In Memoriam: Henry Lee Fisher, Jr.
by Joseph J. Shonka and Geoffrey G. Eichholz
Henry Lee Fisher, Jr., died of melanoma on 13 November 2006. Henry was born on 26 February 1938. He was a lifelong employee of the U.S. Public Health Service (USPHS) and did research at the Environmental Protection Agency facilities in Research Triangle Park.
While on staff at the USPHS, he received a PhD in 1973 from the Georgia Institute of Technology. He was an older and more serious graduate student than his peers. He performed his PhD research at Oak Ridge National Laboratory under the late Dr. Walter Snyder. In that effort (manually performed in the days before CT scanners) he laboriously took Gray's Anatomy and developed the equations used to describe a consistent geometry of all of the organs in a human body. This set of equations is referred to as the Fisher-Snyder Phantom. With the advent during that era of the IBM 360 class mainframe computers, Walter Snyder recognized that computers were capable and that a more precise model would improve internal dosimetry.
The equations that Henry developed were used in the Monte-Carlo program that computed specific absorbed fractions to various tissues in a heterogeneous model of a human. These values have been used widely in nuclear medicine and both internal and external dosimetry. Although some users have transitioned to a voxel-based approach for expressing the geometry of a human body, many (if not most) dosimetry calculations continue to use geometries in the manner first developed by Fisher.
Only a small fraction of PhD theses ever become fundamental elements of a scientific field. Henry's work was of that caliber.