X-ray Tube Design and Operation

The core component of an X-ray tube, it's a sealed, evacuated glass container that houses the cathode and anode.

The negatively charged electrode in an X-ray tube, responsible for emitting electrons.

A thin, coiled wire within the cathode, heated to produce a cloud of electrons.

The positively charged electrode in an X-ray tube, where electrons strike and produce X-rays.

The specific area of the anode that electrons strike, causing the generation of X-rays.

A protective metal casing that encloses the X-ray tube, shielding users from radiation and electrical hazards.

A process where heat generated within the X-ray tube is removed and dissipated into the surrounding environment.

The x-ray tube is sealed and contains the cathode and anode. The glass envelope is radiolucent, rounded to prevent static build-up, and has re-entrant seals to allow for thermal expansion.

The filament is part of the cathode and sits within the focussing cup, which is made of nickel or stainless steel. The focussing cup reduces the area of the focal spot and helps to focus the electron beam.

The anode's surface is made of tungsten because it has a high melting point, low vapour pressure, and high atomic number. It's a good choice for generating x-rays.

The copper cylinder of the anode absorbs the heat generated by the electron beam to prevent damage to the tube. It has a low atomic number, making it a poor source of x-rays. The oil surrounding it acts as an insulator and helps to dissipate the heat.

This is a negative potential applied to the focussing cup. It reduces the size of the focal spot, making it smaller and sharper. This improves the image quality.

When the target gets hot during an exposure, a heat gradient is established, and heat travels from hotter areas to cooler areas. This helps to dissipate heat and prevent damage to the tube.

The process of removing low-energy X-rays from the beam to reduce patient dose and improve image quality.

The combined effect of inherent filtration and additional filtering materials (usually aluminium) placed in the beam to further reduce low-energy X-rays.

A device that restricts the size of the X-ray beam, reducing the volume of irradiated tissue and thereby minimizing scatter and patient dose.

The amount of heat generated during an X-ray exposure. It's crucial to manage heat to prevent damage to the X-ray tube.

The angle of the anode in an X-ray tube affects the size of the focal spot, which impacts heat load and image sharpness.

The blurring effect at the edges of an X-ray shadow, caused by the finite size of the X-ray source.

The size of the area on the anode where electrons hit and produce X-rays.

A technique that focuses the electron beam onto a small area on the anode, reducing the 'penumbra'.

The angle of the anode surface, designed to allow electrons to hit a small area but spread the generated X-rays efficiently.

The area on the anode where electrons hit. It's rectangular in shape.

The apparent size of the focal area when viewed from the perspective of the central X-ray beam. It's typically square.

A protective covering around the X-ray tube, designed to protect users from electrical hazards.

A method of electrical safety where conductive components are connected to the earth, preventing dangerous electrical potentials.

Materials, like oil or rubber, that resist the flow of electricity, protecting users from electric shocks.

A system that limits access to high-voltage components, ensuring electrical safety.

The process by which heat is transferred from the anode to the glass envelope through a vacuum, primarily occurring when the anode is very hot.

A key component of the anode, the target is the specific area where electrons hit, producing X-rays. It's often made of tungsten.

Tungsten is used as the material for the X-ray tube target because its high melting point means it won't melt even when generating X-rays, which produce heat.

The atomic number of an element reflects the number of protons in its nucleus. Tungsten has a high atomic number (74).

Tungsten's high atomic number means it's efficient at converting the energy of incoming electrons into X-rays, leading to stronger X-ray production.

The focusing cup is a component of the cathode, responsible for directing and concentrating the electron beam towards the anode target.

The focusing cup is used to direct the electron beam towards the central axis of the X-ray tube, ensuring the electrons hit the target in a smaller area.

The focusing cup uses a slight negative bias to attract electrons towards the central axis, creating a concentrated beam.

Electrons in the X-ray tube experience two forces: one towards the anode, due to the applied voltage, and another towards the central axis, due to the focusing cup's negative bias.

The negative bias of the focusing cup is stronger than the repulsion between electrons, causing the electron beam to be focused on a small area of the anode.