Development of 166Ho skin patch to treat skin diseases with 1 MW TRIGA reactor

Abstract

Isotopes from the lanthanide series are suitable for intense localized radiotherapy of tumors and melanomas. [superscript 166]Ho is a promising radioisotope for use in medical radiotherapy due to its relatively short half-life of 26.8 hours and emission of high-energy [beta]-particles. [superscript 166]Ho can be produced in suitable quantities using the USGS 1 MW TRIGA reactor located at the Denver Federal Center. A prototype patch was created by RF sputtering holmium oxide onto Kapton foil. The prototype patch showed that [beta]-particles have good penetration and rapid fall-off in the photographic paper. A few short comings were observed in the prototype holmium radiotherapy patch. The current RF sputtering process is slow and non-uniform. This may be due to using a holmium oxide target instead of a holmium metal target. Delamination was observed in some of the prototype patches. A design that contains the holmium deposition will be necessary. The activity and the presence of contaminants were analyzed using gamma-spectra dominated by an 80.6 keV gamma-ray. Irradiation and measurements of a holmium oxide radiotherapy patch that was sputtered for 1 h at 150 W show an activity of 7.03 [plus-minus sign] 0.35 [mu]Ci. Error is largely due to the error in the calibrated sources as well as inaccuracies from systematic error in the solid angle measurements and statistical error in measuring counts.