SPECT/CT-guided elective nodal irradiation for head and neck cancer: Estimation of clinical benefits using NTCP models.

•Lymph drainage mapping can guide elective nodal irradiation in H&N cancer.•This greatly reduces mean irradiation dose to various contralateral organs at risk.•Likely, this significantly decreases several important radiation-related toxicities.•Patients without contralateral lymph drainage profit more than those with it.•Oropharyngeal and oral cavity cancer patients profit more than those with other primaries.