A novel treatment method is disclosed, wherein a patch configured to be placed on a patient's skin is activated, before placement, to deliver localized radiotherapy to a diseased area of the skin. The disclosed devices and methods minimize or prevent collateral damage to the neighboring tissues. In most cases, the disclosed devices and methods include coating a contoured, solid, flexible or conformal substrate with one or more lanthanide elements and then activating (e.g. neutron irradiation) the elements such that its resulting radioisotope emits beta-particles into the diseased skin surface when applied to the patient's skin. Novel processes are described for fabricating and irradiating the lanthanide-based skin patch, for example a holmium-based skin patch.
