analytical equation is proposed in this article. This equation contains four parameters. One of them is the depth of maximum ionization (dm) which can be determined from experiments. The other three parameters can be calculated from the measured percentage depth ionization curve. The values calculated with this equation fit very well with measured data in the buildup region with a difference of 2% or less, and in the falloff region with an error of 2 mm or less in terms of depth. The electron beam energy ranged from 6 to 20 MeV from a Therac 20 Saturne Linear Accelerator. This equation can not be applied beyond the practical range Rp.