1733 / 1840
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