PHILADELPHIA—A device that displays a holograph-like 3-dimensional (3D) image, created from a CT, MRI, or PET dataset, holds promise for more accurate radiotherapy treatment planning (see image on page 1). James C. H. Chu, PhD, professor of radiation oncology, Rush University Medical Center, presented results of a pilot study of the Perspecta Spatial 3D System, developed by Actuality Systems, Inc. (Bedford, Massachusetts), at the 48th Annual Meeting of the American Society for Therapeutic Radiology and Oncology (abstract 2810).

"Many of the tasks involved in radiotherapy treatment planning are 3D in nature, such as volume delineation, beam placement, and plan evaluation," Dr. Chu said, "but current planning displays are 2D in nature." Even 3D renderings must be displayed on a flat computer screen, he said, and may require goggles to get the 3D effect.

The Perspecta Spatial 3D System produces 3D anatomic images by projecting multiple cross-sectional images (using DLP technology from Texas Instruments, Inc) at a rate of 6,000 frames per second onto a screen rotating rapidly at 900 rpm. "The screen is spinning continuously and the image on the screen is changing continuously. Because the screen is spinning so fast and the image is changing so fast, your eye and brain integrate all the individual cross-sections into a 3D object," Dr. Chu told ONI.

The resulting semi-transparent 3D image appears to float in space within a 24-inch dome, allowing a full 360-degree field of view (Figure 1). For radiotherapy treatment planning, the radiation dose distribution can be superimposed on the 3D Perspecta image and viewed and manipulated from any point around the dome.

The Perspecta technology was invented by Gregg Favalora, who launched Actuality Systems from his basement apartment in 1997. He currently serves as chief technical officer of the company. In addition to medical uses, including molecular engineering for drug discovery, the technology is being used in other fields, including oil and gas exploration and by NASA to analyze earth science and astronomical data.

Study Results