How to Calculate the Source Activity from Dose Rate in MCBEND

[gxa]

Hello everyone,
In the MCBEND simulation I've conducted, I have found the dose rate of a gamma source in microSieverts per hour (µSv/h). I also know the distance between the detector and the source. How can I calculate the source activity or strength from this information?
Thank you,
Best wishes

 

[gleem]

You need at least the specific gamma-ray constant for the source.

 

[Vanadium 50]

I have never heard of MCBEND but cannot see how it can calculate without the size, shape and orientation of the detector.