Calculating Radiation Dose Rate for Ra-223 at Varying Distances

[Dariush]

I just want to know the formula for the following question: If the dose rate from a sample of Ra-223 was found to be 20 mSv per hour at 10 micrometres, calculate the dose rate at 30 micrometres. Show your calculations. Give your answer to one decimal place.

I think it is 20 mSv x 10 micrometres / 30 micrometres, but I am not sure if I have to convert to metres or not (if not I get 6.6).

Thanks in advance! :-)

 

[PSRB191921]

If you are punctual (but at 30 micro meter It is not sure) you must applied an inverse square rule

 

[Dariush]

Ok, I have done the calculation because I think I have to square the numbers, right? And I got 2.2222222?

 

[PSRB191921]

Yes 20/9 but I m sure that you are punctual