Modern Bt Techniques - Florence 2016

Very Low Dose Rate

• Example PCa with 125 I implant: • 150 Gy with initial dose rate of 7 cGy/h • If Tpot = 6 days (better 25days?):

Critical dose =120 Gy reached after 140 days (23.5 times Tpot) when Dose Rate is 1.4 cGy/h Compensation dose to overcome repopulation M = 47 Gy (2 Gy.t/Tpot) Effective dose is 120 - 47= 73 Gy not taking into account variations in RBE due to DRE