DEXA scans are normally read based on calcium as the main bone component. If you have been taking strontium, it will be present in your bones. Since strontium is heavier than calcium, it will change the result of the DEXA scan.
The radiologist interpreting your scan should make an adjustment so you will have an accurate reading. You must let him know your daily dose of strontium and how long you have been taking it.
Has anyone had a DEXA scan since beginning strontium therapy? Did the radiologist make a correction, and, if so, of what magnitude? If he did not correct the score, did he at least make a notation of your strontium dose and duration of treatment on your DEXA scan report?
There is a good article on this subject at www.osteopenia3.com/Strontium-dexa-scan.html. I also have a post about it on my blog at http://strontiumforbones.blogspot.com/.