title: Cyclotron production of (99m)Tc: experimental measurement of the (100)Mo(p,x)(99)Mo, (99m)Tc and (99g)Tc excitation functions from 8 to 18 MeV.
abstract: BACKGROUND
  The cyclotron-based (100)Mo(p,2n)(99m)Tc transformation has been proposed as a viable alternative to the reactor based (235)U(n,f)(99)Mo→(99m)Tc strategy for production of (99m)Tc. Despite efforts to theoretically model the amount of ground-state (99g)Tc present at end of bombardment for the (p,2n) reaction, experimental validation has yet to be performed. The co-production of (99g)Tc may have important implications in both the subsequent radiopharmaceutical chemistry and patient dosimetry upon injection.
  
  
  METHODS
  To determine the extent of (99g)Tc co-production, we have experimentally measured the (100)Mo(p,x)(99)Mo, (99m)Tc, and (99g)Tc excitation functions in the 8-18 MeV range using a combination of natural abundance and 97.42% enriched (100)Mo foils along with γ-ray spectrometry and ICP-MS. Although the excitation functions for production of (99)Mo and (99m)Tc have been presented previously in the literature, to the best of our knowledge, this work presents the first experimental evaluation of the (100)Mo(p,2n)(99g)Tc excitation function.
  
  
  RESULTS
  From the experimental cross-section measurements, the (99m)Tc production yields and (99m)Tc/(99m+g)Tc nuclei ratio were calculated for various thick target irradiation conditions. Results suggest that TBq quantities of (99m)Tc can be achieved with a (99m)Tc/(99m+g)Tc nuclei ratio that is on par with the current (99)Mo/(99m)Tc generator standard eluted at a 24-h frequency.
  
  
  CONCLUSIONS
  These findings suggest that the cyclotron production of (99m)Tc may be a feasible alternative to the current reactor-based production strategy.
authors.affiliation: Edmonton PET Centre, Cross Cancer Institute, University of Alberta, Edmonton, AB, Canada. kgagnon1@ualberta.ca
authors.forename: Katherine
authors.initials: K
authors.lastname: Gagnon
authors.forename: François
authors.initials: F
authors.lastname: Bénard
authors.forename: Michael
authors.initials: M
authors.lastname: Kovacs
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Ruth
authors.forename: Paul
authors.initials: P
authors.lastname: Schaffer
authors.forename: John S
authors.initials: JS
authors.lastname: Wilson
authors.forename: Steve A
authors.initials: SA
authors.lastname: McQuarrie
mesh_terms: D017357:Cyclotrons; D008982:Molybdenum / Q000737:chemistry* / Q000302:isolation & purification; D011854:Radiochemistry / Q000295:instrumentation*; D011868:Radioisotopes / Q000737:chemistry* / Q000302:isolation & purification; D013667:Technetium / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D011868:Radioisotopes; D013667:Technetium; D008982:Molybdenum