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X-ray tube, also called Roentgen tube, evacuated electron tube that produces X rays by accelerating electrons to a high velocity with a high-voltage field and causing them to collide with a target, the anode plate. The voltage applied to accelerate the electrons is in the range of 30 to 100 kilovolts.
How an x-ray tube produces X rays?
X-rays are commonly produced in X-ray tubes by accelerating electrons through a potential difference (a voltage drop) and directing them onto a target material (i.e. tungsten). The incoming electrons release X-rays as they slowdown in the target (braking radiation or bremsstrahlung).
How do X rays work step by step?
An X-ray is produced when a negatively charged electrode is heated by electricity and electrons are released, thereby producing energy. That energy is directed toward a metal plate, or anode, at high velocity and an X-ray is produced when the energy collides with the atoms in the metal plate.
How do x-ray machines work?
When the machine is turned on, x-rays travel through the body and are absorbed in different amounts by different tissues, depending on the radiological density of the tissues they pass through. Because of this property, bones readily absorb x-rays and, thus, produce high contrast on the x-ray detector.
What is X-ray beam?
The properties of the X-ray beam depend on what and how the radiation is produced. X-rays are only produced when the ‘beam is on’ and are the result of the collision of accelerated electrons with a target material and thus X-rays are bremsstrahlung radiation.
Which metal is used in X-ray tube?
An X-ray tube consist of a spiral filament acting as the cathode and a water cooled block of copper as the anode. Both electrodes are sealed off in an evacuated glass-(ceramic)-metal cylinder. The filament made out of Tungsten wire is embedded in a narrow steel groove (1 mm x 10 mm).
What is X in X-ray?
Where does the “X” in “X-ray” come from? The answer is that a German physicist, Wilhelm Roentgen, discovered a new form of radiation in 1895. He called it X-radiation because he didn’t know what it was. This mysterious radiation had the ability to pass through many materials that absorb visible light.
What is window in xray tube?
Window: The X-ray tube window typically is made from beryllium because it allows X-rays to pass through but has sufficient strength to hold the vacuum required for the X-ray tube to operate.
What is XRAY grid?
Grids are placed between the patient and the x-ray film to reduce the scattered radiation reaching the detector (produced mainly by the Compton effect) and thus improve image contrast.
What is xray tube voltage?
The power supply for X-ray tubes is a cathode-grounded high-voltage power supply, with tube voltages ranging from 50 kV to 80 kV and power from 50 W to 4 kW.
What is focusing Cup in xray?
A focusing cup is a negatively charged, shallow depression on the surface of the cathode of an x-ray tube, which concentrates the electron beam towards the focal spot of the anode. It is typically composed of nickel. The negative charge of the focusing cup helps to accelerate the electrons towards the anode.
What is Bucky factor?
The Bucky factor is the ratio of radiation on the anti-scatter grid to the transmitted radiation. Hence, the Bucky factor reflects the increased radiation dose required from anti-scatter grid use, as any increase in mAs proportionally increases dose.
What is cassette in radiography?
Cassettes are rigid holders used in conventional and computed radiography (CR) for the screen film system and imaging plate respectively. The back side of the cassette has rubber or felt for adequate contact between the screen film system or with the imaging plate.
What is air gap technique?
The air gap technique is a radiographic technique that improves image contrast resolution through reducing the amount of scattered radiation that reaches the image detector.
Why does the anode crack?
why does the anode crack? It is the condition wherein the filament wire becomes thinner and eventually breaks. The excessive heating of the filament causes the filament to vaporize. It occurs due to prolonged periods of high mA operation.
Why is tube house lined with 3 mm lead?
The metal casing surrounding the insert is made of either aluminium or steel and is lined with about 3 mm of lead to provide sufficient radiation protection. This housing is filled with pure oil that acts as an electrical insulator and as a coolant.
Why is the rotating anode important?
The reason behind the introduction of rotating anodes is related to the dispersal of heat. In the case of a rotating anode tube, the heat of the incoming cathode beam is dispersed evenly across the entire surface of the anode as it rotates. This enables rotating anode users to perform longer scans and at higher doses.
What grid is most vulnerable to grid cutoff?
Most commonly observed grid cutoff, most prominent at a short source to image receptor distance (SID), due to the divergent beam geometry, a small SID will lead to undesired absorption of the primary x-ray beam via the grid lines.
Which grid is used in mammography?
The X-ray Beam Spectrum: One of the most unique features of mammography compared to other radiographic procedures is the x-ray beam spectrum that is used.
How does a grid reduce scatter?
By selectively allowing primary x-rays to be transmitted and scattered x-rays to be absorbed in the grid, image contrast is significantly enhanced; however, the grid attenuates some of the desired primary x-rays that are incident directly on the lead strips and allows transmission of some scattered radiation photons.
