Authors:
T. Lehnert, M. Kissner, H. Korkusuz, U. Voigt-Koop, M. G. Mack, T. J. Vogl; Frankfurt a. Main/DE
DOI:
10.1594/ecr2010/C-2989
Purpose
A fundamental radiologic principle is that patient dose can be reduced with x-ray beam hardening [1,2], which can be achieved by increasing tube voltage and/or beam filtration [3,4]. Unfortunately, tube voltage augmentation and beam filtration both diminish subject contrast. Although subject contrast can be partly recovered with image processing techniques after digital image acquisition, these manipulations can increase the apparent image noise. Thus, despite the adoption of digital technology by many imaging centers, a common strategy still is to simultaneously add beam filtration and reduce the mAs. This strategy is a compromise between dose reduction and image quality.
The development of digital flat-panel detectors that are based on cesium iodide and amorphous silicon may offer a more promising solution to this problem. This technology permits wide exposure latitude, high contrast resolution, and high detective quantum efficiency. It is widely considered superior to both screen-film and storage phosphor radiography [5], because it can provide high image quality even when patient exposure is low.
We hypothesized that images of extremities obtained using a cesium iodide–amorphous silicon system could be diagnostically acceptable at much lower doses than are currently being utilised. It was believed that the digital radiography (DR) system could achieve substantial dose savings by using additional filtration, without sacrificing diagnostic image quality. Thus, the purpose of our study was to investigate to what degree entrance dose could be lowered, and what kind of added filtration could be used without affecting radiologist confidence levels in diagnosing.