re: Full body cancer scans

The main obstacle you'll run into with anything that involves radiation is "Does this person have a medical need that justifies exposing them to radiation, (which is itself a risk factor for cancer)?" That's the question you and your doctor should be asking in my opinion.

Is it a waste of money or a good investment?

Valid question, but not the most important one. You need a professional to help you break down the risk/reward here.

Based on what you've said about family history and your current exposure risk to carcinogens at work, I'd think you could make a good case for yourself, BUT....be prepared to hear no. I could imagine your doctor saying no, and telling you that unless there are symptoms present that you would just be getting this scan to soothe your anxiety, and it's not worth the risk from radiation exposure for just that.

Also, what if the scan shows something? You ready to deal with that? This is why I hope for you that you have someone you know and trust well who has the expertise to talk this through with you.

I'd write down all the family members that had cancer, what kind of cancer, at what age were they diagnosed, what treatment did they receive, and what was the outcome. Try and compare yourself now to them. What age are you? Did they have similar risk factors to you?(work in a plant). To me, it's a lot of questions and thinking and ultimately you have to decide. I know you could just pay out of pocket and go do it, but if you haven't already thought about this a great deal I hope you do. A full body CT scan is a big dose of radiation.