erman ▁ther apy ▁continues ▁to ▁be ▁used ▁due ▁to ▁its ▁effic acy ▁and ▁safety ▁profile . ▁Ind ividual ▁institutions ▁have ▁modified ▁the ▁Go e ck erman ▁reg imen ▁and ▁developed ▁their ▁own ▁protocol s . ▁Standard ▁ther apy ▁includes ▁use ▁of ▁ 2 – 4 % ▁cru de ▁coal ▁tar ▁in ▁a ▁pet role um ▁base ▁applied ▁daily ▁to ▁the ▁ps ori atic ▁pla ques . ▁The ▁minimum ▁period ▁of ▁time ▁for ▁tar ▁application ▁is ▁ 2 - h ours , ▁although ▁it ▁has ▁been ▁recognized ▁that ▁greater ▁periods ▁of ▁time ▁produce ▁better ▁results . ▁The ▁patient ▁is ▁then ▁exposed ▁to ▁broad - band ▁ult rav io let ▁B ▁( U VB ) ▁radiation , ▁although ▁narrow - band ▁U VB ▁may ▁also ▁be ▁used . ▁Labor atory ▁studies ▁have ▁shown ▁that ▁the ▁combination ▁of ▁coal ▁tar ▁and ▁U V ▁light ▁reduces ▁e pid erm al ▁DNA ▁synth esis . ▁ ▁Mod ifications ▁ ▁In ▁ 1 9 5 3 , ▁John ▁In gram , ▁an ▁English ▁der mat ologist , ▁added ▁top ical ▁anth ral in ▁paste ▁to ▁his ▁Go e ck erman ▁reg imen . ▁This ▁is ▁known ▁as ▁the ▁In gram ▁method . ▁ ▁Cost ▁Rec ent ▁publications ▁have ▁compared ▁Go e ck erman ▁ther apy ▁with ▁treatment ▁with ▁more ▁expensive ▁bi olog ic ▁agents . ▁Histor ically , ▁Go e ck erman ▁ther apy ▁was ▁performed ▁as ▁an ▁in pat ient ▁treatment . ▁However , ▁today ▁the ▁treatment ▁can ▁be ▁done ▁with ▁reduced ▁cost ▁as ▁an ▁out pat ient