Adaptive Radiation Therapy

What is ART?

Adaptive radiation therapy is a type of treatment in which a new plan is generated each day to account for changes in the patient’s anatomy. Daily imaging while the patient lies on the treatment table allows the treatment team to change and deliver the radiation dose to the tumor as precisely as possible. This adaptive therapy reduces damage to surrounding healthy tissue and allows for higher prescription doses to the tumor.


The MR-LINAC (MRIdian) at Washington University is the only device of its kind within a 270-mile radius of St. Louis. The Department of Radiation Oncology at Washington University was the first center in the world to install and treat a patient with MR-guided radiation therapy. Since that time, Siteman Cancer Center remains a global leader in MR-guided adaptive radiation therapy. Physicians, physicists and therapists are trained specifically in MR-guided treatments to participate in the adaptive clinical service. This clinical service is not commonly available throughout most cancer centers and is a key component of the specialty cancer care offered at Siteman.

Using MR guidance and adaptive radiation, Siteman radiation oncologists were the first in the world to publish data on treating pancreatic cancer patients with highly ablative radiation doses in five fractions. They have also published important data on MR-guided treatment of oligometastatic disease, lung cancer, ovarian cancer and liver cancer.

“MR guided adaptive radiation therapy has the potential to change how we approach the treatment of a wide range of cancers, but especially tumors in areas with high movement such as the thorax and abdomen,” said Hyun Kim, MD, MR clinical service chief and assistant professor of radiation oncology at Washington University.


The Ethos system is a novel ring gantry LINAC that produces high-quality cone beam CT images while the patient is on the treatment table. This allows physicians to perform CT-based adaptive radiation therapy, which was not previously possible due to the poor quality of on-board cone beam CT images. Investigators at Siteman were the first in the world to obtain patient images with this novel machine and have published extensive research on its potential impact on patient treatments.

How is ART given?

As the patient lies on the treatment table, a linear accelerator machine quickly scans the patient in preparation for their treatment. This imaging allows the established treatment plan to be modified each day to match the patient’s anatomical changes. Both the MRIdian and the Ethos provide gated treatments, meaning that the radiation beam accounts for breathing motion and will only deliver radiation when the tumor is in the proper position. This minimizes toxicity to surrounding organs and improves treatment of the tumor.

Who should consider ART?

ART is especially useful for disease sites where the tumor or nearby organs may move significantly from day to day. It is also beneficial for patients with large tumors or patients whose weight has changed significantly during treatment. ART may be used to treat cancers of the pancreas, cervix, head and neck, prostate and rectum, among others.