Amorphous silicon, flat-panel, x-ray detector: reliability of digital image fusion regarding angle and distance measurements in long-leg radiography.
OBJECTIVE
To evaluate composed long-leg images acquired with a large-area, flat-panel x-ray detector with regard to angle and distance measurements.


METHODS
Radiographs of a long-leg phantom were acquired at 13 different angle settings with a 43-cm x 43-cm digital x-ray detector based on cesium iodide (CsI) and amorphous silicon (a-Si) technology. Three overlapping single images of the phantom were reconstructed at a workstation using a generalized correlation method. Four blinded observers were instructed to determine the angle of the axis of the long-legs as well as the length of "femur" and "tibia" on soft-copy displays. For that, the angle and distance measurement software integrated in the workstation was used. The images were analyzed with and without prior manual fine tuning of the primary composition result according to a mapped scale. Standard of reference was angle and distance determination at the phantom.


RESULTS
On average, the difference between the observers' angle measurements and the standard of reference was 0.4 degrees for both images with and without prior manual correction. Regarding distance measurements, the average discrepancies to the standard were 0.2 cm (femur) and 0.1 cm (tibia) when analyzing images that had undergone manual fine tuning and 0.5 cm and 0.7 cm, respectively, for images without manual correction.


CONCLUSIONS
The evaluated image fusion algorithm in conjunction with a 43-cm x 43-cm flat-panel detector is feasible regarding angle and distance measurements on long-leg images. In the case of inaccurate primary composition, results can be corrected easily by manual fine tuning.
Hamer
Okka W
OW
Department of Diagnostic Radiology, University Hospital of Regensburg, Regensburg, Germany. o.hamer@gmx.de
Strotzer
Michael
M
Zorger
Niels
N
Paetzel
Christian
C
Lerch
Klaus
K
Feuerbach
Stefan
S
Völk
Markus
M
D000465:Algorithms; D002586:Cesium; D006801:Humans; D007454:Iodides; D007867:Leg Bones / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement / Q000295:instrumentation*; D012015:Reference Standards; D012825:Silicon
D007454:Iodides; D002586:Cesium; C040050:cesium iodide; D012825:Silicon