iem

• Permanent radiographic unit


  • Most common machine unit in the radiology department
  • Most basic machine
  • All medical institutions have at least one of this unit
  • Permanently installed in the department
• Permanent radiographic unit


  • Composed of x-ray tube
  • Control console
  • High voltage generator
  • Patient table
  • Vertical cassette holder (VCH)
• Patient table


  • Where the patient lies down during examination
  • Made of hard surface
  • Needed for accurate positioning of the body part
  • Should also be made of translucent material (Plexiglass, Carbon fiber material) to allow as much X-ray photons to pass through and interact with the image receptor
  • Comes with different moving mechanisms for easy patient or part positioning
• Patient table


  • Almost all tables can be moved longitudinally (two-way movement)
  • Some are capable of moving up-and-down on top of the longitudinal and side-to-side movement (6-way floating table)
  • Some table can be tilted to an upright position
• Moving grid


  • Underneath the table
  • Absorbs as much scatter radiation before it reaches the image receptor
• Bucky ray


  Holds the image receptor (cassette) during exposure
• Vertical cassette holder (VCH)


  • Where we put the image receptor for upright radiography (chest x-ray)
  • Modern vertical cassette holder has a moving grid and a Bucky tray
  • Holder can be moved up-and-down to adjust the height of the VCH to the patient's or part's height under study
• Types of radiographic units according to load


  • Low load
  • Medium load
  • High load
• Low load machines


  • Specially designed for extremity examination and mammography
  • Part under examination is easily penetrated
  • Requires low kVP technique (25 -> 40 kVP)
• Medium load machines


  Used for most general radiography (40 -> 130 kVP)
• High load machines


  • 125 -> 150 kVP
  • Not commonly used in medical x-ray, but for industrial x-ray
• 1. X-ray tube mounting system


  • Ceiling mounted
  • Telescopic column
  • Floor-to-ceiling mounted
  • Floor mounted
  • C-arm mount
• Floor-to-ceiling mounted


  • Has a column that attaches the tube to two railings mounted on the floor and ceiling
  • Provides a more stable attachment but restricts movement of the x-ray tube across the long axis of the table
• Floor mounted


  • Has a column that attaches tube to a rail mounted on the floor
  • Similar to floor-to-ceiling mounted tube but allows movement of the x-ray tube across the long axis of the table
  • Offers less stability
• C-arm mount


  • Supports the x-ray tube on one end and the image receptor on the other end
  • Very versatile, allows linear and rotating motion for optimum positioning with respect to the patient
  • Mostly used for digital radiography with flat panel detectors
  • Used for radiographic-fluoroscopic units and interventional angiography
• Mobile x-ray unit


  • Can be moved from one place to another
  • Allow x-ray procedure for patients who cannot be brought to the x-ray department
  • Most is a radiographic unit, some are capable of fluoroscopy
• Mobile radiographic unit


  • Most common
  • Mainly used for bedside radiography
  • Consists of x-ray tube, high voltage generator, control console, wheeled cart, movable tube stand, film-cassette or flat-panel detector storage drawer
  • Parts are the same with permanent radiographic unit but of lower capacity
• Mobile fluoroscopic unit


  • Mostly provide fluoroscopic imaging (real time)
  • Also capable of radiographic imagine
  • Most systems consist of two wheeled units supporting the C-arm and the control console
  • C-arm supports the x-ray tube on one end and the image intensifier or flat-panel digital detector on the other
  • C-arm can perform linear and rotating motions for optimum positioning with respect to the patient
• Battery powered mobile x-ray unit


  • Uses 2 sets of lead-acid or nickel-cadmium batteries, one set powering the motor and the other providing power to the tube
  • Provides wide range of satisfactory kVP and mAs, allows up to 500 exposures without recharging
  • Needs special care and maintenance, heavy, hard to control
• Capacitor discharge mobile x-ray unit


  • Uses a capacitor to store electric charges and use it during operation
  • Lightweight, smaller, easier to maneuver, requires less charging time, consistent image quality
  • Voltage drop can happen at high technical factors, must be charged prior to use
• Modern mobile x-ray units are now equipped with self-propelled units driven by a motor, making transport easier
• Some mobile x-ray units use flat panel detectors as the image receptor
• Safety considerations and maintenance for mobile x-ray units


  • Always check battery level and re-charge if necessary
  • Do not drive unless the tube is properly locked for transport and all other accessories/parts are secured
  • Ensure the motor driven ability and braking system are functioning properly
  • Handle and transport carefully to avoid accidents and collisions
  • Regulation requires the exposure switch shall be arranged so the operator can stand at least 2 meters from the patient, the X-ray tube, and the useful beam to offer radiation protection through distance
• Radiographic-fluoroscopic (RF) unit


  • Used for both still radiography and fluoroscopy
  • Usually have two separate x-ray tubes, one overhead for radiography and one under the table for fluoroscopy
  • Unique part is the image intensifier that acts as the image receptor for fluoroscopic images
  • Fluoroscopy allows seeing the motion of internal structures in real time for evaluation of anatomy and function, but exposes the patient to high radiation