From Static Plans to Daily Adaptation: The Future of Radiation Therapy Is Here at Stephenson Cancer Center

The human body changes during cancer treatment. Tumors can shrink or move, organs shift, and patients may lose weight.

Traditionally, radiation treatment plans were made from a single scan taken about a week before treatment began. That same plan was used for every session, even if the body changed. Because of this, doctors often added “safety margins,” treating a larger area than just the tumor to make sure it was covered. This, however, could expose healthy tissue to unnecessary radiation and cause side effects.

How Varian Ethos With HyperSight Changes Things

OU Health Stephenson Cancer Center is the first health system in Oklahoma to offer the Varian Ethos adaptive radiation therapy system. The Ethos system is a type of linear accelerator (LINAC) that uses high-energy X-ray or electron beams to target and treat tumors. It uses smart technology and artificial intelligence (AI) to adjust treatments based on how the patient’s body looks right before each session.

Before treatment, the machine takes high-quality 3D images of the tumor and surrounding organs using HyperSight’s advanced cone-beam computed tomography (CBCT) scanner.

With these fresh images, doctors can reshape a patient’s treatment based on how the patient’s body looks right before each session. Before treatment, the machine takes high-quality 3D images of the tumor and surrounding organs using HyperSight’s advanced cone-beam computed tomography (CBCT) scanner.

With these fresh images, the Ethos system can update the treatment plan on the spot, matching the tumor’s exact size, shape, and position that day. This fast updating takes minutes, not hours, allowing doctors to target cancer cells more precisely while better protecting healthy tissue.

“If the tumor grows or shrinks or changes in position, or patient anatomy changes, we’re able to account for those changes on a day-to-day basis, allowing us to deliver the radiation therapy more precisely,” said OU Health radiation oncologist Dr. Tyler Gunter, M.D., associate professor in the Department of Radiation Oncology at the University of Oklahoma College of Medicine. “This allows us to increase tumor control and potentially decrease side effects from treatment.”

Radiation That Adjusts in Real Time

Standard radiation therapy machines rely on a treatment plan created from a computed tomography (CT) scan taken about a week before therapy starts.

The Ethos system works differently. Each day, before treatment, the machine takes its own quick, diagnostic-quality scan while the patient lies on the table. The care team compares that day’s anatomy with the original plan. If something has changed, they adjust the plan on the spot and deliver the updated treatment within minutes.

“That is a process that previously would have taken several hours in many cases,” Dr. Gunter said.

The difference matters most for patients whose tumors change quickly. In the past, a patient with significant changes might have started with a less-than-ideal plan while the team rebuilt everything behind the scenes.

“We’ll be able to give the patient the ideal treatment on day one,” Dr. Gunter said.

AI Helps — But People Are in Charge

AI speeds up the process by quickly outlining the tumor and nearby healthy organs on each day’s scan. This task would take hours to do by hand, but the AI can do it in seconds. Doctors review and adjust these AI-generated plans before treatment. The care team — not the AI — makes all medical decisions.

“AI is not making any clinical decisions. It’s merely accelerating our workflow,” Dr. Gunter said. “Ultimately, it is the patient’s treatment team and their physician making these clinical decisions on a daily basis.”

During treatment, cameras and surface-tracking technology monitor the patient in real time. If a patient moves or coughs, the system alerts the team so they can pause and adjust as needed.

What This Means for Patients

This approach allows for more precise treatment that better targets cancer while protecting healthy tissue. It may also reduce side effects and, in some cases, treatment can be completed in fewer visits.

“[This technology allows] us to compress treatments into a shorter period of time, so what may have taken five weeks to treat now may take five days,” Dr. Gunter said. “[This allows] us to serve more patients in Oklahoma.”

The program is starting in June 2026, with initial treatments focused on prostate, pancreatic, lung, and gynecologic cancers. Doctors plan to expand its use to other cancer types over time.

A Team Effort for Better Care

While the system uses advanced technology, patient care depends on a skilled team. Radiation oncologists, radiation therapists, dosimetrists (specialists who calculate radiation doses), medical physicists, nurses, and support staff work together to deliver each treatment.

“We have a few patients slated to begin the treatment [who] will certainly benefit from adaptive radiation therapy,” Dr. Gunter said. “We’re excited to bring this technology to Oklahoma.”

Bringing Advanced Cancer Care Closer to Home

With the addition of Ethos, patients in Oklahoma no longer need to travel beyond their home state for cancer treatment. This progress in cancer treatment at Stephenson Cancer Center reflects OU Health’s tripartite mission of patient care, research, and education. As the state’s only academic health system, OU Health brings the latest in medical innovation to patients across Oklahoma.

Learn More

To learn more about radiation therapy at OU Health Stephenson Cancer Center, call (572) 244-0104.

OU Health Stephenson Cancer Center and its activities are made possible in part through funding from the Oklahoma Tobacco Settlement Endowment Trust (TSET).

The Ethos system represents an investment of more than $3 million and includes the advanced HyperSight imaging solution developed through a collaboration with Siemens Healthineers, combining high-speed, high-quality imaging with smart adaptive therapy to improve cancer treatment.

Varian, the maker of the Ethos adaptive radiotherapy system, is part of Siemens Healthineers, a global leader in medical technology. Their collaboration brings advanced imaging and radiation treatment solutions together to improve cancer care for patients.