I don't recall your cancer, but if it's HNSCC, it usually takes 50Gy IMRT or more to kill the cancer. I guess you can have lesser IMRT, in conjunction other boost treatments, like brachytherapy, IORT, but that's radiation too, in a different form, and would add up go even more radiation. They both can be done alone, but more often as a boost.

After 5 weeks, or 25 treatments, IMRT's effectiveness becomes less each day, and that is worked into the treatment plan. so more is not better, and reason why they usually do treatments in 7-8 weeks, 2Gy a day. There are other different radiation treatments using 5, 6 weeks with accelerated radio delivery, other names I forget, that work to counter this decrease in effectiveness, tumor kill in an allotted time.

Side effects also depends on the fractions, usually between 1.8 to 2Gy, higher is usually unacceptable. Also the amount of time for each delivery. There is much more to it than that, and radiation treatment is very complicated to understand, explain, and say the dosimetrist is like the wizard of oz.

Another type, is photon treatment, which I'm not really familiar with to say, but has been mentioned recently on the board. That may be lesser than other radiation modalities.

Good luck.