PBS-based proton techniques has facilitated treatment of larger fields through gradient junctions. This improves robustness to potential deviations in daily patient set up. Extended field RT for lymphoma (e.g. mantle field, inverted Y) was previously treated using 2D photon techniques. We propose to evaluate use of PBS for EFRT among patients with lymphoma. This case series would study which patients are being selected for treatment, technical considerations with using proton therapy, and comparative dosimetry with proton versus photon techniques for EFRT.