Apr 18 – 23, 2010
Casino Conference Centre
UTC timezone

Isotopic effect observed by distillation of <sup>123</sup>I and <sup>124</sup>I from irradiated <sup>124</sup>TeO<sub>2</sub> target matrix

Apr 20, 2010, 11:45 AM
1h 30m
Gallery (Casino Conference Centre)


Casino Conference Centre

Reitenbergerova 4/95, Marianske Lazne, Czech Republic
Board: PAR.P08
Poster Production and Application of Radionuclides Poster Session - Production and Application of Radionuclides


Mr Jan Ráliš (Nuclear Physics Institute of the ASCR, v.v.i.)


Non-conventional longer-lived PET radionuclides with half-life higher than that of 18F (109 min) are very promising PET tracers for imaging of biochemical processes or body structures requiring slower kinetics. Among them, 124I (4.18 d) plays an important role. Radiochemistry of iodine radioisotopes (123I, 124I, 125I and 131I) is well known. Widely used production process of 124I is based on the (p,n) reaction on highly enriched 124TeO2 (99.4 %), and distillation of iodine from irradiated target matrix at temperatures slightly above the melting point of TeO2 (733 °C). Depending on the entrance beam energy, some amount of 123I can be produced by the (p,2n) reaction (Ethr ≈ 11.5 MeV). For production we have developed our own target system. Target layer is water and helium cooled. The target was irradiated at the beam angle 10° in order to increase effective thickness of the target layer and to get more favourable distribution of the beam over the target area. The entrance proton beam energy varied between 11.5 and 13.2 MeV, beam currents were 10–22 µA and irradiation times 0.5–2 h. The distillation was performed in pre-heated quartz tube (735–750 °C). The radioiodine was carried out with stream of air. The flow rate was set to 25 mL/min. Evaporated iodine was trapped in 0.01M NaOH. Time of separation was 15–20 min. Radionuclidic purity and activity of produced isotopes was measured with γ-ray spectrometry using HPGe detector, in all steps of production (irradiated target, target after distillation and solution of separated product). Since the protons’ entrance energy was higher then treshold of the (p,2n) reaction, we also measured activity of the co-produced 123I. We have observed an interesting effect. The ratio of decay-corrected activities of 123I and 124I in the target matrix after the separation of radioiodine was 2–3 times higher than in the target matrix after irradiation. In accordance to this effect, we also observed that ratio of decay-corrected activities of 123I and 124I in the solution of separated product was proportionally lower than the ratio in target.

Primary author

Mr Jan Ráliš (Nuclear Physics Institute of the ASCR, v.v.i.)


Dr Ondrej Lebeda (Nuclear Physics Institute of the ASCR, v.v.i.)

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