Jost Kloth, Abstract Co-Author: Nothing to Disclose

Volker Ewerbeck, Abstract Co-Author: Nothing to Disclose

Wolfram Stiller PhD, DIPLPHYS, Abstract Co-Author: Nothing to Disclose

Iris Burkholder, Abstract Co-Author: Nothing to Disclose

Hans-Ulrich Kauczor MD, Abstract Co-Author: Research Grant, Boehringer Ingelheim GmbH Research Grant, Siemens AG Research Grant, Bayer AG Speakers Bureau, Boehringer Ingelheim GmbH Speakers Bureau, Siemens AG Speakers Bureau, Novartis AG

Marc-Andre Weber MD, Presenter: Research Grant, Bayer AG Research Grant, Guerbet SA Research Grant, Bracco Group Research Grant, Siemens AG Speakers Bureau, Merck & Co, Inc

Since digital plain radiographs of the full leg are frequently performed in children and young adults, the objective was to reduce the radiation exposure dependent on specific indications and to determine objective quality control criteria to ensure accurate assessment.

Institutional review board approval and informed consent of all participants were obtained. In this prospective, randomized controlled, blinded, two-armed single-center study, 288 patients underwent plain-radiography of the full leg with standard (exposure class of SC 400) and reduced (SC 800) dose. The evaluation of the plain radiographs was conducted using the following criteria: mechanical axis, leg length, and maturation of the epiphyseal plate. Two blinded radiologists evaluated these criteria using scores ranging from 1 (definitely assessable) to 4 (not assessable). If a single criterion had been evaluated with a score of 3 or more points or more than 2 criteria with 2 points, the radiograph was scored as “not assessable“. The study was designed as non-inferiority-trial with pre-specified non-inferiority margin of delta = 0.1, defining the maximum difference of clinically tolerated non-assessable radiographs with reduced dose for claiming non-inferiority. Both dose groups were randomized using a block randomization with the relation 1:1.

279 of 288 plain radiographs were rated similarly by both observers regarding the primary outcome measure (inter-observer agreement of 96.9%). Eleven (3.8%) plain radiographs were scored as not assessable. The rate of non-assessable radiographs with 33% reduced dose was not inferior to the rate of non-assessable radiographs with standard dose (p<0.0001). Also, the individual evaluation of the defined criteria was independent.

Full-leg plain radiography in patients with knee malalignment can be performed at 33% reduced dose without loss of relevant diagnostic information. Since all relevant parameters of orthopedic measurements could be assessed with SC 800 instead of 400, we recommend this setting as new reference parameter for standing full-leg radiography in patients with knee malalignment.

Radiation dose reduction of up to 33% in full-leg radiography is possible without loss of diagnostic information. Thus, an exposure class of SC 800 is recommended in patients with knee malalignment.

Kloth, J, Ewerbeck, V, Stiller, W, Burkholder, I, Kauczor, H, Weber, M, Quality-controlled Dose-reduction of Full-leg Radiography in Patients with Knee Malalignment.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14005542.html