PTK7 and neoplasm: A strong and significant correlation was observed between PTK7 antigen density and surface-bound atoms (r = 0.953, p = 0.0474), indicating that cell surface binding scales with antigen levels. A strong inverse and significant correlation was found between surface-bound atoms and administered activity (r = − 0.960, p = 0.0399), suggesting that greater radioligand binding reduces the required activity for tumor uptake. Internalized atoms showed moderate correlations with both antigen expression (r = 0.508) and bound atoms (r = 0.588), but these were not statistically significant.