DR (Digital Radiography) equipment is favored for its clear image quality, low technical requirements, and relatively reasonable price, making it almost a standard in modern hospitals.
When purchasing medical DR equipment, hospitals should pay attention to the focal spot size of the DR device, as the size of the focal spot has a significant impact on imaging performance.
The X-ray tube, commonly known as the ball tube, is one of the core components of DR equipment and is responsible for generating X-rays by converting electrical energy into X-rays. The focal spot of the DR equipment mentioned in this article refers to the nominal focal spot size of the X-ray tube.
The focal spot is the location where electrons strike the target surface and generate X-rays. The size of the focal spot corresponds to the size of the contact area where electrons hit the anode target. A larger focal spot leads to less sharpness in digital images, with more pronounced edge blurring (penumbra) and less clarity. Conversely, a smaller focal spot results in sharper image edges and clearer images.
Although a smaller focal spot provides clearer images, it has limitations in exposure dose and may be less reliable for imaging thicker areas. Additionally, a smaller focal spot concentrates more energy and generates more heat, which can lead to melting of the focal spot surface. Larger focal spots can handle higher beam currents and produce sufficiently bright X-rays, reducing the imaging time.
To leverage the characteristics of focal spot sizes, many DR devices on the market now use dual-focal-spot technology. This involves using two sets of filaments with different sizes: a larger filament for a larger effective focal spot and a smaller filament for a smaller effective focal spot. For example, the PLX8500 digital X-ray imaging system from Perlove Medical features a high-capacity ball tube and a high-power generator. It allows for dual rotation of the flat panel and X-ray tube, facilitating positioning for various views such as cervical spine and patellar axial views. For patients who cannot move, such as those in wheelchairs, the rotating flat panel detector allows imaging of the upper and lower limbs while seated. The detector can rotate ≥90°, and the X-ray tube can rotate ≥180°, making clinical positioning more convenient and addressing various clinical positioning needs.
