What does the Collimator Scatter Factor (Sc) quantify?

The Collimator Scatter Factor (Sc) quantifies the influence of head scatter on beam output as the collimator field size increases. It is an important parameter in medical dosimetry because the amount of scatter generated by the treatment head becomes more significant as the field size grows larger. This scattering effect must be accounted for in dose calculations to ensure accurate delivery of radiation therapy to the target area.

When a treatment field is increased, more radiation interacts with the collimator and other components of the beam delivery system, leading to additional scattered radiation that affects the total dose received by the patient. Therefore, Sc is essential for adjusting the output of the linear accelerator based on the dimensions of the treatment field, ultimately impacting the precision of radiation treatments. Understanding Sc helps dosimetrists make informed decisions in treatment planning and assures that patients receive the planned dose delivered accurately to the tumor while minimizing exposure to surrounding healthy tissues.