A new tumor-tracking technique delivers higher levels of radiation to moving tumors while sparing healthy tissue in lung cancer patients. This technique is moving closer to the clinic.

Lung cancer patients treated with higher doses of radiation have a survival advantage. This has led to an increased interest in finding novel ways to better track tumors, which are in constant motion because of breathing, in order to up the dosage during radiation therapy without increasing harmful side effects. Respiratory and cardiac motions have been found to displace and deform tumors in the lung and other organs. Because of this, radiation oncologists must expand the margin during radiotherapy, and consequently a large volume of healthy tissue is irradiated, and critical organs adjacent to the tumor are sometimes difficult to spare.

In an effort to shrink that margin, the researchers developed a new, robotic technique that better tracks tumor motion to deliver more precise radiation. After success in simulations, the researchers used a new control system that incorporated both hardware and software, along with the robotic technology. These were added to existing treatment couches used for radiation therapy to determine the tracking system’s feasibility in a clinical setting.

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They found the technology can be integrated onto treatment couches and validated the tumor tracking system capabilities to follow desired trajectories. When the active tracking system was applied, irradiated planning target volume (the area set for treatment) was 20% to 30% less for medium-size tumors and over 50% for small-size tumors.

“The use of tumor tracking technology during radiotherapy treatment for lung cancer would result in significant reduction in dose to critical organs and tissue, potentially decreasing the probability or severity of side effects, and thus improving cancer treatments,” said Yan Yu, PhD, of Thomas Jefferson University.

Based on these results, it can be hypothesized that clinical implementation of real-time tracking is feasible for achieving potentially improved patient outcome.

“With this new technique, it shrinks the margin, and radiation oncologists would be able to administer more radiation and faster to the tumor than conventional methods,” said Adam P. Dicker, MD, PhD, also of Thomas Jefferson University. “And a higher, more targeted dose means a better cure in lung cancer.”

This study was published in Medical Physics (2012; doi:10.1118/1.4758064).