Extended SSDs are primarily used for which of the following treatments?

Extended Source-to-Skin Distances (SSD) are particularly beneficial in the context of Total Body Irradiation (TBI). This technique is commonly utilized for preparing patients for bone marrow transplants or treating certain hematological malignancies. The use of extended SSD allows for a more uniform dose distribution across the entire body while minimizing hotspots and reducing the dose to critical structures, which is essential when treating large areas of the body.

In the case of Total Body Irradiation, achieving a homogenous dose delivery across a large treatment volume is crucial. By increasing the SSD, the radiation beams can cover a broader area with reduced intensity at the surface, which is advantageous when aiming to irradiate the entire body without excessively damaging skin and superficial tissues.

Other treatment types, such as partial breast irradiation and superficial lesions, typically utilize different techniques and parameters. These treatments are more localized and do not require the same extended distances that TBI does. Localized prostate treatments use precise techniques that primarily focus on the prostate region, where extended SSDs are not necessary for effective delivery. Thus, Total Body Irradiation is the most appropriate treatment associated with extended SSDs due to the special considerations in dose distribution for the entire body.