I am a 37 yr old male and i suffer constantly from upper & lower back pain and i use ultra sound therapy to recover.

i wish to buy a ultrasound machine and use it myself or take help of others since the cost of treatment outside is exorbitant.

Now is it safe to use ultra sound on the painful part of the body repeatedly
after some gap ?

I have heard its prolonged use damages tissue and has side effects.

Are this findings true ?
if i decide to buy then how long at a stretch i can use it ?
Pl advice me.