The most recent follow up data from the Hiroshima and Nagasaki exposures, now looking at the low dose level exposures, as well as the current data of low dose incorporated radiation follow up (like thorium) can not be explained by the linear non threshold theory of stochastic radiation damage. Other recent scientific results from lab experiments also do not give straight forward, clear cut results on this question.
Thus, calculating cancer deaths from low dose radiation exposure might be an interesting approach for political or tactical reasons, but can not be justified on a scientific basis anymore. In fact, some scientific results even suggest a reduction of cellular effects after low dose radiation exposure.
In one senctence: the question, whether low dose radiation (<100mSv) causes cancer can not seriously be answered at the moment. It might not.
And, homunculus, dose rate is relevant.