The use of a high energy X-ray generator for Total Ionizing Dose testing is studied on MOS capacitors. Several conditions were studied for the high energy X-ray irradiations (with aluminum and lead filters) and the experimental results are compared to Co-60 irradiations. The effects of both annealing and package lid are also studied. All the results are presented and discussed. It is shown that the simple BEOL stack (only one thin aluminum layer) has no effect on dose deposition in the oxide of MOS capacitors.