The most common option of radiotherapy for patients with limited-stage DLBCL is involved-field radiotherapy (IFRT). The more limited radiotherapy field size changing from IFRT to reasonable margin from gross tumor has been reported to maintain the high rates of local disease control, while minimizing the risks of radiation-induced toxicities. However, the research didn't analyze whether the efficacy of consolidation involved-site radiotherapy (ISRT) be affected by the response of chemotherapy. The biologic definition of clinical target volume (CTV) of ISRT and actual radiotherapy field size need to be ascertained.