RU142218U1 - TARGET DEVICE FOR CYCLOTRON WITH 12-18 MEV PROTON ENERGY FOR OBTAINING RADIONUCLIDE FTOR-18 - Google Patents

Abstract

1. A target device comprising a collimator, a collimator body with cooling, an output foil, a target foil, a helium cooling unit between the foil spaces, a target body, a target pressure flange, a back cover with a target body cooling unit, characterized in that the target water cavity is thin-walled with wall thickness from 0.5 to 2 mm. 2. The target device according to claim 1, characterized in that the water cavity of the target is thin-walled in the shape of a cone. The target device according to claim 1, characterized in that the water cavity of the target is made thin-walled in the form of a sphere.

Description

Technical field

The claimed technical solution relates to medical equipment, namely to the means of producing radionuclides for the production of radiopharmaceuticals used to diagnose a wide range of diseases using positron emission tomography.

State of the art

The ¹⁸ F radionuclide is produced by the nuclear reaction ¹⁸ O (p, n) ¹⁸ F upon irradiation with protons of oxygen enriched with the ¹⁸ O isotope in the chemical form H ₂ ¹⁸ O.

In the prior art, a target device is known in which tantalum is selected as the target body material. Structurally, the housing is made of a disk and a ring 2 mm thick. From the side of the beam entrance, the target volume is closed by a titanium foil 50 μm thick. The working volume of the target is sealed with 20 μm thick fluoroplastic gaskets. The selected materials do not interact with fluorine ions formed in water and practically do not introduce impurity contaminants. Water in the target is irradiated at an excess pressure created by helium. The target withstands excess pressure in a volume of at least 6 kg / cm ² at a working pressure of 2 kg / cm ² . This target device allows you to get up to 0.8 Ki fluorine-18 in 2 hours of exposure. (Radionuclide imaging methods: Textbook. St. Petersburg; St. Petersburg State Polytechnic University, 2006, 75 pp. Authors: BV Zabrodin, VN Lomasov, AV Motorny)

The disadvantages of this technical solution are:

1. a shallow depth of the cavity of the target body for the irradiated material (2 mm) leads to incomplete absorption of protons and thereby to a decrease in the productivity of the target device;

2. the use of fluoroplastic gaskets can lead to the release of fluoroplastic degradation products into irradiated water and a decrease in the radiochemical yield of the radiopharmaceutical when using a radionuclide obtained using this target device;

3. The design of the target body is performed in such a way (a small condensation surface of the chamber for the irradiated material, the absence of fins, laying between the rear wall of the target and the target body), which does not provide sufficient cooling for it and leads to a decrease in the performance of the target device.

Prototype

As a prototype, a target device for producing a fluorine-18 radionuclide containing the target body with a cavity for the irradiated material located in the central part of the front surface of the body, a flange, its back wall and foil was chosen. The target device additionally contains a clamping plate, the target body is solid, made of niobium, has threads 10-32 UNF above and below, the cavity height for the irradiated material is 41 mm, the cavity has an oval shape, its bottom is beveled at an angle of 45 degrees, the back wall the target body has a ribbing, in shape and location matching the oval cavity on the front surface of the target body, the flange has a recess for attaching the target body, located so that the center of the target body is located 11 mm above the center a hole for proton beam, the back wall of the flange has a recess for cooling water circulation, in the upper and lower parts of which there are G1 / 4 threads, one foil is located between the target body and the flange, the other between the flange and the clamping plate (Utility Model Patent DEVICE FOR CYCLOTRON WITH 18 MEV PROTON ENERGY FOR OBTAINING RADIONUCLIDE FLUOR-18 IN THE TYPE OF FLUORIDE ANION №114260).

The disadvantage of this technical solution is the insufficient cooling of the target body, due to the fact that heat is removed only from the rear wall of the target, as a result of which the target overheats with increasing beam current.

A task

The problem to which the technical solution is presented, presented in the utility model, TARGET DEVICE FOR CYCLOTRON WITH 12–18 MeV PROTON ENERGY FOR PRODUCING RADIO NUCLIDE FLUOR-18 consists in optimizing the cooling of the target body.

This problem is solved due to the fact that the water cavity of the target body (1) is made of a thin-walled conical or spherical shape with a wall thickness of 0.5 to 2 mm. Due to this, it becomes possible to supply cooling water to a large surface area of the target body, and heat transfer between the working fluid (H ₂ O ¹⁸ ) and cooling water is improved by reducing the wall thickness made of niobium or tantalum that is poorly conductive of heat.

Technical result

The technical result of this solution is to increase the performance of the target by optimizing heat transfer between the working fluid and cooling water. The maximum target performance at a beam current of 50 μA is 7 Ci for 2 hours of irradiation.

Utility Model Disclosure

The target device contains a collimator (2), a collimator body with cooling (3), an output foil (4), a target foil (5), a helium cooling unit between the foil spaces (6), a back cover (7) with a target body cooling unit (8) target body (9). The target body is made whole of niobium or tantalum (these materials are used because of their high chemical inertness). The water cavity of the target is thin-walled, conical or spherical in shape (9). At the top of the water cavity there is a damping volume (10) to compensate for the thermal expansion of water and the evolved gas phase during evaporation and radiolysis of water, a helium feed channel for purging the target (11) is introduced into the damping volume, and a channel for refueling and discharging is located in the lower part of the water cavity water from the target (12).

Utility Model Implementation

The process of obtaining the fluorine-18 radionuclide is as follows. Passing through the collimator (2), the beam of accelerated protons is cut off, while the part of the beam that can be effectively used for the ¹⁸ O (p, n) ¹⁸ F reaction remains. Then the beam passes through the output foil (4) and the target foil (5). The power released in the form of heat on the foils is removed by a stream of helium supplied to the cavity between the two foils. Next, the beam penetrates directly into the water cavity of the target (1) and is absorbed by the working fluid. Moreover, the greater the beam current, the greater the power absorbed by the working fluid. In order to maximize the heat removal from the target body, the water cavity is made of a thin-walled conical or spherical shape with a wall thickness of 0.5 to 2 mm. In this case, most of the outer side of the water cavity is washed by cooling water through the target cooling system (8), and its thin-walled design allows to maximize the heat transfer between the working fluid and cooling water.

Brief Description of the Drawings

For a better understanding of the design of the target device, the assembly drawing of the target device (Fig. 1) and the drawing of the target body (Fig. 2) are shown:

1 - water cavity of the target body; 2 - collimator; 3 - collimator housing with cooling; 4 - output foil; 5 - target foil; 6 - node helium cooling interfoil space; 7 - a back cover; 8 - cooling unit of the target body; 9 - target body; 10 - damping volume; 11 - helium feed channel; 12 - channel for refueling and discharging water from the target.

Claims (3)

1. A target device comprising a collimator, a collimator body with cooling, an output foil, a target foil, a helium cooling unit between the foil spaces, a target body, a target pressure flange, a back cover with a target body cooling unit, characterized in that the target water cavity is thin-walled with wall thickness from 0.5 to 2 mm. 2. The target device according to claim 1, characterized in that the water cavity of the target is made thin-walled in the shape of a cone. 3. The target device according to claim 1, characterized in that the water cavity of the target is made thin-walled in the form of a sphere.

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