The electron beam flatness is specified for which of the following?

The specification of electron beam flatness encompasses both the central 80% of the field width and the measurements along the X, Y, and diagonal axes. This is essential for ensuring uniform dose distribution across the treatment area, which is critical in radiation therapy.

Flatness refers to the consistency of dose delivered across the radiation field. When assessing electron beam flatness, practitioners evaluate the dose profile to confirm that it remains within specified tolerance levels. The central 80% of the field width is significant because it represents the main area where the radiation dose is intended to be delivered effectively.

Additionally, evaluating flatness along the X, Y, and diagonal axes provides a comprehensive understanding of the uniformity across the entire treatment field. This multidimensional approach ensures that any variations, which could potentially lead to underdosing or overdosing in certain areas, are identified and corrected.

In summary, the correct answer acknowledges the importance of monitoring flatness both across the central field and along multiple axes to achieve optimal safety and effectiveness in radiation treatment planning.