Leon Lidofsky (1924-2016)

Medical Physics
Professor Emeritus of Nuclear Engineering
and Medical Physics




Tufts University, B.S. Physics, 1945

Columbia University, M.S. 1947 / Ph.D. Physics 1952


Leon Lidofsky received his B.S. in Physics at Tufts in 1945 and his M.S. and Ph.D. in Physics at Columbia University in 1952.

After serving as a Research Associate in Physics, he was appointed Professor of Nuclear Science and Engineering at Columbia in 1960 and was one of the original nine members of the faculty of the Department of Applied Physics and Applied Mathematics. His fields of interest have included Nuclear Physics, Radiation Transport, Application of Computers to Nuclear Research and Radiation in Medicine.

He received the Great Teacher Award from Columbia University in 1988.


"My research interests are associated broadly with the transport of radiation in matter and with environmental and safety aspects of nuclear fission power.

Radiation, in interacting with matter, may cause changes in that matter. Typically, the goal of my research in such instances is the development of methods that, given the radiation and material environments, permit the physical consequences of the interactions to be predicted.

A primary application has been in radio-oncology where my students and I have developed and applied methods to permit the detailed and accurate determination of dose distributions resulting from the irradiation of the highly inhomogeneous human body by high energy photon beams.

The same method appears to have value in designing radiation shielding under circumstances where inhomogeneous shields must be used. In other instances, the focus is on the modification of the properties of escaping radiation following interactions of the primary radiation with the irradiated matter. The goal is to enable an inference of those properties of the irradiated matter that would have led to the particular distributions of escaping radiations that were observed. For instance, in usual imaging applications, analyses tend to be based on the assumption that the interaction removes the radiation. Yet, the changes that take place due to non-absorbing interactions may be significant and can serve to provide a further source of information.

Applications cover both medical and non-medical fields. The medical studies range, for instance, from observations of cerebral blood flow for purposes of monitoring brain function to precise in vivo determinations of particular elements in human subjects so that changes associated with medical treatment can be monitored. Those latter measurements require the observation of the products of neutron irradiation of humans. Our present focus is on optimizing the information content of the measurements relative to the dose to which the patient must be subjected.

As an example of a non-medical application, my students and I have treated modifications of CAT images caused by local inclusions of materials within the scanned section whose atomic numbers differ from that of the bulk matter. That capability is useful in, but not limited to, evaluation of techniques for the recovery of heavy shale oil.

My research in environmental and safely aspects of nuclear fission power is distinct from these other interests. I focus on both minimization of risks associated with present technology and changes that would minimize that risk by severely limiting consequences of malfunctions".

Selected Publications

“Differential pencil beam dose computation model for photons”, R. Mohan, C. Chui, L. Lidofsky, Med Phys. Jan-Feb;13(1):64-73, 1986.

“Report to the American Physical Society by the Study Group on Radionuclide Release from Severe Accidents at Nuclear Power Plants”, R. Wilson, K.J. Araj, A.O. Allen, P. Auer, D. Boulware, F. Finlayson, S. Goren, C. Ice, A.L. Sessoms, M.L. Shoaf, I. Spiewak, and T. Tombrello, Reviews of Modern Physics, 1985.

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