JPH0640160B2 - Target device for manufacturing radioisotope 18F - Google Patents

Description

TECHNICAL FIELD The present invention relates to a target device for producing radioisotope ¹⁸ F, and more particularly to Al ₂ ¹⁸ O ₃ or Si ¹⁸ formed from a solid isotope in a target chamber. The present invention relates to an economically advantageous target device for producing ¹⁸ F radioisotope, which is capable of encapsulating O ₂ as a target substance and repeatedly using the target substance.

2. Description of the Related Art Among radioactive isotopes having a half-life of up to 2 to 3 days, a radiopharmaceutical containing a radioactive isotope is used for medical purposes. Among them, the radioisotope ¹⁸ F, which has an extremely short half-life of 109 minutes and is extremely chemically reactive, is suitable for the above purpose, and is actually used as a raw material of a diagnostic drug in an aqueous solution state.

Conventionally, as a method for producing such an aqueous solution of radioisotope ¹⁸ F, a target solution is irradiated with an ion beam generated by a cyclotron and is produced through a nuclear reaction ( ¹⁸ O (P, n) ¹⁸ F). However, the irradiation of the ion beam causes the target solution to generate heat and boils the target, and thus there is a limit to the improvement of the yield and yield of the obtained radioisotope ¹⁸ F.

Therefore, the inventors of the present invention, as an improved method of such a conventional method, forcedly circulate the target in the system, continuously irradiate the circulating target with an ion beam, and cool the target liquid after the irradiation. In order to prevent boiling of the target liquid and continuously synthesize the radioactive isotope (see Japanese Patent Laid-Open No. 60-3600), a device was proposed.

Problems to be Solved by the Invention However, since a target substance such as H ₂ ¹⁸ O used as a target substance in the above-mentioned device is a very expensive substance, H ₂ ¹⁸ O may be effectively used in the above-mentioned device. In addition, a small amount of H ₂ ¹⁸ O must be irradiated with protons at the expense of yield, or a complicated recovery operation must be performed to recover and reuse H ₂ ¹⁸ O from the target solution after the reaction. did not become.

Means for Solving the Problems The present invention has been made in view of the above points, and a target chamber is provided on one side through a partition wall of a target body,
A cooling chamber is formed on the opposite side, the target liquid supply pipeline and the discharge pipeline are communicated with the target chamber, and Al ₂ ¹⁸ O ₃ or Si ¹⁸ O _{2 in} a granular or porous state is formed in the target chamber. A solid target is filled, the solid target is irradiated with a proton beam, and the radioisotope ¹⁸ F generated by the nuclear reaction is dissolved in the target liquid supplied from the target liquid supply pipe and collected. The target device for the production of radioisotope ¹⁸ F.

EXAMPLE An example of the target device for producing the radioactive isotope ¹⁸ F of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a side sectional view of a target device for producing radioisotope ¹⁸ F according to an embodiment of the present invention, and FIG. 2 is a forced circulation type using the target device for producing radioisotope ¹⁸ F according to the present invention. 2 is a flow chart showing the overall configuration of a continuous radioisotope ¹⁸ F synthesizer.

In FIG. 1, reference numeral 1 is a target chamber filled with a target 2 of Al ₂ ¹⁸ O ₃ granules having a particle size of 100 μm or less. The target chamber 1 has a partition wall 3 at the center of the inner cylinder.
It is a void portion sandwiched by a cylindrical target body 3 partitioned by a and a cylindrical flange 5 having an outer diameter smaller than that of the target body 3 and fastening the target body 3 with bolts 4a4b.

The central portion of the cylindrical flange 5 forming the void is opened so as to receive the irradiation of the proton beam 6 from the cyclotron or the like, and the opening 5a is formed. Further, a foil retainer 7 is fitted on the target body 3 side.

In addition, the other target body 3 that constitutes the void portion
Is provided with a cooling chamber 9 on the opposite side (on the right side in the drawing) of receiving the irradiation of the proton beam 6 from the cyclotron, and a cooling chamber 9 is formed for supplying cooling water to the lid 8. A pipe joint 10a and a pipe joint 10b for discharging it are formed.

Further, pipe lines 11a and 11b for supplying and discharging the target liquid to and from the target chamber 1 in the void are formed on the upper side and the lower side of the target body 3, respectively.
The target pipe joints 12a and 12b are respectively screwed to communicate with. Filters 13a and 13b are arranged at the ends of the pipe joints 12a and 12b, respectively, and further, a heat exchanger 14, a buffer tank 15, a shrink pump 16 and the like are arranged at the ends thereof, and both of them are arranged. Connected at the end and circulating circuit 1
Make up 7.

The side of the cylindrical flange 5 and the target body 3 which receives the irradiation of the proton beam 6 from the cyclotron (left side in the figure)
A metal thin film 18 made of aluminum, stainless steel or the like having a thickness of 10 to 40 .mu.m, preferably 20 .mu.m is mounted between the metal thin film 18 and the foil holder 7 on the flange 5 side and the target O on the target body 3 side. The metal thin film 18 is tightly stretched by being sandwiched by the rings 19, and the target liquid in the target chamber 1 does not leak to the outside.

The target chamber 1 may be filled with solid isotope particles such as Al ₂ ¹⁸ O ₃ or Si ¹⁸ O ₂ in the target chamber, or may be formed into a porous body according to the shape of the chamber. It is enclosed.

The target device for producing the radioisotope ¹⁸ F thus configured is fitted into the proton beam irradiation port 20 by the mounting O-ring 21 attached to the outer diameter of the cylindrical flange 5, and the proton beam 6 from the cyclotron is attached. Is irradiated. The accelerated proton beam 6 is the injection opening of the flange.
5a, then through the slit 7a of the foil retainer 7,
Further, the solid target such as Al ₂ ¹⁸ O ₃ or Si ¹⁸ O ₂ that has passed through the metal thin film 18 such as the aluminum foil of 10 to 40 μm and is immersed in the target liquid in the target chamber 1 is irradiated with the nucleus to irradiate the target. Cause a reaction. In order to remove the heat generated thereby, the target chamber 1
The heat inside the target chamber 1 is removed by flowing a cooling liquid into a cooling chamber 9 formed on the opposite side (right side in the drawing) of the injection opening 5a.

On the other hand, the radioactive isotope ¹⁸ F produced by the nuclear reaction is taken out of the target chamber 1 by circulating the target liquid and then separated in the circulation system. At that time, the powder particles of the solid target 2 mixed with the target liquid are separated by the filter 13b so as not to be discharged from the target chamber 1.

In addition, the target device for producing the radioisotope ¹⁸ F and the circulation system attached to the target device can withstand a pressure of 2 to 3 atm because a decomposed gas is generated due to heat generated by a nuclear reaction or vapor is generated. It is a pressure container like this.

As a circulation system, there is a forced circulation type radioisotope ¹⁸ F continuous synthesis device 22 and the like shown in FIG. 2, and the target liquid containing the radioisotope ¹⁸ F produced by irradiation in the device is discharged from the target chamber 1. Then, it is further cooled by the heat exchanger 14, separated into steam and water in the buffer tank 15, and then temporarily held.

When an abnormal reaction occurs, the safety valve 25 operates and is guided to the safety device.

A liquid level sensor 26 is attached to the buffer tank 15 to control the liquid level.
The target solution stored in the target chamber 1 is recirculated to the target chamber 1 by passing through the one-way valves 17a and 17b and the solenoid valves 23b and 23c by the operation of the shrink pump 16. The shrinkage pump 16 sends the air sent from the compressor to the double-acting air cylinder 27 by alternately opening and closing the solenoid valves 23d and 23e to actuate the piston 28 to the left and right to act as a piston on the side of the shrinkage pump 16. The target liquid is circulated by interlocking with the connected piston rod 29.

The target circulating liquid is fed from the re solenoid valve 23g was recovered by the circulation outside by opening the solenoid valve 23f for separating and recovering the radioactive isotope ¹⁸ F generated by the proton beam irradiation.

The methods for separating and recovering the radioisotope ¹⁸ F are as follows.

After irradiating the solid target 2 for a certain period of time, the target circulating liquid is supplied from the solenoid valve 23g and irradiation is performed again together with the liquid circulation, and the produced radioisotope ¹⁸ F is recovered in the target circulating liquid.

-Irradiate the solid target while circulating the target circulating fluid, and collect the target circulating fluid after the irradiation. On this occasion,
Since the irradiation beam is consumed by the target circulating fluid,
The yield is poor but the operation is simple.

-Use only the device shown in Fig. 1 without using the circulation system shown in Fig. 2. That is, after irradiating the solid target 2 for a certain period of time,
Water or the like is introduced into the target chamber 1 and the rear portions of 13a and 13b are closed by a solenoid valve or the like. Irradiation is again performed in this state, and the radioisotope ¹⁸ F dissolved in water is recovered by N ₂ purge or the like.

For example, water is used as the target circulating liquid.

Further, in order to improve the yield, it is recommended to mount the ultrasonic generator 30 on the lid 8 of the cooling chamber and apply ultrasonic vibration to the target chamber 1.

Effects of the Invention As described in detail in the above examples and the like, by enclosing solid Al ₂ ¹⁸ O ₃ or Si ¹⁸ O ₂ in the target chamber and circulating the target liquid and irradiating with a proton beam,
Since the target substance can be repeatedly used, an expensive target substance can be saved, and an economically advantageous target device for producing ¹⁸ F radioisotope can be provided.

As described above, the present invention can exert an excellent effect which has never been seen in the past, and it greatly contributes to the field.

[Brief description of drawings]

FIG. 1 is a sectional view of a target device for producing radioisotope ¹⁸ F according to an embodiment of the present invention, and FIG. 2 is a forced circulation type radioisotope using the target device for producing radioisotope ¹⁸ F of the present invention. It is a flowchart which shows the whole structure of an elemental ¹⁸ F continuous synthesis apparatus. 1: Target chamber 2: Solid target 3: Target body 4a, 4b: Bolt 5: Cylindrical flange 5a: Opening part 6: Proton beam 7: Foil presser 7a: Foil presser opening 9: Cooling chamber 13a, 13b: Filter 14: Heat exchanger 15: Buffer tank 16: Shrink pump 17: Circulation system 18: Metal thin film 19: Target O-ring 20: Proton beam irradiation port 21: Mounting O-ring 22: Radioactive isotope ¹⁸ F continuous synthesizer 25 : Safety valve 26: Liquid level sensor 27: Double acting air cylinder 28: Piston 30: Ultrasonic generator

Claims (1)

[Claims] 1. A target chamber (1) is formed through a partition wall (3a) of a target body (3) on one side, and a cooling chamber (9) is formed on the opposite side, and a target liquid is stored in the target chamber (1). The supply pipe (11a) and the discharge pipe (11b) are connected to each other, and the target chamber (1) is filled with a granular or porous solid target (2) of Al ₂ ¹⁸ O ₃ or Si ¹⁸ O _2. Then, the solid target (2) is irradiated with a proton beam (6), and the radioisotope ¹⁸ F produced by the nuclear reaction is dissolved in the target liquid supplied from the target liquid supply pipe (11a). A target device for producing radioisotope ¹⁸ F, which is characterized by being recovered.