X Ray Tube Insert

X RAY TUBE

X-ray tubes are vacuum tubes that convert incoming electrical power into X-rays. The availability of this controllable X-ray source created the field of radiography, the imaging of partially opaque objects with penetrating radiation. In contrast to other sources of ionizing radiation, X-rays are only produced when the X-ray tube is energized. X-ray tubes are also used in CT scanners, airport baggage scanners, X-ray crystallography, material and structural analysis, and industrial inspection. Growing demand for high-performance computed tomography (CT) scanning and angiography systems has driven the development of high-performance medical X-ray tubes.

X RAY TUBE PARTS

1.   Cathode X-ray tube

As a complementary component to the anode, the cathode has a negative charge that is released during operation, and it points towards the anode for further projection. First, you'll find two other components attached to the cathode, which are the focusing cup and the filament.

These two connected elements are responsible for generating electrons and directing them to the anode, generating a lot of heat in the process. Fortunately, the cathode is made of a molybdenum-nickel alloy, a material that has high heat resistance.

The problem is that the size of the X-ray beam produced and projected by the cathode depends on the size of the focal spot set by the technician operating the machine.

2.   Glass envelope

The glass envelope is an essential vacuum-filled part of the X-ray tube housing and contains the components needed to generate X-ray energy. Typically, these components consist of an anode, cathode, filament coil, focusing cup, and focusing coil. In addition, the glass enclosure is made of Pyrex glass, suitable to withstand the enormous heat generated during radiant production.

However, the generation of radiation creates a tremendous amount of heat, which causes the tungsten material used for the anode to evaporate, creating some deposits on the glassware. These deposits then start to build up and over time can become an obstacle to radiation production and proper projection.

3.   Focus coil

The focusing coil is an attachment to the focusing cup that helps ensure that the focusing cup guides electrons accurately from the cathode to the anode at a predetermined point. While the predetermined point of the anode, also known as the focal point, redirects radiation to the test sample, failure of the focusing coil reduces the efficiency of the focusing cup to direct radiation to the focal point on the anode.

4.   Anode (target)

One of the most important components of an X-ray tube is the anode. The anode acts as a complementary component to the cathode, but functionally, it attracts electrons from the cathode once the X-ray machine operator presses the exposure button. However, the anode itself is positively charged and usually generates a lot of heat during the operation of any X-ray machine.

This heat is responsible for making anodes using highly heat-resistant materials like tungsten. However, the anode's disk rotates very fast to spread the heat generated over its entire surface, avoiding the heat being concentrated in a specific location. But more importantly, the anode acts as a target for electrons from the cathode, at an angle that helps project the electron beam to the detector.

Regardless, if the anode spin fails, the damage to come will be enormous. Although tungsten can handle a lot of energy, it cannot prevent damage to the anode even if it is not rotated during the operation of the X-ray machine.

5.   Tube window

Inside the glass envelope of the X-ray tube housing there is an important opening, not more than 5 cm wide, called the X-ray tube window. The importance of this tube window cannot be overstated, as it remains the only opening through which any radiation generated can exit the glass enclosure. It also ensures that nearly all the electron beam needed to reach the sample under inspection gets there.

However, a small fraction of the radiation does not leave the glass envelope and is eventually absorbed by the glass envelope, ultimately reducing the efficiency of the glass tube. But the good news is that the glass material can be replaced to restore the efficiency of the glass enclosure.

6.   Filament holder

If the two most important parts of an X-ray tube are the cathode and anode, then it is safe to say that the filament holder is the next most important part of the X-ray tube. The reason is that the filament holder holds the X-ray energy-generating filament in place, ensuring that it doesn't fall off during operation.

Depending on the size of the test sample, the filament should produce enough radiation to penetrate the material, and sometimes when the material is so large, the energy can be enormous. Nonetheless, the filament holder ensures that there is no bridge between the filament and the power supply, ensuring that the right amount of energy reaches the filament.

7.   Cooling medium oil

During X-ray machine operation, the rotor and anode disks can rotate at speeds up to 3,200 rpm, generating excessive heat in the process. Likewise, when radiation from the filament strikes the rotating anode disk, the heat builds up further, sometimes reaching extremely high levels. Cooling is very important to keep your machine working at its best. Therefore, cooling oil is provided to dissipate this heat. But that's not all. Since both the cathode and the anode are charged, the cooling oil also acts as an insulating medium to prevent electric shock.

8.   Guide coil

For the power to reach the stator and rotor, the wires are passed through insulating flexible coil material called lead coils. The basic function of the guide coil is to enable electrical connections to navigate the irregular shape of the X-ray tube and to insulate other components in contact with these connection elements.

9.   X-ray tube housing

Typically, X-ray tube assemblies are classified as either internal or external. However, the outer components are usually the enclosures that keep the inner components contained within the tube, simply because the radiation generated travels in different directions within the X-ray tube. The X-ray tube housing is a metal container that prevents leakage of radiation generated inside the X-ray tube.

Additionally, the lead lining inside the enclosure ensures that the operator and others around the machine are not exposed to any radiation exposure. Best of all, because of the high voltage required to generate X-ray radiation, the enclosure acts like an insulating wall, preventing the operator from getting electrocuted.

10.         Induction stator

While the anode and cathode are complementary, the rotor and induction stator also appear to have this relationship. An induction stator is an electric motor that acts as a power for the rotor to spin at sometimes very high speeds as it provides the electricity needed for that activity. Most of the time, the stator uses the induction method, which also uses a set of coils to induce a strong magnetic field to generate the electrical energy needed to rotate, hence the name induction stator.

11.         X-ray tube holder

An X-ray tube holder is simply an external accessory that supports the components of the X-ray tube as a unit without falling apart during operation. Some of these supports include the housing and all its accessories such as screws, anchor plates and metal bars. These elements ensure the rigidity and robustness of the X-ray tube.

However, no matter how securely the X-ray tube holder holds the X-ray tube in place, these elements always need to be checked during regular and routine maintenance activities to ensure they remain intact.

12.         Rotor

The rotor is a very critical part of the X-ray tube as it holds the anode disk in place before, during, and after any X-ray operation. The anode disk can be rotated very fast depending on the size of the sample being examined and the required radiation intensity. Thus, the rotor ensures that during these high-speed operations, the disc is well-supported and rotates according to the set speed.

 The rotor and the anode disk are rigidly connected by the anode disk. However, while the anode disk is made of molybdenum, the rotor is made of copper as its body is not exposed to any radiation. High-strength ball bearings in the rotor make rotation easy and smooth.