The motorized system takes a modified x-ray tube and moves it up vertically while pivoting the tube to keep it pointed toward the phantom and digital detector at image right. During this upward sweep, 71 separate digital chest images are acquired in only 11 seconds. The system then resets its position slowly. The total exposure is the same as a single lateral chest radiograph.

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Chest tomosynthesis is a new imaging technique pioneered at Duke. The method is based on acquisition of chest images from slightly different directions, and then reconstruction of a three-dimensional volume of the thorax. Early results indicate that tomosynthesis is superior to conventional radiography in the detection of pulmonary nodules (lung cancer), and has a lower cost and radiation dose than CT.

The images at the right show a standard chest radiograph (top) and one of the reconstructed tomosynthesis slice images (bottom). The tomo image has removed most of the overlying rib shadows and shows a slice in the middle of the chest.

Note the well-circumscribed nodule indicated by the arrow in the tomo image. Even in retrospect, this nodule is barely visible in the chest radiograph in spite of its rather large 15 mm size.

A magnified view of the nodule-containing region is shown below, with the standard chest radiograph on the left and the tomo slice on the right.

The best way to appreciate the 3D visualization of anatomy is to view the reconstructed slice images as a movie.

You can use the buttons to advance through the movie as a loop or slice by slice. Note the progression of anatomy as you go from one side of the chest to the other, including numerous nodules.