Process for preparing medical radionuclide iodine-123 by using electron accelerator
Through electronic accelerator and photonuclear reaction technology, combined with chemical technology, high-purity iodine-123 was successfully prepared, solving the problems of high preparation costs and waste treatment in the prior art, and achieving efficient and low-cost iodine-123 production.
Patent Information
- Application Number
- CN202411853884.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-16
- Publication Date
- 2025-03-07
AI Technical Summary
In the prior art, when preparing medical radionuclide iodine-123, linear proton accelerators or other high-cost equipment are required, and a large amount of radioactive waste is generated, resulting in higher production costs.
An electron accelerator is used to generate an electron beam to bombard the tungsten target, convert it into gamma photons, and after the photonuclear reaction of xenon-124 gas, it is carried out through a series of chemical processes, including distillation, cation and anion exchange resin treatment, and finally obtains high-purity iodine-123.
Iodine-123 preparation with high yield, high nuclear purity and chemical purity is achieved, reducing production costs and no by-product generation. The irradiated gas can be recycled and reused.
Smart Images
Figure CN119581087A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of radionuclide preparation, and in particular relates to a process for preparing medical radionuclide iodine-123 by using an electron accelerator. Background Art
[0002] In the treatment and diagnosis of diseases, the medical radioactive nuclide iodine-131 has a half-life of up to 8 days and is accompanied by β-decay, making it widely used to examine the thyroid gland and kidneys, but these properties of iodine-131 make it harmful to the health of patients. Another radioactive iodine isotope iodine-123 is also widely used in disease diagnosis. Iodine-123 is the most commonly used radioactive nuclide for SPECT (Single-Photon Emission Computed Tomography) diagnosis. It is used for SPECT imaging of the thyroid gland, brain, myocardium, and kidneys. Its nuclear characteristic parameters are: half-life 13.2 hours, λ ray energy 159keV, decay type: EC (electron capture) into stable tellurium-123.
[0003] Iodine-123 is an isotope with a very short life span and only radiates gamma and X-rays. The radiation dose burden on the thyroid gland is much lower than that of iodine-131, which is about 1% of that of iodine-131. The 159keV gamma rays it emits can be effectively detected by SPECT detectors, and the images are clear and of good quality. Therefore, compared with iodine-131, iodine-123 has certain advantages in the field of nuclear medicine applications.
[0004] However, due to the short half-life of iodine-123, the production of iodine-123 mainly uses linear proton accelerators or protons, deuterons, 3 He and 4 He cyclotron, these production processes will produce radioactive waste when preparing iodine-123, and require a waste treatment system, which is costly. Summary of the invention
[0005] The present invention provides a process for preparing medical radioactive nuclide iodine-123 by using an electron accelerator, aiming to solve the above technical problems.
[0006] The present invention is achieved by a process for preparing medical radioactive nuclide iodine-123 using an electron accelerator, comprising the following steps: The electron accelerator generates an electron beam that bombards the tungsten target and converts the electron beam into gamma photons; The gamma photons irradiate a reaction target chamber filled with xenon-124 gas to perform a photonuclear reaction; Distilled water is injected into the reaction target chamber to elute the product of the photonuclear reaction, 123 I- of the dissolving liquid; The dissolved solution flows through a cation exchange resin to remove impurities and obtain an eluent; The eluent flows through an anion exchange resin, and adsorbs 123 I - ; Desorption with sodium hydroxide solution 123 I - The anion exchange resin is used to obtain Na 123 I solution.
[0007] Furthermore, the step of filling the reaction target chamber with xenon-124 gas comprises: The reaction target chamber is evacuated; Cooling the reaction target chamber using liquid nitrogen; The reaction target chamber is connected to a xenon-124 storage tank, and xenon-124 gas is sucked into the cooled reaction target chamber, so that the pressure of the xenon-124 gas in the reaction target chamber is ≥3MPa at room temperature, and the purity of the xenon-124 gas is ≥99.5%.
[0008] Furthermore, before injecting distilled water into the reaction target chamber to elute the product of the photonuclear reaction, the method further includes: placing the reaction target chamber in a lead can and storing it for several hours according to the duration of the gamma photon irradiation; The reaction target chamber is connected to a gas recovery tank to transfer the gas in the reaction target chamber.
[0009] Furthermore, the cation exchange resin is a 100-200 mesh Dowex 50×8 cation exchange resin, and the anion exchange resin is a 100-200 mesh Dowex 1×8 anion exchange resin.
[0010] Furthermore, the reaction target chamber is a stainless steel cylindrical tube that can withstand 6.0 MPa, and the gamma photons are irradiated along the axis of the stainless steel cylindrical tube.
[0011] Furthermore, the concentration of the sodium hydroxide solution is 0.02 mol / L.
[0012] Furthermore, the duration of irradiating the reaction target chamber with the gamma photons is 2 to 4 hours.
[0013] Furthermore, the thickness of the tungsten target is 2-8 mm.
[0014] Furthermore, the electron beam energy generated by the electron accelerator is 43-50 MeV, the beam current intensity is 2.0-2.5 mA, the beam pulse width is 12 μs, and the repetition frequency is 390 pps.
[0015] The invention provides a process for preparing medical radioactive nuclide iodine-123 by using an electron accelerator, and prepares iodine-123 by using a photonuclear reaction of xenon-124. The process has a high yield, and the nuclear purity and chemical purity of the product iodine-123 are extremely high. No other by-products are generated by using an enriched xenon-124 target, and the irradiated gas can be recycled and reused repeatedly. The product iodine-123 can achieve a better separation and extraction effect by using a relatively simple radiochemical separation method, and the electron accelerator and its related radioactive treatment system have lower operating costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a step diagram of preparing medical radioactive nuclide iodine-123 by using an electron accelerator provided by an embodiment of the present invention.
[0017] Figure 2 This is the gamma-ray energy spectrum for different tungsten target thicknesses.
[0018] Figure 3 The present invention provides a chemical process flow chart for preparing medical radioactive nuclide iodine-123 by using an electron accelerator. DETAILED DESCRIPTION
[0019] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.
[0020] The embodiment of the present invention provides a process for preparing medical radioactive nuclide iodine-123 by using an electron accelerator, and produces iodine-123 by a photonuclear reaction of the following reaction formula:
[0021] The yield of iodine-123 produced by this reaction after irradiation for time t is:
[0022] Where N0 represents xenon-124 ( 124 Xe) molecules, N1 represents the number of xenon-123 ( 123 Xe) molecules, N2 represents the iodine-123 produced by the decay of xenon-123 ( 123 I) number of molecules, N I represents the number of molecules after iodine-123 decays itself, , λ1 and λ2 are decay constants related to the half-lives of xenon-123 and iodine-123, respectively.
[0023] After stopping the irradiation, 123 X eThe process terminates, and only 123 X e Decay into 123 I and 123 I itself decays, and then at time t 123 The output of I is N I (t) is calculated as:
[0024] Where t0 is the irradiation time, and t is the time elapsed from the moment the irradiation stops.
[0025] From the above photonuclear reaction, we can know that after stopping the irradiation, there is still 123 X e Decay into 123 I and 123 I itself decays, so it must be at a certain time t m Make 123 The number of molecules of I reaches the maximum, and the maximum yield time t is obtained m for:
[0026] when , the above formula is simplified to:
[0027] After recovering the remaining gas in the reaction target chamber, 123 The activity A(t) of I is expressed as:
[0028] The above formula is in Curie (Ci), where t is calculated from the time when the remaining gas is recovered, where:
[0029] parameter In the above formula, N e is the number of electrons that produce gamma rays when the electron beam bombards the tungsten target, which depends on the beam intensity of the electron accelerator, and:
[0030] In the above formula They are the average current intensity, macro pulse current intensity, macro pulse width and repetition frequency of the electron accelerator. Among them, the average current intensity is 2.0~2.5mA, and the macro pulse width is 12μs. They are the energy spectrum distribution of gamma rays produced when an electron bombards a tungsten target and The cross-section function of the reaction.
[0031] 124Xe is a gas. The number of molecules N0 in one liter of gas under standard atmospheric pressure is:
[0032] One liter 124 Number of Xe molecules , where q is 124 Abundance of Xe, natural 124 The abundance of Xe is 0.096%, that is, its content in nature is very small. In the embodiment of the present invention, the purity of 99.5% is provided by Tianjin Nuclear Industry Physical and Chemical Engineering Research Institute. 124 Xe gas. The number of molecules undergoing photonuclear reaction refers to the number of molecules used as gas targets. In the embodiment of the present invention, a stainless steel cylindrical tube that can withstand 6.0 MPa is used as the reaction target chamber of the photonuclear reaction. Its dimensions are: radius r = 1.5 cm, length l = 18 cm, then the gas volume is , thus the reaction target chamber 124 Number of Xe molecules for:
[0033] Will Substituting into the above formula, we get 124 The number of Xe molecules, , where p=30 is the air pressure value input during the calculation, that is, the calculation is performed when the density is increased 30 times.
[0034] parameter 123 Xe decays into 123 The half-life of I is 2.1h. 123 I decays into 123 The half-life of Te is 13.2h, then:
[0035]
[0036] The gamma-ray energy spectrum at different tungsten target thicknesses is shown in Figure 2. Figure 2 As shown, in the embodiment of the present invention, a tungsten target with a thickness of 4.5 mm is used.
[0037] The following is a detailed description of the process for preparing medical radioactive nuclide iodine-123 using an electron accelerator through examples.
[0038] Example 1 See also Figure 1 , 3The embodiment of the present invention provides a process for preparing medical radioactive nuclide iodine-123 using an electron accelerator. In the process, all gas circuit (dashed line) and liquid circuit (solid line) switches use 24V solenoid valves and needle valves. The solenoid valves are controlled by the button switch on the control panel after the voltage regulator power supply is re-pressurized. The transfer and process of the liquid are realized by the negative pressure of the peristaltic pump and vacuum pump. Various eluents and washing liquids (NaOH, H2O, CH3OH) are added to their respective storage bottles through the peristaltic pump.
[0039] The process includes the following steps: S1: The electron accelerator generates an electron beam that bombards a tungsten target and converts the electron beam into gamma photons.
[0040] The electron beam energy generated by the electron accelerator used in the embodiment of the present invention is 43~50MeV, the beam current intensity is 2.0~2.5mA, the beam pulse width is 12μs, the repetition frequency is 390pps, the tungsten target thickness is 4.5mm, and the electron beam bombards the tungsten target, which converts the electron beam into gamma photons.
[0041] S2: Gamma photons irradiate the reaction target chamber filled with xenon-124 gas to carry out photonuclear reaction.
[0042] The electron beam is converted into gamma photons by the tungsten target, which irradiate the xenon-124 in the reaction target chamber along the axis of the reaction target chamber to carry out a photonuclear reaction. The iodine-123 generated by the reaction adheres to the inner wall of the reaction target chamber.
[0043] In order to avoid the introduction of impurities, the steps of filling the reaction target chamber with xenon-124 gas before the reaction include: The reaction target chamber is evacuated; The reaction target chamber is cooled by liquid nitrogen; The reaction target chamber is connected to the xenon-124 storage tank, and the xenon-124 gas is sucked into the cooled reaction target chamber, so that the pressure of the xenon-124 gas in the reaction target chamber is ≥3 MPa at room temperature. In the embodiment of the present invention, the pressure of the xenon-124 gas is 4.5 MPa.
[0044] S3: Inject distilled water into the reaction target chamber to elute the product of the photonuclear reaction, and obtain 123 I - of the dissolving liquid.
[0045] Distilled water can dissolve the iodine-123 attached to the wall of the reaction target chamber to form an iodine-123 solution, which contains 123 I - , open solenoid valves 7 and 17, and under the action of the vacuum pump, the dissolved liquid enters the mother liquid bottle No. 1.
[0046] In the embodiment of the present invention, the duration of irradiating the reaction target chamber with gamma photons is 4 hours, and the irradiation is stopped after 4 hours. After the irradiation is stopped, the xenon-123 generated by the reaction continues to decay into iodine-123. Therefore, in order to ensure sufficient reaction and obtain a higher yield of iodine-123, the following steps are also included after the irradiation is stopped and before distilled water is injected into the reaction target chamber to elute the photonuclear reaction products: Place the reaction target chamber in a lead tank and store it for 4 hours and 52 minutes; The reaction target chamber is connected with the gas recovery tank to transfer the gas in the reaction target chamber.
[0047] S4: The dissolved solution flows through a cation exchange resin to remove impurities and obtain an eluent.
[0048] The solution is passed through a cation exchange resin to remove cations and heavy metal impurity ions to obtain 123 I - In the embodiment of the present invention, the cation exchange resin is a 100-200 mesh Dowex50×8 cation exchange resin, and the cation exchange resin is placed in Φ 内 The cation exchange column is in a 3×50 mm cation exchange column, and the cation exchange column is connected to the No. 1 mother liquor bottle.
[0049] S5: The eluent flows through the anion exchange resin and adsorbs on the anion exchange resin 123 I - .
[0050] The eluent is adsorbed by anion exchange resin 123 I - In the embodiment of the present invention, the anion exchange resin is a 100-200 mesh Dowex 1×8 anion exchange resin, and the anion exchange resin is placed in Φ 内 In the 6×80mm anion exchange column, one end of the anion exchange column is connected to the cation exchange column, and the other end is connected to the No. 3 waste liquid bottle, which collects the adsorbed 123 I - After the solution.
[0051] S6: Elution with sodium hydroxide solution 123 I - anion exchange resin to obtain Na 123 I solution.
[0052] Adsorbed on anion exchange resin 123 I - Use 0.02 mol / L sodium hydroxide solution for elution. Before the sodium hydroxide solution flows into the anion exchange column, in order to prevent the oxidation of iodine anions during the preparation process, open the needle valves II, III, and IV to introduce helium to bubble and deoxygenate, so as to avoid 123 I -Oxidized.
[0053] In steps S4 to S6, the dissolved liquid is pumped into the mother liquid bottle No. 1 through the electromagnetic valve No. 7, and the electromagnetic valves No. 8, No. 9, and No. 18 and the vacuum pump and the waste liquid bottle No. 3 are opened to form a negative pressure, so that the dissolved liquid passes through the cation exchange column and the anion exchange column in sequence. After the flow column is completed, the above electromagnetic valves are closed, and the electromagnetic valves No. 2, No. 11, and No. 19 are opened at the same time to elute the anion exchange column with a 0.02M NaOH solution to make the product Na 123 Solution I was collected in product bottle No. 2.
[0054] Example 2 The difference between this embodiment and embodiment 1 is that the duration of irradiating the reaction target chamber with gamma photons is 3.5 hours.
[0055] Example 3 The difference between this embodiment and embodiment 1 is that the duration of irradiating the reaction target chamber with gamma photons is 3 hours.
[0056] Example 4 The difference between this embodiment and embodiment 1 is that the duration of irradiating the reaction target chamber with gamma photons is 2.5 hours.
[0057] Example 5 The difference between this embodiment and embodiment 1 is that the duration of irradiating the reaction target chamber with gamma photons is 2 hours.
[0058] Example 6 The difference between this embodiment and embodiment 1 is that the beam current intensity of the electron beam generated by the electron accelerator is 2 mA.
[0059] Example 7 The difference between this embodiment and embodiment 1 is that the beam current intensity of the electron beam generated by the electron accelerator is 2 mA, and the duration of irradiating the reaction target chamber with gamma photons is 3.5 h.
[0060] Example 8 The difference between this embodiment and embodiment 1 is that the beam current intensity of the electron beam generated by the electron accelerator is 2 mA, and the duration of irradiating the reaction target chamber with gamma photons is 3 hours.
[0061] Example 9 The difference between this embodiment and embodiment 1 is that the beam current intensity of the electron beam generated by the electron accelerator is 2 mA, and the duration of irradiating the reaction target chamber with gamma photons is 2.5 h.
[0062] Example 10 The difference between this embodiment and embodiment 1 is that the beam current intensity of the electron beam generated by the electron accelerator is 2 mA, and the duration of irradiating the reaction target chamber with gamma photons is 2 h.
[0063] After testing, the activity of iodine-123 prepared in Examples 1 to 10 can reach more than 50 mCi / mL, the chemical purity is >95%, and the radionuclear purity is <10 -6 , chemical impurities <1μg / mL, its nuclear purity is high, no other radionuclides were found to be radioactive, and its chemical purity meets medical requirements.
[0064] The activity of iodine-123 after different beam intensities and different irradiation times of the above xenon-124 gas at a pressure of 4.5 MPa is shown in the following table, where t0 is the irradiation time, I b is the beam intensity: t0(h)Ib(mA) 2.0 2.5 3.0 3.5 4.0 2 7.14Ci 8.913Ci 10.67Ci 12.43Ci 14.16Ci 3 10.71Ci 13.37Ci 16.01Ci 18.64Ci 21.25Ci Increasing the beam intensity or raising the gas pressure can further increase the activity of iodine-123.
[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A process for preparing medical radioactive nuclide iodine-123 using an electron accelerator, characterized in that: The following steps are involved: The electron accelerator generates an electron beam that bombards the tungsten target and converts the electron beam into gamma photons; The gamma photons irradiate a reaction target chamber filled with xenon-124 gas to perform a photonuclear reaction; Distilled water is injected into the reaction target chamber to elute the product of the photonuclear reaction, 123 I - of the dissolving liquid; The dissolved solution flows through a cation exchange resin to remove impurities and obtain an eluent; The eluent flows through an anion exchange resin, and adsorbs 123 I - ; Desorption with sodium hydroxide solution 123 I - The anion exchange resin is used to obtain Na 123 I solution.
2. The process for preparing medical radioactive nuclide iodine-123 using an electron accelerator according to claim 1, characterized in that: The step of filling the reaction target chamber with xenon-124 gas comprises: The reaction target chamber is evacuated; Cooling the reaction target chamber using liquid nitrogen; The reaction target chamber is connected to a xenon-124 storage tank, and xenon-124 gas is sucked into the cooled reaction target chamber, so that the pressure of the xenon-124 gas in the reaction target chamber is ≥3MPa at room temperature, and the purity of the xenon-124 gas is ≥99.5%.
3. The process for preparing medical radioactive nuclide iodine-123 using an electron accelerator according to claim 1, characterized in that: Before injecting distilled water into the reaction target chamber to elute the product of the photonuclear reaction, the method further comprises: placing the reaction target chamber in a lead can and storing it for several hours according to the duration of the gamma photon irradiation; The reaction target chamber is connected to a gas recovery tank to transfer the gas in the reaction target chamber.
4. The process for preparing medical radioactive nuclide iodine-123 using an electron accelerator according to claim 1, characterized in that: The cation exchange resin is a Dowex 50×8 cation exchange resin with a mesh size of 100 to 200, and the anion exchange resin is a Dowex 1×8 anion exchange resin with a mesh size of 100 to 200.
5. The process for preparing medical radioactive nuclide iodine-123 using an electron accelerator according to claim 2, characterized in that: The reaction target chamber is a stainless steel cylindrical tube that can withstand 6.0 MPa, and the gamma photons are irradiated along the axis of the stainless steel cylindrical tube.
6. The process for preparing medical radioactive nuclide iodine-123 using an electron accelerator according to claim 1, characterized in that: The concentration of the sodium hydroxide solution is 0.02 mol / L.
7. The process for preparing medical radioactive nuclide iodine-123 using an electron accelerator according to claim 3, characterized in that: The gamma photons irradiate the reaction target chamber for 2 to 4 hours.
8. The process for preparing medical radioactive nuclide iodine-123 using an electron accelerator according to claim 1, characterized in that: The thickness of the tungsten target is 2-8 mm.
9. The process for preparing medical radioactive nuclide iodine-123 using an electron accelerator according to claim 1, characterized in that: The electron beam energy generated by the electron accelerator is 43-50 MeV, the beam current intensity is 2.0-2.5 mA, the beam pulse width is 12 μs, and the repetition frequency is 390 pps.