Adaptive Radiation Therapy

What is ART?

Adaptive radiation therapy (ART) is a type of cancer treatment that changes every day to match the patient’s body. The plan for treatment is new and based on daily imaging created while the patient lies on the treatment table. Taking precise imaging allows the treatment team to change exactly where and how much radiation to use on the tumor. Because the plan only targets the tumor, ART avoids using radiation on healthy tissues, which means higher doses of radiation can be used on the cancerous areas.


The Ethos system is a type of technology called a novel ring gantry linear accelerator (LINAC). The Ethos system is a machine that produces high-quality imagery to show where organs, healthy tissues, and solid tumors are.  As a patient lies on the treatment table, Ethos uses a cone beam CT to scan their body and to create high-resolution imaging. This step is done every day in adaptive radiation therapy (ART).

ART imagery allows Washington University Physicians to:

  • know where to deliver high doses of radiation and
  • send radiation to small areas in the body.

Creating a new treatment plan every day based on what Physicians “see” means the tumor is exposed to high levels of radiation and healthy tissues and organs can remain untouched. This can significantly help health outcomes as well promote recovery from the treatment itself.



The HyperSight system is a machine that creates imaging during adaptive radiation therapy (ART). A patient lies on the treatment table while the machines scans their body to create a large, high-contrast visual that shows exactly where cancerous tissue, healthy tissues, and organs are. The body is always in motion and changes often, so HyperSight’s precise imaging allows Washington University Physicians to create a personalized treatment plan that includes:

  • how much radiation to use
  • where to send the radiation.

HyperSight is programed with this plan, and it sends a beam of radiation to the exact location of the cancer so that it healthy tissues are not exposed. Patients can expect to repeat imaging every day for the most precise treatment plan possible, leading to better outcomes and better recovery.

How is ART given?

The first step in ART is gathering imaging to create that day’s treatment plan. To do this the patient lies on the treatment table, and the Ethos or HyperSight machine quickly scans them. This imaging shows where the patient’s tumor and healthy organs are that day. Next, Washington University Physicians study the imagery decide two things:

  • where to send the radiation beam and
  • how strong a dose of radiation to use that day.

Even small motions like breathing can change a tumor’s position, so the Ethos machine stops and starts the radiation beam, called “gating,” as the body moves to make sure radiation is only used on the tumor. A big benefit to using ART technology is its ability to limit how much and where radiation is used. This doesn’t just help keep healthy tissues and organs healthy, but it also helps lessen negative side effects that are common with radiation like headaches, fatigue, and others.

Who should consider ART?

Bodies are constantly changing, and organs can shift from one place to another during a day. The imaging ART uses shows exactly where tumors and organs are before using radiation so that the beam only treats where the tumor is. This is especially helpful when a tumor in the body is in a place where organs shift quite a bit, like pancreas, cervix, head and neck, prostate and rectum, among others. Patients with large tumors or patients who have gained or lost weight during treatment have good outcomes with ART since the treatment plan is created every day and is based on exactly where the cancer is located.