Is there anything I can do after receiving x-ray scans to prevent possible negative radiation effects?

Other than being in top health with a well functioning immune system prior to exposure, no. However, the cells in your body do not take damage lying down. They get right to work repairing it. There was some interesting research done at MIT a few years ago looking into low dose-rate radiation exposure at around 400 times natural background radiation. https://newsoffice.mit.edu/2012/prolonged-radiation-exposure-0515. Dose rate does have an effect on cell damage and repair, but to help put this into perspective, the radiation dose in this study would average to over a year's worth of natural background radiation in one day. The equivalent number of chest x-rays in one day would be 30. One of the surprising take-aways I had from reading this report was that, on average, each cell repairs 10,000 insults to the DNA per day. The MIT researchers found an increase of about a dozen insults to the DNA per cell, due to the radiation exposure. All of the damage from the radiation appeared to be repaired.  Bottom line - if you undergo a diagnostic imaging procedure, the cells in your body probably have the small amount of damage they sustained repaired by the time you get home and reach for the vitamin bottle.