¹¹C-methane production in small volume, high pressure gas targets

Abstract

The parameters affecting the production of

Production of [15O]water at low-energy proton cyclotrons

“…These effects can produce variations in chemical saturation yield dependant on target-gas composition, irradiation current density, and/or irradiation time. Buckley et al (2000 and2004) have studied the production of or beam current (from 5µA to 40 µA). This suggests that oxygen isotopes are being radiolytically processed to H 2 O and not chemically bonding to the chamber walls.…”

“…The Considerable amounts of ammonia are radiolytically produced in the target (Buckley et al, 2000), and this will raise the pH of the radiotracer solution unless separated (Ferrieri et al, 1994). With our system, the ammonia is separated by the cold trap, and no increase in pH was detected even from ten consecutive batches of radiolabeled water trapped in 20 mL of saline.…”

“…[ 15 O]H 2 O can also be produced directly in the target by adding about 5% hydrogen to the nitrogen target gas (Ferrieri and Wolf, 1983;Ferrieri et al, 1994). This route has the advantage of high specific activity due to the lack of added oxygen carrier material, but a disadvantage is that large amounts of ammonia are radiolytically produced (Buckley et al, 2000).…”

Fully automated and reproducible radiosynthesis of high specific activity [11C]raclopride and [11C]Pittsburgh compound-B using the combination of two commercial synthesizers

“…Production of [ 11 C]methyl iodide [ 11 C]Methyl iodide can be produced following two different 11 C-labeling strategies: the historically named wet' method [14] and the 'gas phase' method, in which [ 11 C]CH 4 (produced either by reduction of cyclotrongenerated [ 11 C]CO 2 or by direct irradiation of N 2 /H 2 gas mixtures with high-energy protons [15,16]) is converted into [ 11 C]CH 3 I by free radical iodination vapor at a high temperature in the gas phase [17,18]. The 'gas phase' method usually provides lower radiochemical yields but higher specific activities, especially when [ 11 C]CH 4 is directly generated in the cyclotron [19,20].…”

Efficient in‐loop synthesis of high specific radioactivity [11C]carfentanil

“…An improvement of specific radioactivity was achieved by using [ 11 C]CH 4 (rather than [ 11 C]CO 2 ) generated in the target as the source of carbon-11 for the synthesis of [ 11 C]CH 3 I. 7 We also report an improved procedure for the synthesis of the precursor to [ 11 C]carfentanil.…”