In case you are curious, the search was done on the terms "medical isolated" with the word "sexy" excluded (that got rid of a lot of unrelated photos). The search was also filtered to only show images with people age 21 or older of any ethnicity except white/Caucasian (since I figure you already found enough to represent this group).
Yes, I was surprised how many of those came up with my first searches. Those are definitely not what you need for a professional healthcare billboard. There are still close to 3000 images in the search link above, but getting rid of a few words can really help make the results a bit more relevant. I hope you find what you are looking for!
I like the female lab tech... Would like photos showing the faces instead of side views and no faces. We want to appeal to people, so smiles and eyes are helpful. Thank you all for ALL your suggestions!