Lawrence A. Shepp

Biography

The collective work of H. Malcolm Hudson, Brian F. Hutton, and Lawrence A. Shepp has resulted in reconstruction algorithms that propelled the success of emission tomography as a clinically feasible method for medical imaging. Dr. Shepp developed the maximum-likelihood expectation-maximization (ML-EM) algorithm in 1982, which provided improved image quality compared to Fourier-based algorithms of the time. However, its heavy computational burden was a barrier to clinical use. Profs. Hudson and Hutton were motivated to overcome the computational workload with faster image reconstruction solutions. First published in 1994, their ordered-subsets expectation-maximization (OS-EM) algorithm applied the ML-EM algorithm successively to well-chosen data blocks. This was key to bringing ML estimation into daily practice for emission tomography. The trio’s work paved the way for techniques that improve image accuracy and precision, while potentially shortening scan duration or helping to reduce the activity of tracer administered to the patient.

Dr. Shepp passed away on April of 2013. Shepp was the Patrick T. Harker Professor of Statistics at the Wharton School of the University of Pennsylvania, Philadelphia, PA, USA and a Professor with the Department of Statistics at Rutgers University, Piscataway, NJ, USA, and as the recipient of the 2014 IEEE Marie Sklodowska-Curie Award with Hudson and Hutton.