JP4885809B2 - O gas recovery device and O gas recovery method - Google Patents

Description

The present invention relates to an apparatus and method for recovering ¹⁸ O gas from a target unit that generates radioactive isotopes by irradiating ¹⁸ O gas with accelerated particles.

Positron tomography (PET) is a medical imaging technique for measuring the concentration of a positron radiopharmaceutical in a living subject. In PET treatment, a radiopharmaceutical such as FDG is administered into the bloodstream of a subject, and then the distribution of positron radioactivity released from the radiopharmaceutical in vivo is imaged by emission tomography. When the subject's tissue interacts with the radiopharmaceutical, a computer reconstruction technique is performed to obtain a tomographic image of the tissue. Radiopharmaceuticals used in PET procedures are produced, for example, by the synthesis of [ ¹⁸ F] F ₂ radioisotopes. [ ¹⁸ F] F ₂ is generated by, for example, an apparatus described in Patent Documents 1 to 3.

These apparatuses supply ¹⁸ O gas to a target unit and irradiate the ¹⁸ O gas with a proton beam generated by a cyclotron. ^{When the 18} O gas collides with the proton beam, it undergoes a nuclear reaction and becomes ¹⁸ F (−) ions and adheres to the wall surface of the target portion. Thereafter, F ₂ gas that has not been activated is introduced into the target portion and irradiated with a proton beam again. Then, ¹⁸ F (−) ions attached to the wall surface are replaced with F ₂ to become [ ¹⁸ F] F ₂ , and are collected together with He gas or the like. The ¹⁸ O gas used when producing [ ¹⁸ F] F ₂ is rare and expensive. In view of this, each of the above-described apparatuses is equipped with a recovery cylinder for appropriately recovering and repeatedly using ¹⁸ O gas. The recovery cylinder communicates with the target unit, and when the recovery cylinder is cooled with liquid nitrogen, the ¹⁸ O gas becomes the boiling point or less and becomes a liquefied state. Then, a differential pressure is generated between the recovery cylinder and the target portion, and ¹⁸ O gas is sucked and recovered from the target portion.
Special table 2003-524787 gazette JP 2006-3362 A JP 2006-3363 A

However, since the conventional apparatus only recovers ¹⁸ O gas using the differential pressure between the target portion and the recovery cylinder, ¹⁸ O gas tends to remain in the target portion and the pipe line. In particular, as the conduit for collecting the ^{18 O} gas becomes narrower, or, since the higher the ^{18 O} gas conduit is longer easily remaining conduit, the diameter and length of the pipe, ^{18 O} gas The recovery efficiency was easy to decrease.

The object of the present invention is to solve the above problems, and to provide an O gas recovery apparatus and an O gas recovery method that can improve the recovery efficiency of ¹⁸ O gas.

In the present invention, ¹⁸ O gas is supplied to a target unit that irradiates ¹⁸ O gas with accelerated particles to generate a radioisotope, and ¹⁸ O gas is liquefied and stored, thereby storing ¹⁸ O gas from the target unit. In the O gas recovery apparatus including the unit, the target unit and the storage unit communicate with each other, the first line through which ¹⁸ O gas flows bidirectionally, the second line that bypasses the first line, And a pump for transferring ¹⁸ O gas from the target portion toward the storage portion.

In this O gas recovery apparatus, ¹⁸ O gas is supplied from the storage unit to the target unit via the first line. Further, the ¹⁸ O gas is liquefied and stored in the storage unit, whereby the ¹⁸ O gas is sucked and recovered from the target unit via the first line. Furthermore, even if ¹⁸ O gas remains in the target portion, the remaining ¹⁸ O gas can be forcibly recovered through the second line by driving the pump. As a result, the recovery efficiency of ¹⁸ O gas can be improved without being affected by the thickness and length of the pipe line.

Further, the first line is arranged between the first branch part on the storage part side, the second branch part on the target part side, and between the first branch part and the second branch part. And the second line is connected to the first branch portion and the second branch portion, and is disposed closer to the first branch portion than the pump. And a second sub-valve arranged on the second branch portion side of the pump. With such a configuration, the opening and closing of the first line and the second line can be adjusted by adjusting the first main valve, the first sub valve, and the second sub valve. Then, when storing ¹⁸ O gas in a liquefied state in the storage unit and collecting ¹⁸ O gas from the target unit, the first subvalve and the second subvalve are closed and the first main valve is opened, When the pump is driven, ¹⁸ O gas can be reliably recovered by closing the first main valve and opening the first sub valve and the second sub valve.

Furthermore, it further includes a third line for replenishing ¹⁸ O gas, and the first line includes a second main valve disposed between the second branch portion and the target portion, a first main valve, And a third branch portion provided between the second branch portion and the third line is preferably connected to the third branch portion. According to such a structure, when ¹⁸ O gas is replenished to a storage part via a 3rd line, a 1st main valve and a 2nd main valve are closed, and a 1st subvalve and a 2nd By opening the auxiliary valve and driving the pump, the ¹⁸ O gas can be reliably replenished.

Moreover, in the oxygen gas recovery method for recovering ^{18 O} gas from the target portion is irradiated with accelerated particles ^{18 O} gas generating radioisotopes in reservoir to contact the target portion via the first line ¹⁸ O gas cooled to below the boiling point, and recovering the ^{18 O} gas in the target portion liquification of ^{18 O} gas, and the step of closing the first line is disposed on a second line which bypasses the first line And driving the pump to transfer the ¹⁸ O gas remaining in the target part to the storage part via the second line.

According to this O gas recovery method, the ¹⁸ O gas is cooled below the boiling point in the storage unit, and after the ¹⁸ O gas in the target unit is recovered by liquefaction of the ¹⁸ O gas, the first line is closed and the pump is driven. Therefore, the load for collecting ¹⁸ O gas by the pump is reduced, and ¹⁸ O gas can be efficiently collected.

According to the O gas recovery apparatus and the oxygen gas recovery method of the present invention, the recovery efficiency of ¹⁸ O gas remaining in the target portion can be improved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a view showing an O gas recovery apparatus according to the present invention. As shown in FIG. 1, the O gas recovery apparatus 1 irradiates [ ¹⁸ O] O ₂ (hereinafter referred to as “ ¹⁸ O gas”) with a proton beam (accelerated particles) and is a radioactive isotope [ ¹⁸ F ] F ₂ (hereinafter referred to as “ ¹⁸ F gas”). The target unit 3 includes a reaction chamber that stores ¹⁸ O gas, a reaction chamber window that transmits a proton beam into the reaction chamber, and a wall portion to which ¹⁸ F (−) ions generated in the reaction chamber adhere. . The volume of the reaction chamber of the target unit 3 is about 90 cc, and is formed of aluminum, silver, nickel, gold-plated copper, or the like.

O gas recovery apparatus 1, together with the stores to liquefy the ^{18 O} gas, a storage unit 5 for supplying the target portion 3 to the ^{18 O} gas, such pipes and valves for communicating the storage unit 5 and the target portion 3 is provided The gas flow part 7 is provided. The storage means 5 is disposed in the first shield chamber 9 shielded by lead or the like, and the main part of the gas flow part 7 is disposed in the second shield chamber 11 shielded by lead or the like.

The storage means 5 includes a recovery cylinder (storage part) 13 for storing ¹⁸ O gas, a dewar bottle 15 for storing liquid nitrogen, and a lowering of the recovery cylinder 13 to immerse the liquid nitrogen in the dewar bottle 15 and recover it. A cylinder-type drive mechanism 17 that raises the cylinder 13 and pulls it up from the liquid nitrogen is provided. When the recovery cylinder 13 is immersed in liquid nitrogen, the ¹⁸ O gas in the recovery cylinder 13 is cooled and liquefied.

The gas flow unit 7 includes a main line (first line) 19 that connects the recovery cylinder 13 and the target unit 3, an ¹⁸ F gas recovery line 25 for recovering ¹⁸ F gas from the target unit 3, and a target unit 3 is provided with an auxiliary line 27 for supplying Ar gas or 2% F ₂ / Ar gas or evacuating the target unit 3 or the main line 19. Further, the gas flow section 7 includes a bypass line (second line) 21 that bypasses the main line 19 and a replenishment line (third line) 23 for replenishing the recovery cylinder 13 with ¹⁸ O gas. ing. The pipes used for the main line 19, ¹⁸ F gas recovery line 25, auxiliary line 27, bypass line 21 and replenishment line 23 are stainless steel pipes having a diameter of about 20 mm to 70 mm.

  The main line 19 can be divided into a first piping part 19a, a second piping part 19b, a third piping part 19c, and a fourth piping part 19d in order from the side close to the recovery cylinder 13. A part of the first piping part 19 a is exposed from the second shield chamber 11 and connected to the recovery cylinder 13. A part of the fourth piping part 19 d is exposed from the second shield chamber 11 and connected to the target part 3.

  A first branch part 19e is formed between the first pipe part 19a and the second pipe part 19b, and a second branch part 19f is provided between the third pipe part 19c and the fourth pipe part 19d. Is formed. The end of the bypass line 21 on the recovery cylinder 13 side is connected to the first branch part 19e, and the end of the bypass line 21 on the target part 3 side is connected to the second branch part 19f. A third branch 19g is formed between the second pipe 19b and the third pipe 19c, and the downstream end of the replenishment line 23 is connected to the third branch 19g. .

  The first piping part 19a is provided with a first electric valve 19h, and the second piping part 19b is provided with a normally closed first control valve (first main valve) 19j. The third piping part 19c is provided with a molecular sieve 19k.

  A fourth branch portion 19m and a fifth branch portion 19n are formed in the fourth piping portion 19d. The fourth branch portion 19m is arranged closer to the target portion 3 than the fifth branch portion 19n. A normally closed fifth control valve (second main valve) 19p and a pressure gauge 19r are provided at the end of the fourth piping portion 19d on the target portion 3 side. The fifth control valve 19p and the pressure gauge 19r are provided so as to be exposed from the second shield chamber 11.

^{The 18} F gas recovery line 25 is connected to the fourth branch portion 19m. ^{The 18} F gas recovery line 25 is provided with a normally closed second control valve 25a, a pressure reducing valve 25b that holds a set pressure of 0.2 MPa to 0.3 MPa, and a mass flow controller 25c.

The incidental line 27 is connected to the fifth branch portion 19n. The auxiliary line 27 has a suction line 29 for evacuating the target unit 3 and the main line 19. The suction line 29 is connected to a first gas supply line 31 that supplies Ar gas, and is further connected to a second gas supply line 33 that supplies 2% F ₂ / Ar gas.

  The suction line 29 is provided with a normally closed control valve, a soda lime section for drying, and the like. A vacuum pump 30 is connected to the downstream end of the suction line 29. By driving the vacuum pump 30, the target unit 3 and the main line 19 are evacuated through the suction line 29.

The first gas supply line 31 is connected to an Ar gas supply unit 32, and further includes a check valve, a normally closed control valve, a pressure gauge, and the like. Ar gas of 1 MPaG to 1.5 MPaG is supplied to the target unit 3 through the first gas supply line 31. The second gas supply line 33 is connected to a 2% F ₂ / Ar gas supply unit 34, and further includes a check valve, a normally closed control valve, a pressure gauge, and the like. 2% F ₂ / Ar gas of 0.2 MPaG to 2 MPaG is supplied to the target unit 3 through the second gas supply line 33.

The bypass line 21 is provided with a diaphragm pump (pump) 35. The diaphragm pump 35 transfers ¹⁸ O gas from the second branch portion 19 f side close to the target portion 3 toward the first branch portion ¹⁹ e side close to the recovery cylinder 13. The bypass line 21 is provided with a normally closed third control valve (second auxiliary valve) 21a on the side closer to the second branch portion 19f than the diaphragm pump 35. A normally closed fourth control valve (first subvalve) 21b is provided on the side close to the branch portion 19e.

The downstream end portion of the replenishment line 23 is connected to the third branch portion 19 g of the main line 19, and the upstream end portion is connected to the ¹⁸ O gas supply cylinder 36. The replenishment line 23 is provided with a second motor operated valve 23a. Note that the third branch portion 19g to which the replenishment line 23 is connected is formed between the first control valve (first main valve) 19j and the fifth control valve (second main valve) 19p in the main line 19. It is provided in between.

  The O gas recovery apparatus 1 includes an electromagnetic valve 37 and a control unit 39 for driving air. The electromagnetic valve 37 is provided on an air supply line connected to the first control valve 19j, the second control valve 25a, the third control valve 21a, the fourth control valve 21b, and the cylinder-type drive mechanism 17. The control valve 19j, 25a, 21a, 21b is opened and closed and the cylinder drive mechanism 17 is driven by opening and closing the electromagnetic valve 37. The control unit 39 is connected to a solenoid valve 37, a first motor operated valve 19h, a second motor operated valve 23a, a diaphragm pump 35, a control valve provided in the auxiliary line 27, and the like, and drive control of the diaphragm pump 35, Opening / closing control of the first and second electric valves 19h, 23a, opening / closing control of the auxiliary line 27, and the like are performed.

Next, supply of ¹⁸ O gas to the target unit 3 by the O gas recovery device 1, generation of ¹⁸ F (−) ions at the target unit 3, liquefaction recovery of ¹⁸ O gas from the target unit 3, The pump recovery of the remaining ¹⁸ O gas, the generation of ¹⁸ F gas at the target unit 3, and the recovery of ¹⁸ F gas will be described in order.

(Supply of ¹⁸ O gas)
As shown in FIG. 2, the control unit 39 opens the fifth control valve 19p and closes the second electric valve 23a (first step). As a result, the main line 19 is opened. The main line 19 is appropriately evacuated via a suction line 29.

Next, the control unit 39 opens the first motor-operated valve 19h and the first control valve 19j, drives the cylinder-type drive mechanism 17, and pulls up the recovery cylinder 13 from the liquid nitrogen in the Dewar bottle 15. As a result, ¹⁸ O that was in the liquid phase becomes ¹⁸ O gas in a gaseous state, and is supplied to the target unit 3 by volume expansion (see the white arrow in FIG. 2). The control unit 39 monitors the pressure gauge 19r and the like, and closes the fifth control valve 19p and the like when the inside of the target unit 3 reaches a predetermined pressure (second step).

(Production of ¹⁸ F (-) ions)
When the supply of ¹⁸ O gas to the target unit 3 is completed, for example, a 16.5 MeV proton beam generated in a cyclotron (not shown) is irradiated to the ¹⁸ O gas in the target unit 3 (third step). . Within the target portion ^{3, 18 O (p, n} ) 18 F nuclear reaction by ¹⁸ F (-) ions are ^generated, 18 F (-) ions attached to the wall portion provided in the target unit 3. After irradiating the proton beam for a predetermined time, for example, about 45 minutes, the proton beam irradiation is stopped (fourth step).

( ¹⁸ O gas liquefaction recovery)
As shown in FIG. 3, the control unit 39 opens the fifth control valve 19 p, drives the cylinder drive mechanism 17, soaks the collection cylinder 13 in the liquid nitrogen of the Dewar bottle 15, and cools the ¹⁸ O gas. And lower than the boiling point (fifth step). Then, the ¹⁸ O gas in the recovery cylinder 13 becomes a liquefied state, and a negative pressure is generated in the recovery cylinder 13. As a result, the differential pressure between the recovery cylinder 13 and the target unit 3 becomes, for example, about 30 kPa, and the ¹⁸ O gas remaining in the target unit 3 flows through the main line 19 and enters the recovery cylinder 13. It is collected (see white arrow in FIG. 3).

⁽¹⁸ pump recovery of O gas)
Most of the ¹⁸ O gas is recovered by the differential pressure between the recovery cylinder 13 and the target unit 3. However, ¹⁸ O gas still remains in the recovery cylinder 13, and pump recovery is performed to forcibly recover the residual ¹⁸ O gas.

  First, the control unit 39 closes the first control valve 19j, and instead opens the third control valve 21a and the fourth control valve 21b (sixth step). As a result, the main line 19 is closed and the bypass line 21 is opened.

Next, as shown in FIG. 1, the control unit 39 drives the diaphragm pump 35 to forcibly suck ¹⁸ O gas remaining in the target unit 3 and transfer it to the recovery cylinder 13 (seventh). Step). As a result, most of the ¹⁸ O gas remaining in the target unit 3 can be recovered (see the white arrow in FIG. 1), and the ¹⁸ O gas recovery efficiency can be dramatically improved.

(Production and recovery of ¹⁸ F gas)
^When the recovery of ¹⁸ O gas is completed, the control unit 39 closes the third control valve 21a and the fourth control valve 21b and closes the bypass line 21, and the control unit 39 sets the second gas supply line 33 and the first gas. The supply line 31 is opened, and 2% F ₂ / Ar gas and Ar gas as a carrier gas are simultaneously supplied into the target unit 3 (eighth step).

When 2% F ₂ / Ar gas and Ar gas are supplied into the target unit 3, the control unit 39 closes the fifth control valve 19 p and the like. Then, the target unit 3 is again irradiated with a proton beam (9th step). By simultaneously supplying 2% F ₂ / Ar gas that has not been activated into the target portion 3 and Ar gas as a carrier gas, ¹⁸ F (−) ions adhering to the wall portion are replaced with F _2. ¹⁸ F gas. Furthermore, this replacement is facilitated by irradiation with a proton beam.

Thereafter, the control unit 39 opens the ¹⁸ F gas recovery line 25 by closing the first gas supply line 31 and the second gas supply line 33, the ¹⁸ F gas generated in the target unit 3 for collecting (10 of Step).

In the above O gas recovery method, in addition to the liquefaction recovery of ¹⁸ O gas, forcible recovery is performed by the diaphragm pump 35, and highly rare ¹⁸ O gas can be efficiently recovered in the recovery cylinder 13.

In particular, in the above O gas recovery method, ¹⁸ O gas remaining in the target unit 3 is recovered by driving the diaphragm pump 35 after recovering ¹⁸ O gas in the target unit 3 using the differential pressure between the recovery cylinder 13 and the target unit 3. Therefore, the driving load of the diaphragm pump 35 can be reduced.

( ¹⁸ O gas replenishment method)
Next, a replenishment method when the ¹⁸ O gas in the recovery cylinder 13 is reduced will be described. As shown in FIG. 4, when the ¹⁸ O gas is replenished, the control unit 39 opens the first motor operated valve 19 h and the first control valve 19 j of the main line 19, and the second recharge line 23. The motorized valve 19j is opened (first step). In this state, the replenishment line 23 is opened.

Next, immersed collection cylinder 13 in Dewar 15, liquefied cooled to ¹⁸ O gas, by opening the refill line ^{23, 18} O gas replenishment toward the ¹⁸ O gas supply cylinder 36 to the collecting cylinder 13 Is done.

Further, when the amount of ¹⁸ O gas in the recovery cylinder 13 is insufficient, the control unit 39 closes the first control valve 19j and opens the third control valve 21a and the fourth control valve 21b. The bypass line 21 is opened (third step). Next, the control unit 39 drives the diaphragm pump 35 to suck ¹⁸ O gas from the ¹⁸ O gas supply cylinder 36 and transfer the ¹⁸ O gas to the recovery cylinder 13 (fourth step). As a result, ¹⁸ O gas can be efficiently replenished (see the white arrow in FIG. 4).

In the O gas recovery apparatus 1 described above, ¹⁸ O gas is supplied from the recovery cylinder 13 to the target unit 3 via the main line 19. In the recovery cylinder 13, ¹⁸ O gas is liquefied and stored, and ¹⁸ O gas is sucked and recovered from the target unit 3 through the main line 19. Furthermore, even if ¹⁸ O gas remains in the target portion 3, the remaining ¹⁸ O gas can be forcibly recovered through the bypass line 21 by driving the diaphragm pump 35. As a result, the recovery efficiency of ¹⁸ O gas can be improved.

In the present embodiment, the ¹⁸ O gas recovery efficiency depends on the capacity (attainment pressure) of the diaphragm pump 35. For example, the internal pressure of the target portion 3 when the diaphragm pump 35 is not driven is 0.2 MPaG. Assuming that the ultimate pressure of the diaphragm pump 35 is −0.05 MPaG, for example, if the capacity of the target unit 3 is 0.1 L, 0.25 NL of ¹⁸ O gas is obtained each time as shown in the following formula (1). Can be recovered.

  (0.2MPaG − (− 0.05MPaG)) / 0.1 × 0.1L = 0.25NL (1)

Further, in the O gas recovery apparatus 1, ¹⁸ F gas is recovered by utilizing the fourth piping portion 19d that is a part of the main line 19 where ¹⁸ O gas is supplied and recovered. When ¹⁸ O gas is recovered using the differential pressure between the recovery cylinder 13 and the target unit 3, the ¹⁸ O gas recovery efficiency increases as the diameter of the fourth pipe portion 19d increases. On the other hand, the fourth pipe unit 19d is because it is also used in the recovery of ^{18 F} gas, the diameter increases, recovery loss of ^{18 F} gas accompanying the deposition of the ^{18 F} gas is increased. However, in the O gas recovery apparatus 1, since the forced recovery of ¹⁸ O gas by the diaphragm pump ^35, without lowering the recovery efficiency of ¹⁸ O gas, can reduce the diameter of the fourth pipe portion ^{19d, 18} O Both improvement in gas recovery efficiency and reduction in loss of ¹⁸ F gas can be achieved.

  The present invention is not limited to the above embodiment. For example, the pump provided in the second line is not limited to a diaphragm pump, and any pump that can transfer gas can be used.

It is a figure which shows the O gas collection | recovery apparatus concerning 1st Embodiment of this invention, and shows the time of ¹⁸ O gas pump collection | recovery. It is a figure which shows an O gas collection | recovery apparatus and shows the time of supply of ¹⁸ O gas. It is a figure which shows O gas collection | recovery apparatus and shows the time of liquefaction collection | recovery of ¹⁸ O gas. It is a figure which shows an O gas collection | recovery apparatus and shows the time of ¹⁸ O gas replenishment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... O gas collection | recovery apparatus, 3 ... Target part, 13 ... Recovery cylinder (storage part), 19 ... Main line (1st line), 19e ... 1st branch part, 19f ... 2nd branch part, 19g ... 3rd branch part, 19j ... 1st control valve (1st main valve), 19p ... 5th control valve (2nd main valve), 21 ... Bypass line (2nd line), 21a ... 2nd 3 control valves (second sub-valve), 21b... Fourth control valve (first sub-valve), 23... Refilling line (third line), 35.

Claims (4)

¹⁸ with ^O gas is irradiated with accelerated particles to supply the ^{18 O} gas to the target portion to generate a radioactive isotope, reservoir for sucking the ^{18 O} gas from the target portion by liquefying storing the ^{18 O} gas In the O gas recovery device provided with a section,
A first line that communicates the target unit and the storage unit, and the ¹⁸ O gas flows bidirectionally;
A second line that bypasses the first line;
A pump that is disposed on the second line and that transfers the ¹⁸ O gas from the target portion toward the storage portion;
An O gas recovery device comprising: The first line is
A first branch portion on the storage portion side, a second branch portion on the target portion side, a first main valve disposed between the first branch portion and the second branch portion; Have
The second line is connected to the first branch part and the second branch part, and is arranged on the first branch part side of the pump, and the pump 2. The O gas recovery device according to claim 1, further comprising: a second sub valve disposed closer to the second branch portion than the second sub valve. A third line for replenishing the ¹⁸ O gas;
The first line is provided between a second main valve disposed between the second branch portion and the target portion, and between the first main valve and the second branch portion. And a third branch part,
The O gas recovery apparatus according to claim 2, wherein the third line is connected to the third branch portion. ^In the oxygen gas recovery method of recovering the ¹⁸ O gas from a target portion that generates radioactive isotopes by irradiating ¹⁸ O gas with accelerated particles,
A step of the ^{18 O} gas is cooled below the boiling point at the reservoir to contact the target portion via the first line, collecting the ^{18 O} gas in the target portion liquification of the ^{18 O} gas,
Closing the first line;
Driving a pump disposed on a second line that bypasses the first line, and transferring the ¹⁸ O gas remaining in the target part to the storage part via the second line;
A method for recovering oxygen gas, comprising:

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