18556
A variety of nanostructures including inorganic , organic and lipid nanoparticles have been labeled with positron or gamma emitting radioisotopes through versatile radiochemistry in a number of disease models to track their in vivo fate , image biomarkers , and monitor treatment response .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
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