The impact of image processing algorithms on digital radiography of patients with metalic hip implants

To investigate the impact of image processing algorithms on image quality of digital radiographs. This study was motivated from a case of a patient with metallic hip implant, where the anatomy around the implant was misrepresented, due to failure of the processing algorithm.

A quality control phantom was imaged using a digital radiographic unit and the standard examination protocol for Pelvis anteroposterior (AP) projection. The original image was reprocessed with all available selections of Diamond View, which is a processing algorithm for optimizing image quality of different anatomic regions. The same procedure was repeated for two other examination protocols, Femur AP and Hip AP, which differ in terms of harmonization kernel and gain, and look up table settings. The whole procedure was repeated with a Pb strip, 2 cm wide and 3 mm thick, positioned close to the right phantom edge, in order to simulate a metallic hip implant. Using ImageJ a number of regions of interest (ROIs) were positioned on the phantom images and the impact of processing parameters on certain image characteristics and image quality indices was evaluated.

Processing parameters have a strong impact on image characteristics, but in terms of image quality, differences between images with and without the implant are small. Exception is the regions in the vicinity of the implant, where larger differences, that could affect diagnosis, were observed.

In case of doubt, additional processing with settings which minimize the risk of anatomic misrepresentation should be used.