Which volume does PTV refer to in radiation therapy?

PTV stands for Planning Target Volume in radiation therapy. This term is integral to the process of developing a treatment plan for patients undergoing radiotherapy. The PTV encompasses the clinical target volume (which includes the tumor and surrounding tissues at risk for harboring cancer cells) plus an additional margin that accounts for potential uncertainties in tumor positioning, patient movement, and variations in treatment delivery.

By defining the PTV, radiation oncologists ensure that the prescribed dose of radiation adequately covers the entire area where cancer might be present, while also accounting for any variations that might occur during treatment. This helps in optimizing the treatment plan to effectively target the tumor while minimizing exposure to surrounding healthy tissue, thereby reducing potential side effects.

The other terms mentioned in the options, while related to tumor volume, do not accurately describe the comprehensive scope that PTV embodies. Understanding PTV is crucial for anyone involved in radiation therapy to ensure effective and precise treatment.