**3. Conclusion**

104 Recent Advances in Arthroplasty

Fig. 9. Case 2 patient (71-year-old woman; Gonarthrosis, post total knee arthroplasty; TKA). AP radiographs of the knee joint prostheses are demonstrated. AP radiograph is difficult to visualize 3D information in an AP radiograph as shown. The use of artifact reduction tomosynthesis (w=0.06) allowed better visualization of the prosthesis caused by the blurring

Fig. 10. Blurring occurs along the sweep direction and results from imaging studies show that a high contrast structure exists out of the slice plane that is continuously perpendicular

**X-ray radiography**

**(+15mm)**

**Off-focus plane**

**FBP**

**Artifact reduction**

to the sweep direction.

**(-15mm) In-focus-plane Off-focus plane**

of anatomic structures above and below the visualized planes.

The digital linear tomosynthesis images in this review were acquired using linear motion of the X-ray tube and detector. The type of motion used during data acquisition dictates the type of blurring of off-focal-plane objects in the image. Linear motion blurs objects in one dimension only, which leads to linear streak artifacts caused by high-contrast off-focal-plane objects. On the other hand, 3D reconstruction schemes, such as tomosynthesis and CT, require complete knowledge of the X-ray source projection geometry prior to exposure. This limitation precludes much of the potential task-dependent flexibility. This limitation also precludes accurate reconstruction from projections acquired from a patient who moves unpredictably between exposures, as this is geometrically equivalent to not knowing the projection geometry.

Use of digital linear tomosynthesis in imaging of prostheses appears promising. The results of the prosthesis study suggest that digital linear tomosynthesis can improve image quality compared with conventional radiography by removing overlying structures and providing limited 3D information. In addition, the digital linear tomosynthesis method appears to allow for significant improvement of images corrupted by metal artifacts. Digital linear tomosynthesis provided higher quality images than CT. Tomosynthesis is the best solution for cases in which the high-attenuation feature causing the artifacts can be segmented accurately from the projection.

Artifact reduction processing showed an adequate overall performance, but its effectiveness strongly depended on the image region. Digital linear tomosynthesis images gave good results independent of the type of metal present in the patient and showed good results for the removal of noise artifacts, particularly at greater distances from metal objects. The potential for application of digital linear tomosynthesis to the imaging of prostheses appears promising. Flexibility in the choice of imaging parameters in artifact reduction processing based on the desired final images and realistic imaging conditions may be beneficial.
