In Compton scattering, the energy of the back-scattered photon is approximately:

In Compton scattering, the energy of the back-scattered photon can be estimated using the relationship between the energy of the incident photon, the scattering angle, and the properties of the electron it interacts with. When a photon collides with an electron and is back-scattered (scattered at an angle of 180 degrees), it loses a significant amount of energy.

The energy of the back-scattered photon is determined through the Compton formula, which calculates the energy lost by the photon when it interacts with the electron. At a back-scattering angle, the energy of the scattered photon can be estimated to be roughly 0.225 MeV, which corresponds to the correct answer.

This value of approximately 0.225 MeV for the back-scattered photon reflects the balance between the initial energy of the photon and the energy transferred to the electron during the scattering event. Overall, understanding how this relationship works is crucial for medical dosimetry professionals, as it aids in calculating dosages and understanding radiation interactions in tissues.