The other day I was doing some routine testing on one of the pediatric portable x-ray units (a Siemens Mobilette Hybrid XP). When I looked at the kV and radiation output wave form, I saw this odd stepping behaviour (radiation output wave form is the green line).
Normally I expect to see a pretty flat curve, maybe a little bit of a decline depending on the type of generator. While I don't know the particulars about the Mobilette's generator, I'm thinking at least part of it is a capacitive discharge type generator, which would explain the drops. I'm going to have to investigate this a little more to see if it's normal.