In EDX you are interested in the atomic percent of the elements in the compound.The response in EDX is proportional to atomic concentration of the element in the compound. and can be calibrated to measure it.
To get the atomic percent you need only to apply the conversion procedure:
the doping in gram moles mdm= the mass of the dopant md divided by the atomic weight of the dopant,
Then the semiconductor in gram moles msm= The mass of the semiconductor ms/ its atomic weight. Here it is assumed elementary material.
Then you can calculate the atomic percent by calculating the ratio mdm/msm and multiplying it by 100.
For more details please see the Electron Microscopy Advanced Techniques at the link