What does the Scatter Air Ratio (SAR) measure?

The Scatter Air Ratio (SAR) specifically measures the contribution from scattered radiation to the overall dose delivered to a point in a medium, usually air. It quantifies how much of the dose at a particular measurement point is due to radiation scattered from surrounding structures rather than from the primary beam itself. This is crucial in radiotherapy and dosimetry because it helps in understanding and calculating how much of the radiation dose reaching a tumor or nearby healthy tissue is due to scattered photons, thus allowing for more accurate treatment planning and dose distribution assessments.

Understanding SAR is vital for medical dosimetrists as it directly impacts the effectiveness of radiation treatment while minimizing adverse effects on healthy tissue. By being able to account for scattered radiation, dosimetrists can ensure more precise targeting of tumor tissues while protecting surrounding healthy tissues from unnecessary radiation exposure.