DigiBit: A system for adjusting radiographic exposure factors in the digital era

Objective: To develop an exposure adaptation system for direct radiography that can accurately adjust exposure factors such as milliampere seconds (mAs), kilovoltage peak, and source-to-image distance for patients of differing size. Methods: The DuPont Bit System was used to select the mAs for 60 combinations of exposure factors for an anthropomorphic pelvic phantom. The exposure index (EI) with a target value of 1500 ± 2% was used to evaluate whether each image was exposed correctly. The DuPont Bit System was then adapted for direct radiography so the mAs could be adjusted to achieve both the target bit value and the target EI. Results: With the DuPont Bit System, an EI of 1500 ± 21.6% was achieved in all 60 radiographs, whereas the target EI of 1500 ± 2% was achieved in 16 radiographs. With the modified version of the DuPont Bit System, "the DigiBit system," achieving the target EI increased to 38 out of 60 radiographs. Discussion: The DigiBit system is an exposure adjustment system designed for direct radiography. In situations where automatic exposure control is not available, the Digibit system allows adjustment of radiographic exposure. It is potentially a valuable tool for radiography. Conclusion: The DigiBit system provides an accurate method of adjusting exposure factors for direct radiography.