Feature | July 31, 2014

New Targets for Radiation Therapy Include Cardiac AF Ablations and Renal Denervation

July 31, 2014 — Radiation therapy may offer a promising new noninvasive alternative treatment for the millions of Americans whose high blood pressure doesn’t respond to medication, suggests preliminary research presented at the 56th annual meeting of the American Association of Physicists in Medicine (AAPM) in Austin, Texas.

Nearly 78 million Americans have high blood pressure, or hypertension, putting them at risk for heart disease, heart failure, stroke and kidney disease. In more than a quarter of people receiving treatment, standard therapy (lifestyle changes and medication) doesn’t help. Radiation therapy may provide a solution for people with this treatment-resistant form of hypertension.

A second study presented at the meeting suggested magnetic resonance imaging (MRI)-guided radiation therapy also may be an alternative treatment for atrial fibrillation (AF), a common arrhythmia that affects more than 2.5 million Americans, significantly impairs the quality of life, increases the risk of stroke five-fold and doubles the risk of death.


Radiation Therapy for Hypertension

Blood pressure is controlled by a combination of nerve signals and hormonal interactions between the brain, heart, blood vessels and kidneys. Radiation therapy can be used to disrupt the signals in the nerves that are wrapped around the renal arteries to the kidney. While researchers are exploring alternative methods to treat resistant hypertension, most are not effective.

“We have the tools to focus radiation so precisely, we can target the nerves responsible while sparing the nearby healthy structures such as the spine and kidneys,” said Peter G. Maxim, Ph.D., lead author of the study and assistant professor in the department of radiation oncology at Stanford University School of Medicine & Cancer Institute. “It’s noninvasive and could be done in a single treatment.”

In the study, six hypertensive pigs were treated with 40 Gy of radiation in a single treatment to the nerves surrounding the arteries leading to the kidneys. All animals survived to the follow-up point with no adverse events. Pathologic examination revealed moderate damage to the nerves and minimal damage to nearby critical organs, highlighting the targeting accuracy and precision of radiation delivery to the intended target. The blood pressure continued to drop in the three-month follow-up period after treatment by about 30 percent on average, which is beneficial, but not enough to bring it to normal. Researchers did not track the blood pressure beyond three months, but plan a future study with two-year follow-up to determine the dynamic changes in blood pressure. In the current study, researchers radiated the entire renal artery, and future research will consider how much radiation should be used and precisely what areas should be irradiated.

“This is a very promising method that’s worth exploring in detail — our study shows there is something to it,” said Maxim. “It could be beneficial for millions of patients.”


MRI Guidance of Radiation Therapy for Atrial Fibrillation

In another study, researchers tested a special cardiac MRI on four patients, demonstrating it is possible to image the beating heart accurately enough to guide radiation therapy to treat AF arrhythmias. Previous research conducted by the German members of the team found that targeted cardiac radiation therapy can isolate the source of the arrhythmia. The challenge is to image a beating heart accurately to ensure the radiation therapy reaches the target without damaging the heart or surrounding tissues.

“The ideal treatment would be noninvasive, but the challenge is you can’t see the heart from the outside,” said Paul Keall, Ph.D., lead author of the study and a professor of medicine at the University of Sydney, Australia. “Our approach combines MRI and radiation therapy to see the beating heart and treat the AF. The treatment uses the exquisite targeting accuracy of modern image-guided radiation therapy [IGRT] to hit the AF and avoid critical structures near the heart, such as the esophagus, blood vessels and the spinal cord.”

The researchers are working to further develop the cardiac MRI and test it in patients. AF can be treated with medication or other therapies such as ablation. Ablation to isolate the electrical signal is a common treatment, but is invasive, requiring insertion of a wire into the vein and feeding it to the heart. If studies are successful, MRI-guided radiation therapy could offer a noninvasive alternative to AF patients.

For more information: www.aapm.org

Related Content

Top Score in Multiple Brain Metastases TROG 2018 Treatment Plan Study Achieved With Accuray Precision

Image courtesy of Accuray Inc.

News | Treatment Planning | May 24, 2018
Daniela Schmitt, Ph.D., took top honors in the overall category of the 2018 TROG Plan Study: Stereotactic Radiosurgery...
News | Computed Tomography (CT) | May 21, 2018
The Istituto Oncologico Veneto (IOV) in Padua, Italy, has acquired MILabs’ latest-generation Versatile Emission...
Mercy Signs Multi-System, Multi-Hospital Agreement for Accuray Radiotherapy Systems
News | Radiation Therapy | May 16, 2018
Accuray Inc. signed a multi-system, multi-hospital agreement with Mercy for the acquisition of Accuray Radixact and...
ViewRay Unveils New Soft Tissue Visualization Technologies for MRIdian Linac
News | Image Guided Radiation Therapy (IGRT) | April 30, 2018
ViewRay Inc. announced new magnetic resonance imaging (MRI) technologies under development for its MRIdian Linac...
MedStar Georgetown Conducts World's First Hyperscan Proton Therapy Treatment
News | Proton Therapy | April 27, 2018
For the first time, cancer patients in the Washington, D.C. metropolitan region have access to proton therapy, now...
Designed to support a broad range of planning and delivery technologies, SunCheck 2.0 streamlines and standardizes workflows, allowing greater overall focus on patient safety.
Technology | Quality Assurance (QA) | April 27, 2018
Sun Nuclear Corp. released significant new functionality for its SunCheck Platform for patient and machine quality...
RayStation Users Win Inaugural Treatment Planning World Championships
News | Treatment Planning | April 27, 2018
In the first World Championships of Treatment Planning, arranged by radiation oncology analytics company ProKnow and...
Brainlab Introduces New Hi-Res Planning Algorithm for VersaHD
News | Treatment Planning | April 24, 2018
Brainlab announced the implementation of a software solution that can achieve better radiation dose conformity around...
Shorter Radiotherapy Courses Safe and Effective for Prostate Cancer
News | Prostate Cancer | April 23, 2018
Radiotherapy given in high doses over a shorter period of time is safe and effective for prostate cancer patients,...
Elekta Expands Mosaiq Oncology Information System With PalabraApps
News | Oncology Information Management Systems (OIMS) | April 20, 2018
April 20, 2018 — Elekta announced that it is making a strategic investment in PalabraApps LLC to advance the developm
Overlay Init