Involved-node radiotherapy (INRT) in patients with early Hodgkin lymphoma: Concepts and guidelines

Background and purpose: To describe new concepts for radiation fields in patients with early stage Hodgkin lymphoma treated with a combined modality. Patients and materials: Patients receiving combined modality therapy with at least 2 or 3 cycles of chemotherapy prior to radiotherapy. Pre- and postchemotherapy cervical and thoracic CT scans are mandatory and should be performed, whenever possible, in the treatment position with the use of image fusion capabilities. A pre-chemotherapy PET scan is strongly recommended to increase the detection of involved lymph nodes. Results: Radiation fields are designed to irradiate the initially involved lymph nodes exclusively and to encompass their initial volume. In some cases, radiation fields are slightly modified to avoid unnecessary irradiation of muscles or organs at risk. Conclusions: The concept of involved-node radiotherapy (INRT) described here is the first attempt to reduce the size of radiation fields compared to the classic involved fields used in adult patients. Proper implementation of INRT requires adequate training and an efficient prospective or early retrospective quality assurance program