Holmium-161 produced using 11.6 MeV protons: A practical source of narrow-band X-rays

We present a novel technique to produce narrow-band X-rays by preparing 161Ho from the bombardment of dysprosium foil by 11.6 MeV protons. The activated foil produces predominantly 45–55 keV X-rays, which are suitable for activating iodinated radio-sensitizing agents (e.g. IUdR) for oncological therapy. We demonstrate that clinically useful quantities of the nuclide are easily produced with a medical cyclotron which is far from the current state of the art.