Inclusion Criteria:  Age less than 22 years Patients with a histologic diagnosis of papillary throid cancer Presence of an neurotrophic tyrosine kinase receptors (NTRK)-fusion, RET-fusion, anaplastic lymphoma kinase (ALK)-fusion, BRAF V600 mutation, BRAF-fusion or other targetable alteration identified in a Clinical Laboratory Improvement Amendments and College of American Pathologists (CLIA/CAP) laboratory Anatomically evaluable disease on chest Computed tomography (CT) (i.e. visible tumor on a chest CT; tumors do not need to be >1 centimeter (cm)  Patients for whom systemic therapy with an oncogene-specific kinase inhibitor is planned either from commercial supply or as part of a separate therapeutic clinical trial/compassionate access protocol/single patient investigational new drug (IND). Such agents include, but are not limited to:  Larotrectinib, entrectinib, selitrectinib, and repotrectinib for NTRK fusions Selpercatinib and pralsetinib for RET fusions Crizotinib, lorlatinib, repotrectinib, and alectinib for ALK fusions Dabrafenib and/or trametinib for BRAF V600 mutations Trametinib and selumetinib for BRAF fusions  Exclusion Criteria:  No prior oncogene-specific targeted therapy allowed. However, patients may enroll within 7 days of starting oncogene-specific therapy if a pre-therapy WBS is available. Prior therapy with non-oncogene specific multi-thyrosine kinase inhibitors (such as sorafenib, lenvatinib, and/or cabozantanib) is allowed. Females who are pregnant or breastfeeding are excluded due to the potential risks of the RAI used in the WBS to the fetus/neonate. Patients who require sedation/general anesthesia to complete a WBS are excluded.