title: Assessing the performance and longevity of Nb, Pt, Ta, Ti, Zr, and ZrO₂-sputtered Havar foils for the high-power production of reactive [18F]F by proton irradiation of [18O]H2O.
abstract: As water-soluble ionic contaminants, which arise following proton irradiation of [18O]H2O have been associated with decreased [18F]FDG yields, the minimization of these contaminants is an asset in improving the [18F]F reactivity. To this end, we have previously demonstrated that the use of Nb-sputtered Havar foils results in decreased radionuclidic and chemical impurities in proton irradiated [18O]H2O, improved [18F]FDG yields, and improved [18F]FDG yield consistency when compared with non-sputtered Havar. Resulting from the highly reactive chemical microenvironment within the target however, this niobium layer is observed to degrade over time. To find a material that displays increased longevity with regards to maintaining high [18F]F reactivity, this project extensively investigated and compared Havar foils sputtered with Nb, Pt, Ta, Ti, Zr and ZrO₂. Of the materials investigated, the results of this study suggest that Ta-sputtered Havar foil is the preferred choice. For similar integrated currents (~1,000,000 μA min), when comparing the Ta-sputtered Havar with Nb-sputtered Havar we observed: (i) greater than an order of magnitude decrease in radionuclidic impurities, (ii) a 6.4 percent increase (p=0.0025) in the average TracerLab MX [18F]FDG yield, and (iii) an overall improvement in the FDG yield consistency. Excellent performance of the Ta-sputtered foil was maintained throughout its ~1,500,000 μA min lifetime.
authors.affiliation: Department of Physics, University of Alberta, Edmonton, AB, Canada. kgagnon1@ualberta.ca
authors.forename: K
authors.initials: K
authors.lastname: Gagnon
authors.forename: J S
authors.initials: JS
authors.lastname: Wilson
authors.forename: E
authors.initials: E
authors.lastname: Sant
authors.forename: C J
authors.initials: CJ
authors.lastname: Backhouse
authors.forename: S A
authors.initials: SA
authors.lastname: McQuarrie
mesh_terms: D017357:Cyclotrons; D019788:Fluorodeoxyglucose F18 / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification; D008855:Microscopy, Electron, Scanning; D009556:Niobium / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry*; D011522:Protons; D013635:Tantalum / Q000737:chemistry*; D014025:Titanium; D014867:Water; D015040:Zirconium / Q000737:chemistry*
chemical_list: D011522:Protons; D009556:Niobium; D014867:Water; D019788:Fluorodeoxyglucose F18; D010984:Platinum; D013635:Tantalum; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide