Adriana, I personally think the bone scan more stressful as it can show even old injuries or arthritis etc and there are many false positives as happened to me recently.
I think they don't do the pet/ct as often because it's far more expensive but in my case my bone scan was followed up with this and was negative. My onc said the pet can show cancer at the molecular level so would be more accurate. I also had two MRI's, one inconclusive and one negative.
I hope this helps a little