What is the common range of accelerator photon beam qualities used in radiation therapy?

The correct range of accelerator photon beam qualities commonly used in radiation therapy is between 6 to 21 MV. This range is significant as it corresponds to the energy levels typically utilized in clinical settings to ensure effective treatment depths and dose distributions for various malignancies.

Photon beams in this energy range can penetrate tissues adequately to target tumors while minimizing exposure to surrounding healthy tissues. Lower energy beams, such as those in the 1 to 5 MV range, are less common for deeper tumors due to their limited penetration capabilities. Higher energy beams, such as 15 to 30 MV or 20 to 40 MV, while available, are specifically employed in certain situations or specialized treatments and are not as frequently used in standard radiation therapy protocols as the 6 to 21 MV range. This makes the 6 to 21 MV category the most prevalent for a variety of radiation therapy treatments.