The mean total cumulative dose of NBUVB for achieving clearance was 12.13 4.02 J/cm ( 2 ) in group MN , compared with 34.48 13.13 J/cm ( 2 ) in group N ( P < 0.0001 ) , while the mean total cumulative dose of MTX was 116.04 20.47 mg in group MN compared with 298.63 60.26 mg in group M ( P < 0.0001 ) .