ELECTROCHEMICAL Sr-90/Y-90 GENERATOR

Objectives

Y-90, a radionuclide well suited for endoradiotherapy, is distributed from specialized production sites where stocks of Sr-90 are routinely processed. The state of the art of Sr-90/Y-90 separation technology is not really applicable to hospitals for safety reasons, thus a large portion of the costs of Y-90 therapy comes from transportation. New technologies are needed in order to provide the possibility of local distribution of Y-90 from remotely operated generator systems, making this therapeutic agent available at more competitive price.

Results

The separation procedure typically lasts for 60 min and the final product is formulated in 0.05 M HCl having a total volume from 0.25 to 2.0 ml. The vial with the product can be autoclaved and the preparation is suitable for labeling monoclonal antibodies and peptides. Depending on the activity concentration of the stock solution of Sr-90, batch sizes of 37 GBq Y-90 can be made available on daily basis. The most critical quality factor of Y-90 is its contamination with Sr-90. The technical solution allows producing the Y-90 in the quality parameters required from the pharmacopoeia.

Methods

Electrochemical separation of Sr-86/Y-86 is nowadays well established and used for the production of Y-86. The same basic principle has been applied in developing an automated generator for daily Y-90 supply. The generator consists of a shielded reservoir containing a stock solution of Sr-90 of high purity, being in transient equilibrium with Y-90. A fraction of this stock solution is transferred to the electrochemical cell, where a two step separation is performed using platinum electrodes. After the separation the solution from the electrochemical cell is transferred back to the stock solution maintaining the total Sr-90 inventory practically constant. Due to the fact that only a portion of the stock solution is processed one can milk the generator every day providing practically the same yield day after day.

The operation of the generator is completely automated and computer controlled and it is suitable for installation in general purpose hotcell. Operators are required only to insert the empty and to remove the vial with the product from the hotcell and to replace the sterile filters prior to milking the generator. Small amounts of 90Sr lost during the washing procedures are collected in a dedicated reservoir and can be recovered from time to time if required.

Conclusions

The newly developed Sr-90/Y-90 generator allows for daily production of 37 GBq Y-90 batches and local distribution from specialized regional centers. Widespread use of this technology could bring targeted radioimmunotherapy to a significantly larger number of patients even in developing countries.

I-123/I-124 Production Unit

The module allows the production of radio-iodine using medical PET cyclotrons. It has been specifically developed for the production of I-124 for PET; however other radionuclides of iodine, e.g. I-123, can be produced as well. The production technology is based on irradiation of highly enriched tellurium oxide targets 124TeO2 for I-124 and 123TeO2 for I-123, respectively using the COSTIS target station. This target station may be adapted to any of the existing PET cyclotrons.

The Process

• • Highly enriched 124TeO2 is irradiated with about 15 MeV proton beam, with a beam density of up to 20 µA/cm2.
• • Under optimal temperature-controlled conditions the radio-iodine is released within 2 minutes at a temperature above the melting point and trapped within a further few minutes in a very small volume of a trapping solution, providing high radioisotope concentration.
• • After annealing the target can be immediately re-used for the next irradiation without any further treatment.
• • The practical production rates are 18.5 and 150 MBq·µA-1·h-1 for I-124 and I-123, respectively.

The heart of the module is a specially developed very small quartz furnace that is optimized for minimal heat release, fast dynamic behavior in temperature regulation, low inner dead volume and small trapping volume. The furnace is operated automatically providing a dedicated and optimized temperature protocol.

The irradiated target disc (Pt that carries the TeO2 target material) is inserted manually into the target holder with a suitable distance tool and the furnace is closed. All further operations (temperature program and delivering and control of gas flow and liquids) are fully automated and remotely controlled. An automatic cleaning program is provided. The process is fast (~30 minutes) providing high radiochemical yields (>95 %) and high radio-iodide concentration (trap volume 0.5 – max. 1 ml). Losses of the expensive enriched target material are negligibly low (< 0.2 mg/per cycle). The whole operation of the module is GMP compliant.