# Why do you think isotopes of N are used in medicine as opposed to other elements with stable isotopes like boron, neon or sodium?

Isotopes, ""^15N, ""^13C, are the same chemically as the isotope they replace. They are not the same spectroscopically. Mass spectroscopy would certainly differentiate between the isotopes. In addition, there might be additional spectroscopies that allows the isotope to be interrogated: ""^2H $N M R$ spectroscopy is an example.
The use of ""^10B in drugs that target cancerous tissue allows neutron capture therapy. The idea is that a ""^10B laced drug would label a tumour so that it could be selectively targeted by radiation.