X-Ray Machine

Overview

A radiographic X-ray machine produces projection images of the body by passing a controlled X-ray beam through the patient onto a detector. Dense structures such as bone attenuate more of the beam than soft tissue, so the transmitted pattern forms a shadow image. A digital radiography system replaces film with an electronic flat-panel detector, giving an immediate image and a measured dose.

X-rays are generated in the X-Ray Tube Assembly, a rotating-anode tube insert in an oil-filled, lead-lined housing. An induction stator spins the anode while a heated filament boils off electrons that are accelerated across the tube and strike the tungsten target, producing X-rays; the rotating anode and circulating oil spread and carry away the intense heat. The tube is energized by the High-Voltage Generator, a high-frequency inverter that steps mains up to the selected kilovoltage and regulates the tube current and exposure time.

How it works

Between the tube and patient, the Collimator limits the beam to the region of interest with motorized lead blades, projects a matching light field for alignment, and adds aluminum or copper filtration to harden the beam and cut skin dose. The tube is aimed and positioned by the Tube Stand / Gantry tube stand and the patient lies on the Patient Table, whose floating top and Bucky tray hold the anti-scatter grid and detector.

The transmitted beam lands on the Flat-Panel Detector, an indirect-conversion flat panel where a cesium-iodide scintillator turns X-rays to light over a TFT photodiode array that reads out a digital image in seconds. The operator selects technique and reviews images at the Control Console, and tube housing heat is rejected by the Tube Cooling Unit unit, which circulates the housing oil through a fan-cooled radiator.