Originally Published MDDI December 2004

R&D DIGEST

Imaging Technology Moves to the Fourth Dimension

Maria Fontanazza

Through analysis of lung tumor motion and position, researchers at the University of Pittsburgh may have found a way to treat tumors directly while limiting the exposure of healthy tissue to radiation. The researchers used a new scanner system to track and predict tumor motion within the lungs.

As a person breathes, the chest wall expands and causes the lung tumor to move. This natural motion poses a problem because it makes reaching the tumor without exposing healthy tissue to radiation hazards more difficult.

Dwight Heron, MD, assistant professor of radiation oncology at the University of Pittsburgh Medical Center, explains that three-dimensional technology only provides a static image at one instance in time. However, when dealing with parts of the body that move, such as the abdomen, pelvis, or chest, there is the need for a technology that accounts for time as well. One solution to this problem is the four-dimensional computed tomography (4-D CT) scanner developed by General Electric Healthcare (Waukesha, WI).

For the experiment, researchers used the 4-D CT machine to measure lung tumor movement in patients being treated for lung cancer. The scanner presented images based on the respiratory cycle phase of the lung to account for tumor motion. “This is a revolutionary technology, because it adds the fourth dimension of time,” says Heron.

The study also found that the movement of the tumor is linked to its location on the lungs. “With 4-D CT, we now have the ability to watch the motion in near real time,” says Heron. By understanding motion and location, doctors have a more-accurate target for therapy. “We can time the point at which we fire [radiation therapy] and pretty much be certain as to where it will hit. We can reach a smaller margin with better probability.”

Heron admits that the new CT process is a bit time consuming, and he says he would like to see a technology that has the ability to capture real-time images very quickly. This would allow doctors to see what is happening with the tumor on a regular basis. “There's an increasing dependence on image guidance in the field of radiotherapy,” Heron says. “I think the equipment manufacturers will have to catch up quickly.”

Heron also hopes to see improvements made in the resolution of images to capture more data simultaneously. The more image slices that can be obtained, the more data a doctor has on a specific location. “Radiotherapy is getting more and more specific, with tighter margins,” says Heron. “The more accurate information we can attain, the lower the toxic treatment, and the better it is for the patient.”

The study was conducted at the University of Pittsburgh Cancer Institute and the University of Pittsburgh School of Medicine Shadyside Hospital.

Copyright ©2004 Medical Device & Diagnostic Industry