Improved small scale production of iodine-124 for radiolabeling and clinical applications.

AIM: This work describes a small-scale production of iodine-124 using a 16.5 MeV cyclotron, and a subsequent validation of the formulated sodium [124I]iodide solution for routinely clinical applications. METHODS: Iodine-124 (124I) was produced via the 124Te(p, n)124I reaction using a 16.5 MeV GE PETtrace® cyclotron. Irradiation was performed with a pre-prepared solid target consisting of [124Te]TeO2 (99.93%) and Al2O3. Different layer thicknesses, irradiation and extraction parameters were tested. After irradiation at the cyclotron, the shuttle with irradiated material was transferred fully automatically via a tube system to the Comecer ALCEO® Halogen 2.0 extraction unit. Iodine-124 was subsequently extracted in form of sodium [124I]iodide ([124I]NaI) in 0.05 N aqueous NaOH solution, followed by reconstitution and validation for preclinical and clinical uses. RESULTS: Good result was achieved using a beam degradation foil of 500 µm thickness in combination with beam currents between 10 and 15 µA. Under these conditions, up to 150 MBq no-carrier-added [124I]NaI was obtained after a 2 h irradiation time in less than 500 µl 0.05 N NaOH. Isolation of [124I]NaI, including evaporation and extraction at the ALCEO® Halogen EVP unit was accomplished in 90 min 24 h after production (irradiation), the amount of iodine-123 as assessed by gamma-ray spectroscopy was less than 1.5%. The undesirable iodine-125 was not detectable by gamma spectroscopy. The extracted [124I]NaI could be used directly for radiolabeling purposes, and after buffering with phosphate buffered saline (PBS) and sterile filtration for clinical applications. CONCLUSIONS: Through the optimized conditions for irradiation and extraction, iodine-124 was produced in good radiochemical yields and high radionuclide purity. The generated injectable [124I]NaI solution was sterile, non-pyrogenic and ready for preclinical and clinical applications after a sterile filtration through a 0.22 µm membrane filter.

Multi-group approximation, scattering and calibration coefficients, uncertainty estimates and detection limits of a NaI(Tl)-based gamma spectrometry set-up for low-level activity analysis.

This paper describes a quantitative radioactivity analysis method especially suitable for environmental samples with low-level activity. The method, consisting of a multi-group approximation based on total absorption and Compton spectra of gamma rays, is coherently formalized and a computer algorithm thereof designed to analyze low-level activity NaI(Tl) gamma ray spectra of environmental samples. Milk powder from 1988 was used as the example case. Included is a special analysis on the uncertainty estimation. Gamma sensitiveness is defined and numerically evaluated. The results reproduced the calibration data well, attesting to the reliability of the method. The special analysis shows that the uncertainty of the assessed activity is tied to that of the calibration activity data. More than 77% of measured 1461-keV photons of (40)K were counted in the range of clearly lower energies. Pile-up of single line photons ((137)Cs) looks negligible compared to that of a two-line cascade ((134)Cs). The detection limit varies with radionuclide and spectrum region and is related to the gamma sensitiveness of the detection system. The best detection limit always lies in a spectrum region holding a line of the radionuclide and the highest sensitiveness. The most radioactive milk powder sample showed a activity concentration of 21+/-1 Bq g(-1)for (137)Cs, 323+/-13 Bq g(-1) for (40)K and no (134)Cs.

[Photometric analysis of sodium and cesium iodides in the air of the work area]. / Fotometricheskoe opredelenie iodidov natriia i tseziia v vozdukhe rabochei zony.

The contributors propose a photometric technique for detecting sodium and caesium iodides in the working zone air. The technique is based on the oxidation of I-ions with bromine water, interacting of the educed iodine and redundant potassium iodide with concomitant formation of complex I3- ions, followed by 350-365 mm photometric measurements of the product. Air sample taking is performed by condensating on AFA--VP filtres. The lower limit of I-ions content measurements is 5 micrograms. The measurement range for sodium and caesium iodides is 0.2-50 mg/m3. Data is provided for the reproduction of the technique which can be used both in special laboratory and industrial conditions.

On the radiochemical quality control of [123I] sodium iodide for thyroid scanning.

Use of [123I]sodium iodide of too high specific activity in preparations for the diagnosis of disorders of the thyroid can lead to erroneous values for protein bound iodine and 24 h iodine uptake in the thyroid. Commonly used radiochemical quality control methods such as thin layer chromatography and the procedure described in the 21st edition of the U.S. Pharmacopoeia failed to reveal impurities in such preparations. A simple and quick check method is described, for indicating preparations unsuitable for diagnosis of thyroid disorders.

Radiolytic breakdown of sodium iodide (131I) in sodium iodide (131I) capsules.

Sodium iodide (131I) capsules are widely used for both diagnosis and therapy. The radiochemical purity of both diagnostic and therapeutic capsules in use in Australia was studied by gel chromatography, high voltage electrophoresis and paper chromatography. It was found that in two of the three bands of therapeutic capsules examined, significant quantities of a labelled high molecular weight component was produced with the result that these capsules failed to meet British Pharmacopoeia, BP, and United States Pharmacopoeia, USP, requirements for radiochemical purity well before their quoted expiry time. The nature of the impurity has not been identified but it is thought to be either iodinated gelatin or an iodinated capsule component.