Emphysema is not a type of cancer; nor is asthma.
Having a bone scan as a result of this diagnosis seems peculiar to me. I can only assume that since the most common cause of both emphysema and lung cancer is smoking, the presence of one (emphysema) might trigger a screening test for the other (metastatic lung cancer).
I would understand it more if you had been scheduled for a CT scan, as this can help determine the extent and severity of the emphysema.
An excellent site about emphysema is given below. Among other things, you can read about the sorts of tests that should be expected.
http://www.mayoclinic.com/invoke.cfm?objectid=C585E4B1-9390-48CE-8A709FFA1BF33DF7&dsection=1
(If that link doesn't work, let me know)