82, passed away peacefully on April 23, 2026, in Milwaukee, Wisconsin, while listening to classical music.

He was born on August 14, 1943, in Carlisle, Pennsylvania, to William Howard Gray and Bonita Margaret (Scohier) Gray.

Joel served in the United States Air Force from 1963 to 1967, where he began developing his lifelong expertise in photographic science and quality control. His curiosity and dedication to precision led him to pursue higher education, earning a Bachelor of Science in Photographic Sciences and Engineering, summa cum laude, from the Rochester Institute of Technology in 1970; a Master of Science in Optical Sciences from the University of Arizona in 1974; and a Ph.D. in Radiological Sciences from the University of Toronto in 1977.

While still in graduate school, Joel’s work gained national recognition when he was awarded a contract from the U.S. Food and Drug Administration to develop foundational texts on quality assurance in medical imaging. These publications, along with his later book Quality Control in Diagnostic Imaging (1983), helped establish standards in the field.

Joel became the first medical physicist in the Department of Radiology at Mayo Clinic in Rochester, Minnesota, in 1977. During his distinguished career, he made lasting contributions to medical physics, including research that changed the way scoliosis imaging is performed, significantly reducing radiation exposure for young patients. He also founded a clinical medical physics residency program at Mayo Clinic and later played a key role in developing one of the first diagnostic medical physics residency programs in a private practice setting.

A prolific scholar and educator, Joel authored more than 175 peer-reviewed publications and contributed to reports for the National Council on Radiation Protection and Measurements and the International Atomic Energy Agency. He was a Distinguished Emeritus Member of the NCRP and served as an expert, consultant, and teacher throughout his career. He received the Edith Quimby Lifetime Achievement Award from the American Association of Physicists in Medicine (2011) and an FDA award in 2015 for his contributions to improving radiation safety in dental imaging.

Joel was deeply engaged in his professional community, holding memberships in over 20 professional societies and serving in leadership roles in several. He mentored students and residents, leaving a lasting impact on the next generation of medical physicists.

In addition to his academic and clinical work, Joel was an entrepreneur and innovator. From 2006 to 2025, he founded and ran DIQUAD, LLC, where he developed patented technology to monitor radiation dose and image quality of dental X-ray units through a mail-based system. This work reflected his lifelong commitment to improving patient safety through practical, accessible solutions.

Beyond his professional accomplishments, Joel had a love of travel that began during his Air Force service and continued throughout his life. He visited more than 56 countries, embracing both business and leisure opportunities to explore the world. Joel had long-lasting friendships worldwide and travelled as often as he could.

Joel also enjoyed food - cooking, dining out, and trying anything imaginable. He had a passion for applying his scientific mind to cooking, often experimenting to perfect techniques for his favorite dishes—earning the affectionate nickname “Science Dad” from his daughter.

Joel will be remembered for his intellect, dedication to medical physics and improving patient safety, and his passion for learning, travel, and sharing a good glass of wine with those he loved.

He is survived by his son, Adam Gray; his daughter, Kiersten Berger; and grandchildren Aden, Gavin, Mason, Morgan, and Harmon. He was preceded in death by his parents, brother Gary Gray, and longtime partner, Beverly Linkus. In accordance with his wishes, no formal funeral or memorial service will be held. Memorial contributions in his memory may be made to the Mayo Clinic. At his request, his family will gather privately to spread his ashes in the woods.