Ah OK, Tomotherapy. Yeah, it's basically like a LINAC mating with a CT machine to produce some crazy hybrid idea. My description of the treatment doesn't change too much, though. I don't know what x-ray energies are used in Tomo, but I don't believe it matters because you'll probably get typical energies. If the energies are in the normal range, the maximum amount of energy is delivered at a depth of 1.5 cm to 3.3 cm in human tissue. Anything closer or further than the peak gets less energy, so doctors want the peak to be located where the tumour is. Bone complicates things a bit and change the depth a bit, but regardless, I think most of that radiation will be delivered to your spine from the back. Otherwise, they're delivering the peak energy to an organ in the front, and less to the back, which is where the spine is. The only thing that I don't really understand about spine treatment is how they approach delivering radiation to bone, or how they spare your nerves. They will also wipe out some of your white blood cells, no? I think you're the wrong person for me to ask.
Anyway, it should be no problem compared with MRI, like you said. However, remember not to move during tomo, either. The treatment plans are produced assuming you're in a particular position. Once you move 2 mm, the treatment is off by 2 mm. If you move sliiiightly side to side, I guess it's not a big deal as long as you don't fidget too much. Remember, their treatment plan can't tell them, or you, how much radiation they delivered to the tumour. It can only tell them how much they THINK they delivered if nothing changes. Unfortunately, things change. Lungs move, people fidget, and things go pear-shaped really badly sometimes. Just remember to relax when you're in the machine. You may get strapped down, but think of that as being an advantage for you.