The global medical imaging community mourns the loss of Willi Kalender, PhD, a visionary medical physicist who passed away on October 21 at the age of 75. Kalender's pioneering work laid the essential foundation for what Asto CT represents today, particularly through his advancements in spiral CT (often called helical CT) which continuously rotates the CT scanner as the patient is translated through the x-ray fan beam and innovative dose reduction techniques that have transformed both imaging quality and patient safety.

Prof. Willi Kalender dedicated his life to advancing diagnostic radiology, especially CT imaging technology. He began his studies in physics and mathematics at the University of Bonn, completed a master’s and Ph.D. in medical physics at the University of Wisconsin, and achieved his Habilitation at the University of Tübingen in 1988.

Starting in 1979, Kalender worked in Siemens Medical Systems’ research labs, where he led the Medical Physics group from 1988. In 1995, he became the founding professor of the Institute of Medical Physics at Friedrich-Alexander-University Erlangen-Nuremberg and later served as a distinguished visiting professor at Stanford.

"Willi was as brilliant as he was dedicated," shared Dr. David Ergun, PhD, a former classmate from the University of Wisconsin and a medical physicist. "His groundbreaking ingenuity made it possible to see the world inside the human body in ways we could only dream of. His work has touched countless lives."

"Dr. Rock Mackie, a colleague in medical physics, added, “Willi’s vision and tenacity were unparalleled. He wasn’t just advancing imaging technology—he was making medical care safer, faster, and more effective for patients everywhere. Willi was very approachable. I reached out to him early in my tomotherapy days when I read his first paper on spiral CT as I thought it showed a way to better deliver that type of therapy. He was very kind and always offered me encouragement which grew into friendship. His impact will be felt for generations.”

Kalender's groundbreaking developments in helical spiral CT and dose reduction have not only enhanced the diagnostic capabilities of modern CT scanners but have also significantly improved patient outcomes by minimizing radiation exposure. His dedication to advancing medical technology has left an indelible mark on the field, earning him the respect and admiration of peers worldwide.

To honor Willi Kalender’s legacy and share your own memories, please visit the tribute board: Memorial and obituary for Willi Kalender