The present invention relates to a system for automatically producing radioisotopes.
Radioisotopes have long been produced by cyclotron irradiation for medium- or low-energy (5-30 MeV) medical applications. Radioisotopes have many important industrial and scientific uses, the most important of which is as tracers: by reactions with appropriate non-radioactive precursors, radiodrugs are synthesized and, when administered in the human body, permit diagnosis and therapy monitoring by Positron Emission Tomography (PET), especially in the treatment of tumours. By measuring radiation, it is also possible to follow all the transformations of the element and/or related molecule in chemistry (reaction mechanism research), biology (metabolism genetics research), and, as stated, in medicine for diagnostic and therapeutic purposes.
The only automated passage in known systems for producing radioisotopes is that between the irradiation station and the purifying station, where the desired radioisotope is separated not only from the target carrier material but also from the non-reacting target and any impurities (WO9707122).
Moreover, in known production systems, once the target has been irradiated, the target carrier, on which the starting metal isotope is deposited, is dissolved together with the target and subsequently removed from the manufactured radioisotope by means of a purification process.
Such a solution obviously calls for more complex, prolonged purification than that required to simply separate the manufactured radioisotope from the starting isotope.
It is an object of the present invention to provide a system for automatically producing radioisotopes, and which provides for more efficient production, in terms of output, as compared with known systems.
According to the present invention, there is provided a system for automatically producing radioisotopes, characterized by comprising a target carrier; an electrodeposition unit for electrodepositing a target in said target carrier; an irradiation unit for irradiating said target in said target carrier; first transfer means for transferring the target carrier from the electrodeposition unit to the irradiation unit; an electrodissolution unit for electrodissolving the irradiated target without corroding said target carrier (8); second transfer means for transferring the target carrier from the irradiation unit to the electrodissolution unit; a purifying unit for purifying the radioisotope of the non-reacting target and impurities; third transfer means for transferring the electrodissolved irradiated target from the electrodissolution unit to the purifying unit; and a central control unit for controlling the operating units and transfer means to automate the entire process.
In a preferred embodiment, the electrodeposition unit and the electrodissolution unit comprise the same electrolytic cell, and the first transfer means and second transfer means coincide.
In a further preferred embodiment, the first transfer means and second transfer means comprise a conduit connected to a pneumatic system and housing said target carrier in sliding manner.
A non-limiting embodiment of the invention will be described by way of example with reference to the accompanying drawings, in which:
a shows a section of the target carrier according to another embodiment;
a shows a section of the electrolysis unit according to another embodiment;
Number 1 in
System 1 comprises an electrolysis unit 2 for both electrodeposition and electrodissolution; an irradiation unit 3 fixed directly to a cyclotron C; a purifying unit 4; transfer means 5 for transferring the target between electrolysis unit 2 and irradiation unit 3; transfer means 6 for transferring the dissolved target from electrolysis unit 2 to purifying unit 4; and a central control unit 7 for fully controlling operation of system 1.
System 1 comprises a target carrier 8 (
As shown in
As shown in
Electrolysis unit 2 comprises an electrolytic cell 19; and a heater 20 housed, in use, inside cylindrical cavity 13 of target carrier 8.
As shown in
As shown in
Heater 20 comprises an electric resistor 28, and a temperature probe 29.
As shown in
As shown in
As shown in
As shown in
In actual use, a target carrier 8 is picked up by gripping head 15 and placed on heater 20, so that heater 20 is housed inside cylindrical cavity 13 of target carrier 8; and electrolytic cell 19 is then lowered into the
At this point, electrolytic cell 19 is raised, and gripping head 15 removes target carrier 8 and places it either on a supporting member 16, pending irradiation, or directly inside terminal 17, from which it is blown inside conduit 18 by a stream of compressed air. Target carrier 8 is fed along conduit 18 to terminal 35 of irradiation unit 3, where the presence of carrier 8 is detected by a sensor.
On reaching terminal 35, target carrier 8 is retained by grip pin 31 by virtue of the vacuum produced in outer annular conduit 40. Pneumatic cylinder 34 then lowers terminal 35 and conduit 18, and rotary actuator 32 and linear actuator 33 move grip pin 31 and target carrier 8 into the irradiation position. More specifically, carrier 8 is successively rotated 90° and translated to position cylindrical cavity 12 facing an irradiation opening 45 shown in
On reaching terminal 17, the target carrier is picked up by gripping head 15 and placed back on heater 20 as described previously; at which point, electrolytic cell 19 is lowered so that disk electrode 25 contacts the edge portion of coating 12a of cylindrical cavity 12 of target carrier 8. This time, however, unlike the electrodeposition operation described above, a portion of the coating of cylindrical cavity 12 is preferably left exposed to employ its catalyst properties for the electrodissolution reaction. Once the above situation is established, an acid solution, from purifying unit 4 and comprising nitric or hydrochloric acid, is fed in by delivery tube 21, and target carrier 8 is appropriately heated by resistor 28.
At this point, electrodissolution is performed, by inverting one polarity of the electrodes with respect to electrodeposition, and the resulting solution is sent by a stream of inert gas to purifying unit 4.
Once the acid solution is removed from the electrolytic cell, the electrolysis unit is cleaned and dried using deionized water and ethyl alcohol, after which, gripping head 15 can pick up another target carrier 8 and commence another work cycle.
The acid solution from the electrodissolution operation, and therefore containing the starting metal isotope and the radioisotope obtained by irradiation, is transferred to reactor 44 where the nitric acid is evaporated. The isotope/radioisotope mixture is re-dissolved in a hydrochloric acid solution, radioactivity is measured, and the solution is transferred in a stream of helium to ionic purification column 42. The starting metal isotope is recovered and used for further deposition.
The preparation of two radioisotopes will now be described in more detail by way of example.
—Preparation of radioisotope 60Cu, 61Cu, 64Cu—
A solution of 10 ml of (60Ni, 61Ni, 64Ni) comprising nickel sulphate and boric acid is fed into a vessel in purifying unit 4. Once target carrier 8 and electrolytic cell 19 are set up as shown in
Once target carrier 8 and electrolytic cell 19 are set up as shown in
—Preparation of radioisotope 110In—
A 10 ml solution of cadmium-110 comprising cadmium fluoborate and ammonium fluoborate is fed into a vessel in purifying unit 4 and to electrodeposition unit 2, where target carrier 8 and electrolytic cell 19 are set up as shown in
When the above operations are completed, target carrier 8 is transferred automatically along conduit 18 to the irradiation unit, and, after irradiation, is transferred automatically back to electrolysis unit 2.
Electrodissolution is performed using a 4 ml solution of nitric acid 4M contained in a vessel in purifying unit 4. The acid solution is circulated for about 2 minutes at a flow rate of 0.5-2 ml/min inside cylindrical cavity 12 of target carrier 8 maintained at ambient temperature; in which conditions, dissolution is quantitative. When dissolution is completed, the acid solution containing cadmium-110/indium-110 is transferred automatically to purifying unit 4, where the indium-110 is separated by ionic purification from the cadmium-110 and any other radioactive and metal impurities.
The system according to the present invention has the advantage of preparing radioisotopes automatically and so ensuring high output levels.
Moreover, by providing for electrodissolution of the irradiated metal, the system according to the present invention avoids dissolution of the target carrier, with obvious advantages at the purification stage.
Number | Date | Country | Kind |
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05425262.2 | Apr 2005 | EP | regional |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2006/061853 | 4/24/2006 | WO | 00 | 10/14/2009 |