August 11, 2009

Spin-Off Company Aims to Commercialize Diffraction Enhanced Imaging

A company founded by several current and former Brookhaven employees hopes to transfer a high-resolution, low-dose imaging technique from the synchrotron to the doctor's office.

Image of a human thumb. This image was acquired on the x-ray-tube-based DEI prototype system. Soft tissue structures such as muscle and ligaments can be clearly seen.

Standard x-ray imaging produces a picture that shows bone very clearly, but, if a contrast agent is not used, distinguishes poorly among non-calcified soft tissue such as ligaments, cartilage, or blood vessels. In addition, it delivers a significant amount of radiation to the patient, a dose that might contribute to cancer and affect fetal development.

But a technique developed at Brookhaven in the mid-1990s, called diffraction enhanced imaging (DEI), uses a specialized analyzer crystal to detect the subtle scattering of x-rays as they pass through a tissue, generating images with very high contrast but requiring very low radiation dose. In contrast to conventional sources, synchrotron x-ray beams are thousands of times more intense and extremely concentrated into a narrow beam. The result is a lower x-ray dose with a higher image quality.

However, synchrotrons have limited usefulness for clinical diagnosis.

"While synchrotrons have been essential to the early development of DEI, they are far too expensive and complex to be used for routine clinical imaging," said Dean Connor, a former Brookhaven DEI researcher now working for the University of North Carolina.

To make DEI a reality in the doctor's office, Connor helped form NextRay, a company made up of scientists and engineers from Brookhaven, the University of North Carolina, and the University of Saskatchewan.

The team has designed, built, and tested a prototype DEI system based on a tungsten-target x-ray tube, similar to those used in conventional x-ray systems. Their results show that the same type and quality of contrast seen in the synchrotron images can be accomplished with an off-the-shelf source. The results of this study were published in a recent edition of the journal Academic Radiology*.

Chest radiograph (a) and DEI image (b) of the chest of a living rabbit. The DEI image was acquired with 1/5th the radiation dose. Note that, with DEI, the lungs appear to be dense (bone-like) because the air in the lungs strongly refracts the x-rays.

"We were very pleased with how well the prototype system worked," Connor said. "The images that we generated with this inexpensive, off-the-shelf system were consistent with the quality of images we've become accustomed to."

For example, the team successfully imaged the lungs of a living rabbit with one fifth of the dose required by conventional x-ray imaging.

NextRay plans to extend the research findings to develop a general-purpose clinical DEI system. To accomplish this, the company has teamed up with Triple Ring Technologies, a California-based medical device engineering firm with vast experience in developing medical imaging systems.

Connor said he hopes the new system will be ready for first-stage FDA trials in about two years. Meanwhile, the NSLS will be used as a "wind tunnel" for further testing of the system.

* C. Parham, Z. Zhong, D.M. Connor, L.D. Chapman, E.D. Pisano, "Design and Implementation of a Compact Low-Dose Diffraction Enhanced Medical Imaging System," Academic Radiology, 16 (8), 911-917 (2009).

C. Muehleman, J. Li, D.M. Connor, C. Parham, E.D. Pisano, Z. Zhong, "Diffraction-Enhanced Imaging of Musculoskeletal Tissues Using a Conventional X-Ray Tube," Academic Radiology, 16 (8), 918-923 (2009).