No, a dowel rod won't work.
I use fractional & letter drill bit sets.
Try bits until you find the correct size to just slip fit in the tube. Then lay the tube on a steel block or smooth anvil.
Using a small smooth-face hammer, tappy, tap, tap the dents out using the smooth drill shank as inside support.
Once you have all the dents peened smooth, roll the tube on a flat surface to see if it is straight. If not straighten it further.
Finally, use a flap of 400 grit emery paper in a slotted dowel rod or cleaning rod and a drill to polish the inside of the tube.
rc
