How should the PTV - CTV margin be set for optimal patient treatment?

Setting the PTV-CTV (Planning Target Volume - Clinical Target Volume) margin involves balancing the need for adequate coverage of the tumor while minimizing dose to surrounding healthy tissues. An optimal PTV-CTV margin should not be established too liberally, which could lead to unnecessary exposure of healthy tissues and increase the risk of side effects. Conversely, a conservative margin may lead to underdosing the target and potentially leaving cancer cells untreated.

The intended approach is to find a balance—neither too liberal nor too conservative. This ensures that the entire Clinical Target Volume receives the prescribed dose while keeping within acceptable limits for adjacent healthy structures. This approach allows for a more personalized treatment plan based on the specifics of the tumor, its location, and the patient's anatomy and movement patterns. Proper margin settings contribute significantly to the effectiveness of radiotherapy while maintaining patient safety and quality of life.