Development of a new mini-invasive tumour hyperthermia probe using high-temperature water vapour

Abstract

A new mini-invasive hyperthermia probe using high-temperature water vapour for deep regional tumour treatment was developed in this paper. The vacuum insulation mechanism was incorporated into the probe to avoid heating damage to the normal tissues around the edge of the insertion path. To better understand the heat transfer behaviour in living tissues due to operation of the probe, theoretical models based on the Pennes' equation were established and two closed form analytical solutions under constant flux or temperature heating at the tip of probe were obtained. Parametric studies were performed to investigate the influence of various parameters on the temperature response of tissues heated by the probe. Further, several simulating experiments on the actual heating performance of the probe fabricated in this paper were conducted on the in vitro biological materials (fresh pork) and phantom gel. It was demonstrated that the probe can cause a high enough temperature over the treatment area to thermally destroy the tumour tissue in due time, while the temperature over the surrounding healthy tissues can be kept below a safe threshold value. This mini-invasive heating probe may have significant applications in future clinical tumour hyperthermia.

Nomenclature

R₀ Radius of the probe (m); C Specific heat of tissue (J kg⁻¹°C); k Thermal conductivity of tissue (W m⁻¹°C); W_b Blood perfusion (kg m⁻³ s); W Transformed temperature (°C); C_b Specific heat of blood (J kg⁻¹°C); Q_m Metabolic rate of tissue (W m⁻³); T_a Artery temperature (°C); T_p Constant temperature at the tip of probe (°C); T_c Body core temperature (°C); T Tissue temperature (°C); q₀ Constant heat flux at the tip of probe (W m⁻²); r,r’ Radial positions (m); t,τ Time (s); C₁,C₂ Constant

Greek letters

ρ Density of tissue (kg m⁻³); α Thermal diffusion (m² s⁻¹); β Constant; θ Transformed temperature (°C)

Subscripts

a Artery; b Blood; c Constant; m Metabolism; p Probe

Nomenclature

R₀ Radius of the probe (m); C Specific heat of tissue (J kg⁻¹°C); k Thermal conductivity of tissue (W m⁻¹°C); W_b Blood perfusion (kg m⁻³ s); W Transformed temperature (°C); C_b Specific heat of blood (J kg⁻¹°C); Q_m Metabolic rate of tissue (W m⁻³); T_a Artery temperature (°C); T_p Constant temperature at the tip of probe (°C); T_c Body core temperature (°C); T Tissue temperature (°C); q₀ Constant heat flux at the tip of probe (W m⁻²); r,r’ Radial positions (m); t,τ Time (s); C₁,C₂ Constant

Greek letters

ρ Density of tissue (kg m⁻³); α Thermal diffusion (m² s⁻¹); β Constant; θ Transformed temperature (°C)

Subscripts

a Artery; b Blood; c Constant; m Metabolism; p Probe