Large thermal stresses easily exceeding the tissue yield strength may
develop in the frozen region around a cryosurgical probe. A new integr
odifferential solution for the heat transfer problem of biological tis
sues freezing around a cryosurgical probe is presented in this article
. This solution is suitable for cases of high Stephan numbers and for
a temperature-dependent forcing function at the cryoprobe. A new solut
ion for the thermal stresses around a cryosurgical probe is also prese
nted, based on an elastic-perfectly plastic model. It is proposed that
thermal stresses beyond the elastic limit of the frozen region may sh
arply increase the mechanical damage to the cell membranes due to plas
tic deformation. It was found that plastic deformation always starts a
t the cryoprobe surface; however, plastic deformation may also be form
ed near the freezing front at high cooling rates and large cryoprobes.
It is demonstrated that under some conditions plastic deformation may
occur in the entire frozen region. A parametric study to identify the
best cooling protocol for maximal plastic deformation is presented. (
C) 1996 Academic Press, Inc.