January 1, 2007 Radiation therapy requires visualizing exactly where a tumor is located, usually from looking at hundreds of different X-ray , CT or PET scan images. A new system patches together 2D images into one 3D view of the tumor, enabling radiation oncologists to target the tumor more precisely. The images are projected into a dome-shaped, rotating projector screen for 3D visualization.
CHICAGO -- More than half of all cancer patients will have radiation therapy. Planning treatment is tough for doctors because they have to look at stagnant images and visualize exactly where a tumor is located. Now, a 3D dome gives them a better view.
When doctors give a radiation treatment, they see hundreds of images -- images they have to piece together to plan where to put their beams.
"Left then looking slice by slice at a large number of sequential images and trying to stack them up, so to speak, in the mind's eye," Ross Abrams, a radiation oncologist at Rush University Medical Center in Chicago, tells DBIS.
Now, medical physicists at Rush University Medical Center are using a new device to help doctors see images like never before. Instead of viewing two-dimensional pictures, the Perspecta Spatial 3D dome lets them see the tumor in 3D, offering two main benefits...
"Number one -- come up with a better quality plan because they can use a better beam orientation, and number two -- they will be able to evaluate the effectiveness of the plan much more quickly," James Chu, a medical physicist at Rush University Medical Center, tells DBIS.
Dr. Abrams says, "It lets you see all the information at once rather than seeing it slice-by-slice or bit-by-bit."
It's a difference doctors hope will improve treatment for millions.
The 2D images are transported from a computer to the Perspecta. The machine calculates the images and sends them upward. They then hit three mirrors and reflect onto a rotating projector screen in the dome.
In the first research study, the Perspecta was better at helping doctors plan radiation about half the time. Researchers hope improvements in the technology will make it better all the time. The Perspecta can make images from X-rays, MRIs, CT and PET scans 3D. Right now, only three centers in the country have the technology.
BACKGROUND: An advanced 3D display system initially developed with automobile design in mind might prove beneficial in the treatment of cancer patients. Rush Medical Center in Chicago, Illinois, is testing the Perspecta Spatial 3D system to improve evaluation and planning of cancer radiation treatments.
HOW IT WORKS: The system consists of a 24-inch dome that plugs into a PC to display holographic (full-color and full-motion) MRI, CT scans and nuclear medicine images in a true 3D space. Compared to standard 2D displays, this 3D image enables physicians to work more precisely and efficiently because they can view and manipulate the images from any vantage point around the 360-degree dome. The effectiveness of radiation therapy depends on the ability to concentrate high doses of radiation on the tumors while minimizing how much the healthy surrounding tissue is exposed, to keep side effects to a minimum. Without the system, oncologists must analyze hundreds of “slices” of 2D digital images to determine where the radiation is hitting.
ABOUT HOLOGRAMS: A hologram is a three-dimensional picture, used not only for medical imaging, but also for heads-up displays for airplane pilots to assist in navigation, among other applications. But while a photograph is an actual physical image, a hologram picture merely contains information about the size, shape, brightness and contrast of the object being recorded. This information is based on how light reflects off the imaged object. Shine a light on a hologram and the stored information takes the incoming light and uses it to re-create the original light waves, so your eyes and brain now perceive the object as being in front of you.
WHAT IS IONIZING RADIATION? X-rays and gamma rays are both forms of ionizing radiation. Ions are electrically charged atoms, a byproduct of an X-ray, for example, knocking electrons off of atoms. The resulting free electrons then collide with other atoms to create even more ions. An ion’s electrical charge can lead to unnatural chemical reactions inside cells, particularly at the higher energy levels of X-rays. It can break DNA chains, causing the cell to either die or develop a mutation and become cancerous, which can then spread. And if the mutation occurs in a sperm or egg, the result can be birth defects, which is why pregnant women should never be subjected to X-rays. In the early days following their discovery, X-rays were widely considered to be harmless. Radiologists thought nothing of daily exposure to the rays, even though a Scottish researcher who routinely used a fluoroscope to test the quality of X-rays by holding his hand between the tube and the fluorescent screen, developed tumors and eventually lost both his hands. Other reported problems included redness of the skin, numbness, infection and severe pain.
The American Association of Physicists in Medicine contributed to the information contained in the TV portion of this report.
Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.