Patent Description:
As a technique in the related art, a liquid target device as described in <CIT> and <CIT> has been known. A target liquid is accommodated in the liquid target device and the target liquid is irradiated with a charged particle beam accelerated by a particle accelerator such that a radioisotope (RI) of the target liquid is generated. <CIT> discloses a target system for irradiating a sample material by an accelerated particle beam. International Patent Publication No. <CIT> discloses a radioisotope production apparatus and a radioisotope production method for producing a radioisotope by a nuclear reaction between a target liquid and radiation.

<CIT> is an example of gas cooled liquid target device.

In a liquid target device as described above, a so-called target foil covers an opening upstream of an accommodation portion of a target. In the case of such a device configuration, the target foil may be damaged during the irradiation with the charged particle beam. When the target foil is damaged, the target liquid may flow into the particle accelerator side.

It is desirable to provide a liquid target device in which target liquid is prevented from flowing out toward a particle accelerator side even when a target foil is damaged.

The present invention discloses a liquid target device according to claim <NUM>. Advantageous embodiments are disclosed in the dependent claims.

According to the liquid target device, the vacuum foil and the intermediate foil that partition the beam passage are provided between the target foil of the liquid accommodation portion and the vacuum region. Therefore, even in a case where the target foil is damaged and a target liquid held in the liquid accommodation portion flows out toward the second gas chamber, the movement thereof is restricted by the intermediate foil and thus the target liquid is prevented from moving to the vacuum region via the first gas chamber. Therefore, even when the target foil is damaged, the target liquid can be prevented from flowing out toward the particle accelerator side.

Here, a flow system for the cooling gas relating to the first gas chamber and a flow system for the cooling gas relating to the second gas chamber may be independent of each other.

According to such a configuration, even when the target liquid flows out to the second gas chamber and the target liquid is discharged to the outside of a system along with movement of the cooling gas, the target liquid can be prevented from being erroneously supplied to the first gas chamber or the like since the flow system for the cooling gas relating to the second gas chamber and the flow system for the cooling gas relating to the first gas chamber are independent of each other.

The liquid target device may further include a pipe through which a fluid discharged from the second gas chamber flows and a recovery unit that is provided in the pipe and recovers a foreign substance contained in the fluid.

In a case where a configuration, in which the recovery unit that recovers the foreign substance contained in the fluid is provided in the pipe through which the fluid discharged from the second gas chamber flows, is adopted, even when the target liquid leaks into the second gas chamber and flows to the pipe along with movement of the cooling gas, the target liquid can be recovered in the recovery unit and thus the target liquid can be prevented from flowing out to a subsequent stage.

A flow system for the cooling gas relating to the first gas chamber may be shared with another liquid target device that is different from the liquid target device.

In a case where one particle accelerator is provided with a plurality of liquid target devices, a flow system for a cooling gas may be shared with another liquid target device. In such a case, when a foreign substance such as the target liquid which is different from a cooling gas intrudes into the shared flow system, the influence thereof may become wide-ranging. However, when a configuration in which the flow system for the cooling gas relating to the first gas chamber that is on a side distant from the liquid accommodation portion in which the target liquid is accommodated is shared with the other liquid target device is adopted, the other liquid target device can be prevented from being influenced even in a case where the target foil is damaged.

According to the present invention, provided is a liquid target device in which a target liquid is prevented from flowing out toward a particle accelerator side even when a target foil is damaged.

Hereinafter, an embodiment of the present invention will be described in detail with reference to attached drawings. Note that, the same reference numerals are assigned to the same constituent elements in description of the drawings and repetitive descriptions thereof will be omitted.

<FIG> is a schematic configuration view of a liquid target device used in a radioisotope manufacturing system. The radioisotope manufacturing system (hereinafter, "RI manufacturing system") including a liquid target device <NUM> is an apparatus that manufactures a radioisotope (hereinafter, "RI") by irradiating a target liquid T with a charged particle beam B. The RI manufactured by means of the system is used to manufacture a radiopharmaceutical (including radioisotope drug), which is a radioisotope-labeled compound, for example. The target liquid T is, for example, <NUM>O water, an acidic solution containing a metallic element such as <NUM>Zn, <NUM>Ni, and natY, and the like. Examples of a radioisotope-labeled compound generated from the target liquid T as described above include <NUM>F-FDG (fluorodeoxyglucose), <NUM>Ga-PSMA, <NUM>Cu-DOTA-trastuzumab, <NUM>Zr-trastuzumab as compounds to be used in a PET inspection (positron emission tomography inspection) in a hospital or the like.

The RI manufacturing system includes a particle accelerator in addition to the liquid target device <NUM>. The particle accelerator is an accelerator that emits the charged particle beam B. Examples of charged particles include protons and heavy particles (heavy ions). Note that, as the particle accelerator, for example, a cyclotron, a linear accelerator (linac), or the like is used. As the charged particle beam, for example, a proton beam, a deuteron beam, an α-beam, or the like is used. In the following description, words such as "upstream side" and "downstream side" will be used corresponding to the upper stream and the lower stream of the charged particle beam emitted from a particle accelerator <NUM>.

The liquid target device <NUM> is mounted into a manifold <NUM> that is provided in a port for emission of the charged particle beam, the port being provided in the cyclotron. The cyclotron adjusts the trajectory of the charged particle beam in an acceleration space such that the charged particle beam is extracted from the port. The extracted charged particle beam is incident into the manifold <NUM> and reaches the liquid target device <NUM>.

The liquid target device <NUM> is configured to include a cooling unit <NUM> and a target holding unit <NUM>. Note that, although the cooling unit <NUM> and the target holding unit <NUM> will be described separately in the present embodiment, the way in which the units are classified can be appropriately changed.

The cooling unit <NUM> is provided in a state of protruding from the manifold <NUM> of the cyclotron. The cooling unit <NUM> includes a beam passage <NUM>, through which the charged particle beam B passes, at a position corresponding to an irradiation axis of the charged particle beamB. The beam passage <NUM> is formed to have a circular section with the irradiation axis of the charged particle beam B as a center line and is formed to extend along the irradiation axis.

The cooling unit <NUM> includes two sets of foils on the beam passage <NUM>. By a vacuum foil <NUM>, a region in the beam passage <NUM> that is upstream of the vacuum foil <NUM> is kept vacuum. In other words, a region upstream of the vacuum foil <NUM> is a vacuum region A1. In addition, an intermediate foil <NUM> is provided downstream of the vacuum foil <NUM> in the beam passage <NUM>. The vacuum foil <NUM> and the intermediate foil <NUM> are thin circular foils formed of metal such as titanium and chromium or an alloy thereof and the thickness thereof is approximately <NUM> to <NUM>. As a foil, for example, a Havar foil or the like containing iron, cobalt, nickel, chromium, molybdenum, manganese, tungsten, or the like can be used. However, the foil is not limited thereto. In addition, the intermediate foil <NUM> may be provided by stacking two foils as described above. <FIG> shows a state where two foils 32a and 32b are stacked to form the intermediate foil <NUM>. In a case where the intermediate foil <NUM> is formed by stacking the two foils 32a and 32b, the mechanical strength of the intermediate foil <NUM> can be increased.

In addition, the cooling unit <NUM> includes two sets of cooling flow paths <NUM> and <NUM> through which a cooling gas such as helium is blown to the beam passage <NUM>. The cooling flow path <NUM> is configured to include a pair of cooling flow paths 12a and 12b. In addition, the cooling flow path <NUM> is configured to include a pair of cooling flow paths 13a and 13b.

The cooling flow path <NUM> is provided between the vacuum foil <NUM> and the intermediate foil <NUM> on the beam passage <NUM>. The cooling flow paths 12a and 12b are provided to face each other with the beam passage <NUM> interposed therebetween. In addition, each of the cooling flow paths 12a and 12b branches into a portion facing a upstream side and a portion facing a downstream side. A cooling gas is blown to the vacuum foil <NUM> on the upstream side through a portion of the cooling flow path 12a that faces the upstream side and the cooling gas is blown to the intermediate foil <NUM> through a portion of the cooling flow path 12a that faces the downstream side (refer to <FIG> also). The cooling flowpath 12b is provided as a flowpath through which a cooling gas blown from the cooling flow path 12a is discharged from the beam passage <NUM>.

The cooling flow path <NUM> is provided downstream of the intermediate foil <NUM> on the beam passage <NUM>. The cooling flow paths 13a and 13b are provided to face each other with the beam passage <NUM> interposed therebetween. In addition, each of the cooling flow paths 13a and 13b branches into a portion facing a upstream side and a portion facing a downstream side. A cooling gas is blown to the intermediate foil <NUM> on the upstream side through a portion of the cooling flow path 13a that faces the upstream side and the cooling gas is blown to atarget accommodation portion <NUM> (liquid accommodation portion) through a portion of the cooling flow path 13a that faces the downstream side (refer to <FIG> also). The cooling flow path 13b is provided as a flow path through which a cooling gas blown from the cooling flow path 13a is discharged from the beam passage <NUM>.

The target holding unit <NUM> has an approximately columnar shape and includes a target foil <NUM>, a target container portion <NUM>, and a cooling mechanism <NUM>. The target holding unit <NUM> is connected to the cooling unit <NUM> at a position downstream of the cooling flow path <NUM>.

The target container portion <NUM> is disposed on an upstream side of the target holding unit <NUM>. The target foil <NUM> is interposed between the target container portion <NUM> and the cooling unit <NUM> on the upstream side. Note that, a configuration in which the target foil <NUM> is supported by being interposed between members constituting the target holding unit <NUM> may also be adopted and a configuration in which the target foil <NUM> is supported by being interposed between members constituting the cooling unit <NUM> as shown in <FIG> may also be adopted.

In the case of a configuration as shown in <FIG>, a portion of a front surface of the target foil <NUM> is exposed with respect to the beam passage <NUM>. The target foil <NUM> allows a beam to pass therethrough but blocks a fluid such as the target liquid T and a helium gas. The target foil <NUM> is a Havar foil or a thin circular foil formed of metal such as niobium or an alloy and the thickness thereof is approximately <NUM> to <NUM>.

The target container portion <NUM> includes the target accommodation portion <NUM> that is formed at a center portion as seen in front view and in which the target liquid T can be accommodated and a buffer portion <NUM> that is positioned above the target accommodation portion <NUM> and communicates with the target accommodation portion <NUM>. The target accommodation portion <NUM> and the buffer portion <NUM> are configured as a closed space formed when a front surface side of the target container portion <NUM> is closed by the target foil <NUM>. A portion of the closed space is the target accommodation portion <NUM> in which the target liquid T is stored and a portion of the closed space that is above the liquid surface of the target liquid T is the buffer portion <NUM>. In other words, the target foil <NUM> separates the beam passage <NUM> from the target accommodation portion <NUM> and the buffer portion <NUM>. The target liquid T is supplied to the target accommodation portion <NUM> through a pipe <NUM> such that the target accommodation portion <NUM> is filled with the target liquid T and the target liquid T after processing is recovered through the pipe <NUM> again.

The cooling mechanism <NUM> is provided rearward of a rear wall <NUM> constituting the target accommodation portion <NUM> and the buffer portion <NUM>. The cooling mechanism <NUM> cools the target accommodation portion <NUM> and the buffer portion <NUM> by supplying a cooling water that comes into contact with the rear wall <NUM>. The cooling mechanism <NUM> includes a rear water path <NUM> that is immediately rearward of the rear wall <NUM>, a water introduction path <NUM> through which the cooling water is introduced into the rear water path <NUM>, and a water discharge path <NUM> through which the cooling water is discharged from the rear water path <NUM>. The cooling water is supplied from the outside through a cooling water supply pipe connected to the water introduction path <NUM>. By the cooling mechanism <NUM> as described above, the target liquid T in the target accommodation portion <NUM> is cooled. In addition, when the buffer portion <NUM> is cooled by the cooling mechanism <NUM>, vapor evaporated from the target liquid T in the target accommodation portion <NUM> is condensed in the buffer portion <NUM> and returns to the target accommodation portion <NUM> due to the own weight thereof. Note that, the pressure in the target accommodation portion <NUM> and the buffer portion <NUM> is increased by an inert gas (for example, He) supplied through a pipe <NUM> and thus the boiling point of the target liquid T increases.

As described above, in the liquid target device <NUM>, the vacuum foil <NUM>, the intermediate foil <NUM>, and the target foil <NUM> form two gas chambers on the beam passage <NUM> through which a cooling gas passes. That is, a first gas chamber R1 into which a cooling gas is supplied from the cooling flow path <NUM> (12a and 12b) and a second gas chamber R2 into which a cooling gas is supplied from the cooling flow path <NUM> (13a and 13b) are formed on the beam passage <NUM>. The first gas chamber R1 and the second gas chamber R2 are separated from each other by the intermediate foil <NUM>.

Next, the flow of cooling gases supplied to the first gas chamber R1 and the second gas chamber R2 will be described with reference to <FIG>. In the liquid target device <NUM>, a flow system for the cooling gas supplied to the first gas chamber R1 and a flow system for the cooling gas supplied to the second gas chamber R2 can be made independent of each other. Note that, a flow system for a cooling gas refers to a pipe system relating to supply of the cooling gas to a gas chamber and discharge of the cooling gas from the gas chamber.

In <FIG>, three liquid target devices <NUM> (1A, 1B, and 1C) are shown. Although one liquid target device <NUM> has been described in <FIG>, a plurality of the liquid target devices <NUM> may be attached to one particle accelerator in an actual case. For example, in a case where a particle accelerator is a cyclotron, the cyclotron is provided with a plurality of ports and the liquid target device <NUM> may be attached to each port via a manifold. In this case, the plurality of liquid target devices <NUM> are installed in a state of being somewhat close to each other. <FIG> schematically shows a state in which the three liquid target devices <NUM> (1A, 1B, and 1C) are disposed in parallel. However, in an actual case, adj acent liquid target devices <NUM> maybe different from each other in installation angle depending on the configuration of the particle accelerator or the like.

In this case, a cooling gas supplied to the first gas chamber R1 on the upstream side can be shared between the adjacent liquid target devices <NUM>. That is, a flow system S1 for the cooling gas supplied to the first gas chamber R1 is shared with another liquid target device. In the case of an example shown in <FIG>, a cooling gas supplied to the liquid target device 1A is supplied to the beam passage <NUM> (first gas chamber R1) of the liquid target device 1B from the cooling flow path 12a of the liquid target device 1B via a pipe L1 after being discharged from the cooling flow path 12b. Then, the cooling gas supplied to the first gas chamber R1 of the liquid target device 1B is supplied to the liquid target device 1C from the cooling flow path 12a of the liquid target device 1C via a pipe L2 after being discharged from the cooling flow path 12b. As described above, regarding a flow system for a cooling gas with respect to the first gas chamber R1, a configuration in which cooling flow paths provided with respect to the first gas chambers R1 of the liquid target devices <NUM> adj acent to each other from among the plurality of liquid target devices <NUM> are connected to each other via a pipe and a cooling gas is supplied via the pipe can also be adopted.

Meanwhile, a flow system S2 for a cooling gas to the second gas chamber R2 can be provided to be independent of an adjacent liquid target device <NUM>. <FIG> shows the flow system S2 for a cooling gas supplied to the liquid target device 1B. In the case of such a supply system, a cooling gas (helium gas) cooled in a helium cooling and pressurizing device <NUM> is sent to the cooling flow path 13a via a pipe L3 and is supplied to the second gas chamber R2 from the cooling flow path 13a. As described above, a flow system for a cooling gas relating to the first gas chamber R1 and a flow system for a cooling gas relating to the second gas chamber R2 can be made independent of each other.

Note that, a cooling gas discharged from the second gas chamber R2 via the cooling flow path 13b is returned to the helium cooling and pressurizing device <NUM> via a pipe L4. Note that, on the pipe L4, a gas-water separation device <NUM> and a filter <NUM> are provided. The gas-water separation device <NUM> and the filter <NUM> function as a recovery unit that recovers a foreign substance including the target liquid T in a case where the target foil <NUM> is damaged and the target liquid T flows into the pipe L4. Here, the "foreign substance" refers to all substances different from a cooling gas which is a fluid supposed to flow through the flow systems S1 and S2. The only fluid supposed to flow through the pipe L4 is a helium gas.

The gas-water separation device <NUM> is provided to prevent the target liquid T from flowing to the subsequent stage in a case where a fluid (helium gas) flowing through the pipe L4 contains the target liquid T with the target foil <NUM> being damaged. Although the configuration of a device for gas-water separation is not particularly limited, a configuration in which gas-water separation can be performed by changing the shape of a tank as shown in <FIG> may be adopted. In addition, a function of performing a neutralization process with respect to liquid or a gas recovered in the gas-water separation device <NUM> may be provided.

The filter <NUM> is provided to remove water vapor and the like contained in a gas flowing through the pipe L4. In addition, in a case where a gas of which a component is different from the helium gas is contained in the gas, a filter that can adsorb the component may be used.

A gas flowing from the second gas chamber R2 is returned to the helium cooling and pressurizing device <NUM> via the gas-water separation device <NUM> and the filter <NUM> on the pipe L4. Since the gas passes through the gas-water separation device <NUM> and the filter <NUM>, the target liquid T flowing in can be removed even in a case where the target foil <NUM> is damaged. Therefore, the helium cooling and pressurizing device <NUM> can be prevented from being damaged.

As described above, in the liquid target device <NUM> according to the present embodiment, the vacuum foil <NUM> and the intermediate foil <NUM> that partition the beam passage <NUM> are provided between the target foil <NUM> defining the target accommodation portion <NUM> (liquid accommodation portion) and the vacuum region A1 on the upstream side. Therefore, even in a case where the target foil <NUM> is damaged and a target liquid held in the target accommodation portion <NUM> flows out toward the second gas chamber R2, the movement thereof is restricted by the intermediate foil <NUM>. Therefore, the target liquid is prevented from moving to the vacuum region on the upstream side via the first gas chamber R1. Therefore, even when the target foil <NUM> is damaged, the target liquid can be prevented from flowing out toward the particle accelerator side.

In a configuration in the related art, no intermediate foil <NUM> is provided and a gas chamber through which a cooling gas passes is configured as one chamber. Therefore, in a case where the target foil <NUM> is damaged and the target liquid T leaks into the gas chamber, the target liquid T may flow to a position downstream of the vacuum foil <NUM>. In this case, the target liquid T may flow to the vacuum region A1 on the upstream side when the vacuum foil <NUM> is damaged. When the target liquid T flows to the vacuum region A1, the particle accelerator on the upstream side may be influenced. Particularly, in a case where an acidic target liquid T is used, the vacuum region A1 may be corroded by an acid, which results in a serious influence. With regard to this, in the liquid target device <NUM> according to the present embodiment, the beam passage <NUM> is provided with the two gas chambers separated from each other by the intermediate foil <NUM> such that the leakage of the target liquid T is prevented from reaching the vacuum foil <NUM>. Therefore, even when the target foil <NUM> is damaged, the target liquid T moving toward the particle accelerator can be suppressed.

In addition, the flow system S1 for a cooling gas relating to the first gas chamber R1 and the flow system S2 for a cooling gas relating to the second gas chamber R2 can be made independent of each other. According to such a configuration, even when the target liquid T flows out to the second gas chamber R2 and the target liquid T is discharged to the outside of a system via the flow system S2 along with movement of a cooling gas, the target liquid T can be prevented from being erroneously supplied to the first gas chamber R1 or the like since the flow system S2 for the cooling gas relating to the second gas chamber R2 and the flow system S1 for the cooling gas relating to the first gas chamber R1 are independent of each other. That is, only the second gas chamber R2 comes into contact with the target liquid T and the first gas chamber R1 can be prevented from coming into contact with the target liquid T and thus the target liquid T can be prevented from moving toward the particle accelerator.

In addition, the pipe L4 through which a fluid discharged from the second gas chamber R2 flows and the gas-water separation device <NUM> and the filter <NUM> as the recovery unit that is provided in the pipe L4 and recovers a foreign substance contained in the fluid may further be provided. According to such a configuration, even when the target liquid T leaks into the second gas chamber R2 and flows to the pipe L4 along with movement of the cooling gas, a foreign substance relating to the target liquid T can be recovered in the recovery unit and thus the target liquid T can be prevented from flowing out to a subsequent stage. That is, the foreign substance relating to the target liquid T can be prevented from being discharged out of the system and a pump, a pipe, and the like for supply of a cooling gas to the second gas chamber R2 like the helium cooling and pressurizing device <NUM> can be prevented from coming into contact with a substance relating to the target liquid T.

In addition, as described above, the flow system S1 for the cooling gas supplied to the first gas chamber R1 is shared with another liquid target device different from the liquid target device. In a case where one particle accelerator is provided with a plurality of liquid target devices, a flow system for a cooling gas may be shared with another liquid target device. In such a case, when a foreign substance such as the target liquid T which is different from a cooling gas intrudes into the shared flow system, the influence thereof may become wide-ranging. However, when a configuration in which the flow system for the cooling gas relating to the first gas chamber R1 that is on a side distant from the target accommodation portion <NUM> is shared with another liquid target device is adopted as in the case of the liquid target device <NUM> described above, the other liquid target device can be prevented from being influenced even in a case where the target foil <NUM> is damaged.

Starting with the above-described embodiment, the present invention can be carried out in various modes that are variously modified and improved on the basis of the knowledge of those skilled in the art. In addition, modification examples can also be configured using technical features described in the above-described embodiment. The configurations of each embodiment may be appropriately combined with each other.

For example, the shape or the like of each part constituting the liquid target device <NUM> can be appropriately changed. For example, although the second gas chamber R2 has been described as a portion of the cooling unit <NUM>, a configuration relating to the second gas chamber R2 may be configured as a portion of the target holding unit <NUM>.

In addition, a structure or the like supporting the foils is not limited to that described in the above-described embodiment. In addition, the intermediate foil <NUM> does not need to be formed by stacking two foils and may be configured by using one foil.

In addition, the number of gas chambers provided in the beam passage <NUM> may be three or more. However, since the number of members separating gas chambers from each other (members corresponding to intermediate foil <NUM>) increases as the number of gas chambers increases, the efficiency of irradiation of the target liquid T with a charged particle beam may be lowered.

In addition, a configuration in which the flow system S1 for the cooling gas relating to the first gas chamber R1 and the flow system S2 for the cooling gas related to the second gas chamber R2 are not independent from each other may also be adopted. However, for example, when a configuration in which a cooling gas discharged from the second gas chamber R2 is prevented from being directly supplied to the first gas chamber R1 is adopted, a foreign substance relating to the target liquid T can be prevented from flowing to the first gas chamber R1 in a case where the target liquid T leaks into the second gas chamber R2 as described above. In addition, a configuration in which the flow system S1 for the cooling gas relating to the first gas chamber R1 is not shared with another liquid target device <NUM> may also be adopted.

Claim 1:
A liquid target device (<NUM>, 1A, 1B, 1C) comprising:
a liquid accommodation portion (<NUM>) in which a target liquid (T) is accommodated;
a beam passage (<NUM>) through which a charged particle beam (B) emitted from a particle accelerator (<NUM>) passes to reach the liquid accommodation portion (<NUM>);
a target foil (<NUM>) that separates the beam passage (<NUM>) and the liquid accommodation portion (<NUM>) from each other;
a vacuum foil (<NUM>) that separates a vacuum region (A1) provided upstream of the beam passage (<NUM>) and the beam passage (<NUM>) from each other; and
a first gas chamber (R1), a second gas chamber (R2) and an intermediate foil (<NUM>) that separates the first gas chamber (R1) and the second gas chamber (R2) from each other,
wherein the beam passage (<NUM>) is provided within the first gas chamber (R1) and the second gas chamber (R2);
the first gas chamber is configured for a first cooling gas to be provided into the first gas chamber (R1) at a position between the vacuum foil (<NUM>) and the intermediate foil (<NUM>), and
characterised in that the second gas chamber comprises
a cooling flow path (<NUM>) for a second cooling gas to be supplied into the second gas chamber (R2) at a position between the intermediate foil (<NUM>) and the target foil (<NUM>).