Here's the inside of a radiation treatment machine I repaired. It's what I've been doing for the last 30+ years to make a living, but will not be doing any longer. I'm going to be quiting now.
This section of the machine is called the modulator. It stores a lot of energy in a large bank of capacitors which gets discharged into a klystron amplifier tube. The klystron makes microwaves that accelerate electrons into a target to produce the x-rays that are used to treat many types of cancers.