I am not sure that I have answers about how to measure dose at all. I have read much on the topic and there is little that I have found that is really accessible to those that are technically knowledgeable but not experts. What I have learned is that you compute the exposure rate with a detector sensitive to the radiation that you are measuring. Determine the energy per unit of radiation and take the product of exposure and energy per unit of radiation. This energy number is then divided by the amount of mass that absorbed the energy. This is the simple answer. After this there are many assumptions that are made to get an effective dose which is the number that represents the relative health risk. Fortunately beta radiation is limited to direct damage to the skin and doesn't penetrate deeply so the risks are only for skin cancer. I hope that this helps.

Thank you very much