Imaging Physics Group

The imaging physics group supports a wide range of imaging modalities across the institution. The physicists are all board certified by American Board of Radiology. We ensure regulatory compliance of all imaging equipment and play an instrumental role in acquiring and maintaining national accreditation. The group also has established an approach to optimizing radiation dose and image quality through two avenues: research and innovation, and clinical data analysis.

Meet Our Physicists

In research and innovation, we have focused on the taskbased assessment of CT low-contrast detectability and minimum dose. We identified the relationship of the dose to minimum detectable contrast and the lesion size, stating this in the form of a power law, and we established the explicit patient size dependency of this relationship. Published in peer-reviewed journals and resulting in the awarding of a U.S. patent, this work helps clinicians “image gently” and “image wisely,” in keeping with campaigns of the American College of Radiology and other professional organizations.

Employing the physics practice of using a data-driven approach, we identified outliers and investigated causes, allowing for evidence-based protocol optimization especially for challenging cases. With this approach, we can now evaluate imaging technique and dose data at a very high level.

Figure 1 demonstrates patient dose tracking for two different CT scanners.

Figure 2 demonstrates the clinical image quality improvement after performance of phantom studies for significant metal artifact reduction.

Another example is the exposure reduction in digital radiography (DR). We currently collect and review data on more than 30,000 DR X-rays per month. The institution’s average rejection rate, 15% when we started tracking, has been brought down to 2%, even as we have brought on new facilities. The effort also involved frequent education provided by our group on DR quality and dose. Figure 3 shows a drop of the exposure index from 1600 to 1400, amounting to exposure reduction by 37%.

Figure 3

Our Physicists

Yifang (Jimmy) Zhou, PhD

Chief Medical Physicist
Department of Imaging

Dr. Zhou received Ph.D. in Radiological Sciences at University of California, Irvine.  He worked in research and development before joining Cedars-Sinai in 2003 as a diagnostic imaging physicist. Dr. Zhou is board certified in Diagnostic Radiological Physics by American Board of Radiology. Dr. Zhou is Chief Medical Physicist in the Department of Imaging.

Clinical Areas: CT: protocol tuning and dose reduction, Fluoroscopy/Angiography Lab, Mammography, Digital radiography, Nuclear Medicine

Alexander Scott, PhD

Diagnostic Imaging Physicist
Nuclear Imaging Physicist

Dr. Scott was awarded his Ph.D. in high-energy physics in 2007.  He continued as a post-doc at University of Minnesota researching matter-antimatter correlations before joining a residency program at University of Alabama at Birmingham in diagnostic imaging physics.  After completion of his residency, Dr. Scott joined CSMC as a diagnostic imaging physicist.

Dr. Scott manages the QA programs for nuclear medicine and digital radiography.  He assists CSMC clinical partners with performing and submitting the ACR and ICANL accreditations for x-ray and nuclear modalities.  He also provides radiation consults for patients receiving x-ray imaging procedures or radionuclide therapies.  His current research is centered around dose management in digital radiography.

Clinical Areas: Radiography, Fluoroscopy, CT, Mammography, Nuclear Medicine

Di Zhang, PhD

Diagnostic Physicist

Dr. Zhang received his Ph.D. in Biomedical Physics in 2012 at UCLA and joined Toshiba America Medical Systems as a clinical science manager. He earned his MBA degree at UCLA’s fully employed MBA program in 2016 and later joined Landauer Medical Physics as a regional director and oversaw the medical physics operation there until the spring of 2019, when he joined CSMC, and assumed the role of diagnostic physicist.

He is a well published scientist with proven skills of research and development, clinical research, and project management. He drives the efforts to ensure patient safety and improve medical imaging quality by optimizing system performance to meet and exceed industry standards as well as regulatory and accreditation body requirements.

Clinical Areas: X-ray, Fluoroscopy, CT, Mammography, Nuclear Medicine

Nader Binesh, PhD

MRI Physicist

Dr. Binesh, got his Ph.D. in physics of NMR in 1997 and joined UNC-CH as post-doctoral fellow. He later joined UCLA Spectroscopy research team in 1999 as a fellow & worked there as research scientist till fall of 2005, when he joined CSMC, and assumed the role of MRI physicist.

He keeps all the MRIs under check (QA and PM) to make sure they all work perfectly. He has been instrumental for introduction of brain perfusion & spectroscopy to help in diagnose and grade brain lesions without any biopsy. He implemented the DTI, fiber-tracking and functional MRI to help neuro surgeons plan their surgery much better. These techniques help surgeons to be more precise & prevent any loss of functions (such as movement, speaking…) after major brain surgeries. 

Clinical Areas: Brain Perfusion, DTI and fiber-tracking, Spectroscopy, Functional MRI, Quality check and Accreditation

Christina Lee R.T. (R)(M)(QM)(ARRT)

Medical Physics Assistant

Christina earned her Bachelor of Science degree in Radiologic Technology and holds ARRT credentials in radiography, mammography and quality management.  She previously worked as a mammography technologist where she also performed MQSA quality control activities.  Christina currently supports the medical physicists with advanced testing in CT, mammography, cath lab and interventional.  She performs physics testing on radiography and fluoroscopy units and monitors regulatory testing data.   

Clinical Areas: Radiography, Fluoroscopy, Mammography