Board of Directors
Najeeb Mohideen

Najeeb Mohideen, MD, FRCR, FASTRO, FACR


Dr. Najeeb Mohideen is a Radiation Oncologist at Northwest Community Hospital in Arlington Heights, Illinois. A champion for innovation, he is a recognized leader in the study and technological advancements of radiation oncology.

Dr. Mohideen completed his medical degree from the Armed Forces Medical College Pune, and Radiation Oncology residencies from the Royal College of Radiologists, London, UK and Loyola University Medical Center (LUMC), Maywood, IL. He joined the faculty of LUMC and was an Associate Professor in Radiation Oncology and Urology at Loyola prior to joining Northwest Community Hospital.

He holds many National leadership positions in Radiation Oncology. He has served on the Board of Directors of the American Society for Radiation Oncology (ASTRO) and has also chaired its Health Policy Council. He is currently Chair of the Radiation Oncology Economics Committee for the American College of Radiology and also chairs ASTRO’s Payment Reform Workgroup. He has served on the ASTRO Image Guided Radiotherapy Task Force and Brain Metastases Guideline Committee. He is also currently a member on the Medicare Evidence Development & Coverage Advisory Committee (MEDCAC). He is a Fellow of the American Society of Radiation Oncology and the American College of Radiology.

Since 2015, Dr. Mohideen has served on the Board of Directors of the Radiosurgery Society. He was Secretary from 2016 - 2021, April 2021 - April 2023, he served as President and as of April 2023 is Chairman of the Board.

Berend (Ben) J. Slotman

Berend (Ben) J. Slotman, MD, PhD, FASTRO, FARS, HFACR


Berend (Ben) J. Slotman, MD, PhD, FASTRO, FARS, HFACR, is Professor and Chairman of the Department of Radiation Oncology at Amsterdam University Medical Centers, The Netherlands. He is an expert in the field of SRS/SBRT and has co-authored more than 450 peer-reviewed publications and has coordinated numerous clinical trials. He is finishing his term as President of ESTRO in May of this year and is a long-term advocate for SRS/SBRT in the international community.

Dr. Slotman received his MD (1985) and PhD (1990) both with highest honor (cum laude) at VU University in Amsterdam, The Netherlands and he was registered as radiation oncologist in 1994. He also served as chairman of one of the six divisions of the VU academic center from 2006-2016. Since 2019, he is also the head of the department of Radiation Oncology at the Academic Medical Center (AMC) in Amsterdam. As the two university hospitals VUmc and AMC will merge into Amsterdam university medical centers, Ben Slotman’s task is to lead and unite the two academic departments.

His expertise lies mainly in the field of radiotherapy for lung and brain malignancies and the early clinical implementation of new technologies. He has (co-)organized many conferences and has coordinated a number of trials, including the EORTC study on prophylactic cranial irradiation in extensive-stage small cell lung cancer (published in New Engl J Med 2007) and the international randomized trial on the role of thoracic irradiation in these patients (published in The Lancet 2017). His research activities are further concentrated on intra- and extracranial stereotactic radiotherapy and the introduction of various new technologies in radiotherapy, most recently being stereotactic MRI-guided adaptive radiotherapy. He is associate editor of the Journal of Radiosurgery and SBRT.

He was awarded an honorary fellow of the American College of Radiology in May 2017 and received the Jacob Fabrikant award of ISRS in June 2017. In 2018 he was awarded as FASTRO. He is past-president of the American Radium Society (2017-8), was a member of the Board of ISRS (2013-2017), became president of ESTRO in 2020, and has been on the Board of Directors of the Radiosurgery Society since 2016, and he has served as President since 2023.

John J. Kresl



Dr. John Kresl is an internationally recognized expert in stereotactic radiosurgery and stereotactic body radiotherapy and has been Visiting Professor at a number of medical centers and universities in the USA and abroad and is frequently an invited lecturer at seminars throughout the world. Dr. Kresl serves as the current Medical Director of the Phoenix CyberKnife and Radiation Oncology Center and is a Managing Partner for Palo Verde Cancer Specialists and Radiation Oncologists of Central Arizona (ROCA). He has served as Co-medical Director of the CyberKnife & Gamma Knife Programs and Assistant Director for the Center for Thoracic Disease at St. Joseph’s Hospital & Medical Center and Barrow Neurological Institute in Phoenix, Arizona until 2008, and Medical Director of the Department of Radiation Oncology at Banner University Medical Center-Phoenix, Arizona until 2018, and Chief Medical Director for Alliance Oncology, Irvine, California until 2015. Dr. Kresl maintains an active clinical practice in radiation oncology for all tumor sites.

Dr. Kresl has served as the principal investigator and co-investigator on clinical protocol investigations and has published more than 250 abstracts, manuscripts, book chapters and textbooks related to the field of radiation oncology and the discipline of radiosurgery/SBRT. He also was or remains the editor/editorial reviewer for several textbooks and publications. Dr. Kresl’s involvement in oncology research has led to two registered U.S. patents for novel methods of diagnosing and treating cancer, and co-founding of two biotech companies and one software as service company. Dr. Kresl remains involved in radiation oncology research and development as an active advisory board member for Varian, ViewRay and Reflexion, and past advisory board member for Accuray, Elekta, BrainLab, and Radion.

Dr. Kresl is Certified by the American Board of Radiology in Radiation Oncology and is the current Treasurer and Executive Board Member of The Radiosurgery Society (RSS), member of the Healthcare Policy Council, Government Relations Council, Code Development and Valuation Committee and Code Utilization and Applications Committee for ASTRO, and is the current Vice-Chairman of the Board for Accuray Exchange for Radiation Oncology (AERO). Dr. Kresl is a past chairman of the ASTRO Workforce Committee, and past member of the ASTRO Health Policy Council, Scientific Program Committee and Research Council, and ACR Radiation Oncology Counselor-at-Large, and past chairman of the ACR Committee on Human Resources. Dr. Kresl became President-Elect of the RSS Board of Directors in 2024, and will become President in 2025.

Percy Lee

Percy Lee, MD, FASTRO


Dr. Lee is a Clinical Professor in the Department of Radiation Oncology and Medical Director of Orange County & Coastal Region Radiation Oncology for the City of Hope in Duarte, CA. Previously Dr. Lee was at MD Anderson Cancer Center, where he was executive section chief in radiation oncology and section chief of thoracic radiation oncology. As executive section chief, he worked alongside the division head and other section chiefs to align and execute the clinical and research priorities of the department of radiation oncology. As thoracic section chief, he partnered with other leaders to improve access to multidisciplinary care and clinical trials for patients through the thoracic service line efforts. Before that, he was chief of UCLA’s services in thoracic radiation oncology and gastrointestinal radiation oncology as well as vice chair of education and residency program director. There, Dr. Lee initiated leading-edge programs in stereotactic body radiation therapy, which uses high doses to precisely cover tumors, and MRI-guided radiation therapy, which employs imaging technology to accurately identify the specific area where treatment should be focused.

Dr. Lee has research interests in applying novel technologies such as MRI-guided radiation therapy in the clinic and led the clinical implementation of the MRI-guided radiation therapy program at UCLA as the 3rd site in the world with this innovation. He is a national PI for a number of cutting-edge trials using SBRT for thoracic and pancreatic cancer, some of which leverage the use of SBRT with novel immunotherapeutic agents. He has co-authored more than 150 peer-reviewed publications, many of them on the expanded role and evidence for SBRT in various clinical settings. He has served in various leadership roles within national organizations such as ASTRO, ABR, ARS, ACR, and RSS. With RSS, he has been an active member of the scientific meeting planning committee, invited for speaking and moderating roles at the scientific meetings as well as webinars. He believes that the RSS is a great conduit to wider adoption of radiosurgery in the community and fostering clinical and technical innovations to increase its reach. Dr. Lee joined the RSS BOD in April, 2021 and was elected Treasurer in April, 2024.

Helen Shih

Helen Shih, MD, MS, MPH, FASTRO


Helen Shih, MD, is a radiation oncologist with multiple interests in clinical care, research, education, and administrative leadership. She is a Professor of Radiation Oncology at Harvard Medical School and a practicing radiation oncologist at MGH. Following completing her residency at MGH in 2005, she has remained on staff and leads the Central Nervous System (CNS) and Ocular Services in the Department of Radiation Oncology. Her patients comprise a wide range of malignant and benign tumors and non-tumor indications for radiation treatment. Her research interests reflect her patient populations, specifically to improve patient care and outcomes, reduce radiation treatment-related toxicity, and to advance radiotherapy tools with specific attention to the role of proton therapy. She is the Medical Director of the MGH Proton Therapy Centers. She is also an advocate for education of every level of medical training for physicians and other staff alike. She previously served as the departmental medical school clerkship director, residency program director, and proton fellowship director. She enjoys mentorship and teaching of her trainees, and of junior faculty, both within her department or in other disciplines or institutions. She has led many roles beyond MGH, such as CNS Section Editor of the International Journal of Radiation Oncology * Biology * Physics and CNS Scientific Program Chair of the American Society of Radiation Oncology (ASTRO) Annual Meeting. Beyond radiation oncology, Dr. Shih has a second passion in drug addiction which extends to other areas of education, prevention, community leadership, and research. Dr. Shih joined the RSS BOD in April 2020 and was elected Secretary in April of 2024.

Grace Gwe-Ya Kim

Grace Gwe-Ya Kim, PhD, FAAPM

Medical Physics Officer

Dr. Kim is a Professor and Assistant Vice-Chair of Clinical Medical Physics in the Department of Radiation Medicine and Applied Sciences at the University of California, San Diego. Dr. Kim earned her doctoral degree from Yonsei University in Korea. After her graduation in 2001, she worked as a scientific officer for 7 years in the Medical Device Safety Bureau at the Ministry of Food and Drug Safety in Korea. Dr. Kim completed her post-doc fellowship in the Department of Radiation Oncology at Stanford. She is an active AAPM member and is currently serving in the Patient Safety Sub-Committee and Task Group 379 as Chair, in the Global Data and Information Exchange Committee as a vice-chair, and in other 8 committees. She also serves as a member of the IEC United States Technical Advisory Group (US-TAG) as a representative of ASTRO. Her research focuses on implementing novel treatment techniques, patient safety, and improvements in intracranial radiosurgery procedures.

Pantaleo Romanelli

Pantaleo Romanelli, MD

Neurosurgery Officer

Dr. Romanelli,born in Novi Velia(SA),Italy on September 28 1969, earned his MD from the University of Naples, Italy , graduating Summa Cum Laude in 1994. He’s a certified specialist in Neurosurgery and Child Neurology and Psichiatry.

Dr. Pantaleo Romanelli is a neurosurgeon specializing in Functional Neurosurgery, Epilepsy Surgery and Stereotactic Radiosurgery with a clinical practice at the CDI Cyberknife Center in Milan. CDI is today recognized as a leading world center for LINAC radiosurgery, with a special reknown for the treatment of functional brain disorders like Trigeminal Neuralgia, neuropathic pain , epilepsy and spasticity( a novel radiosurgical treatment developed by Dr Romanelli at CDI, currently evaluted by a US prospective trial) . Dr Romanelli is now moving to US as Founder and Director of Stereotactic Radiosurgery at a novel SRS center focused on the treatment of Functional Brain Disorders, The Renaissance Center for Radiosurgery and Precision Radiotherapy (Orlando,FL).

Dr Romanelli’s clinical research is focused on the treatment of Trigeminal Neuralgia,Neuropathic Pain,Spasticity ,Epilepsy and Movement Disorders . He is currently leading a US trial on the treatment of spasticity with radiosurgery. He’s also studying the role of Synchrotron-generated Microbeams to develop novel treatments for epilepsy and brain tumors.

Dr Romanelli is currently a Milestone member of the Radiosurgery Society(RSS) and serves as Chairman of the RSS Functional Radiosurgery Working Group . Dr Romanelli is a member of the Medical Advisory Board of the International Cancer Institute in India. He’s also member of the advisory board of the journal Stereotactic and Functional Radiosurgery.

Shalom Kalnicki

Shalom Kalnicki, MD, FASTRO, FACR, FACRO


Dr. Shalom Kalnicki is Professor and Chairman of the Department of Radiation Oncology at Montefiore Medical Center and Albert Einstein College of Medicine. A physician, researcher and instructor, Dr. Kalnicki has led this internationally-recognized radiation oncology department since 2004.

Considered an innovator in the field, Dr. Kalnicki has pioneered research in the radiation treatment of cancer, including intensity-modulated radiation therapy, image-guided radiation therapy, target motion management with 4-D radiation planning, stereotactic body radiation therapy, and functional tumor imaging with PET-CT fusion techniques.

Dr. Kalnicki’s radiation oncology research has had implications for treating brain, head and neck, thoracic, upper abdominal and pelvic malignancies and includes quality-of-life issues such as socio-economic disparities and the impact of family caregiver support on patients’ compliance.

Dr. Kalnicki has served on the RSS Board of Directors since 2014. From 2017 - 2019 he served as President and from 2019 - 2021 as Chairman.

Stanley H. Benedict

Stanley H. Benedict, PhD, FAAPM, FACMP


Dr. Stanley Benedict received an MS in Radiological Health Physics from San Diego State University, PhD in Biomedical Physics from UCLA, and diplomat in Radiological Therapeutic Physics from the American Board of Radiology. He has served as Chief of Clinical Physics at Virginia Commonwealth University, Director of Clinical Physics at the University of Virginia, and is currently Professor and Vice Chair of Clinical Physics in the Department of Radiation Oncology at the University of California at Davis in Sacramento, California.

Dr. Benedict scholastic has over 100 scientific publications, book chapters, and proceedings, and over 200 abstracts and scientific presentations at international symposia. Dr. Benedict has been PI, co-PI, co-investigator, and collaborator on a wide array of public and privately funded clinical medical physics research, including projects involving image guided radiation therapy, stereotactic radiosurgery, and radiation biology.

Dr. Benedict was the Chair of the AAPM Task Group 101 on Stereotactic Body Radiation Therapy, and is one of the editors of the CRC Press book entitled, Stereotactic Radiosurgery and Stereotactic Body Radiation Therapy (2014). Stan joined the Board of Directors in April 2017, and is also serving on the RSS Physics Committee.

Iris C. Gibbs

Iris C. Gibbs, MD, FACR, FASTRO

Dr. Iris Gibbs is a Professor of Radiation Oncology and Associate Dean of MD Admissions at Stanford Medicine, where her clinical and research expertise are pediatric and adult brain tumors, and robotic radiosurgery. As former Co-Director of Stanford CyberKnife Radiosurgery program, Dr. Gibbs contributed to building world- renowned clinical programs for the innovative radiation treatment of central nervous system tumors and robotic radiosurgery. Dr. Gibbs has served as committee chair for RSS and is a dedicated member of the International Stereotactic Radiosurgery Society (ISRS).

In 2014, Dr. Gibbs was appointed as Associate Dean for Medical School Admissions of Stanford Medicine. She is a 2015 Hedwig van Ameringen Executive Leadership in Academic Medicine (ELAM) Fellow and a fellow of the American Society of Radiation Oncology, American College of Radiology, and Association for Women Radiologists. In addition to leadership service roles for Radiological Society of North America (RSNA), American Society of Radiation Oncology (ASTRO), and the American Board of Radiology (ABR), Dr. Gibbs is the immediate past chair of the Section on Radiology for the National Medical Association.

Dr. Gibbs joined the RSS Board of Directors in 2016. She served as President from 2019 - 2021 and assumed the role of Chairperson from 2021 - 2023.

Simon S. Lo


Dr. Simon Lo is Professor and Vice-Chair for Strategic Planning of Radiation Oncology and Professor of Neurological Surgery as well as the Director of SBRT at the University of Washington Department of Radiation Oncology in Seattle, Washington. He is also the Co-chair of the Appointment and Promotion Committee and a member of the leadership team for Leading Academic Participating Site of NCTN, Fred Hutchinson Cancer Research Center.

Dr. Lo has edited 8 textbooks with 5 comprehensive textbooks in SRS/SBRT and published over 240 full peer-reviewed papers, a majority of which focused on SRS/SBRT for all body sites and has led the SBRT programs in 3 NCI-designated Comprehensive Cancer Centers. He has led or participated in numerous practice guidelines in SRS/ SBRT, brain metastases, primary brain tumors, spinal metastases, and bone metastases. Dr. Lo was also a member of the American Board of Radiology CNS/ pediatrics committee. He is a co-founder and core member of the International Radiosurgery Oncology Consortium for Kidney (IROCK). He is the Immediate Past President of CARROS (Radiation Oncology Chapter) and the Assistant Councilor (American Radium Society Representative) of the American College of Radiology. He is the Radiation Therapy Panel Chair for the AANS/CNS low-grade glioma guidelines.

Dr. Lo joined the RSS Board of Directors in 2019 and served on the 2022 RSS Scientific Meeting Planning Committee and is the Medical Director of the ACRO-RSS Distinction in Practice in Stereotactic Radiotherapy Accreditation Program.

Shankar Siva

Shankar Siva, PhD, MBBS, FRANZCR

Dr. Siva is an Associate Professor Radiation Oncology, Peter Maccallum Cancer Centre, Victoria, Australia. Shankar is a Radiation Oncologist and NHMRC fellow at the Peter Mac and leads the Stereotactic Ablative Body Radiotherapy (SABR) program and Australia's first dedicated SABR clinic. He completed his PhD with the Molecular Radiation Biology (Martin) Laboratory focusing on translational investigations in precision high-dose lung radiotherapy. He published the first original research from Australia on the use of the SABR technique.

Shankar leads multiple clinical trials in the treatment of lung and urological cancers at the Peter Mac, and is chair of three TransTasman Radiation Oncology Group (TROG) studies in the fields of oligometastases, lung and kidney cancers. He is Co-Chair of the TROG Genitourinary Group, is an executive member of Radiation Oncology Research Committee (RORC) of the Royal Australian and New Zealand College of Radiologists (RANZCR) and Management Advisory Committee (MAC) of the Australasian Lung Cancer Trials Group (ALTG) amongst other leadership roles. He has research interests in high-tech radiotherapy delivery, radiation biology and radiation immunology. Dr. Siva joined the RSS Board of Directors in April 2020.

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