Introduction of tungsten alloy collimator
A tungsten alloy collimator is a device that shrinks particle beams or light waves. Shrinking means making the particle rays go in a specific direction, that is, only allowing rays parallel to the collimator to pass, or making the space cross-section beam narrower to limit the amount of radiation.
A tungsten alloy collimator is a component of the radiation head of a medical accelerator. In addition to the primary and secondary collimators, the electron beam limiter is equipped under the radiation head for the collimation of electron radiation. Its main function is to limit the range of electron radiation in order to protect normal tissues outside the target area and prevent critical organs from being irradiated.
1 | 2 | 3 | 4 | ||
Tungsten(%) | 90 | 92.5 | 95 | 97 | |
Density(g/cc) | 16.85-17.25 | 17.15-17.85 | 17.75-18.35 | 18.25-18.85 | |
Hard(HRC) | 32 | 33 | 34 | 35 | |
| Ultimate tensile strength | ksi | 110 | 110 | 105 | 100 |
Mpa | 758 | 758 | 724 | 689 | |
| Yield strength 0.2% | ksi | 75 | 75 | 75 | 75 |
Mpa | 517 | 517 | 517 | 517 | |
| Elongation(%) | 5 | 5 | 3 | 2 | |
Advantages of a tungsten alloy collimator
Under the same thickness conditions, the radiation shielding ability of tungsten alloy is more than 1.7 times that of lead. When the radiation is stronger, the difference in the shielding ability of the two is more obvious; tungsten alloy material has environmental protection characteristics, while lead is toxic, and tungsten alloy shielding parts are not harmful to human safety when manufacturing radiation detectors; tungsten alloy is easy to cut, and its density and hardness are higher than lead materials. After sintering, tungsten alloy shielding parts can reach a very low thickness; tungsten has the highest melting point among metals, and tungsten alloy can be used as a radiation detection material in certain high-temperature environments; tungsten alloy has high stability under various special gas conditions, such as chlorine, bromine, or other halogen gases used as quenching gases.
Working principle of tungsten alloy collimator
The tungsten alloy collimator is a component of the radiation head of the medical accelerator. The component that produces a radiation field with a certain shape and contour is called a collimation system, and the component that produces a radiation field with a regular shape and contour is called a regular field collimation system. A regular field refers to a radiation field with a square, rectangular, or circular contour of variable size.
Application fields of tungsten alloy collimators
Tungsten alloy collimators can be divided into neutron ray collimators, X-ray collimators, and gamma ray collimators according to the different rays. As a part of the ray accelerator, tungsten alloy collimators are mainly used in the field of radiotherapy. Radiotherapy is used to treat malignant tumors and some benign diseases in various parts of the human body, and radiation can also be used to treat cancer. Tungsten alloy collimators can also be used as part of ray detectors in industrial detection, such as nuclear power plant radiation detection, oil drilling exploration, pipeline detection, etc.
The manufacturing process of tungsten alloy collimator
First, not least, 90% of tungsten metal powder is mixed with equal proportions of iron and nickel metal powder. During this process, heat treatment is performed. The sintering temperature can be controlled at about 1450 °C to 1500 °C. At this time, the pressed green or loose powder body is heated to a temperature below the melting point of its basic components (about 0.7~0.8T absolute melting point). Heat treatment can improve the strength of the pressed green or loose powder body and increase the density of the tungsten alloy.
