Automated radiopharmaceutical production and quality control system
11135321 · 2021-10-05
Assignee
Inventors
- Mark Khachaturian (Knoxville, TN, US)
- Doug Ferguson (Clinton, TN, US)
- Aaron McFarland (Knoxville, TN, US)
- Atilio Anzellotti (Knoxville, TN, US)
- Clive Brown-Proctor (Knoxville, TN, US)
Cpc classification
B01J19/0093
PERFORMING OPERATIONS; TRANSPORTING
A61K51/0491
HUMAN NECESSITIES
International classification
A61K51/00
HUMAN NECESSITIES
B01J19/00
PERFORMING OPERATIONS; TRANSPORTING
Abstract
An automated radiopharmaceutical production and quality control system includes a particle accelerator, a radiopharmaceutical micro-synthesis subsystem, and quality control subsystem. The micro-accelerator of the improved biomarker generator is optimized for producing radioisotopes useful in synthesizing radiopharmaceuticals in quantities on the order of multiple unit doses, allowing for significant reductions in size, power requirements, and weight when compared to conventional radiopharmaceutical cyclotrons. The radiopharmaceutical micro-synthesis subsystem encompasses a small volume chemical synthesis system comprising a microreactor and/or a microfluidic chip and optimized for synthesizing the radiopharmaceutical in small quantities, allowing for significant reductions in processing time and in the quantity of radioisotope required. The automated quality control subsystem is used to test the composition and characteristics of the radiopharmaceutical to ensure that it is safe to inject.
Claims
1. An automated radiopharmaceutical production and quality control system for automatically producing a quantity of radiopharmaceutical on an order of up to ten unit doses, said system comprising: a computer that receives a selection input identifying a selected radiopharmaceutical; a cyclotron in communication with said computer, said cyclotron to produce a radioisotope associated with said selected radiopharmaceutical, said cyclotron initiating production of the radioisotope upon receiving computer activating; and a chemical production subsystem to transfer, synthesize, and purify said radioisotope into a maximum quantity of a radiopharmaceutical on the order of up to ten unit doses using a disposable microfluidic radiopharmaceutical synthesis card; said disposable microfluidic radiopharmaceutical synthesis card including: at least one reaction vessel configured to receive a radioisotope and at least one reagent, said reaction vessel being configured to receive energy from an energy source, whereby when said radioisotope and said at least one reagent are mixed in said reaction vessel and energy is provided to said reaction vessel from said energy source, a radiopharmaceutical is synthesized; at least one purification component to purify said radiopharmaceutical; and a vessel adapted to receive said radiopharmaceutical following the passage of said radiopharmaceutical through said purification component; a draw line connected between said disposable microfluidic radiopharmaceutical synthesis card and an automated quality control system for radiopharmaceuticals, said draw line configured to extract at least one small volume of said radiopharmaceutical from said disposable microfluidic radiopharmaceutical synthesis card and to transfer said at least one small volume to said an automated quality control system for radiopharmaceuticals, said automated quality control system for radiopharmaceuticals to test the radiopharmaceutical to ensure that it is safe for injection, said an automated quality control system for radiopharmaceuticals comprising: a high performance liquid chromatography column and a radiation probe to measure the radioactivity of said radiopharmaceutical, said high performance liquid chromatography column to receive a first portion of the at least one small volume of said radiopharmaceutical from said draw line; and a sample line and a multi-port switching valve to receive a second portion of said at least one small volume from said draw line and to distribute sample volumes of said second portion to multiple analytical testing devices to perform various quality control tests on the radiopharmaceutical, wherein the multiple analytical testing devices receiving sample volumes from said multi-port switching valve are able to conduct tests on the sample volumes of radiopharmaceutical from the second portion while the first portion is passing through said high performance liquid chromatography column, wherein said cyclotron, said chemical production subsystem and said automated quality control system for radiopharmaceuticals are all controlled by said computer, wherein said cyclotron, said chemical production subsystem and said automated quality control system for radiopharmaceuticals run simultaneously in series or in parallel, and wherein while said chemical production subsystem is producing dose N in a series of doses, said automated quality control system for radiopharmaceuticals is analyzing dose N−1, said dose N−1 having just emerged from said chemical production subsystem and said cyclotron is simultaneously producing said radioisotope to go into dose N+1.
2. The system of claim 1., wherein said cyclotron produces said radioisotope associated with said selected radiopharmaceutical by locating a target substance in a magnetic field generated by said cyclotron and bombarding said target substance with said particle beam without said particle beam exiting said magnetic field.
3. The system of claim 1, wherein said radioisotope associated with said selected radiopharmaceutical is .sup.18F, .sup.11C, .sup.124I, .sup.13N, .sup.15O, or .sup.68Ga.
4. The system of claim 1, wherein said selected radiopharmaceutical is produced in a specified maximum quantity determined by a level of radioactivity of said quantity, and wherein said selected radiopharmaceutical and the level of radioactivity is selected from the group consisting of [18F]2-fluoro-2-deoxy-D-glucose with a maximum radioactivity level of approximately 250 mCi, [18F]Sodium Flouride with a maximum radioactivity level of approximately 250 mCi, [18F]fluoromisonidazole with a maximum radioactivity level of approximately 170 mCi, [18F] 3′-deoxy-3′fluorothymidine with a maximum radioactivity level of approximately 170 mCi, [18F] fluorocholine with a maximum radioactivity level of approximately 60 mCi, [18F]Fallypride with a maximum radioactivity level of approximately 250 mCi, [18F]Florbetaben with a maximum radioactivity level of approximately 180 mCi, [18F]Florbetapir with a maximum radioactivity level of approximately 300 mCi, [18F]-fluoro-ethyl-tyrosine with a maximum radioactivity level of approximately 200 mCi, [18F]flutemetamol with a maximum radioactivity level of approximately 150 mCi, [18F]FDOPA with a maximum radioactivity level of approximately 200 mCi, [11C]Choline with a maximum radioactivity level of approximately 100 mCi, [11C]acetate with a maximum radioactivity level of approximately 450 mCi, [11C]N-Methylspiperone with a maximum radioactivity level of approximately 200 mCi, [11C]Carfentanil with a maximum radioactivity level of approximately 100 mCi, and [11C]Raclopride with a maximum radioactivity level of approximately 100 mCi.
5. The system of claim 1 wherein said cyclotron has a maximum beam power selected from the group consisting of 50 W, 75 W, 100 W, 125 W, 150 W, 175 W, and 200 W.
6. The system of claim 5, wherein said cyclotron produces the radioisotope associated with said selected radiopharmaceutical with a beam of charged particles having an average energy within a range selected from the group consisting of 5 MeV to 18 MeV, 5 MeV to 10 MeV, 7 MeV to 10 MeV, 8 MeV to 10 MeV, and 7 MeV to 18 MeV.
7. The system of claim 6, wherein said average energy of said charged particles is in the range of 5 MeV to 10 MeV.
8. The system of claim 6, wherein said charged particles are selected from the group consisting of protons and deuterons and wherein said average energy of said charged particles is in the range of 5 MeV to 10 MeV and said maximum beam power is 200 W.
9. The system of claim 1, wherein said computer prints out a dose record summarizing the results of the quality control tests.
10. The system of claim 1, wherein said system simultaneously manages manufacture of said radioisotope, production of said radiopharmaceutical and quality control of said radiopharmaceutical.
11. The system of claim 1, wherein said system activates an ion source which generates a beam of charged particles accelerated through a magnetic and electric field to an energy greater than or equal to a nuclear binding energy of a target substance.
12. The system of claim 11, wherein said system selects the target substance for said radioisotope of said radiopharmaceutical.
13. The system of claim 12, wherein said charged particles hitting said target substance produces a selected radioisotope.
14. The system of claim 13, wherein said system generating said beam of charged particles with a maximum beam power of 200 W, said charged particles selected from the group consisting of protons and deuterons, and said charged particles accelerated to an average energy at least equal to the nuclear binding energy of said target substance.
15. The system of claim 14, wherein said system produces said radioisotope in a maximum quantity per production run on an order of up to ten unit doses from said target substance by bombarding said target substance with said charged particles.
16. The system of claim 15, wherein said target substance associated with said radiopharmaceutical is moved into said beam of charged particles by said computer.
17. The system of claim 1, wherein said system receives said radioisotope from manual injection into said disposable microfluidic radiopharmaceutical synthesis card.
18. The system of claim 1, wherein said system has a vacuum pump attached to a vent line of said disposable microfluidic radiopharmaceutical synthesis card to remove vapor formation.
19. The system of claim 1, wherein said disposable microfluidic radiopharmaceutical synthesis card includes an RF ID chip or bar code to identify said radiopharmaceutical associated with said disposable microfluidic radiopharmaceutical synthesis card.
20. The system of claim 1, wherein said system has a shield around the cyclotron reducing a radiation field outside the shield to acceptable levels of (<1 mrem/hr).
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
(1) The above-mentioned features of the invention will become more clearly understood from the following detailed description of the invention read together with the drawings in which:
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DETAILED DESCRIPTION OF THE INVENTION
(17) An improved biomarker generator and a method suitable for efficiently producing short lived radiopharmaceuticals in quantities on the order of a unit dose is described in detail herein and illustrated in the accompanying figures. The improved biomarker generator includes a particle accelerator and a radiopharmaceutical micro-synthesis system. The micro-accelerator of the improved biomarker generator is optimized for producing radioisotopes useful in synthesizing radiopharmaceuticals in quantities on the order of one unit dose allowing for significant reductions in size, power requirements, and weight when compared to conventional radiopharmaceutical cyclotrons. The radiopharmaceutical micro-synthesis system of the improved biomarker generator is a small volume chemical synthesis system comprising a microreactor and/or a microfluidic chip and optimized for synthesizing the radiopharmaceutical in quantities on the order of one unit dose allowing for significant reductions in the quantity of radioisotope required and the processing time when compared to conventional radiopharmaceutical processing systems.
(18) As used herein, “microreactors” and “microfluidic chips” refer broadly small volume reaction systems including microscale, nanoscale, and picoscale systems. As used herein, the term “radiopharmaceutical” encompasses any organic or inorganic compound comprising a covalently-attached radioisotope (e.g., 2-deoxy-2-[.sup.18F]fluoro-D-glucose ([.sup.18F]FDG)), any inorganic radioactive ionic solution (e.g., Na[.sup.18F]F ionic solution), or any radioactive gas (e.g., [.sup.11C]CO.sub.2), particularly including radioactive molecular imaging probes intended for administration to a patient or subject (e.g., by inhalation, ingestion, or intravenous injection) for imaging purposes. Such probes are also referred to in the art as radiotracers and radioligands and, more generically, as radiochemicals. The terms “patient” and “subject” refer to any human or animal subject, particularly including all mammals. A “unit dose” refers to the quantity of radioactivity that is administered for medical imaging to a particular class of patient or subject. A unit dose of the radiopharmaceutical necessarily comprises a unit dose of a radioisotope.
(19) As previously discussed, conventional radiopharmaceutical production focuses on generating a large amount of the radioisotope, typically on the order of Curies, in recognition of the significant radioactive decay that occurs during the relatively long time that the radioisotope undergoes processing and distribution. The improved biomarker generator of the present invention departs significantly from the established practice in that it is engineered to produce a per run maximum amount of radioisotope on the order of tens of millicuries. The micro-accelerator produces a maximum of approximately 2.59 GBq (70 mCi) of the desired radioisotope per production run. A particle accelerator producing a radioisotope on this scale requires significantly less beam power than conventional particle accelerators used for radiopharmaceutical production. The micro-accelerator generates a particle beam having a maximum beam power of 200 W. In various embodiments, the micro-accelerator generates a particle beam having a maximum beam power of approximately 200 W, 175 W, 150 W, 125 W, 100 W, 75 W, or 50 W. As a direct result of the dramatic reduction in maximum beam power, the micro-accelerator is significantly smaller and lighter than a conventional cyclotrons used in radiopharmaceutical production and requires less electricity. Many of the components of the micro-accelerator are less costly and less sophisticated compared to conventional cyclotrons used in radiopharmaceutical production.
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(21) Each of the permanent magnets 20 and the dees 45 are wedge-shaped. Each permanent magnet 20 has a first end positioned proximate to the center of the array and a second positioned proximate to the periphery of the array. Likewise, each dee 45 has a first end positioned proximate to the center of the array and an second end positioned proximate to the periphery of the array. Each of the dees 45 defines a main channel 14 through which ions travel as they are accelerated. When the dees 45 are disposed with the valleys, the faces of the permanent magnet pole tips are disposed in substantially the same plane as the side of the of the corresponding horizontal member of the dees that define the main channel 14. In the illustrated embodiment, the horizontal inner surfaces of the dees are substantially co-planar with the corresponding pole faces of the magnet pairs. When the upper and lower platforms 29 are engaged, a magnet gap is defined between corresponding permanent magnets 20 of the upper and lower platforms 29. Accordingly, the entire channel has a substantially homogeneous height, which provides an unobstructed flight path for the ions being accelerated therein.
(22) The upper and lower platforms 29 are supported by a plurality of legs 37. In the illustrated embodiment and best viewed in
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(24) The permanent magnet cyclotron 10a provides substantial improvements with respect to cost and reliability when compared to conventional cyclotrons producing particle beams with energies of 10 MeV or less using electromagnets or superconducting magnets. Because the permanent magnet cyclotron 10a allows for the exclusion of the electromagnetic coils of the common to conventional radiopharmaceutical cyclotrons, the volume and weight are significantly reduced. In one embodiment, the volume and weight of the micro-accelerator are 40% of the volume and weight of conventional radiopharmaceutical cyclotrons, with a corresponding minimum equipment cost savings of approximately 25% of the equipment cost of conventional radiopharmaceutical cyclotrons. Additionally, eliminating the electric power needed to excite the electromagnet coils in a conventional cyclotron magnet significantly reduces the power requirements and realizes a significant savings in energy usage. The power requirements are further reduced as a result of the lower acceleration voltage of 8 MeV to 10 MeV or less applied to the dees. As a result of these improvements, the reliability of the permanent magnet cyclotron 10a is enhanced as compared to conventional radiopharmaceutical cyclotrons. As a result of the smaller size and lighter weight, more facilities are capable of operating the present invention, especially in situations where space is of concern. Further, because of the ultimately reduced purchase and operating costs, the permanent magnet cyclotron 10a is also more affordable. While the permanent magnet cyclotron 10a is presently not practical for higher acceleration voltages due to the increased magnetic field requirements of the permanent magnets, such embodiments are not excluded from the spirit of the present invention.
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(26) To facilitate low-power operation, the ion source of one embodiment of the micro-accelerator is optimized for positive ion production. Beams of positively-charged particles generally are more stable than beams of negatively-charged particle because the reduced likelihood of losing an electron at the high velocities that charged particles experience in a cyclotron. Losing an electron usually causes the charged particle to strike an interior surface of the cyclotron and generate additional radiation. Minimizing the production of excess radiation reduces the amount of shielding required. Additionally, a positive ion cyclotron requires significantly less vacuum pumping equipment. Reducing the amount of shielding and vacuum pumping equipment reduces the size, weight, cost, complexity, power requirements, and power consumption of the cyclotron. In one embodiment, the ion source is optimized for proton (H.sup.+) production. In an alternate embodiment, the ion source is optimized for deuteron (.sup.2H.sup.+) production. In another embodiment, ion source is optimized for alpha particle (He.sup.2+) production.
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(28) In the illustrated embodiment, the internal target 183 includes a stainless steel tube 192 that conducts the target substance. The stainless steel tube 192 has a target section centered in the path that the particle beam 184 travels following the final increment of acceleration. The longitudinal axis of the target section is substantially parallel to the magnetic field 182 generated by the magnet system and substantially perpendicular to the electric field generated by the RF system. The remainder of the stainless steel tube 192 is selectively shaped and positioned such that it does not otherwise obstruct the path followed by the particle beam 184 during or following its acceleration. The internal target 183 defines an opening 196 that is positioned in a path of the particle beam 184. A target window 198, which comprises a very thin layer of a foil such as aluminum, seals the opening 196 and prevents the target substance from escaping. Also, a pair of valves 200 control the flow of the target substance and hold a selected volume of the target solution in place for irradiation by the particle beam 184.
(29) The diameter of the stainless steel tube 192 varies depending on the configuration of the internal target cyclotron 10b. Generally, the diameter is less than or equal to the increase in the orbital radius of the charged particles over one orbit, which in this embodiment is approximately four millimeters. Thus, in one embodiment, the diameter of the stainless steel tube 192 is approximately four millimeters. Because the charged particles gain a predetermined fixed quantity of energy that is manifested by an incremental fixed increase in the orbital radius of the beam, the charged particles do not interact with the stainless steel tube 192 prior to the final increment of acceleration, which would result in an undesirable situation that reduces the efficiency of the particle beam 184.
(30) The micro-accelerator is designed to produce a particle beam in which the charged particles have an average energy sufficient to overcome the binding energy of the target isotope. In the area of radiopharmaceutical production, the minimum effective average energy of the charged particles is 5 MeV. Higher average particle energies result in more efficient radioisotope production and shorter production times. The micro-accelerator 112 produces a particle beam of charged particles with an average energy in the range of 5 MeV to 18 MeV. In one embodiment, the charged particles have an average energy in the range of 5 MeV to 10 MeV. In another embodiment, the charged particles have an average energy in the range of 7 MeV to 10 MeV. In another embodiment of the micro-accelerator 112, the charged particles have an average energy in the range of 8 MeV to 10 MeV. In yet another embodiment of the micro-accelerator 112, the charged particles have an average energy in the range of 7 MeV to 18 MeV. In more specific embodiments of the micro-accelerator 112, the charged particles are protons, deuterons, or alpha particles with an average energy in the range of 5 MeV to 18 MeV, 5 MeV to 10 MeV, 7 MeV to 10 MeV, 8 MeV to 10 MeV, or 7 MeV to 18 MeV. In a further embodiment, the micro-accelerator 112 generates a particle beam with a beam current of approximately 1 μA consisting essentially of protons having an energy of approximately 7 MeV, the particle beam having beam power of approximately 7 W and being collimated to a diameter of approximately 1 mm.
(31) At lower average particle energies, fewer charged particles will be successful in destabilizing the target isotope and production time increases. As production time increases to a point that it is significant with respect to the half-life of the radioisotope, some of the radioisotope that has been produced will decay. The quantities of the radioisotope for which the micro-accelerator is designed are small enough to be practicable even when the ratio of production to decay is small. The various embodiments of the micro-accelerator are limited to producing a radioisotope with a maximum radioactivity of approximately 2.59 GBq (70 mCi) per production run. In one embodiment, the micro-accelerator produces a maximum of approximately 0.666 GBq (18 mCi) of fluorine-18 per production run. In another embodiment, the micro-accelerator produces a maximum of approximately 0.185 GBq (5 mCi) of fluorine-18 per production run. In yet another embodiment, the micro-accelerator produces a maximum of approximately 1.11 GBq (30 mCi) of carbon-11 per production run. In further embodiment, the micro-accelerator produces a maximum of approximately 1.48 GBq (40 mCi) of nitrogen-13 per production run. In still further embodiment, the micro-accelerator produces a maximum of approximately 2.22 GBq (60 mCi) of oxygen-15 per production run. Such embodiments of the micro-accelerator are flexible in that they can provide an adequate quantity of radioisotope for each of various classes of patients and subjects that undergo PET imaging.
(32) The improved biomarker generator of the present invention may be embodied in many different forms. The permanent magnet cyclotron 10a, the improved RF cyclotron, and the internal target cyclotron 10b are examples of suitable components for use in a particle accelerator optimized as a micro-accelerator. Moreover, the various features of the permanent magnet cyclotron 10a, the improved RF cyclotron, and the internal target cyclotron 10b can be mixed and matched in a single micro-accelerator. Thus, one embodiment of the micro-accelerator is a combination of the permanent magnet cyclotron 10a with the internal target 183 of the internal target cyclotron 10b. Another embodiment of the micro-accelerator is a combination of the permanent magnet cyclotron 10a with the improved RF system. Yet another embodiment of the micro-accelerator is a combination of the internal target cyclotron 10b with the improved RF system. A still further embodiment is the combination of the permanent magnet cyclotron 10a with the improved RF system and the internal target 183 of the internal target cyclotron 10b.
(33) Variations in the overall architecture of the micro-accelerator and the radiopharmaceutical micro-synthesis system are contemplated. For example, one embodiment, the micro-accelerator is a two-pole cyclotron. In another embodiment, the micro-accelerator is a four-pole cyclotron. Using a four-pole cyclotron may be advantageous in certain applications, because a four-pole cyclotron accelerates charged particles more quickly than a two-pole cyclotron using an equivalent accelerating voltage. The micro-accelerator described herein emphasizes the generation of a positively-charged particle beam; however, the acceleration of negatively-charged particles is necessary for certain applications and is considered within the scope of the present invention. The micro-accelerator described herein emphasizes the use of permanent magnets; however, the use of small electromagnets (weighing up to approximately 3 tons) is not outside the scope of the present invention for certain applications where a higher beam power is required. While the foregoing discussion emphasizes the use of a micro-accelerator, other types of particle accelerators may be used for production of the particle beam. Acceptable alternatives for the cyclotron include linear accelerators, radiofrequency quadrupole accelerators, and tandem accelerators. The production quantities, the ion source types, and the particle beam energies, ranges, diameters, particles, and powers apply to the various embodiments and modifications of the micro-accelerators.
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(36) After irradiation, the radioisotope and at least one reagent are transferred to the radiopharmaceutical micro-synthesis system 114. The radioisotope undergoes processing such as concentration, as necessary. Ultimately, the radiopharmaceutical micro-synthesis system 114 combines the radioisotope with the reagent to synthesize the biomarker. In this context, a reagent is a substance used in synthesizing the biomarker because of the chemical or biological activity of the substance. Examples of a reagent include a solvent, a catalyst, an inhibitor, a biomolecule, and a reactive precursor. A reactive precursor is an organic or inorganic non-radioactive molecule that, in synthesizing a biomarker or other radiopharmaceutical, is reacted with a radioisotope, typically by nucleophilic substitution, electrophilic substitution, or ion exchange. The chemical nature of the reactive precursor varies and depends on the physiological process that has been selected for imaging. Exemplary organic reactive precursors include sugars, amino acids, proteins, nucleosides, nucleotides, small molecule pharmaceuticals, and derivatives thereof. Synthesis refers to the production of the biomarker by the union of chemical elements, groups, or simpler compounds, or by the degradation of a complex compound, or both. Synthesis, therefore, includes any tagging or labeling reactions involving the radioisotope and any processes (e.g., concentration, evaporation, distillation, enrichment, neutralization, and purification) used in producing the biomarker or in processing the target substance for use in synthesizing the biomarker. The latter is especially important in instances where (1) the volume of the target substance is too great to be manipulated efficiently within some of the internal structures of the radiopharmaceutical micro-synthesis system and/or (2) the concentration of the radioisotope in the target substance is lower than is necessary to optimize the synthesis reaction(s) that yield the biomarker. Accordingly, one embodiment of the radiopharmaceutical micro-synthesis system incorporates integrated separation components providing the ability to concentrate the radioisotope. Examples of suitable separation components include ion-exchange resins, semi-permeable membranes, or nanofibers. Such separations via semi-permeable membranes usually are driven by a chemical gradient or electrochemical gradient. Another example of processing the target substance includes solvent exchange. Continuing the example from above, the concentration of fluorine-18 obtained from a proton bombardment of [.sup.18O]water is usually below 1 ppm. This dilute solution needs to be concentrated to approximately 100 ppm in order to optimize the kinetics of the biomarker synthesis reactions. This processing occurs in the radiopharmaceutical micro-synthesis system 114.
(37) The improved biomarker generator enables the small scale in-situ production of a radioisotope and synthesis of biomarkers. Thus, the micro-accelerator 112 produces a sufficient quantity of the radioisotope for the radiopharmaceutical micro-synthesis system 114 to synthesize of the biomarker on the order of a unit dose of the biomarker. In one embodiment, the micro-accelerator 112 generates the radioisotope in a quantity on the order of a unit dose. In another embodiment, the micro-accelerator 112 generates the radioisotope in a quantity on the order of a precursory unit dose of the radioisotope. A precursory unit dose of the radioisotope is a dose of radioisotope that, after decaying for a length of time approximately equal to the time required to synthesize the biomarker, yields a quantity of biomarker having a quantity of radioactivity approximately equal to the unit dose appropriate for the particular class of patient or subject undergoing PET. For example, if the radiochemical synthesis system requires 20 min to synthesize a unit dose of a biomarker comprising carbon-11 (t.sub.1/2=20 min), the precursory unit dose of the carbon-11 radioisotope has an radioactivity equal to approximately 200% times the radioactivity of a unit dose of the biomarker in order to compensate for the radioactive decay. Similarly, if the radiopharmaceutical micro-synthesis system requires 4 min to synthesize a unit dose of a biomarker labeled with oxygen-15 (t.sub.1/2=2 min), the precursory unit dose of the oxygen-15 radioisotope has an radioactivity equal to approximately 400% times the radioactivity of a unit dose of the biomarker in order to compensate for the radioactive decay.
(38) In some instances, the precursory unit dose of the radioisotope may be used to compensate for a radiopharmaceutical micro-synthesis system having a yield fraction that is significantly less than 100% of the radioactivity supplied. Further, the precursory unit dose may be used to compensate for radioactive decay during the time required in administering the biomarker to the patient or subject. One skilled in the art will recognize that the synthesis of a biomarker comprising a positron-emitting radioisotope should be completed within approximately the two half-lives of the radioisotope immediately following the production of the unit or precursory unit dose to avoid the significant increase in inefficiency that would otherwise result.
(39) The chemical production module, the dose synthesis card and the sample card operate in conjunction with a complete PET biomarker production system. As shown in
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(42) Having been synthesized, the [.sup.18F]FDG in solution passes from the reaction vessel 110a through a post-reaction channel 1101 into a solid phase extraction column 160a, where some undesirable substances are removed from the solution, thereby clarifying the radiopharmaceutical solution. In some embodiments of the present invention, the solid phase extraction (SPE) column 160a comprises a length with an ion exchange resin, a length filled with alumina, and a length filled with carbon-18. The radiopharmaceutical passes through the purification component column 160a and in some embodiments passes through a second purification component 1601 with a mobile phase that in many embodiments includes acetonitrile from the organic input 124a. The purification components 160a 1601 can be single phase extraction components or trap and release purification components depending on the radiopharmaceutical. As some of the mobile phase and impurities emerge from the SPE column 160a, they pass through a second post-reaction channel 1542 and through a three-way valve 175 and waste channel 1104 into a waste receptacle 210. As the clarified radiopharmaceutical solution emerges from the SPE column 160a, the radiopharmaceutical solution next passes through the second post-reaction channel 1542 and through the three-way valve 175 into a filter channel 1103 and then through a filter 170a. The filter 170a removes other impurities (including particulate impurities), thereby further clarifying the radiopharmaceutical solution. In many embodiments the filter 170a includes a Millipore filter with pores approximately 0.22 micrometers in diameter.
(43) Once the radiopharmaceutical solution has passed through the filter 170a, the clarified radiopharmaceutical solution travels via the post-clarification channel 1105 into the sterile dose administration vessel 1200, which in the illustrated embodiment is incorporated into a syringe 1202 or a collection vial. In some embodiments, the dose administration vessel is filled beforehand with a mixture of phosphate buffer and saline.
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(45) In some embodiments of the present invention, the CPM holds sufficient amounts of reagents and solvents that are required during the radiopharmaceutical synthesis process to carry out multiple runs without reloading. Indeed, in some embodiments the CPM is loaded with reagents and solvents approximately once per month, with that month's supply of reagents and solvents sufficient to produce several dozen or even several hundred doses of radiopharmaceutical. As the reagents and solvents are stored in the CPM, it is easier than under previous systems to keep the reagents and solvents sterile and uncontaminated. In some embodiments, a sterile environment is supported and contamination inhibited by discarding each dose synthesis card and the sample card after one run; these components of the system are adapted to be disposable.
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(47) While sample radiopharmaceutical solution is flowing through the fixed-volume fluid loop 517, the injection valve 516 is rotated a second time, so that the injection valve is again in State A. At this point in time, mobile phase solvent from the HPLC pump 503 passes through the third injection valve line 563 and into the injection valve 516; within the injection valve 516, the mobile phase solvent from the third injection valve line 563 is directed into the fifth injection valve line 565. The mobile phase solvent within the fifth injection valve line 565 enters the fixed-volume fluid loop 517, pushing the sample radiopharmaceutical solution within the fixed-volume fluid loop 517 out of the fixed-volume fluid loop 517 and through the sixth injection valve line 566 into the injection valve 516. Within the injection valve 516, the sample radiopharmaceutical solution from the fixed-volume fluid loop 517 is directed into the fourth injection valve line 564. (In some embodiments, the fixed-volume loop 517 has a volume of approximately 20 microliters. However, those of skill in the art will recognize that other volumes the fixed-volume loop 517 are possible and are contemplated by the present invention.)
(48) Conveyed along the fourth injection valve line 564, the sample radiopharmaceutical solution from the fixed-volume fluid loop 517 passes by at least one radiation probe 542, which is part of or connected to a radiation detector 522. Next, the sample radiopharmaceutical solution passes by or through a UV/VIS detector 502 to test the optical clarity of the sample radiopharmaceutical solution. In some embodiments, the UV/VIS detector 502 comprises a ultra-violet and visible light spectrometer. In some embodiments, the UV/VIS detector 502 comprises a UV spectrophotometer. In some embodiments, the UV/VIS detector 502 comprises a UV spectrophotometer with a deuterium light source. In some embodiments, the UV/VIS detector 502 comprises a UV spectrophotometer with a tungsten-halogen light source. In some embodiments, the UV/VIS detector 502 comprises a UV spectrophotometer like the Smartline UV Detector 2500, manufactured by KNAUER. In some embodiments, the HPLC-based QCM 50 includes a detector comprises a spectrophotometer that detects a range of the electromagnetic spectrum that includes infrared light. In some embodiments, the HPLC-based QCM 50 includes multiple detectors, including, in some embodiments, multiple UV/VIS detectors or, in some embodiments, multiple spectrophotometers or spectrometers.
(49) In some embodiments, the UV/VIS detector 502 tests the sample radiopharmaceutical solution for the presence of residual Krypotofix. Generally, a purified radiopharmaceutical solution will be considered to pass quality control testing for Kryptofix if the residual concentration of Kryptofix in the final product is less than or equal to 50 micrograms per milliliter solution.
(50) In some embodiments, the radiopharmaceutical solution from the fixed-volume fluid loop 517 passes by or through the UV/VIS detector 502 before entering the HPLC column 515. In In some embodiments, the radiopharmaceutical solution from the fixed-volume fluid loop 517 passes by or through a UV/VIS detector after entering and passing though the HPLC column 515.
(51) After passing by or through the UV/VIS detector 502, the sample radiopharmaceutical solution passes into the HPLC column 515. The HPLC column 515 separates [.sup.18F]FDG within the sample radiopharmaceutical solution from any other radioactive products or other organic impurities. In this way, the HPLC column 515 assists testing the radiochemical identity of the sample radiopharmaceutical solution—that is, the HPLC column 515 helps to identify the ratio of [.sup.18F]FDG (or other desired radiopharmaceutical compound) to other radioactive products (such as free F-18 ion and [.sup.18F]FTAG). The HPLC column 515 separates the [.sup.18F]FDG from other compounds based on their different retention time, making possible the identification of the [.sup.18F]FDG based on retention time and allowing other instruments to analyze the [.sup.18F]FDG separately from other compounds. Thus, in some embodiments, after exiting the HPLC column 515, the sample radiopharmaceutical solution passes through a refractive index detector (RI detector) 505. The RI detector 505 detects, measures and quantifies the presence of compounds as they are eluted from the HPLC column 515. [.sup.18F]FDG is identified based on its retention time, as are other compounds present in the sample radiopharmaceutical solution. In general, [.sup.18F]FDG has a slightly shorter retention time compared to FDG that lacks a radioisotope. In some embodiments, the radiochemical purity of the separated [.sup.18F]FDG within the sample radiopharmaceutical solution is also measured after the elution of the separated [.sup.18F]FDG within the sample radiopharmaceutical solution from the HPLC column 515.
(52) In many embodiments, the RI detector 505 also measures the residual concentration in the sample radiopharmaceutical solution of solvents such as acetonitrile and ethanol. Generally, a purified radiopharmaceutical solution will be considered to pass quality control testing if the residual concentration of acetonitrile in the sample radiopharmaceutical solution is less than or equal to 400 ppm.
(53) As shown in
(54) Generally, after the sample radiopharmaceutical solution is eluted from the HPLC column 515 and tested for radiochemical identity, radiochemical purity, and the presence of residual impurities, the sample radiopharmaceutical solution is conveyed to the waste vessel 507. In some embodiments, HPLC-based QCM 50 according to the present general inventive concept also includes, on the line carrying the sample radiopharmaceutical solution from the HPLC column 515 to the waste vessel 507, a backpressure valve 506.
(55)
(56)
(57) In some embodiments of the present general inventive concept, where the system in use includes a component or components for detecting the presence of residual phase transfer catalyst in the finished radiopharmaceutical solution, an iodine reagent is mixed with a sample solution containing the phase transfer catalyst Kryptofix 2.2.2; this mixture causes a red suspension to form, which can be observed visually. The concentration of Kryptofix 2.2.2 in the solution is proportional to the color intensity of the suspension, and visual differences were observed for solutions having a Kryptofix 2.2.2 concentration in the range of 0 to 100 ppm.
(58) In some embodiments, the iodine reagent and the sample solution containing Kryptofix 2.2.2 are mixed together before the mixture is passed through the detector chamber or the iodine reagent and the sample solution containing Kryptofix 2.2.2 are mixed together inside the detector chamber. Next, the mixture enters the detector chamber. The presence or absence of suspension is determined visually, and the absorbance is measured with a detector. The concentration of Kryptofix 2.2.2 in the mixture is determined by comparing the absorbance results with a calibration curve obtained from test solutions having known Kryptofix 2.2.2 concentrations.
(59) In general, the subsystem used to determine the concentration of the phase transfer catalyst comprises reservoirs for the sample and iodine solutions connected to a metering device and a UV-Vis cell or microfluidic chip with a clear window for detection. In some embodiments, the phase transfer catalyst is Kryptofix 2.2.2. Overall, the present general inventive concept permits concentration determination having the following characteristics: simplicity, specificity, low toxicity, and high throughput, which are desirable for [18F]-labeled radiotracers owing to the relatively short half-life of the [18F] isotope (109 min).
(60) In some embodiments, the iodine reagent is mixed with a sample solution containing Kryptofix 2.2.2, which causes a red suspension to form. The concentration of Kryptofix 2.2.2 in the solution is proportional to the color of the suspension. In some embodiments, the iodine reagent and the sample solution containing Kryptofix 2.2.2 are mixed together before the mixture is passed through the detector chamber. Next, the mixture enters the detector chamber. The presence or absence of suspension is determined visually, and the absorbance is measured with a detector. The concentration of Kryptofix 2.2.2 in the mixture is determined by comparing the absorbance results with a calibration curve obtained from test solutions having known Kryptofix 2.2.2 concentrations.
(61) Although the foregoing description emphasizes the production of biomarkers labeled with fluorine-18, such as [.sup.18F]FDG, the radiopharmaceutical micro-synthesis system is flexible and may be used to synthesize biomarkers labeled with other radioisotopes, such as carbon-11, nitrogen-13, or oxygen-15. Further, the improved biomarker generator discussed herein is flexible enough to produce quantities on the order of a unit dose of biomarkers that are labeled with radioisotopes that do not emit positrons or for producing small doses of radiopharmaceuticals other than biomarkers. One skilled in the art will recognize also that the radiopharmaceutical micro-synthesis system may comprise parallel circuits, enabling simultaneous production of unit doses of a variety of biomarkers. Finally, one skilled in the art will recognize that the improved biomarker generator may be engineered to produce unit doses of biomarker on a frequent basis.
(62) From the foregoing description, it will be recognized by those skilled in the art that an improved biomarker generator has been provided. The improved biomarker generator described herein allows for the nearly on-demand production of a biomarker in a quantity on the order of one unit dose. Because the half-lives of the radioisotopes most suitable for safe molecular imaging of a living organism are very short, nearly on-demand production of unit doses of biomarkers presents a significant advancement for both clinical medicine and biomedical research. The reduced size, weight, and cost, the reduced infrastructure (power and structural) requirements, and the improved reliability of the micro-accelerator coupled with the speed and overall efficiency of the radiopharmaceutical micro-synthesis system make in-house biomarker generation a viable option even for small regional hospitals. The various embodiments of the micro-accelerator generate the magnetic field using permanent magnets, move the target into the magnetic field allowing the magnet system to help contain radiation generated during radioisotope production, incorporate the improved RF system described herein, and use combinations of these features to provide the aforementioned improvements over conventional cyclotrons used in radiopharmaceutical production.
(63) A system according to the present general inventive concept allows for automated sampling and analysis of a radiopharmaceutical solution in real time. In some embodiments, a cyclotron, chemical production module, and quality control module are all controlled by the same computer, and all three component subsystems (cyclotron, chemical production module, and quality control module) run simultaneously, in series or in parallel. In some embodiments, for example, while a CPM is producing dose N in a series of doses, the QCM is analyzing dose N−1 (said dose N−1 having just emerged from the CPM), and the cyclotron is simultaneously producing the radioisotopes to go into dose N+1. Such a setup helps to streamline the process of generating radiopharmaceutical doses. Some embodiments include automating the entire workflow. Various embodiments of systems according to the present general inventive concept also facilitate the use of small target volumes for radioisotope precursor target materials.
(64) While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant's general inventive concept.