There are many forms of radiation, and many ways in which they damage cells. Moreover which cells get damaged is important, which cells, which organs. The concept and use of REMs is a dangerous oversimplification, imo. I never liked the concept.
In instant case: we have NO experience with the long term biological effect of back-scatter x-rays and also none with devices that use the terahertz radiation. What has been done to calibrate the REM so far is modeling or various sorts.
The REM dosages you read of during an airline flight are not x-rays, they are cosmic rays. The two things do different kinds of damage. In fact the body may be more able to repair the damage from cosmic rays than a REM equivalent of x-rays, or terahertz radiation.
“In fact the body may be more able to repair the damage from cosmic rays than a REM equivalent of x-rays, or terahertz radiation.”
Or both or all may cause hormesis.
For now I’ll go with what the health physics guys say about dose and its measurement, when comparing 15 KeV photons to the flight environment.
I’ve seen some flight spectra, there are loads of photons, from air interaction and also from the mass of the plane. I’m more concerned with the neutron flux (for NSEU, not human effects), though at a bit higher altitude.