Isodose curves are normalized at peak depth for what type of treatments?

Isodose curves are normalized at the peak depth, which is fundamentally associated with the concept of isocentric treatment techniques. In the context of treatment planning, the peak depth typically refers to the depth at which the radiation dose is at its maximum, which is particularly relevant in determining the distribution of dose delivered to the tumor and surrounding tissues.

In SSD (Source-to-Surface Distance) type treatments, the depth of the tumor can vary significantly as the source is placed at a fixed distance from the skin surface. Thus, normalizing at the peak depth in SSD treatments helps ensure that the prescribed dose is delivered effectively at the depth of interest, where the maximum dose is needed, making it easier to maintain uniformity in the dose distribution as it allows for less variability in the treatment outcomes.

In contrast, SAD (Source-to-Axis Distance) techniques involve positioning the radiation source and central axis in relation to the isocenter rather than the surface. The normalization process operates under slightly different principles, focusing on delivering dosage optimally at varying depths corresponding to the central axis of the tumor rather than relying on surface measurements.

Normalization at peak depth is crucial for precise dosimetry, ensuring that the treatment plan accurately targets the tumor while minimizing exposure to healthy tissue.