There is no increased mortality in the paper. The paper only looks at risk of death from solid tumors. I'd be surprised if the authors haven't done the calcula

There is no increased mortality in the paper. The paper only looks at risk of death from solid tumors. I'd be surprised if the authors haven't done the calculation of total mortality and decided that there is no discernible radiation dose-dependent effect on total mortality or total QALY. In a better world, that would also be a very good paper, but it isn't in ours. That's why they are looking for solid tumor mortality.