How to cite: Frank SJ. MRI-Assisted Radiosurgery (MARS) for LDR/HDR/EBRT for Prostate Cancer Treatment. Grand Rounds in Urology. February 2026. Accessed Oct 2026. https://grandroundsinurology.com/mri-assisted-radiosurgery-mars-for-ldr-hdr-ebrt-for-prostate-cancer-treatment/
Summary
Steven J. Frank, MD, FACR, FABS, FASTRO, Professor of Radiation Oncology, and Executive Director, Particle Therapy Institute, University of Texas MD Anderson Cancer Center, Houston, Texas, discusses magnetic resonance imaging (MRI)-assisted radiosurgery (MARS), an imaging-driven approach designed to improve the precision, quality assurance, and safety of radiation therapy for prostate cancer in low-dose-rate (LDR) brachytherapy, high-dose-rate (HDR) brachytherapy, and external beam radiation therapy (EBRT).
He discusses historical challenges in radiation quality assurance, highlighting complications in early brachytherapy programs with limited imaging guidance and verification methods. Dr. Frank emphasizes that improved imaging technologies now allow clinicians to better verify radiation dose delivery and minimize treatment-related complications. MRI guidance underpins the MARS approach, enabling precise visualization of prostate anatomy and delivery of treatment.
For LDR, MARS integrates MRI imaging to address limitations of ultrasound and computed tomography (CT) in visualizing implanted radioactive seeds and critical anatomic structures. MRI allows improved identification of structures such as the external urethral sphincter, which may be difficult to distinguish on ultrasound but plays an important role in urinary function. Avoiding radiation exposure to this structure can help reduce urinary toxicity. The MARS workflow also incorporates specialized MRI-visible markers that enable accurate localization of implanted seeds and improved post-implant dosimetry assessment.
Dr. Frank describes the development of intraoperative MRI workflows that allow immediate evaluation of implant quality during the procedure. Patients can be transported directly from the operating room to an MRI scanner for verification of radiation dose distribution. If the implant is suboptimal, additional seeds can be placed immediately to optimize dosimetry.
The MARS concept is also applied to HDR brachytherapy, where MRI-visible catheter markers improve visualization and treatment planning compared with traditional CT-based planning. EBRT may also benefit from MRI-guided targeting and improved fiducial markers that reduce imaging artifacts and dose perturbations associated with traditional metal markers.
Dr. Frank asserts that MRI-assisted radiosurgery enhances treatment precision and quality assurance throughout prostate radiation therapy workflows, potentially improving oncologic outcomes while preserving urinary, sexual, and rectal function.
The International Prostate Cancer Update (IPCU), is a multi-day, CME-accredited conference focused on new developments in prostate cancer treatment, diagnosis, and prevention. IPCU 36 featured lectures, interactive discussions, panel roundtables, debates, and case reports. This conference is led by expert physicians and is designed for urologists, medical oncologists, radiation oncologists, and other healthcare professionals involved in the diagnosis and treatment of prostate cancer.
The goal of this educational program is to equip healthcare professionals involved in the diagnosis and treatment of prostate cancer with the up-to-date clinical knowledge and tools they need to best treat their patients. The program will discuss the treatment of prostate cancer from diagnosis to treating advanced and metastatic disease. The conference aims to give physicians exposure to a comprehensive review of treating prostate cancer patients and to give them a chance to discuss the issues with peers and experts.
ABOUT THE AUTHOR
Steven J. Frank, MD, is an endowed tenured professor of Radiation Oncology and holds the Bessie McGoldrick Professorship in Clinical Research at The University of Texas MD Anderson Cancer Center. Dr. Frank is the Executive Director of the Particle Therapy Institute and Deputy Head of Strategy for the Division of Radiation Oncology.
Dr. Frank was instrumental in facilitating the restructuring of MD Anderson’s Proton Therapy Center through an asset acquisition and a subsequent expansion of a second Proton Therapy Center to advance Intensity Modulated Proton Therapy (IMPT). Dr. Frank is amongst the first, if not the first, to use IMPT to treat head and neck tumors, and he is the Principal Investigator of an NIH/NCI -sponsored multi-institutional Phase II/III randomized trial in advanced-stage oropharyngeal cancer that compares outcomes after chemoradiation given by IMRT versus IMPT.
Dr. Frank has approximately 300 peer-reviewed publications, has authored many book chapters, and has recently published the first textbook on Proton Therapy, based on the MD Anderson experience. Dr. Frank’s lab is studying the biologic enhancement factor of proton therapy and FLASH radiotherapy for head and neck cancer, as well as MRI-Assisted Radiosurgery (MARS) as the next generation of prostate brachytherapy. Dr. Frank’s expertise in MRI radiotherapy has led to the development and FDA approval of multiple novel positive-contrast implantable markers for use in MRI-guided LDR and HDR prostate brachytherapy and external beam radiation therapy.
As founder of the company, C4 Imaging, Dr. Frank has developed the MRI marker technology at MD Anderson, has been granted 31 national and international patents, developed three FDA-approved products, and has established MRI-Assisted Radiosurgery (MARS) at MD Anderson for the treatment of prostate cancer. He has funding from the NIH, the Prostate Cancer Foundation, the Texas Ignition Fund, Hitachi, and MD Anderson, and he has also raised multiple rounds of private equity financing to advance C4 technology.
Dr. Frank has served as the past President and Chairman of the Board of the American Brachytherapy Society and is the 2023 recipient of the Ulrich Henschke Award, the highest honor awarded by the ABS to a practitioner of brachytherapy. Dr. Frank has served as the chair for the head and neck oral boards for the American Board of Radiology over the last six years and will join the Board of Trustees in October 2023. Dr. Frank is a fellow of the ABS, ACR, and ASTRO.
Prior to entering medicine, Dr. Frank served in the military as a U.S. Navy Diver and submarine officer on the fast attack nuclear submarine USS Batfish (SSN-681). He is married to Dr. Ivy Frank, a veterinarian, and his hobbies include golf, flying, and coaching softball for his four daughters.
