The spectrum of X-ray energies changes as the X-rays pass through tissue due to the energy dependence of the linear attenuation coefficient: this is a phenomenon known as beam hardening. Typical energy distribution of the beam from the X-ray source is shown below. Sketch the energy spectrum after the beam has passed through the body (show both incident and transmitted spectra on the same diagram).

?

Relative number of X-rays 0 30 60 90 120 150 X-ray energy