How does diaphragm skin distance affect electron contamination?

The diaphragm skin distance plays a significant role in influencing electron contamination in radiation therapy. As the distance between the diaphragm and the patient's skin increases, the percentage of contaminating electrons reaching the skin decreases. This occurs because electrons have a limited range; when they travel to the skin from a greater diaphragm distance, there is a higher likelihood that they will scatter or lose energy before reaching the target area.

Thus, positioning the diaphragm further away from the skin allows for a more controlled and focused beam of radiation, while minimizing the scatter of unwanted electrons that could contribute to contamination. The increased distance effectively reduces the amount of electron contamination that can impact the treatment area, helping clinicians ensure that healthy tissue is spared while delivering the prescribed dose more precisely to the tumor or target area. This approach is essential in achieving optimal treatment efficacy while minimizing potential side effects on surrounding healthy tissue.