Chest/Lungs:

CXR: Evaluation of the lungs demonstrated gradual increase in lung density, with the higher numbers of added gel layers. The right lung nodule was not seen on any of the images. The left nodule was barely seen with or without gel layers. Even when retrospectively evaluated they appeared as hazy slight increased opacities and did not have the appearance of a nodule (Fig. 2).

DTS: The increasing number of the gel layers had minimal impact on the lung opacity. All studies clearly revealed the embedded lung nodules and the anatomic structures of the chest without reduction in quality despite thicker soft tissues (Fig. 2). 

Fig 2: Chest radiograph (upper row) and chest DTS (lower row) of the phantom with and without gel layers. The embedded lung nodules are clearly seen on all the DTS studies (red arrows) regardless of the number of gel layers. The right lung lesion is not seen on any of the CXR and the left lung lesion is barely seen, as slight haziness, without the appearance of a distinct nodule (yellow arrow).

Thoracic Skeleton:

Conventional radiography: Depiction of the costovertebral joints was limited. Depiction gradually reduced as the soft tissues became thicker (Fig. 3). 

DTS: The costovertebral joints were clearly seen on all DTS studies. The added gel layers had minimal impact on the quality (Fig. 3)

Fig 3: Thoracic skeleton radiographs (upper row) and thoracic skeleton DTS (lower row) of the phantom with and without gel layers. A costovertebral joint that is in the plane of focus is marked by the red arrow. The joints are barely seen on the radiographs and are clearly seen on the DTS with only minimal impact of increasing soft tissue thickness.