What is the rough energy of a 10 MeV electron beam incident on water phantom at a depth of 2 cm?

The energy of an electron beam in a water phantom decreases as it penetrates the tissue due to interactions such as ionization and scattering. For a 10 MeV electron beam, the depth dose characteristic indicates that the energy at a specific depth can be estimated based on the range of electrons in water.

Electrons lose energy rapidly in water, and the percentage of the initial energy remaining at a given depth tends to follow a predictable pattern, typically dropping to about 60-70% at roughly 2 cm depth for a 10 MeV beam. Considering this reduction, calculating the remaining energy could yield approximately 6 MeV at a depth of 2 cm, which corresponds well with empirical data from dosimetry.

This understanding is fundamental in medical dosimetry, where knowing the energy at various depths and how it affects dose distribution is crucial for effective treatment planning. As such, the choice indicating 6 MeV reflects this knowledge of electron beam energy loss in tissue and is consistent with dosimetric principles.