Which method can be used to check the symmetry and flatness of the clinical photon beam?

To evaluate the symmetry and flatness of a clinical photon beam, both film and a beam profiler can be employed effectively.

Using film involves placing a radiation-sensitive film in the beam's path and exposing it to radiation. The developed film provides a visual representation of the dose distribution across the beam, highlighting any areas of asymmetry and variability in flatness.

On the other hand, a beam profiler utilizes electronic measurements to assess the beam's profile. It provides immediate feedback on beam characteristics, including symmetry and flatness, through data that can be analyzed in real-time.

Both methods are valid and widely accepted practices in the field of medical dosimetry for ensuring that treatment beams are delivering uniform and precise dosages to patients. This dual capability underscores the importance of having multiple means of verifying beam quality to maintain safety and efficacy in radiation therapy.