Firouzbakht M L, Schlyer D J, Fowler J S
Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
Nucl Med Biol. 1999 Oct;26(7):749-53. doi: 10.1016/s0969-8051(99)00036-0.
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 (18)O(p,n)18F 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 and 1 silver) have four cooling fins extending radially and are different lengths, 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 incident on the target material at a beam current of 25 microA with no detectable volatilization of the target material, although yields did decrease slightly when compared with lower current runs. The target with the single cooling block showed volatilization at about 8 microA. The two copper targets of different lengths did not show a difference in the volatilization of the target material at the beam current limit of our cyclotron (25 microA). The shorter target did maintain production with a lower amount of gas frozen into the target, while the longer target maintained production at higher beam currents. Targets of this type are compatible with low energy, high current accelerators because very thin windows may be used.
本文描述了四种低温靶设计，用于利用富含氧-18的二氧化碳气体，通过(18)O(p,n)18F核反应生产氟化物形式的氟-18。靶呈圆锥形，由铜或银制成，二氧化碳在液氮温度下冻结在圆锥体中。其中三个靶（2个铜靶和1个银靶）有四个径向延伸的散热片，长度不同，另一个靶在圆锥体后部只有一个散热器。带有四个散热片的靶在束流为25微安、17.4兆电子伏质子入射到靶材料上时可以运行，靶材料没有可检测到的挥发，尽管与较低电流运行相比产率确实略有下降。带有单个冷却块的靶在约8微安时出现挥发。在我们回旋加速器的束流极限（25微安）下，两个不同长度的铜靶在靶材料的挥发方面没有差异。较短的靶在冻结到靶中的气体量较少时仍能保持生产，而较长的靶在较高束流下保持生产。这种类型的靶与低能量、高电流加速器兼容，因为可以使用非常薄的窗口。
