Percent Depth Dose (PDD) is normalized at what location for the SSD technique?

Percent Depth Dose (PDD) is a critical concept in radiation therapy that helps in understanding how the dose of radiation decreases with depth in tissue. When using the Source-to-Surface Distance (SSD) technique, PDD is normalized at the depth of maximum dose, known as D-Max.

At this specific depth, the dose delivered is at its peak due to the buildup effect, where secondary electrons produced by the radiation contribute to the dose deposited in the tissue. This normalization point is essential for calculating how much dose will be available at various depths, providing a comprehensive view of how the radiation dose behaves throughout the treatment area.

Normalizing PDD at D-Max allows clinicians to accurately determine the required dose at deeper tissue levels based on surface dose measurements, ensuring effective treatment planning. Understanding PDD and its relation to depth is crucial for dosimetrists to optimize radiation delivery for patient safety and treatment efficacy.