Lymphomas
For some hematologic malignancies, particularly Hodgkin lymphoma, larger radiation therapy (RT) fields were the historical norm. Advances in systemic therapy, imaging, and RT techniques have prompted an evolution in RT field design. In the context of more accurate imaging and multi-modality therapy, a more conformal treatment may achieve a superior therapeutic index due to less normal tissue in the treatment field. However, more conformal fields also require accurate target definition and advanced treatment delivery systems to avoid a geographical miss. In place of osseous anatomy defining radiation fields, target volumes are now defined by cross-sectional imaging. In many cases, target delineation is influenced by in vivo response to systemic therapy. Irradiation of critical normal structures in close proximity to RT targets can lead to significant morbidity and mortality. Advanced RT delivery systems are now equipped with several technologies to minimize the exposure of normal tissues. These include intensity-modulated radiation therapy, image-guided radiation therapy, and respiratory motion management. Within this chapter, the delineation of RT targets in patients with both Hodgkin and non-Hodgkin lymphoma is discussed, including strategies to minimize normal tissue injury.
