Ml. Firouzbakht et al., Cryogenic target design considerations for the production of [F-18]fluoride from enriched [O-18]Carbon dioxide, NUCL MED BI, 26(7), 1999, pp. 749-753
Four cryogenic target designs are described for the production of fluorine-
18 in the chemical form of fluoride using oxygen-18-enriched carbon dioxide
gas utilizing the O-18(p,n)F-18 nuclear reaction. The targets are conical
in shape and made of copper or silver and the carbon dioxide is frozen into
the cone at liquid nitrogen temperatures. Three of the targets (2 copper a
nd 1 silver) have four cooling fins extending radially and are different le
ngths, and one target has only a single heat sink at the rear of the cone.
The targets with four cooling fins could be run with 17.4 MeV protons incid
ent on the target material at a beam current of 25 mu A with no detectable
volatilization of the target material, although yields did decrease slightl
y when compared with lower current runs. The target with the single cooling
block showed volatilization at about 8 mu A. The two copper targets of dif
ferent lengths did not show a difference in the volatilization of the targe
t material at the beam current limit of our cyclotron (25 mu A). The shorte
r target did maintain production with a lower amount of gas frozen into the
target, while the longer target maintained production at higher beam curre
nts. Targets of this type are compatible with low energy, high current acce
lerators because very thin windows may be used. NUCL MED BIOL 26;7:749-753,
1999. (C) 1999 Elsevier Science Inc. All rights reserved.