Dual-Energy Fluoroscopy Could Improve Lung Tumor Visualization

By Chuck Seegert, Ph.D.

A new dual-energy fluoroscopic technique has improved lung cancer tumor imaging. The beauty of the approach is that it works with existing X-ray equipment and could be rapidly implemented using only software.

The density of objects determines how much radiation they attenuate, with bones absorbing much more than soft tissues. For chest X-rays, this means that the shadows of the bones often overlie the soft tissue of the lungs, which sometimes obscures nodules or other structures of interest. Traditional dual energy (DE) radiographs are based on this difference and combine two images, one taken at a lower power setting than the other. These images are then overlaid, and subtraction is used to remove undesirable objects from the final image.

Now, a new approach from Loyola University researchers may reinvigorate this mature technology, according to a recent press release from the University.

“Dual-energy imaging has been used for decades by radiologists to detect lung tumors,” said John Roeske, Ph.D., professor and director of Radiation Physics at Loyola’s Department of Radiation Oncology, according to the press release. “When combined with fluoroscopy, the hybrid dual-energy technology can enhance the visibility of tumors to improve treatment for patients.”

Fluoroscopy is another widespread technology that is present in nearly all hospitals. It often uses an X-ray tube placed below the X-ray table that beams energy up into a fluorescent detector. Images of the anatomy can generally be viewed in real-time as the radiologist performs a procedure.

Historically, it was thought that fluoroscopy could be used for real-time DE diagnostics, but to do so would require a “fast switching” X-ray generator, according to a paper presented by Roeske at the 56th annual meeting of the American Society for Therapeutic Radiology and Oncology. With the new approach, however, an initial set of images is obtained from the patient using fluoroscopy. These images are used to subtract overlying bony structures during real-time fluoroscopic imaging. By having the patient hold their breath, the approximation of anatomy to the initial images was very close, which allowed many frames of the study to be accurately subtracted.

“This technology does not require that hospitals replace their standard X-ray machines since the dual-energy images are created using a software approach,” Roeske said in the press release. “The hybrid technique removes present obstacles making this a great benefit to clinicians and patients.”

Professor Roeske and his colleagues have patented the technology necessary to perform the new radiographic approach, according to the press release. Commercialization of the cost-saving technology could be of benefit to increasingly frugal hospital environments.