JP6380939B2 - Cyclotron control device, cyclotron, cyclotron control program, and method for producing radiopharmaceutical - Google Patents

Description

  The present invention relates to a cyclotron control device, a cyclotron, a cyclotron control program, and a method for producing a radiopharmaceutical.

  A cyclotron is a typical particle accelerator, and is a device that generates a high-energy particle beam by accelerating charged particles that are moving circularly in a magnetic field with a high-frequency electric field. A charged particle having a mass larger than that of an electron is referred to as a heavy charged particle, and a particle beam such as a proton beam, deuteron beam, or α ray generated and irradiated by a cyclotron is a beam of heavy charged particles (heavy ion beam). Cyclotrons are used for various purposes. One example is the generation of radionuclides used in the production of radiopharmaceuticals. The particle beam is irradiated onto the target to generate a nuclear reaction. For this reason, a desired radionuclide is generated by selecting a target type.

  Patent Documents 1 and 2 disclose conventional cyclotrons. In Patent Document 1, a static electromagnet is formed by a main electromagnet called a lower electromagnet and an upper electromagnet arranged opposite to each other, and negative ions are accelerated by generating a high-frequency electric field by an accelerating electrode (dee electrode) in the static magnetic field. Thus, a cyclotron for producing a heavy charged particle beam is described. Also in Patent Document 2, a static magnetic field is formed by disk-shaped magnetic poles (main electromagnets) arranged opposite to each other and coils arranged around the disk-shaped magnetic poles, and negative ions are accelerated by an accelerating electrode arranged in the static magnetic field. A cyclotron that generates a heavy charged particle beam is described. Patent Document 2 describes that convergence of a heavy charged particle beam is improved by sector focusing by alternately forming valley regions and mountain regions called sectors on opposite surfaces of magnetic poles and applying strength to the magnetic field. Has been.

  The cyclotron is roughly classified into a positive ion acceleration type and a negative ion acceleration type when classified according to the positive and negative charges of the particles constituting the beam. The positive ion acceleration type is a method in which a trajectory is changed by applying an electric field to a positively charged particle beam with an electrostatic deflector and taken out from the accelerator. The negative ion acceleration type is a system in which a negatively charged particle beam collides with a thin film called a stripper foil to change the trajectory by stripping electrons and take out from the accelerator. The negative ion acceleration type is currently mainstream because of its high extraction efficiency.

JP-A-5-144597 JP 2010-287419 A

  The heavy charged particles are periodically accelerated by a Lorentz force from a static magnetic field formed by the main electromagnet and a high frequency electric field formed by the accelerating electrode to become a high-speed heavy charged particle beam. For this reason, when the strength of the static magnetic field formed by the main electromagnet fluctuates, the radius of rotation of the heavy charged particles and the degree of convergence of the beam fluctuate sensitively. For example, even when a direct current of the same strength is applied to the main electromagnet, when the temperature of the magnetic pole rises, the magnetization of the magnetic pole decreases according to Curie's law, and the magnetic field received by the heavy charged particles also decreases. For this reason, the convergence of the heavy charged particle beam becomes loose, and the ratio of the extracted beam that is accurately irradiated to the target decreases, so that it is difficult to maintain a desired nuclear reaction at the target.

  On the other hand, in recent years, there has been a demand for continuous operation of a cyclotron for a long time, such as when a large amount of radiopharmaceutical is produced. In this case, the heat generation of the main electromagnet becomes significant. However, since the main electromagnet is in a strong radiation environment and a severe environment for the temperature sensor, it is extremely difficult to measure and control the temperature of the main electromagnet using the temperature sensor. In addition, it is difficult to use the temperature sensor from the viewpoint that it becomes a foreign object to the static magnetic field and impairs the convergence of the heavy charged particle beam.

  The present invention has been made in view of the above-described problems, and a cyclotron capable of accurately irradiating a target with a heavy charged particle beam even if the cyclotron is continuously operated for a long time, and a control apparatus therefor Etc. are provided.

  According to the present invention, the heavy charged particles supplied from the ion source are accelerated while rotating in a magnetic field environment formed by applying a magnet current to the main electromagnet to form a heavy charged particle beam; A control unit for a cyclotron comprising a beam extraction unit that changes a trajectory of a charged particle beam and extracts the beam from the accelerator and emits the beam toward a target, the magnet current controlling the magnet current applied to the main electromagnet A control means; a beam current value indicating an amount of the heavy charged particle beam whose trajectory is changed by the beam extraction unit; and a target current value generated when the emitted heavy charged particle beam collides with the target. Output monitor means for acquiring an index value indicating the degree of deviation over time, and the index value acquired by the output monitor means as a first threshold value And an irradiation state determination unit that determines the degree of deviation in comparison, and when the magnet current control unit determines that the degree of deviation is greater than or equal to a predetermined value by the irradiation state determination unit, A cyclotron control device is provided that is characterized by an increase.

  Further, according to the present invention, the ion source and the heavy charged particle beam supplied from the ion source are accelerated while rotating around in a magnetic field environment formed by applying a magnet current to the main electromagnet. A cyclotron is provided that includes an accelerator, a beam extraction unit that changes the trajectory of the heavy charged particle beam, extracts the beam from the accelerator, and emits the beam toward a target, and the cyclotron control device.

  In addition, according to the present invention, an accelerator that accelerates heavy charged particles supplied from an ion source while rotating around a magnetic field environment formed by applying a magnet current to a main electromagnet to form a heavy charged particle beam; A program for controlling a cyclotron comprising: a beam extraction unit configured to change a trajectory of the heavy charged particle beam and to extract the beam from the accelerator and output the target toward a target, wherein the program changes the trajectory in the beam extraction unit An index value indicating the degree of deviation between a beam current value indicating the amount of the heavy charged particle beam to be generated and a target current value generated when the emitted heavy charged particle beam collides with the target is obtained over time. A determination process for comparing the acquired index value with a first threshold to determine the divergence degree, and the divergence degree is not less than a predetermined value in the determination process. If it is determined that there is, cyclotron control program characterized by executing a current control process for increasing the magnet currents to be applied to the main electromagnet, to the cyclotron is provided.

  Further, according to the present invention, an accelerator that accelerates heavy charged particles supplied from an ion source while rotating around a magnetic field environment formed by applying a magnet current to a main electromagnet to form a heavy charged particle beam; A beam extraction unit for changing a trajectory of a heavy charged particle beam and extracting the heavy charged particle beam from the accelerator and emitting the beam toward a target, and manufacturing the radiopharmaceutical using a cyclotron, wherein the heavy charged particle beam is applied to the target An irradiation step of generating a radionuclide by irradiation, a beam current value indicating an amount of the heavy charged particle beam whose trajectory is changed by the beam extraction unit, and the emitted heavy charged particle beam collides with the target. An index value indicating a degree of deviation from the target current value to be generated is acquired over time, and the obtained index value is compared with a first threshold value to determine the deviation. The radiopharmaceutical is produced using the adjustment step for increasing the magnet current and the generated radionuclide and labeled precursor compound when the degree is determined and the degree of deviation is determined to be greater than or equal to a predetermined level. And a labeling step, wherein the irradiation step is continuously performed before and after the adjustment step.

  According to the present invention, when it is determined that the degree of deviation between the beam current value and the target current value is greater than or equal to a predetermined value, the magnet current applied to the main electromagnet is increased. For this reason, it is possible to compensate for the decrease in magnetization due to the temperature increase of the main electromagnet by increasing the magnet current. Therefore, according to the present invention, even if the cyclotron is continuously operated for a long time and the temperature of the main electromagnet rises, it is possible to continue to irradiate the target with the heavy charged particle beam accurately.

It is a top view which shows typically the structure of the cyclotron of embodiment of this invention. It is a functional block diagram of a cyclotron. It is a figure which shows an example of the display screen of a cyclotron control apparatus. It is a flowchart which shows the process in a cyclotron control apparatus. It is a graph which shows typically the time change of the amount of magnet current application.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same constituent elements are denoted by the same reference numerals, and redundant description is omitted as appropriate. FIG. 1 is a plan view schematically showing the structure of the cyclotron 100 of the present embodiment. FIG. 2 is a functional block diagram of the cyclotron 100 of the present embodiment.

First, the outline of the cyclotron 100 will be described. The cyclotron 100 accelerates the heavy charged particles by accelerating the ion source 20 and the heavy charged particles P supplied from the ion source 20 in a magnetic field environment formed by applying the magnet current IM to the main electromagnet 50. Accelerator 30 to be a beam PB, a beam extraction unit 40 for changing the trajectory of the heavy charged particle beam PB, extracting it from the accelerator 30 and emitting it toward the target 34, and the cyclotron control device 10 of this embodiment. .

The cyclotron control device 10 is a control device for the cyclotron 100. The present embodiment 10 includes a magnet current control unit 18, an output monitor unit 14, and an irradiation state determination unit 16.
The magnet current control unit 18 is a control unit that controls the magnet current IM applied to the main electromagnet 50.
The output monitor unit 14 is a means for acquiring an index value exemplified by a transmission value TR described later by measurement or calculation. The index value includes a beam current value EPR indicating the amount of the heavy charged particle beam PB whose trajectory is changed by the beam extraction unit 40, and a target current value TG generated when the emitted heavy charged particle beam PB collides with the target 34. , A parameter indicating the degree of divergence of, and will be described in detail later. Hereinafter, when simply described as “divergence degree”, it represents the degree of deviation between the beam current value EPR and the target current value TG. The output monitor unit 14 acquires this index value over time.
The irradiation state determination unit 16 is a unit that compares the index value acquired by the output monitor unit 14 with a first threshold value to determine the degree of deviation.
The cyclotron control device 10 of the present embodiment is characterized in that the magnet current control unit 18 increases the magnet current IM when the irradiation state determination unit 16 determines that the degree of deviation is greater than or equal to a predetermined value.

  Next, the cyclotron control device 10 and the cyclotron 100 of the present embodiment will be described in detail.

  The cyclotron 100 irradiates a target 34 disposed inside a beam tube 32 with a high-speed, high-energy heavy charged particle beam PB accelerated by an accelerator 30 to generate a nuclear reaction to generate a radioisotope. It is. The cyclotron 100 may be disposed inside a shield (not shown) that is made entirely of a metal material such as lead and shields radiation. In FIG. 1, two beam extraction units 40 are provided in the accelerator 30, and a heavy charged particle beam PB can be extracted from the two beam tubes 32. The length and shape of the beam tube 32 are not particularly limited, and the intermediate portion is not shown in FIG.

In the present embodiment, an anion acceleration type cyclotron 100 is illustrated. The anion acceleration type cyclotron 100 is suitable for mass production of radioisotopes. The heavy charged particles P accelerated by the accelerator 30 are charged particles heavier than electrons, such as protons and deuterons. In the present embodiment, negative hydrogen ions (H ⁻ ) are exemplified as the heavy charged particles P. The heavy charged particles P are accelerated while rotating around the accelerator 30 to become a heavy charged particle beam PB (indicated by a two-dot chain line in FIG. 1).
As a feature of the anion-accelerated cyclotron 100, the beam extraction unit 40 includes a stripper foil 42 that collides the heavy charged particle beam PB and captures electrons from the heavy charged particle P. The stripper foil 42 is made of a carbon thin film.
By passing the negative hydrogen ions (H ⁻ ) accelerated by the accelerator 30 through the stripper foil 42, electrons are stripped from the negative hydrogen ions and instantly converted into positive ions (H ⁺ ). For this reason, the direction of the Lorentz force applied to the heavy charged particle beam PB is instantaneously reversed, and the heavy charged particle beam PB undergoes an orbital change by receiving an outward force from the magnetic field of the accelerator 30 and is taken out to the beam tube 32. It is.

  A beam of heavy charged particles P generated by applying an arc voltage to the ion source 20 is called an arc current, and the amount of this beam is called an arc current value. By increasing the arc current value, more beams of heavy charged particles P are extracted by the beam extraction unit 40 and irradiated toward the target 34. As described above, the beam extraction unit 40 is an electrostatic deflector in the case of the positive ion acceleration type, and is a stripper foil in the case of the negative ion acceleration type. The amount of the heavy charged particle beam PB whose trajectory is changed by the beam extraction unit 40 and extracted from the accelerator is referred to as a beam current, and this amount of beam is referred to as a beam current value EPR. In the case of the negative ion acceleration type, the amount of electrons removed from the heavy charged particles P by the stripper foil 42 corresponds to the beam current value EPR. The amount of the beam actually irradiated onto the target 34 is called a target current, and this amount of beam is called a target current value TG.

  The accelerator 30 includes a main electromagnet 50 and a high-frequency electrode 52. A vacuum pump is connected to the acceleration space 31 and is substantially kept in a vacuum state. The main electromagnet 50 and the high-frequency electrode 52 are opposed to each other with the acceleration space 31 in which the heavy charged particle beam PB makes a circular motion. The high frequency electrode 52 is also referred to as a dee electrode. In FIG. 1, for convenience, the side of the main electromagnet 50 and the high-frequency electrode 52 that are disposed opposite to each other and that is disposed above the acceleration space 31 is not illustrated.

The main electromagnet 50 includes a magnetic pole 51, a coil 56, and a DC power supply 58. The coil 56 is wound around the magnetic pole 51, and a DC power source 58 is connected to apply a magnet current IM. The DC power supply 58 is signal-connected to the cyclotron control device 10.
In the magnetic pole 51, a valley region 51a having a small thickness and a mountain region 51b having a thickness larger than the valley region 51a are alternately and repeatedly formed in a plurality of places. The valley region 51a has a lower magnetic flux density than the mountain region 51b. Thereby, the convergence of the heavy charged particle beam PB is improved. In FIG. 1, for convenience, the mountain region 51b is hatched. The high frequency electrode 52 is disposed at a position corresponding to the valley region 51 a of the magnetic pole 51. By applying a magnet current IM to the main electromagnet 50, a uniform magnetic field environment is formed. The direction of the magnetic field is the front-rear direction in FIG. The cyclotron control device 10 has a function of a magnet current control unit 18 (see FIG. 2) that controls a magnet current IM applied to the main electromagnet 50.
A high frequency power supply 54 is connected to the high frequency electrode 52 to supply a high frequency signal. The frequency of the high frequency power source 54 is set so as to be synchronized with the rotation period of the heavy charged particle beam PB. In the uniform magnetic field environment formed by the main electromagnet 50, the high-frequency power source 54 forms a periodic electric field, whereby the heavy charged particles P are continuously accelerated while circling.

  The radius of rotation of the accelerated heavy charged particle beam PB increases with acceleration. When the heavy charged particle beam PB is sufficiently accelerated, the trajectory of the heavy charged particle beam PB becomes the outermost periphery of the acceleration space 31. The stripper foil 42 of the beam extraction unit 40 is disposed on the outermost periphery of the acceleration space 31. The sufficiently charged heavy charged particle beam PB collides with the stripper foil 42 and the trajectory of the heavy charged particle beam PB as described above. Will be changed. In the present embodiment, a pair of beam extraction portions 40 and a stripper foil 42 are provided around the acceleration space 31 corresponding to the pair of beam tubes 32.

  The beam extraction unit 40 includes a stripper foil 42 and a foil drive unit 43. The stripper foil 42 is attached so as to protrude from the tip of the foil drive unit 43, and is disposed so as to protrude inward and horizontally with respect to the acceleration space 31 of the accelerator 30. The foil drive unit 43 adjusts the direction and the protruding length of the stripper foil 42. The beam extraction unit 40 is a probe that detects the amount of electrons removed from the heavy charged particle beam PB by the stripper foil 42 as a beam current value EPR. The beam extraction unit 40 is signal-connected to the cyclotron control device 10, transmits the detected beam current value EPR to the cyclotron control device 10, and the foil drive unit 43 performs stripper foil based on the control signal from the cyclotron control device 10. 42 is driven.

FIG. 1 shows an external ion supply type cyclotron 100. In the external ion supply type cyclotron 100, the ion source 20 is arranged outside the accelerator 30. The specific structure and arrangement of the ion source 20 are not particularly limited, and may be an internal ion supply type in which the ion source 20 is arranged inside the accelerator 30.
Various ion sources 20 have been proposed. As a negative ion source, a volume generation type that emits thermoelectrons by energizing a metal wire such as a filament 24 or an RF antenna is widely known. Specifically, in the ion source 20, a source plasma is generated by applying an arc voltage to the thermoelectrons emitted by applying a current to the filament 24 or RF antenna arranged in a source gas atmosphere such as hydrogen gas. Then, a high voltage is applied to the source plasma to extract a negative ion beam.

In this embodiment, a filament drive type ion source 20 is illustrated. The ion source 20 includes a hollow plasma generation unit 22 and a filament 24 arranged so as to be exposed inside the plasma generation unit 22. In addition, when using the high frequency drive type ion source 20, an RF antenna may be arranged in the plasma generation unit 22 instead of the filament 24. A source gas such as hydrogen gas is supplied to the plasma generator 22. A current (filament current) is applied to the filament 24 in a source gas atmosphere to emit thermoelectrons, and an arc voltage is applied to the thermoelectrons to accelerate and collide with the source gas to generate arc discharge and plasma. Is generated. When the filament 24 is energized, the inside of the plasma generation unit 22 is heated to about 3000 ° C., for example. By applying a high voltage to the generated plasma at the extraction electrode 25, a beam of heavy charged particles P (heavy charged particle beam PB) of negative ions such as hydrogen ions (H ⁻ ) is ionized toward the plasma generating unit 22. It is pulled out to the supply port 26. The ion supply port 26 is disposed inside the acceleration space 31 of the accelerator 30, and the heavy charged particles P are discharged into the acceleration space 31 through the ion supply port 26 and accelerated. The amount of thermoelectrons emitted from the filament 24 is increased by increasing the filament current supplied to the filament 24 disposed in the plasma generation unit 22, and as a result, the amount of heavy charged particles P supplied to the ion supply port 26. Will increase.

  The cyclotron control device 10 includes a supply control unit 12 that controls the supply amount of the heavy charged particles P supplied from the ion source 20 to the accelerator 30. The supply control unit 12 has at least a function of maintaining the supply amount of the heavy charged particles P up to a predetermined set amount and then maintaining the set amount. The supply control unit 12 of the present embodiment adjusts the filament current value applied to the plasma generation unit 22 to increase or decrease the amount of the heavy charged particle beam PB supplied from the ion source 20 to the accelerator 30, that is, the arc current value. Increase / decrease adjustment. As shown in FIG. 2, the ion source 20 is signal-connected to the supply control unit 12 of the cyclotron control device 10.

  The heavy charged particle beam PB supplied from the ion supply port 26 to the acceleration space 31 is accelerated by the static magnetic field generated by the main electromagnet 50 and the alternating electric field generated by the high frequency electrode 52 as described above, and collides with the stripper foil 42. To be taken out from the acceleration space 31. The heavy charged particle beam PB extracted from the acceleration space 31 exceeds the desired beam width due to magnetic field errors, repulsion due to charges between the heavy charged particle beams PB, scattering due to collision with the stripper foil 42, and the like. Particles (called beam halos) are generated. A collimator 44 disposed in the trajectory from the stripper foil 42 to the target 34 reduces this beam halo. The collimator 44 is a device that narrows the beam width of the heavy charged particle beam PB traveling in the axial direction of the beam tube 32 toward the target 34.

  Increasing the arc current value increases the amount of the heavy charged particle beam PB, so that the beam current value EPR and the target current value TG also tend to increase. However, the entire amount of the beam extracted by the beam extraction unit 40 is not irradiated onto the target 34, and a difference occurs between the beam current and the target current due to various factors. One of the factors is a loss in the collimator 44 that is disposed between the beam extraction unit 40 and the target 34 and through which the heavy charged particle beam PB passes (hereinafter sometimes referred to as “collimator loss”). In addition, even if the heavy charged particle beam PB whose trajectory has been changed by colliding with the stripper foil 42 is subjected to collimation by the collimator 44, 100% of the heavy charged particle beam PB is not irradiated to the target 34. Irradiation results in loss (hereinafter sometimes referred to as “external loss”).

  The collimator 44 of this embodiment is disposed in the vicinity of the entrance of the beam tube 32. The structure of the collimator 44 is not particularly limited, but a multistage collimation system can be used in this embodiment. The collimator 44 according to the present embodiment includes, for example, three stages: a probe collimator 44a disposed at the most upstream, a buffer collimator 44b, and a target collimator 44c disposed closest to the target 34. The probe collimator 44a includes a deflecting electromagnet, and the beam halo of the heavy charged particle beam PB hitting the probe collimator 44a loses a part of energy and is scattered and increases in amplitude in a certain direction. The scattered beam halo is mainly removed by the buffer collimator 44b, and further energy is lost. The target collimator 44c includes a quadrupole electromagnet, and further reduces the beam halo to narrow the beam width of the heavy charged particle beam PB. Even when passing through the target collimator 44c, a part of the energy of the heavy charged particle beam PB is lost. Each stage of the collimator 44 is signal-connected to the cyclotron control device 10, and information (collimator current value) indicating the amount of collimator loss at each stage is transmitted to the cyclotron control device 10.

The heavy charged particle beam PB that has passed through the collimator 44 is introduced into the beam tube 32 and collides with the target 34. The target 34 is cooled by a liquid or gaseous cooling solvent. Target 34 may be solid or liquid. The heavy charged particle beam PB collides with the target 34 to generate a nuclear reaction. Examples of the radionuclide include ¹¹ C, ¹³ N, ¹⁵ O, and ¹⁸ F. A target current value TG corresponding to the amount of the heavy charged particle beam PB colliding with the target 34 is measured using an electrometer (not shown). The electrometer is signal-connected to the cyclotron control device 10 and transmits the measured target current value TG to the cyclotron control device 10.

  The cyclotron control device 10 is a control unit of the cyclotron 100, and is connected to the beam extraction unit 40, the collimator 44, and the target 34 (electrometer), respectively, and acquires the beam current value EPR, the collimator current value, and the target current value TG, respectively. .

The cyclotron control device 10 reads a computer program and executes a corresponding processing operation so that a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an I / F (Interface) unit, It can be implemented as hardware constructed with general-purpose devices such as. The cyclotron control device 10 includes a display screen DP that is an output device that displays various types of information.
As shown in FIG. 2, the cyclotron control device 10 includes a supply control unit 12, an output monitor unit 14, an irradiation state determination unit 16, and a magnet current control unit 18, as well as an arithmetic processing unit and a storage unit. Yes.

  FIG. 3 is a diagram illustrating an example of the display screen DP of the cyclotron control device 10. Various types of information indicating the state of the cyclotron 100 are displayed on the display screen DP. The display screen DP of this embodiment includes an arc current display unit 62, a beam current value display unit 63, a collimator current value display unit 64, a target current value display unit 65, a transmission value display unit 66, and a magnet setting display unit 70. Yes.

The arc current display unit 62 displays an arc current value indicating the amount of the heavy charged particle beam PB generated by applying a filament voltage and an arc voltage to the ion source 20.
The beam current value display unit 63 displays the beam current value EPR transmitted from the beam extraction unit 40. The cyclotron 100 of this embodiment includes a pair of beam extraction units 40, and the beam current value EPR transmitted from each beam extraction unit 40 is individually displayed as EPR1 and EPR2 on the display screen DP.
The collimator current value display unit 64 displays the current value lost by the collimator 44 through which the heavy charged particle beam PB extracted from the pair of beam extraction units 40 passes. The collimator current value display unit 64 obtains and displays the collimator current value in the probe collimator 44a, PCL1 and PCL2, obtains and displays the collimator current value in the buffer collimator 44b, and collimator in the target collimator 44c. It includes TCL1 and TCL2 that acquire and display current values.
The target current value display unit 65 displays the target current values TG generated when the heavy charged particle beam PB incident on the pair of beam tubes 32 collides with the target 34 as TG1 and TG2.

  The transmission value display unit 66 displays an index value that is a parameter indicating the degree of deviation between the beam current value EPR and the target current value TG. As the degree of divergence between the beam current value EPR and the target current value TG, a relative ratio or difference between them, or a numerical value correlated with these can be used. The output monitor unit 14 of the present embodiment performs all the steps of irradiating the heavy charged particle beam PB, that is, the first supply step ST10, the second supply step ST18, and the third supply step ST26 (see FIGS. 4 and 5). The index value is calculated over time and displayed on the transmission value display unit 66.

Various parameters can be selected as the index value. In this embodiment, the index value acquired by the output monitor unit 14 is the ratio of the target current value TG to the beam current value EPR (= target current value TG). / Transmission value TR indicating beam current value EPR). Transmission value display unit 66 displays transmission values TR calculated individually based on target current values TG1 and TG2 and beam current values EPR1 and EPR2 as TR1 and TR2.
In the example shown in FIG. 3, the transmission value TR1 = 87/113 = 0.77 and the transmission value TR2 = 100/123 = 0.81.

  The transmission value TR indicates the ratio of the heavy charged particle beam PB taken out by hitting the stripper foil 42 and irradiated on the target 34. Therefore, when the transmission value TR is high, the heavy charged particle beam PB is efficiently irradiated onto the target 34, in other words, it means that the beam loss is small. Causes of beam loss include collimator loss due to the beam halo being removed by passage of the collimator 44, and external loss that loses energy when the beam is irradiated outside the collimator 44 and the target 34. Can be considered.

When it is determined that the transmission value TR, which is an index value, is less than or equal to the predetermined value, that is, the degree of deviation between the target current value TG and the beam current value EPR is greater than or equal to the predetermined value, the supply control unit 12 Do different controls. The irradiation process will be described later with reference to FIG. 5. Specifically, in the first supply step ST10 corresponding to the initial irradiation process, the magnet current IM is kept constant and is supplied from the ion source 20 to the accelerator 30. An increase in the supply amount of heavy charged particles P is suppressed. In the third supply step ST26 corresponding to the irradiation process after the middle period, the magnet to be applied from the DC power source 58 to the coil 56 in a state where the supply amount of the heavy charged particles P is maintained constant, that is, the arc current is maintained constant. The application amount of the current IM is increased.
As a result, in the initial irradiation process, it is estimated that the condition setting of the cyclotron 100 is insufficient, and the collimator 44 or the outside is intensively irradiated with the beam, and the collimator loss and the external loss are increased. The supply amount of the charged particles P is suppressed. As a result, it is possible to avoid damage to the cyclotron 100 or generation of an excessive beam current value EPR in order to obtain a desired target current value TG to overload the cyclotron 100. On the other hand, in the irradiation process after the middle period, it is estimated that the temperature of the magnetic pole 51 of the main electromagnet 50 is increased and the magnetization is decreased, the convergence of the heavy charged particle beam PB is decreased and the trajectory is deviated. Increase the current IM. Thereby, the strength of the static magnetic field formed by the main electromagnet 50 is restored, and the trajectory of the heavy charged particle beam PB is corrected.

  The output monitor unit 14 calculates two transmission values TR of TR1 and TR2 corresponding to the pair of beam extraction units 40 and the target 34, and displays them on the transmission value display unit 66. The supply control unit 12 supplies the heavy charged particles P when at least one of these TR1 and TR2 is determined to be equal to or less than a predetermined value, that is, when at least one of the divergence degrees represented by TR1 and TR2 is determined to be equal to or greater than a predetermined value. Control is performed to suppress excess or increase the application amount of the magnet current IM.

In addition, as the index value, a beam difference value obtained by subtracting the collimator current value and the target current value TG from the beam current value EPR may be used. In this case, the larger the index value (beam difference value), the larger the beam loss. Then, the supply control unit 12 of the cyclotron control device 10 determines that the beam difference value is greater than or equal to a predetermined value, that is, the degree of deviation between the target current value TG and the beam current value EPR is greater than or equal to the predetermined value. Alternatively, the supply amount of the heavy charged particles P supplied to the accelerator 30 may be controlled so as not to be excessive. As a result, it is possible to prevent an external loss from becoming excessive and damage to an unspecified location inside the cyclotron 100 can be prevented, and an overload of the cyclotron 100 can be avoided.
Specifically, index value (beam difference value) = beam current value EPR1-probe collimator current value PCL1-buffer collimator current value BF1-target collimator current value TCL1-target current value TG1. In the above formula, EPR2, PCL2, BF2, TCL2, and TG2 may be used instead of EPR1, PCL1, BF1, TCL1, and TG1.

The display screen DP includes a vacuum degree display unit 67, a magnet current value display unit 68, a high frequency voltage value display unit 69, and a magnet setting display unit 70 as other display units. The cyclotron control device 10 acquires information indicating the degree of vacuum measured inside the ion supply port 26 and the acceleration space 31 and displays the information on the degree-of-vacuum display unit 67. In the cyclotron control device 10, the magnet current value display unit 68 displays the set value of the magnet current applied to the main electromagnet 50. The cyclotron control device 10 is signal-connected to the main electromagnet 50 and has the function of the magnet current control unit 18. The magnet current control unit 18 causes the DC power source 58 to apply the magnet current control unit 18 corresponding to the set value variably set based on the user's operation to the main electromagnet 50. The high frequency voltage value display unit 69 displays the value of the high frequency voltage applied from the high frequency power source 54 to the high frequency electrode 52. Such a high frequency voltage can be variably set based on a user operation.
The magnet setting display unit 70 sets and displays a first threshold value as a reference value for performing a determination for increasing the magnet current IM in the irradiation process after the middle period. The first threshold value may be variably set based on a user operation, or may be automatically set by the cyclotron control device 10. A specific method for setting the first threshold will be described later.

  FIG. 4 is a flowchart showing processing in the cyclotron control apparatus 10. FIG. 5 is a graph schematically showing the change over time of the application amount of the magnet current IM. The vertical axis in FIG. 5 represents the magnitude of the magnet current IM energized from the DC power source 58 to the coil 56, and the horizontal axis represents the elapsed time from the start of energization. The operation of the cyclotron control device 10 and the program executed by the cyclotron control device 10 will be described below with reference to FIGS.

The program executed by the cyclotron control device 10 is a program for controlling the cyclotron 100. As described above, the cyclotron 100 accelerates the heavy charged particles P supplied from the ion source 20 while circling in the magnetic field environment formed by applying the magnet current IM to the main electromagnet 50 to generate the heavy charged particle beam PB. And a beam extraction unit 40 that changes the trajectory of the heavy charged particle beam PB and extracts the heavy charged particle beam PB from the accelerator 30 and emits it toward the target 34.
The program of the cyclotron control device 10 causes the cyclotron 100 to execute a determination process (determination step ST32) and a magnet current increase process (magnet current increase step ST34).
The output monitor unit 14 includes a beam current value EPR indicating the amount of the heavy charged particle beam PB whose trajectory is changed by the beam extraction unit 40, and a target current value generated when the emitted heavy charged particle beam PB collides with the target 34. An index value indicating the degree of deviation from TG is acquired over time (step ST30). In the determination process (determination step ST32), the irradiation state determination unit 16 compares the index value acquired in step ST30 with the first threshold value to determine the degree of deviation.
In the magnet current increasing process (magnet current increasing step ST34), the magnet current control unit 18 applies the main electromagnet 50 when it is determined in the determination process (determination step ST32) that the degree of deviation is greater than or equal to a predetermined value. Increase the magnet current IM.

  Next, the control process in the cyclotron control device 10 will be described in detail.

  The magnet current control unit 18 of the cyclotron control device 10 controls the magnet current IM in multiple stages as shown in FIG. Specifically, the first supply step ST10 corresponding to the initial irradiation step, and the second supply step ST18 which is executed after the first supply step ST10 and further increases the supply amount of the heavy charged particles P until reaching the second set amount. And a third supply step ST26 which is executed after the second supply step ST18 and maintains the supply amount of the heavy charged particles P at the second set amount. The third supply step ST26 is a general term for processes from when the arc current value is stabilized until the irradiation of the heavy charged particle beam PB is completed. In the third supply step ST26, the process of increasing the magnet current IM based on the index value is repeated over time. For this reason, the third supply step may be referred to as a current control step.

  The first supply step ST10 corresponding to the initial irradiation process is performed from time T0 to time T1. In the first supply step ST10, the magnet current IM is constant at the initial value IM0. In the first supply step ST10, the supply controller 12 increases the supply amount of the heavy charged particles P from a slight initial amount to the first set amount. In the first supply step ST <b> 10, a predetermined filament current is applied to the filament 24 of the ion source 20, heavy charged particles P are generated inside the plasma generation unit 22, and supplied from the ion supply port 26 to the acceleration space 31. The supply controller 12 increases the supply amount of the heavy charged particles P from the initial amount to the first set amount by gradually increasing the filament current applied to the filament 24 (step ST11).

The supply controller 12 gradually increases the filament current value while the supply amount of the heavy charged particles P per unit time (that is, the arc current value) is less than the first set amount (step ST12: NO). Continue ST10.
In the process of determining the supply amount of the heavy charged particles P per unit time in step ST14, various modes can be selected. For example, the first set amount that is the target value of the arc current value and the arrival time until the arc current value reaches the first set amount from the start of irradiation of the heavy charged particle beam PB are set in advance. The filament current value can be forcibly increased over the arrival time (for example, 40 seconds) to increase the arc current value to the first set amount. In this case, the output monitor unit 14 may monitor the elapsed time from the start of irradiation in step ST12 and determine whether or not this elapsed time has reached the set value for the arrival time.
In addition, a means for measuring the amount of heavy charged particles P supplied from the ion supply port 26 to the acceleration space 31 is provided, and the output monitor unit 14 obtains a measurement value by this measuring means, and the supply amount of heavy charged particles P It may be determined that the first set amount has been reached.

In the first supply step ST10, the output monitor unit 14 obtains the beam current value EPR and the target current value TG from the beam extraction unit 40 and the target 34 for each sufficiently short predetermined time interval, and transmits the transmission value TR (index value). Is calculated and obtained.
When the amount of heavy charged particles P supplied from the ion source 20 to the accelerator 30 reaches the first set amount (step ST12: YES), the first supply step ST10 ends. Next, the irradiation state determination unit 16 determines whether the transmission value TR is a second threshold value (step ST14). The second threshold value is preferably set to a value that the transmission value TR sufficiently exceeds when the arrangement of the collimator 44, the magnetic field environment generated by the main electromagnet 50, the state of the stripper foil 42, and the like are normal. The second threshold value is preset and stored in the cyclotron control device 10, and can be set to 0.6 to 0.8, for example. The second threshold value may be variably set by the user. When the irradiation state determination unit 16 determines that the transmission value TR is smaller than the second threshold value, the supply control unit 12 may stop the increase in the supply of the heavy charged particles P and perform various adjustments (not shown). ) As various adjustments, the direction of the collimator 44 (probe collimator 44a, buffer collimator 44b, target collimator 44c) is adjusted, the direction of the stripper foil 42 and the protruding length from the foil drive unit 43, the main electromagnet 50, and the like. It is better to increase or decrease the magnet current applied to the. By these various adjustments, the beam halo can be reduced to improve the directivity of the heavy charged particle beam PB, or the target 34 can be irradiated with the heavy charged particle beam PB more accurately. Various adjustments may be made manually by the user while visually confirming the numerical values of the parameters displayed on the transmission value display section 66 and the like of the display screen DP, or the optimum value of the transmission value TR is searched by the cyclotron control device 10. You may adjust automatically.

  If it is determined in step ST14 that the transmission value TR, which is an index value, is greater than or equal to the second threshold and the degree of deviation is less than a predetermined value, the magnet current control unit 18 optimizes the magnet current IM (step ST16: FIG. 4 and FIG. 4). (See FIG. 5). In optimizing the magnet current IM, it is preferable to monitor the transmission value TR with the output monitor unit 14 while adjusting the magnet current IM little by little, and determine the magnet current IM that maximizes the transmission value TR as the optimum value IM1. Although FIG. 5 illustrates the case where the optimum value IM1 is larger than the initial value IM0, the present invention is not limited to this. The optimum value IM1 of the magnet current IM is preferably 400A or more and 600A or less, for example 500A.

  From time T2 when the magnet current IM is set to the optimum value IM1, the second supply step ST18 is performed. In the second supply step ST18, the supply amount of the heavy charged particles P is further increased from the first set amount by further increasing the filament current applied to the filament 24 (step ST19). The output monitor unit 14 repeats this until the supply amount of the heavy charged particles P becomes a sufficient value (step ST20: NO). When the supply amount of the heavy charged particles P reaches the second set amount, the cyclotron control device 10 ends the second supply step ST18. During the second supply step ST18, the magnet current IM is constant at the optimum value IM1.

Although the specific determination process performed in step ST20 is not particularly limited, in the present embodiment, during the execution of the second supply step ST18, the output monitor unit 14 acquires the target current value TG, and the target current value TG is obtained. By comparing with the second set amount, it is determined that the supply amount of the heavy charged particles P has reached a desired amount. When the second supply step ST18 is finished, the increase in the supply amount of the heavy charged particles P from the ion source 20 to the accelerator 30 is stopped (step ST22), and thereafter, the supply amount of the heavy charged particles P is made constant. The end time of the second supply step ST18 is T3 (see FIG. 5).
At the time T3 when the second supply step ST18 ends or at a timing after that, the output monitor unit 14 acquires the beam current value EPR and the target current value TG, calculates the index value (transmission value TR), and stores it in a batch record or the like. Record (step ST24). The irradiation state determination part 16 sets the 1st threshold value used by electric current control step ST26 based on this index value.

  The first threshold is based on the index value (transmission value TR) acquired by the output monitor unit 14 at a predetermined timing (step ST24) after the supply amount of the heavy charged particles P reaches the set amount (second set amount). Is set corresponding to a value with a large degree of deviation. Thereby, the state in which the degree of deviation is slightly worse than when the supply amount of the heavy charged particles P is stabilized can be set as a determination threshold value in the determination step ST32. Specifically, for example, the transmission value TR may be acquired at time T4 when 10 minutes have elapsed since the second supply step ST18 was completed. When the transmission value TR at this time is, for example, 85%, the first threshold value may be 84.5%, which is a slight decrease in the transmission value TR. The difference between the transmission value TR and the first threshold value at the end of the second supply step ST18 may be 5% or less, preferably 1% or less.

  The current control step (current control step) ST26 is from the setting of the first threshold value to the end of irradiation with the heavy charged particle beam PB. In the current control step ST26, when the heavy charged particle beam PB is irradiated for a predetermined time (step ST27) and the irradiation end determination is denied and the irradiation is continued (step ST28: NO), the output monitor unit 14 determines the beam current. The value EPR and the target current value TG are acquired, and the transmission value TR is updated (step ST30).

  The irradiation state determination unit 16 determines whether the updated transmission value TR is a first threshold value (for example, 89.5%). If it is determined that the transmission value TR is greater than or equal to the first threshold (determination step ST32: YES), irradiation with the heavy charged particle beam PB is continued again for a predetermined time (step ST27). The predetermined time is not particularly limited, but may be 1 minute or more and 5 minutes or less. As a result, the frequency of the determination step ST32 does not become excessive, and the deterioration of the convergence of the heavy charged particle beam PB can be detected promptly.

  When the irradiation value determination unit 16 determines that the transmission value TR is less than the first threshold value in the determination step ST32 (determination step ST32: NO), the magnet current control unit 18 increases the magnet current IM (magnet current increase step ST34).

Although the specific increase process of the magnet current IM in the magnet current increase step ST34 is not particularly limited, in the present embodiment, the process of increasing the magnet current IM by a predetermined increase width is performed once or a plurality of times. Illustrate. The rising width can be 0.001A or more and 0.02A or less. The increase width can be set to 10 ⁻⁶ (1 ppm) or less compared to the optimum value IM1 (for example, 500 A) of the magnet current IM.
In the present embodiment, as an example, the maximum number of repetitions is set to 5 times.

After increasing the magnet current IM in the magnet current increasing step ST34, the magnet current control unit 18 subtracts 1 from the remaining number of increases (step ST36), and determines the remaining number. When the remaining number is 1 or more (step ST38: NO), the output monitor unit 14 acquires the beam current value EPR and the target current value TG, and updates and acquires the index value. The irradiation state determination unit 16 compares the index value that has been updated and acquired with the first threshold value and updates and determines the degree of deviation (determination step ST32).
When it is determined that the index value determined to be updated is equal to or greater than the first threshold and the degree of deviation is less than the predetermined value (determination step ST32: YES), the magnet current control unit 18 stops increasing the magnet current IM. Return to step ST27.

As a result of the above update determination, when the increase width of the magnet current IM becomes equal to or greater than a predetermined value, the magnet current control unit 18 stops increasing the magnet current IM regardless of the degree of deviation determined to be updated. Specifically, when it is determined that the index value determined to be updated is still less than the first threshold (determination step ST32: NO), the magnet current increasing step ST34 to step ST38 are repeated. Then, the increase of the magnet current IM is repeated 5 times, and when the remaining number becomes 0 (step ST38: YES), the increase of the magnet current IM is stopped and the process returns to step ST27. This prevents excessive application of the magnet current IM when the transmission value TR is decreased due to factors other than a decrease in magnetization of the main electromagnet 50, such as an increase in collimator loss or external loss. Is done.
When returning to step ST27, the irradiation of the heavy charged particle beam PB is continued again for a predetermined time. At this time, the remaining number of increases of the magnet current IM is reset to an initial value (for example, 5 times).

  When the heavy charged particle beam PB is irradiated again for a predetermined time from the time T5 returning to the step ST27 and reaches the time T6, after the irradiation end determination (step ST28) is performed, the output monitor unit 14 revisits the index value. (Transmission value TR) is calculated, and the magnet current control unit 18 determines whether the index value is a first threshold value (step ST32). Thereafter, the above process is repeated. When it is determined that the index value is less than the first threshold value, the magnet current increasing step ST34 to step ST38 are repeated each time, and the process returns to step ST27 (time T7: see FIG. 5).

  Then, when the third supply step ST26 is continued and a predetermined irradiation time has elapsed (step ST28: YES), the cyclotron control device 10 stops the supply of the heavy charged particle P and the irradiation of the heavy charged particle beam PB.

  As described above, by using the cyclotron control device 10 of the present embodiment, it is detected with high accuracy that the transmission value TR has decreased due to the main electromagnet 50 being heated and the magnetization of the magnetic pole 51 being decreased. This can be solved by increasing the magnet current IM. Thereby, a stable target current value TG can be obtained over a long period of time, for example, 2 hours or more.

By using the cyclotron control device 10 of the present embodiment, a nuclear reaction occurs in the target 34 and a radionuclide is generated. Radionuclides can be used for radiopharmaceutical production and radiotherapy.
In particular, according to the cyclotron 100 equipped with the cyclotron control device 10 of the present embodiment, the target 34 can be continuously irradiated with the heavy charged particle beam PB for a long time as described above, and the radiopharmaceutical can be mass-produced. it can. That is, according to the cyclotron control device 10 of the present embodiment, the following method for producing a radiopharmaceutical (hereinafter sometimes referred to as the present method) is provided.

The present method includes an accelerator 30 that accelerates the heavy charged particles P supplied from the ion source 20 to circulate in a magnetic field environment formed by applying a magnet current to the main electromagnet 50 to form a heavy charged particle beam PB; The present invention relates to a method of manufacturing a radiopharmaceutical using a cyclotron 100 including a beam extraction unit 40 that changes a trajectory of a heavy charged particle beam PB and extracts the heavy charged particle beam PB from an accelerator 30 and emits it toward a target 34.
This method includes an irradiation step of generating a radionuclide by irradiating the target 34 with the heavy charged particle beam PB, a current control step ST26, and a labeling step, and the irradiation step is performed before and after the current control step ST26. It is characterized by being performed continuously.
In the current control step ST26, the index value is acquired over time, the degree of divergence is determined by comparing the acquired index value with the first threshold value, and when it is determined that the divergence degree is greater than or equal to a predetermined value, Increase IM. The index value includes a beam current value EPR indicating the amount of the heavy charged particle beam PB whose trajectory is changed by the beam extraction unit 40, and a target current value TG generated when the emitted heavy charged particle beam PB collides with the target 34. The transmission value TR can be used as described above. In the labeling step, a radiopharmaceutical is produced using the produced radionuclide and the labeled precursor compound. The labeling step is a step of producing a radiopharmaceutical using the produced radionuclide and the labeling precursor compound, and includes various processes such as hydrolysis and purification. A known method can be used for the labeling step. For example, by this ^method, the ¹⁸ O water (oxygen 18 labeled water), to generate a ¹⁸ F as radionuclides, labeled step, TATM (1,3,4,6-tetra -O- acetyl as a labeling precursor compound ¹⁸ F-FDG (fluorodeoxyglucose) can be produced using 2-O-trifluoromethanesulfonyl-β-D-mannopyranose).
According to this method, after the beam output of the heavy charged particle beam PB is once stabilized, it is possible to suppress the beam output from decreasing due to the temperature increase of the main electromagnet 50 and to stably produce the radionuclide for a long time. can do.

As an example of this method, the optimum value IM1 was set to 500A as described above, the first threshold value was set to 84.5%, and ¹⁸ F was generated as a radionuclide. This method is not applied, that is, the production yield of ¹⁸ F when the magnet current IM is fixed at the optimum value IM1 in the current control step ST26, and the magnet current IM is increased in the current control step ST26 by applying this method. The production yield of ¹⁸ F was compared. As a result, the average value of the production yield of ¹⁸ F was 3215.3 MBq / μA when this method was not applied, but was improved to 3449.5 MBq / μAh as a result of applying this method. The relative standard deviation (RSD:%) = (standard deviation / average value) × 100 of the production yield of ¹⁸ F was 8.0% when this method was not applied, whereas Application of the method improved to 4.5%. Thereby, according to this method, not only the production yield of the radionuclide was improved, but also the production yield was confirmed to be stable.

  According to the cyclotron control device 10 of the present embodiment, its control program, and the cyclotron 100 including the cyclotron control device 10, a heavy charged particle beam is generated due to heating of the main electromagnet 50 without attaching a temperature sensor to the main electromagnet 50. The cyclotron control device 10 detects that the convergence state of PB has deteriorated, and this can be eliminated by a slight increase in the magnet current IM. In addition, since the convergence state of the heavy charged particle beam PB can be optimally maintained as described above while maintaining the arc current constant in the third supply step ST26, the load on the collimator 44 and the filament 24 is increased. Nor.

  The present invention is not limited to the above-described embodiment, and includes various modifications and improvements as long as the object of the present invention is achieved.

The above embodiment includes the following technical idea.
(1) An accelerator that accelerates heavy charged particles supplied from an ion source while circulating in a magnetic field environment formed by applying a magnet current to a main electromagnet to form a heavy charged particle beam, and the heavy charged particle beam A control unit for a cyclotron comprising: a beam extraction unit that changes the trajectory and takes out from the accelerator and emits it toward the target; and a magnet current control unit that controls the magnet current applied to the main electromagnet; The degree of divergence between the beam current value indicating the amount of the heavy charged particle beam whose trajectory is changed by the beam extraction unit and the target current value generated when the emitted heavy charged particle beam collides with the target. Output monitor means for acquiring the index value shown over time, and comparing the index value acquired by the output monitor means with a first threshold value before An irradiation state determination unit that determines the degree of deviation, and the magnet current control unit increases the magnet current when the irradiation state determination unit determines that the degree of deviation is greater than or equal to a predetermined value. A cyclotron control device.
(2) The first threshold value further includes a supply control means for maintaining the set amount after the supply amount of the heavy charged particles supplied from the ion source to the accelerator is increased to a predetermined set amount. However, in the above (1), the degree of deviation is set corresponding to a value larger than the index value acquired by the output monitoring means at a predetermined timing after the supply amount reaches the set amount. Cyclotron control device.
(3) After the magnet current control unit increases the magnet current, the output monitor unit updates and acquires the index value, and the irradiation state determination unit compares the updated and acquired index value with a first threshold value. Then, the degree of divergence is determined to be updated, and the magnet current control means stops the increase in the magnet current when it is determined that the degree of divergence determined to be updated is less than a predetermined value (1) or ( The cyclotron control device according to 2).
(4) After the magnet current control unit increases the magnet current, the output monitor unit acquires and updates the index value, and the irradiation state determination unit compares the updated and acquired index value with a first threshold value. The divergence degree is determined to be updated, and the magnet current control means stops the increase of the magnet current regardless of the divergence degree determined to be updated when the increase width of the magnet current exceeds a predetermined value. The cyclotron control device according to any one of (1) to (3).
(5) The cyclotron control according to any one of (1) to (4), wherein the index value acquired by the output monitoring unit is a transmission value indicating a ratio of the target current value to the beam current value. apparatus.
(6) an ion source and an accelerator that accelerates the heavy charged particles supplied from the ion source while rotating around the magnetic field environment formed by applying a magnet current to the main electromagnet to form a heavy charged particle beam; A cyclotron comprising: a beam extraction unit that changes the trajectory of the heavy charged particle beam, extracts the beam from the accelerator, and outputs the beam toward the target; and the cyclotron control device according to any one of (1) to (5) above. .
(7) An accelerator that accelerates heavy charged particles supplied from an ion source while circulating in a magnetic field environment formed by applying a magnet current to a main electromagnet to form a heavy charged particle beam, and the heavy charged particle beam A program for controlling a cyclotron comprising: a beam extraction unit that changes a trajectory and takes it out from the accelerator and emits it toward a target, wherein the program changes the trajectory in the beam extraction unit An index value indicating the degree of deviation between the beam current value indicating the amount of the particle beam and the target current value generated when the emitted heavy charged particle beam collides with the target is obtained over time. A determination process for comparing the index value with a first threshold value to determine the divergence degree, and the determination process determines that the divergence degree is greater than or equal to a predetermined value. Case, the said cyclotron control program and the magnet current increasing process of increasing the magnet current, characterized in that to be executed by the cyclotron to be applied to the main electromagnet.
(8) An accelerator that accelerates heavy charged particles supplied from an ion source while rotating around a magnetic field environment formed by applying a magnet current to a main electromagnet to form a heavy charged particle beam; A radiopharmaceutical manufacturing method using a cyclotron comprising: a beam extraction unit that changes a trajectory and takes out from the accelerator and emits the target toward the target, wherein the target is irradiated with the heavy charged particle beam and the radionuclide is irradiated A beam current value indicating the amount of the heavy charged particle beam whose trajectory is changed by the beam extraction unit, and a target current value generated when the emitted heavy charged particle beam collides with the target And obtaining an index value indicating the degree of deviation over time, and comparing the obtained index value with a first threshold value to determine the degree of deviation. A current control step for increasing the magnet current when the degree of divergence is determined to be greater than or equal to a predetermined level, and a labeling step for producing the radiopharmaceutical using the generated radionuclide and labeled precursor compound; And the irradiation step is performed continuously before and after the current control step.

DESCRIPTION OF SYMBOLS 10 Cyclotron control apparatus 12 Supply control part 14 Output monitor part 16 Irradiation state determination part 18 Magnet current control part 20 Ion source 22 Plasma generation part 24 Filament 25 Extraction electrode 26 Ion supply port 30 Accelerator 31 Acceleration space 32 Beam tube 34 Target 40 Beam Extraction unit 42 Stripper foil 43 Foil drive unit 44 Collimator 44a Probe collimator 44b Buffer collimator 44c Target collimator 50 Main electromagnet 51 Magnetic pole 51a Valley region 51b High frequency electrode 54 High frequency power source 56 Coil 58 Coil power source 62 Arc current display unit 63 Beam current Value display unit 64 Collimator current value display unit 65 Target current value display unit 66 Transmission value display unit 67 Vacuum degree display unit 68 Magnet current value display unit 69 Pressure value display unit 70 Magnet setting display unit 100 Cyclotron DP display screen IM Magnet current P Heavy charged particle PB Heavy charged particle beam TG Target current value TR Transmission value EPR Beam current value

Claims (8)

Accelerating heavy charged particles supplied from an ion source while turning around in a magnetic field environment created by applying a magnet current to the main electromagnet to make a heavy charged particle beam, and changing the trajectory of the heavy charged particle beam A control unit for a cyclotron comprising: a beam extraction unit that extracts from the accelerator and emits toward the target;
Magnet current control means for controlling the magnet current applied to the main electromagnet;
A degree of divergence between a beam current value indicating the amount of the heavy charged particle beam whose trajectory is changed by the beam extraction unit and a target current value generated when the emitted heavy charged particle beam collides with the target. Output monitoring means for obtaining the index value over time;
An irradiation state determination unit that compares the index value acquired by the output monitor unit with a first threshold value to determine the degree of deviation, and
The cyclotron control device according to claim 1, wherein the magnet current control means increases the magnet current when it is determined by the irradiation state determination means that the degree of deviation is not less than a predetermined value. A supply control means for maintaining the set amount after increasing the supply amount of the heavy charged particles supplied from the ion source to the accelerator until reaching a predetermined set amount;
The first threshold value is set in correspondence with a value having a greater degree of deviation than the index value acquired by the output monitoring means at a predetermined timing after the supply amount reaches the set amount. 2. The cyclotron control device according to 1. After the magnet current control means increases the magnet current, the output monitoring means updates and acquires the index value, and the irradiation state determination means compares the updated and acquired index value with a first threshold value. Update the divergence degree,
The cyclotron control device according to claim 1, wherein the magnet current control unit stops the increase of the magnet current when it is determined that the degree of deviation determined to be updated is less than a predetermined value. After the magnet current control means increases the magnet current, the output monitoring means updates and acquires the index value, and the irradiation state determination means compares the updated and acquired index value with a first threshold value. Update the divergence degree,
4. The magnet current control unit according to claim 1, wherein when the increase width of the magnet current becomes equal to or greater than a predetermined value, the magnet current control unit stops increasing the magnet current regardless of the degree of deviation determined to be updated. 5. The cyclotron control device described.   5. The cyclotron control device according to claim 1, wherein the index value acquired by the output monitoring unit is a transmission value indicating a ratio of the target current value to the beam current value. 6. An ion source;
An accelerator that accelerates the heavy charged particles supplied from the ion source to circulate in a magnetic field environment formed by applying a magnet current to the main electromagnet to form a heavy charged particle beam,
A beam extraction unit for changing the trajectory of the heavy charged particle beam and extracting the beam from the accelerator to be emitted toward the target;
A cyclotron control device according to any one of claims 1 to 5;
Cyclotron equipped with. Accelerating heavy charged particles supplied from an ion source while turning around in a magnetic field environment created by applying a magnet current to the main electromagnet to make a heavy charged particle beam, and changing the trajectory of the heavy charged particle beam A program for controlling a cyclotron comprising: a beam extraction portion that is extracted from the accelerator and emitted toward a target;
The program is
A degree of divergence between a beam current value indicating the amount of the heavy charged particle beam whose trajectory is changed by the beam extraction unit and a target current value generated when the emitted heavy charged particle beam collides with the target. A determination process of acquiring an index value over time, and determining the degree of deviation by comparing the acquired index value with a first threshold;
A cyclotron control that causes the cyclotron to execute a magnet current increasing process for increasing the magnet current applied to the main electromagnet when the degree of deviation is determined to be greater than or equal to a predetermined value in the determining process. program. Accelerating the heavy charged particles supplied from the ion source while rotating around the magnetic field environment formed by applying a magnet current to the main electromagnet to make a heavy charged particle beam, and changing the trajectory of the heavy charged particle beam And a beam extraction part that is extracted from the accelerator and emitted toward the target, and a method for producing a radiopharmaceutical using a cyclotron comprising:
An irradiation step of irradiating the target with the heavy charged particle beam to generate a radionuclide;
A degree of divergence between a beam current value indicating the amount of the heavy charged particle beam whose trajectory is changed by the beam extraction unit and a target current value generated when the emitted heavy charged particle beam collides with the target. An index value is acquired over time, the acquired index value is compared with a first threshold value to determine the degree of deviation, and when the degree of deviation is determined to be greater than or equal to a predetermined value, the magnet current is increased. Current control step to
Using the produced radionuclide and a labeled precursor compound to produce the radiopharmaceutical, and
The method for producing a radiopharmaceutical, wherein the irradiation step is continuously performed before and after the current control step.

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