( a ) Strict criteria based on three tests : ( i ) USG negative , ( ii ) no tracer uptake or less than twice the background activity in the thyroid bed on DxWBS and/or up to 0.2 % RAIU , and ( iii ) Tg < 0.2 ng/ml ; ( b ) lax criteria based on three tests : ( i ) USG negative , ( ii ) no tracer uptake or less than twice the background activity in the thyroid bed on DxWBS and/or 0.2 % RAIU , and ( iii ) Tg < 2 ng/ml ; ( c ) strict criteria based on two tests : ( i ) USG negative and ( ii ) Tg < 0.2 ng/ml ; ( d ) lax criteria based on two test : ( i ) USG negative and ( ii ) Tg < 2 ng/ml .
