FLUOROSCOPY

What is fluoroscopy?

• Fluoroscopy is an imaging technique commonly used by physicians to obtain real-time moving images of the internal structures of a patient through the use of a fluoroscope. In its simplest form, a fluoroscope consists of an x-ray source and fluorescent screen between which a patient is placed. Fluoroscopy is used for examination of moving internal structures and fluids.

FLUOROSCOPY AND ASSOCIATED PARTS

SPECIAL DEMANDS OF FLUOROSCOPY

• Fluoroscopy is a dynamic process; thus, the radiologist must adapt to moving images that are sometimes dim.
• Illumination- levels are measured in units of lumen per square meter or lux.
• Radiographs are visualized under illumination levels of 100 to 100 lux

Image-Intensifier Tube

Image Intensification

• Input phosphor
  •Made of cesium iodide (CsI)
  •Receives radiation exiting patient
  •Emits light photons


• Photo cathode
  •Responds to light exiting input phosphor
  •Emits electrons
  
• Electrostatic lenses
• •Focus electrons
  
• Output phosphor
  •Receives electrons from photocathode
  •Emits 50-75× more light than received by photocathode

Flux Gain

Flux Gain=Number of output light photons/
Number of input x-ray photons

Brightness Gain

Brightness gain = Minification gain × Flux gain

Magnification Modes

• Better spatial resolution
• Better contrast resolution
• Higher patient dose
  

Vidicon Television Camera Tube

Fiber Optics vs Lens System Coupling

A Television Picture Tube (CRT)

LINEAR TOMOGRAPHY

Tomography otherwise known as body section radiography, planigraphy, laminography or stratigraphy, is the process of using motion of the X-ray focal spot and image receptor (e.g. film) in generating radiographic images where object detail from only one plane or region remains in sharp focus. Linear tomography is one of the most basic techniques. As the tube and film move from the first position to the second, all points in the focal plane project to the same position on X-ray film.Points above or below the focal plane do not project to the same film positions and are blurred. By changing the relative motion of the film and tube, the focal plane can be adjusted upward or downward.

Linear Tomography is a radiographic technique that uses motion to demonstrate anatomy lying in a plane of tissue, while blurring or eliminating structures above and below the plane of interest. This technology led to the development of CT (Computerized Tomography), which is more widely used today. In addition to linear tomography, other types of tube and film motion have been used. These motions include circular, elliptical, hypocycloidal, trispiral. Each of these motions has advantages regarding the way in which out of plane structures are blurred. For example, a linear structure which is aligned with the linear motion of a linear tomograph, will not appear blurred, except at the ends, whereas such a structure will be blurred by the circular motion of a circular tomograph.

PURPOSE

By moving an x-ray source and the film in opposite directions during the exposure structures in the focal plane appear sharper, while structures in other planes appear blurred. By adjusting the direction and range of the movement, operators can select different focal planes which contain the structures of interest.

PRINCIPLE

The tube and the image receptor move during the exposure in opposite directions around a stationary fulcrum, the pivot point.
The tube and the image receptor are attached by a rod as described in the equipment section of this blog.

EQUIPMENT USED

Most features of a tomographic x-ray imaging system appear similar to those of a conventional radiographic imaging system.

What is a "Radiologic Technologists"?

Radiologic technologists, also referred to as radiographers, take x rays and administer nonradioactive materials into patients’ bloodstreams for diagnostic purposes.
In addition, radiology technologists produce x-ray films (radiographs) of parts of the human body for use in diagnosing medical problems. They prepare patients for radiologic examinations by explaining the procedure, removing jewelry and other articles through which x rays cannot pass, and positioning patients so that the parts of the body can be appropriately radiographed. To prevent unnecessary exposure to radiation, these workers surround the exposed area with radiation protection devices, such as lead shields, or limit the size of the x-ray beam. Radiographers position radiographic equipment at the correct angle and height over the appropriate area of a patient’s body. Using instruments similar to a measuring tape, they may measure the thickness of the section to be radiographed and set controls on the x-ray machine to produce radiographs of the appropriate density, detail, and contrast. They place the x-ray film under the part of the patient’s body to be examined and make the exposure. They then remove the film and develop it.
Radiologic technologists must follow physicians’ orders precisely and conform to regulations concerning the use of radiation to protect themselves, their patients, and their coworkers from unnecessary exposure.
In addition to preparing patients and operating equipment, radiologic technologists keep patient records and adjust and maintain equipment. They also may prepare work schedules, evaluate purchases of equipment, or manage a radiology department.
Experienced radiographers may perform more complex imaging procedures. When performing fluoroscopies, for example, radiographers prepare a solution of contrast medium for the patient to drink, allowing the radiologist (a physician who interprets radiographs) to see soft tissues in the body.
Some radiographers specialize in computed tomography (CT), and are sometimes referred to as CT technologists. CT scans produce a substantial amount of cross-sectional x rays of an area of the body. From those cross-sectional x rays, a three-dimensional image is made. The CT uses ionizing radiation; therefore, it requires the same precautionary measures that radiographers use with other x rays.
Radiographers also can specialize in Magnetic Resonance Imaging as an MR technologist. MR, like CT, produces multiple cross-sectional images to create a 3-dimensional image. Unlike CT, MR uses non-ionizing radio frequency to generate image contrast.
Another common specialty for radiographers specialize in is mammography. Mammographers use low dose x-ray systems to produce images of the breast.