The types of filtration include inherent filtration of the enclosure, compensation filters, and aluminum sheets, which serve as added filters. This process results in overall decreased x-ray tube output but generates a more uniform beam with overall increased average x-ray energy. The process of filtering out the low-energy photons is termed beam hardening. Filters absorb these low-energy photons, thereby reducing the unnecessary dose to the patient. The x-ray beam arising from the tube contains photons of varying energy with a high proportion of low-energy photons, which have a negligible impact on image production as they cannot traverse the patient to reach the detector and thereby only contribute to patient dose and not image quality. X-ray quantity is determined by mAs, kVp, distance, and filtration, while x-ray quality is determined by kVp and filtration. Bremsstrahlung x-rays are produced by electron deceleration secondary to atomic field effects with the production of diagnostic range x-rays from this loss of energy. Characteristic x-rays are produced as a process of ionization by inner electron-shell emission and subsequent filling of the orbital void. X-ray Production - The primary result from electron acceleration from the cathode to the anode includes heat production, bremsstrahlung x-rays, and characteristic x-ray production.

Tube rating charts can help in assessing exposure levels, and it’s relation to tube durability. Tube failure has many causes, the primary of which include excessive anode heating, anode cracking/pitting, and filament vaporization. The cathode, which contains a tungsten filament, serves as the electron source, while a rotating anode, composed of a tungsten disc, serves as the electron target. The vacuum tube is composed of an anode and cathode within an enclosure. Among its many functions, the primary one is to avoid leakage and help in the dissipation of heat. Ĭeiling Support and the Vacuum Tube - The ceiling support system helps provide the primary support for an x-ray tube and serves as a protective apparatus. A technologist needs to be aware that variation in supply voltage in clinics and hospitals result in a large variation in the production of an x-ray beam, which in turn affects image quality and patient exposure. Power for Production - Power is provided by the high-voltage generator, which allows for increasing an output voltage to a kVp needed for x-ray production. Electronic timers are the most accurate and allow for time interval selection, while AEC terminates exposure based on detected radiation intensity. Timing Circuits - The different types of timing circuits include synchronous timers, electronic timers, mAs timers, and automatic exposure control (AEC). The number of x-rays reaching an image receptor is also related to the time that the tube is energized, which is initiated and terminated by the radiographer. Control of milliampere (mA), which constitutes the x-ray tube current traversing from the cathode to the anode, is monitored with an mA meter. The console allows a technologist to establish an x-ray beam of adequate quantity (number of x-ray photons) and quality (effective energy of x-ray photons). Operating consoles allow an operator to select a kVp, mA, and time. X-ray imaging systems can be generally composed of a few primary components: the operating console, the high-voltage generator, the x-ray tube, and the receiver. X-ray System Components - X-ray currents are measured in milliamperes(mA) while x-ray voltages are measured in kilovolt peak (kVp). Computed tomography (CT) employs an x-ray source coupled with a detector array that is rotating around the patient with subsequent reconstruction of images into different planes. Fluoroscopy is classically employed with an x-ray tube under an examination table while providing images on a monitor or display typically in real-time. Radiography employs film or a solid-state image receptor to acquire static images for interpretation by a radiologist. X-ray examinations are generally classified into three categories: radiography, fluoroscopy, and computed tomography.

Tungsten disk xray