Computed Radiography Photostimulable Phosphor Plate Receptors: Effect on Grid Conversion Factors

Abstract

Background: Grid conversion factors were established for using grids with varying ratios for film-screen systems. Evidence from the physics community suggests that the relationship between grid conversion factors and exposure to the receptor does not apply with different types of digital imaging receptors.

Purpose: To evaluate the relationship among analog grid conversion factors when using various grid ratios with a photostimulable phosphor plate (PSP) receptor system.

Methods: Three experiments were conducted using a range of grid ratios (6:1, 8:1, 12:1) to assess the effect of conversion factors on exposure indicators with a computed radiography PSP receptor.

Results: When using the analog grid conversion factors established for varying grid ratios with a PSP receptor and constant peak kilovoltage (kVp), the plate was overexposed with an exposure indicator outside the acceptable limits.

Conclusion: The discussion of antiscatter grids in radiologic technologist literature should remain in the context of receptor type and digital imaging system being used so that technologists can make appropriate decisions about the use of grids while minimizing patient radiation dose. Calibrated grid conversions based on the digital systems in use and the radiologist's image quality preference could be created within radiology departments.

Keywords: analog; digital; grid conversion factors; grid ratios; photostimulable phosphor plate receptor.