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Grids in Radiography & Grid Ratio

When a doctor sends you to have an X-Ray, you may worry about the potential health consequences. An X-ray machine -- or other type of digital imaging machine -- uses radiation to take an internal "picture" of your body, often with a heavy apron draped over you, while the technician goes behind a barrier to trigger the machine. As long as the radiologist knows and practices grid patterns and ratios, the radiation they shoot your way produces a lovely "picture" without medical damage.

  1. Grid Ratio

    • The right ratio creates a wall that repels "scatter," potentially-damaging radiation.

      Grid ratio is determined by calculating the height of the lead strips ("h") divided by the distance ("D") between those strips, called "interspace" distance. If, for example, the lead strips are eight units high and one unit apart, the grid ratio is 8:1. A good grid ratio generally means that the lead strips more effectively reject secondary radiation, thus making a higher-quality image. Screen-film imaging, traditionally used for x-rays, sometimes leads to the "Bucky Factor," which is a presumption that higher grid ratios allow us to safely expose patients to higher doses of radiation.

    Grid Frequency

    • Radiological frequency is a resolute bandwidth for optimum patient care.

      Grid frequency is the number of lead strips, or grid lines, per unit of distance (inches or centimeters). Low-frequency grids contain between 100 and 120 lines per inch. Medium-frequency grids contain 120-150 lines per inch. High-frequency grids have 150-170 (or more) lines per inch. High-frequency grids are used most commonly with portable imaging devices and many digital radiography systems.

    Grid Patterns

    • In radiology, grid patterns assist in minimizing radiation and maximizing its picture.

      If we consider lines (or strips of lead) as the strips of a blind, grid patterns are the angles at which radiographers open the blinds to capture an image. Some patterns are defined as parallel strips. Other patterns feature strips that are perpendicular. Some patterns deliberately set the strips at an angle known to yield the best image for a specific radiography purpose. Radiology technicians consider different grid patterns in order to meet a patient's specific x-ray needs.

    Grid Types

    • Digital radiography is the transition from analog x-ray film.

      Scatter removal grids enhance the quality of images projection radiography. The secondary radiation, called "scatter," is disbursed by a group of thin lead strips (usually in the form of a heavy apron draped over the patient), so the scatter doesn't fog the image. According to Radiation Protection of Patients (RPOP), digital radiography is akin to retiring the artifacts of analog technology - in this case, film. Doctors need not wait for the "picture," they can view it by computer quickly. In addition, radiologists can efficiently process the results with software imaging tools, much like consumers do at home with their digital camera's pictures.

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