Analysis of thermal stress in cryosurgery of kidneys

Xiaoming He, John C Bischof

Research output: Contribution to journalArticle

Abstract

In this study, the thermal stress distribution in cryosurgery of kidney was investigated using a multi-physics finite element model developed in ANSYS (V7.0). The thermal portion of the model was verified using experimental data and the mechanics portion of the model (elastic) was verified using classic analytical solutions. Temperature dependent thermal and mechanical properties were used in the model. Moreover, the model accounts for thermal expansion due to both temperature change and volumetric expansion associated with phase change of tissue water to ice. For a clinical cylindrical cryoprobe inserted into the renal cortex from the top-middle renal capsule, it was found that the thermal stress distributions along the radial position are very different at different depths from the top renal capsule. The thermal stress is much higher at both ends than in the middle of the cryoprobe surface. It was found that there might be more tissue next to the top renal capsule which undergoes microcrack formation or plastic deformation. Furthermore, it was found that macrocrack formation is more likely to occur in tissue adjacent to the cryoprobe surface (especially on the sharp point tip) and during the thawing phase of cryosurgery. Because the thermal stress adjacent to the cryoprobe is much higher than the yield stress of frozen renal tissue, a plastic stress model is required for better modeling of the thermal stress distribution in cryosurgery of kidney in future although the computational effort will be drastically increased due to the strong nonlinear nature of the plastic model and more studies are required to understand the mechanical properties of frozen tissue.

Original languageEnglish (US)
Article numberIMECE2004-62164
Pages (from-to)803-809
Number of pages7
JournalAmerican Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD
Volume375
Issue number1
DOIs
StatePublished - Jan 1 2004

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Cryosurgery
Thermal stress
Tissue
Capsules
Stress concentration
Plastics
Mechanical properties
Thawing
Ice
Microcracks
Thermal expansion
Yield stress
Plastic deformation
Mechanics
Thermodynamic properties
Physics
Temperature
Water

Cite this

Analysis of thermal stress in cryosurgery of kidneys. / He, Xiaoming; Bischof, John C.

In: American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD, Vol. 375, No. 1, IMECE2004-62164, 01.01.2004, p. 803-809.

Research output: Contribution to journalArticle

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