We would like to outline briefly the technique of Dual Energy, an option available on our RIVIERA rad systems.
This technique allows for the selective display of tissues of different densities, using exposures at different energy levels. In this way, the Radiologist has the possibility to clearly discriminate structures which are otherwise hard to identify on conventional exposures.
In other words, it helps in overcoming the limitation of three-dimensional patient volume projections and anatomy on a two-dimensional image plane.
Dual-energy subtraction is based on body tissues differential attenuation for low- and high-energy X-ray photons. Bone contains calcium and so it has a higher attenuation coefficient at lower beam energy than soft tissues.
Two exposures are taken then at two different kilo-voltages on the same target area and digitally subtracted; hence, structures that contain calcium (including bone) can be removed from images, leaving soft tissues and lungs clearly visible.
One of the major advantage of this technique is that it makes calcification more conspicuous, an essential aid in characterizing pulmonary nodules.

In our RIVIERA equipment, two images are automatically acquired, one high-kilovolt exposure and one low-kilovolt exposure with a very short delay between them.
Dual-energy subtraction images are then displayed, i.e the standard un-subtracted images, the soft tissue–selective image and the bone-selective image.