In this study, we included 341 patients who had undergone surgery (near total/total thyroidectomy) for WDTC (papillary and follicular cancer thyroid) and were referred to the Nuclear medicine unit for 131I ablation of the residual functioning thyroid tissue. The patients were collected from nuclear medicine units at Kasr Al aini Hospital (NEMROK) and National Cancer Institute. They were classified into 2 major groups: Group 1: patients who received ablative dose after performing diagnostic whole body scan (183 patients).Group 2: patients who received directly ablative dose without diagnostic whole body scan (153 patients).