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How can DOFRP produce MRI coils for Toshiba?

Products: MRI coils
Customer: Toshiba
Cooperation time: Since 2012

1. MRI coils problems and solutions

1.1 How to make the mold?

Difficulty: Toshiba has a pretty high requirement about the precision of volume coils.

Coils are designed with dual bellmouth. Our engineer considered that there may be a problem of mold release during the production process. After the repeated review and confirmation of our technical staff, we used a special FRP mold design style and divided it into two parts, a mobile end and a fixed end.

1.2 High strength volume coils

Requirement: We must control the proportion within 68% to 73%.

When the magnetic resonance imaging machine is operating, there may be cracks and other problems if the internal parts of MRI scanners can’t support the corresponding high strength. As a result, it can’t provide high quality images, even may have a serious effect on the patient’s detection results or even personal safety. Of course, we mustn’t let it happen.

DOFRP coils provide high strength and can help to form high quality images. To meet the need, first of all, we took strict control of the fiberglass material. Then, we investigated the properties of different kinds of fiberglass resin. Considering about making the special shape, we make sure that the proportion of fiber quantity and each material must be weighed. What’s more, we record the using amount before and after each production to confirm whether the product proportion is average.

1.3 High flatness, smooth FRP inner wall

Difficulty: There is an end difference between the active end and the mobile end of the magnetic resonance coil. And it’s prone to displacement (leakage) problems.

We must make the thickness of these volume coils to be even, and the fiberglass resin must be fully saturated. It can help the coil to avoid cracking problems. During the filament winding process, we have repeatedly reviewed the control of the number of circular and crossed winding layers for MRI coils. To better precisely control the winding number of each layer and meet the need for thickening some special positions, we have adopted various controls. For example, using different tools to compare and adding an auxiliary digital device, making special marks on the tracks of the platform.

1.4 Zero impurity

Requirement: there must be no impurity in MRI machines.

If there are any magnetic metals or organic matters in MRI machines, it will affect the measured result and image quality. First of all, we check the quality of the raw material before putting them into storage. And any foreign matter is not allowed to mix in them. Besides for the 5S management, we require to use the clean measurement tool in the workshop. What’s more, the workers should use the disposable glove and change it in time. Also, they will clean and maintain the mold for MRI coils regularly. If these skilled workers find any foreign matters during the surface coils manufacturing process, they will pick them up.

Besides, we use the PET film for the final protection of the quadrature coil. The next day, we repeatedly check its surface status and the inner wall to confirm the quality. Until now, we have been producing over 1000 units of MRI coils for Toshiba. And those coils we provide have stable image quality and get a good review from our customer.

2. Types of coil

Magnetic resonance imaging is an imaging technique that uses the signals generated by the resonance of the nucleus in the magnetic field to reconstruct the image. The basic principle of magnetic resonance imaging (MRI) is to place the human body in a special magnetic field to release absorbed energy. The energy released is collected by an external receptor and processed with an electronic computer to get an image. This operation does not need injection of contrast agent, has no ionizing radiation, and it’s certainly safe.

There are many different types of coil for MRI. For example, shim coils, gradient coils, radio frequency (RF) body coils, and patient coils. These MRI coils have different functions. Firstly, the shim coil can improve the homogeneity. Secondly, gradient coils are used for imaging, and they also include active shields. As for RF coil, it can transmit the B1 field and receive signal. Last but not least, patient MR coil is always used to detect MR signal, some of which transmit or receive. During an MRI, your body may experience many types of coil. Such as MRI head coil, shoulder, knee, breast, cervical spine, ankle, upright brain, upright cervical spine, etc.

Mr Ozawa, who has 16 years experience in FRP industry, is now in charge of medical FRP equipment. As he said:
“How to achieve zero impurity? You need to do constantly experiment and monitor, strictly control the FRP material and the whole glass fiber production process.”

3. Imaging influence factors

Research has shown that the MRI image quality depends on the signal to noise ratio and RF coils. For one thing, to get high quality images, we can first improve the signal to noise ratio. The common ways are to sample larger volumes or increase the strength of the magnetic field. You can also use the surface coils to improve the local signal. For another, the RF coil can transmit and receive radio frequency signals in MRI equipment. As a transmitter, RF coils can create a magnetic field. And radio frequency receive coils are responsible for detecting the magnetic resonance signal. What’s more, we now widely apply the receive coils for parallel imaging. To get a high quality MRI coil, you can choose us DOFRP to be a supplier.

We use the filament winding method to produce MRI coils. And it has many advantages. First of all, you can design the winding principle according to the force of the coil. It can help to give full play to the fiber strength. Secondly, the winding coil is 40% to 60% lighter than the others. Thirdly, we often adopt mechanized and automatic production. The filament winding process only needs a few operating workers and is fast in speed. Finally, for the same product, we can reasonably select several materials, including resin, fiber, and lining. Compounding them, and you can reach the optimal technical and economic effect.