Meet Our Radiologists
Radiologists are physicians that utilize a variety of imaging technologies such as ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) to diagnose or treat diseases. They provide referring physicians with the information
that they need to give the appropriate treatment to their patients. All of our Radiologists are certified by the American Board of Radiology. Areas of subspecialty training within the Rads, Inc. group include Body Imaging, Neuroradiology, Musculoskeletal Imaging, Nuclear Medicine, Emergency Radiology, and Vascular
and Interventional Radiology.

Richard Porzio, MD

Board Certified Diagnostic Radiologist
Subspecialty Training in Body Imaging
American Board of Radiology

Dr. Richard Porzio joined RaDS, Inc. after completing a Body Imaging Fellowship at Stanford University in Palo Alto. A native of the San Jose area, Dr. Porzio earned a Bachelors of Science degree in Biopsychology from the University of California at Santa Barbara, graduating with Honors.

After completing a year of research in Neurology at Stanford University, he attended medical school at Wayne State University. Dr. Porzio returned to Northern California for post-graduate training at Santa Clara Valley Medical Center in San Jose and fellowship training at Stanford University Medical Center in Palo Alto. Throughout his education, Dr. Porzio has earned many honors including University of California Regent Scholar and Radiology Chief Resident at SCVMC.

Dr. Porzio's state of the art training in Ultrasound, Computed Tomography, and Magnetic Resonance Imaging ensures that his patients receive the highest quality diagnostic care.

Dr. Porzio is currently President of RaDS, Inc.

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Sam Kokoris, MD

Board Certified Diagnostic Radiologist
Computer Imaging Specialist
American Board of Radiology

Dr. Sam Kokoris joined RaDS, Inc., then known as Central Valley Imaging, in 1997 and has been an instrumental part of the company's growth. As a native of San Joaquin County, Dr. Kokoris attended the University of California, Davis where he received a Bachelor of Science degree in Genetics in 1987.

He earned his Medical Degree at the University of Southern California School of Medicine in 1991 and spent the following year as a Radiology Research Fellow. Internship followed at Cedars-Sinai Medical Center in Los Angeles. Dr. Kokoris returned to Northern California to complete his Radiology Residency at Santa Clara Valley Medical Center in 1997.

Throughout his education and training, Dr. Kokoris achieved several honors including three coveted scholarships, the Dean's Scholar Award, and a seat on SMS Data Systems Radiology Advisory Panel.

Dr. Kokoris has published papers in collaboration with highly recognized pioneers in the field of Radiology on such subjects as clot capturing, gene expression, and cardiovascular and interventional radiology.

Dr. Kokoris currently serves as the Vice-President and IT Director of RaDS, Inc.

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T. Tejpal Singh, MD

Board Certified Diagnostic Radiologist
Subspecialty Training in Neuroradiology &
Musculoskeletal Imaging

American Board of Radiology

Dr. Tejpal Singh joined RaDS, Inc. after finishing a MRI fellowship in Neuroradiology and Musculoskeletal imaging at the University of California, San Diego. Prior to that, he completed Medical School and Residency at UC Davis, with a one year internship at San Joaquin General Hospital.

Dr. Singh also brings an engineer's perspective to the field of Radiology and medicine, having obtained Master of Science degrees in Electrical and Computer Engineering from the California Institute of Technology, Pasadena and the University of Southern California, respectively. He now combines these skills to enhance patient care with efficient use of resources and cutting edge technology.

He has authored several papers in MRI and is a reviewer of an international MRI educational lecture series.

Dr. Singh serves as the CFO of RaDS, Inc.

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Kyle Yu, MD

Board Certified Diagnostic Radiologist
Subspecialty Training in Musculoskeletal Imaging
American Board of Radiology

A native Californian, Dr. Kyle Yu received his undergraduate training in biology at Stanford University, graduating with distinction in 1985. He then attended medical school at the University of California, San Diego. After completing an internship in internal medicine at St. Mary's Hospital in San Francisco, he entered the Diagnostic Radiology Scholars Program at the University of California, San Francisco, where he received his radiology residency training.

After residency, Dr. Yu continued his radiology training at U.C.S.F., completing clinical fellowships in MR imaging & ultrasound, abdominal imaging, and a mini-fellowship in musculoskeletal MRI at the San Francisco Magnetic Resonance Center. Due to his interest in health care policy, Dr. Yu also undertook postdoctoral fellowships in health services research in the Advanced Training in Clinical Research Program and in the Health Services Research Training Program at the U.C.S.F. Institute for Health Policy Studies.

After completing his radiology training in 1996, Dr. Yu joined the attending staff in the Department of Radiology at U.C.S.F. as Assistant Professor. During his short but productive academic career, Dr. Yu published over 30 articles in peer-reviewed journals, authored a number of book chapters, gave numerous lectures both locally and nationally, and was co-investigator on several research grants, including one from the N.I.H. Dr. Yu also served as Director of the Radiology Residency Program at Santa Clara Valley Medical Center in San Jose, California.

Dr. Yu has received a number of honors and awards during his education and academic career. After undergraduate training at Stanford, he was invited to join the Phi Beta Kappa Society. He received the Walter L. Robb Fellowship award at the end of his radiology residency training at U.C.S.F. While in academic practice, Dr. Yu received the General Electric-AUR Radiology Research Academic Fellowship and Editor's Recognition award for distinction as a peer reviewer for the journal Radiology. He was also awarded a N.I.H. grant from the National Cancer Institute for "Imaging in Risk Assessment of Prostate Cancer Patients."

Dr. Yu has been with RaDS, Inc. since 2004 where he strives to provide high quality patient care and excellent service to referring physicians. His subspecialty expertise is in body and musculoskeletal MR imaging, with other areas of interest including oncologic imaging and women's imaging. Dr Yu is currently serving as Medical Director of the Department of Radiology at Saint Louise Regional Hospital.

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Mario Sattah, MD

Board Certified Diagnostic Radiologist
Subspecialty Certification in Vascular &
Interventional Radiology

American Board of Radiology

Dr. Mario Sattah joined RaDS, Inc. in 2006 bringing with him experience in Diagnostic, Vascular, and Interventional Radiology.

Dr. Sattah graduated from Emory University in Atlanta, Georgia with a Bachelor of Science in Biology and a Bachelor of Arts in Philosophy. He continued at Emory earning his M.D. in 1994 followed by a General Surgery Internship in 1995. From 1996-2000 he completed his Diagnostic Radiology Residency through the Emory University Hospital Radiology Program. Dr. Sattah continued his Radiology education by completing a Vascular and Interventional Fellowship also at Emory University.

Throughout his education and training, Dr. Sattah has achieved several honors such as being a recipient of the Dean's Scholarship and graduating Summa Cum Laude from Emory as an undergraduate. He was also a member of two prestigious honor societies, Phi Beta Kappa and Alpha Epsilon Delta.

Dr. Sattah is Board Certified in Diagnostic, Vascular, and Interventional Radiology making him a valuable addition to RaDS, Inc. He is currently serving as the Medical Director of the Radiology Department at Doctors Hospital of Manteca.

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Conway Lien, MD

Board Certified Diagnostic Radiologist
Subspecialty Certification in Neuroradiology
American Board of Radiology

Dr. Conway Lien joined RaDS, Inc. in 2007 after completing a Neuroradiology Fellowship at Stanford University Medical Center in Palo Alto.

Dr. Lien graduated with Honors from the University of California, Berkeley earning a Bachelor Degree in Molecular and Cell Biology. He attended Medical School at Tufts University School of Medicine in Boston. After earning his MD in 2000, he returned to California where he interned at Santa Clara Valley Medical Center. Dr. Lien also completed his Radiology Residency at Santa Clara Valley Medical Center serving as Chief Resident from 2003 to 2004.

Dr. Lien is Board Certified in both Diagnostic Radiology and Neuroradiology. His extensive training and distinguished educational background is reflected in the high level of diagnostic care he provides.

Dr. Lien is currently serving as Medical Director of the Department of Radiology at Regional Medical Center San Jose.

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Robert Lim, MD

Board Certified Diagnostic Radiologist
Subspecialty Training in Emergency Radiology
American Board of Radiology

Dr. Robert Lim joined RaDS, Inc. in 2008 after completing an Emergency Radiology Fellowship at Massachusetts General Hospital, an affiliate of Harvard Medical School.

Dr. Lim graduated from Cornell University, Ithaca, New York with a Bachelor of Science in 1997. He then attended SUNY Upstate Medical University, Syracuse, NY where he earned his Medical Degree. His training continued with an Internal Medicine Internship at St. Vincent's Hospital at Worcester Medical Center followed by his Diagnostic Radiology Residency at Tufts New England Medical Center, Boston, MA.

Dr. Lim was a member of the Alpha Epsilon Delta Honor Society and has received Clinical Honors in Radiology and Pediatrics. He received the Radiology Achievement Award in 2002 and served as the Chief Radiology Resident at Tufts New England Medical Center from 2005-2006.

His strong academic background, up to date training, and professionalism has made Dr. Lim an excellent addition to RaDS, Inc.

Dr. Lim is currently serving as the Medical Director of the Radiology Department at Sutter Tracy Community Hospital.

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Keith Kwok, MD

Board Certified Diagnostic Radiologist
Subspecialty in Neuroradiology
American Board of Radiology

Dr. Keith Kwok joined RaDS, Inc. in 2013 after completing a Neuroradiology Fellowship at USC/LAC Medical Center in Los Angeles, California.

Dr. Kwok was born in Hong Kong and is a native of Bellevue, Washington. He graduated with Magna Cum Laude from the University of Washington earning a Bachelor Degree in Biochemistry. He later spent two years at a Howard Hughes Medical Institute neuroscience lab as a research technologist. He attended Medical School at George Washington University School of Medicine in Washington, DC. After earning his MD in 2004, he finished his internship in general surgery at University of California at Davis Medical Center. Dr. Kwok subsequently completed his Radiology Residency at Monmouth Medical Center in Long Branch, New Jersey in 2012.

Throughout his education and medical training, Dr. Kwok has published and presented extensively at national meetings in radiology and neurosurgery. He was co-editor and co-author in the Textbook of Neuro-oncology.

Dr. Kwok is Board Certified in Diagnostic Radiology with a subspecialty in Neuroradiology. He is passionate about his work in radiology and providing the highest level of care to his patients.

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Nidhi Gupta, MD

Board Certified Diagnostic Radiologist
Subspecialty Training in Abdominal Imaging
American Board of Radiology

Dr. Nidhi Gupta graduated Summa Cum Laude from the University of California, Los Angeles earning her Bachelor of Science in Physiological Science with a minor in Neuroscience. She then received her medical degree at the Keck School of Medicine of the University of Southern California. Her medical training continued with an internship in Internal Medicine at the University of California, Irvine followed by a diagnostic radiology residency at Santa Clara Valley Medical Center in San Jose. She then completed a one-year fellowship in Abdominal Imaging at the University of California, San Francisco, which included training at the San Francisco VA Medical Center and San Francisco General Hospital.

Following completion of her fellowship, Dr. Gupta worked as a pool physician in general radiology at Kaiser Permanente South San Francisco. In October 2012 she accepted the position of Assistant Clinical Professor in Abdominal Imaging at the University of California, San Francisco, and the San Francisco VA Medical Center.
Dr. Gupta joined RaDS, Inc. in August 2013.

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Wayne Tran, MD

Board Certified Diagnostic Radiologist
Subspecialty Training in Nuclear Medicine
American Board of Radiology

Dr Wayne Tran completed his undergraduate and medical school training at Creighton University in Omaha, Nebraska in 2007. He then began his radiology residency at Maine Medical Center in Portland, Maine. During this time, Dr. Tran served as Department Chair of Radiology at the University of New England (UNE) Medical School from 2010-2012, and was named Clinical Professor of the Year both of those years. Additionally, he was an adjunct professor at the UNE School for Physicians Assistants from 2010-2012. Dr. Tran gave many presentations at multiple conferences during his residency and served as Chief Resident from 2011-2012.

Wayne Tran joined Rads, Inc. in August of 2013 after completing a Nuclear Medicine fellowship at UCSF.

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Joseph Marshall, MD

Board Certified Diagnostic Radiologist
Subspecialty Training in Vascular &Interventional Radiology
American Board of Radiology

Dr. Joseph Marshall recently joined CVIMA bringing 12 years of experience in Diagnostic, Vascular and Interventional Radiology. A native Southern Californian,
Dr. Marshall graduated with highest honors in 1983 from San Diego State University with a Bachelors of Science degree in Biology. From there he received his MD degree from the University of California, Davis in 1988. Internship and residency followed in Internal Medicine at UCSF, Fresno becoming board certified in 1992. After residency, Dr. Marshall practiced and taught Internal Medicine at the VA Hospital in Fresno for 4 years becoming Chief of General Internal Medicine.

Realizing his true calling was Radiology, Dr. Marshall then completed 4 years of Diagnostic Radiology residency at UCSF, Fresno becoming Chief Resident and obtaining board certification in 2001. Further training ensued at Emory University in Atlanta, Georgia with subsequent board certification in Vascular and Interventional Radiology in 2002.

Dr. Marshall has practiced Diagnostic, Vascular and Interventional Radiology first in Hawaii and then Iowa for the past 12 years.

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Garth Harley, MD

Board Certified Diagnostic Radiologist
Subspecialty Training in Neuroradiology
American Board of Radiology

Dr. Harley joins Central Valley Imaging Medical Associates with an impressive educational background. Dr. Harley graduated from Georgetown University, School of Medicine in 1988. After completing his Internship, in surgery, at California Pacific Medical Center, San Francisco he entered into the Diagnostic Radiology program at Santa Clara Valley Medical Center.

In 1996, Dr. Harley completed his Fellowship training at Stanford University in Neuroradiology. Dr. Harley was also a clinical instructor in Diagnostic Radiology at Stanford University.

Throughout his education, Dr. Harley received several honors in clinical coursework and was named outstanding Intern at California Pacific Medical Center,
San Francisco.

Dr. Harley is a commercial, multiengine and instrument rated pilot. He currently holds a world record in large formation skydiving and still remains a current
instructor in skydiving.

Since 1999, Dr. Harley has been in private practice, striving to provide quality patient care. Dr. Harley has also previously served as committee member of the Santa Cruz County Medical Review and Advisory Board, as well as Medical Director of Cabrillo College Radiologic Technologist Program.

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Michael Rigdon, MD

Board Certified Diagnostic Radiologist
Subspecialty Training in Body Imaging
American Board of Radiology

Michael Rigdon joined Radiology Diagnostic services in 2013, after having worked in private practice in the central valley area of California for 20 years. A native of the Seattle area, he earned his undergraduate degree at the University of Washington with a Bachelor of Science in Chemical Engineering. He participated in several research projects in chemistry and chemical engineering while attending the University of Washington and the University of California at Berkeley. He served as president of Tau Beta Pi, the engineering honor society, his senior year
at Washington.

Dr. Rigdon earned his M.D. degree from the University of Washington and then traveled to the east coast where he completed his residency in diagnostic radiology at Hackensack Medical Center in New Jersey. He received the honor of Chief Resident while at HMC. He returned to the Bay Area and completed his fellowship training in Computed Tomography and Magnetic Imaging in Abdominal Imaging at the University of California at San Francisco.

Dr. Rigdon is currently an associate radiologist with Radiology Diagnostic Services.

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Niv Decalo, MD

Board Certified Diagnostic Radiologist
Subspecialty Training in Body Imaging
American Board of Radiology

Dr. Niv Decalo joins Radiology Diagnostic Services, Inc. in 2014 after completing a Body Imaging Fellowship at the University of California, San Francisco.

Dr. Decalo graduated with Honors from Brandeis University in 1999 with a Bachelor of Science in Biochemistry. After spending 2 years at the Dana Farber Cancer Institute in Boston, he then attended Tufts University School of Medicine where he earned his Medical Degree in 2005. His training continued with a Surgery Internship at Stamford Hospital in Stamford, CT, followed by Diagnostic Radiology Residency at Hartford Hospital in Hartford, CT.

Dr. Decalo then spent several years in private practice in Connecticut before moving to the West Coast to complete his fellowship at UCSF. Dr. Decalo's work experience as well as his strong educational background and up to date training in Abdominal Imaging make him a welcome addition to RaDS, Inc.

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Thomas Efird, MD

Board Certified Diagnostic Radiologist
Subspecialty Training in Musculoskeletal and Body Imaging
American Board of Radiology

Thomas Efird joined Radiology Diagnostic Service, Inc. in 2014. Dr. Efird completed his residency in Diagnostic Radiology at Stanford University Medical Center. He continued his training at Stanford University, completing a combined Musculoskeletal and Body Imaging Fellowship.

A Central Valley native raised in Fresno, Dr. Efird received his undergraduate education at Stanford University, earning a Bachelor of Arts degree in English Literature. He attended medical school at Tulane University School of Medicine, and remained at Tulane for an internship in Internal Medicine. Dr. Efird has earned multiple honors during his career, including induction into the Alpha Omega Alpha honor society and serving as Chief Resident and Chief Body Imaging Fellow at Stanford. Dr. Efird received his Board Certification from the American Board of Radiology in 2009.

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