3 Gy is nowhere near what could be qualified as a "Low dose".
"A whole-body acute exposure to 5 grays or more of high-energy radiation usually leads to death within 14 days. LD1 is 2.5 Gy, LD50 is 5 Gy and LD99 is 8 Gy.[11] The LD50 dose represents 375 joules for a 75 kg adult. " https://en.wikipedia.org/wiki/Gray_(unit)#Radiation_poisonin...
"A whole-body acute exposure to 5 grays or more of high-energy radiation usually leads to death within 14 days. LD1 is 2.5 Gy, LD50 is 5 Gy and LD99 is 8 Gy.[11] The LD50 dose represents 375 joules for a 75 kg adult. " https://en.wikipedia.org/wiki/Gray_(unit)#Radiation_poisonin...