THE PROBLEM:

Delivery of radiation or pharmacological therapy via implants requires precisely reproducible manufacturing. But unexplained performance differences do occur. The addition of a radioactive element to the surface of metal pellets intended for implantation had become highly variable—some took the intended dose but others were either much higher or lower.

THE ANALYSES:

Nothing in the process was known to have changed, but very high magnification of the surface of the wire substrates by field emission scanning electron microscopy (FESEM) showed very different surface structures, and therefore surface areas available to the isotope.

THE OUTCOME:

Thorough microanalysis allowed the differences to be tracked back to a change in the electropolishing process at a supplier.