Heat generation and transfer behaviors of ti-coated carbon steel rod adaptable for ablation therapy of oral cancer

Abstract

For the purpose of developing a novel ablation therapy for oral cancer, the heat generation and transfer properties of a Ti-coated carbon steel rod with 20-mm length and 1.8-mm outer diameter were investigated by means of a high-frequency induction technique at 300 kHz. The heat generation measurement performed using water (15 mL) revealed that the difference of the inclination angles (θ = 0°, 45° and 90°) relative to the magnetic flux direction only slightly affects the heating behavior, exhibiting the overlapped temperature curves during an induction time of 1200 s. These results suggest that the effect of the shape magnetic anisotropy is almost eliminated, being convenient for the precise control of the ablation temperature in clinical use. In the experiments utilizing a tissue-mimicking phantom, the heat transfer concentrically occurred in the lateral direction for both the planar surface and a 10-mm deep cross-section. However, the former exhibited a considerably lower increase in temperature (ΔT), probably due to the effect of heat dissipation to the ambient air. No significant heat transfer was found to occur to the lower side of the inserted Ti-coated carbon steel rod, which is situated in the longitudinal direction.

Figure 1

Partial experimental set up showing the specimen placed in a high-frequency induction coil to measure the heating behaviors (a) in water (15 mL) and (b) tissue-mimicking phantom at different inclination angles relative to the magnetic flux direction.

Figure 2

Complete experimental setup for measuring the heat transfer behavior of the tissue-mimicking phantom subjected to the insertion of the Ti-coated carbon steel rod in the high-frequency induction field of 1.69 kA/m at 300 kHz.

Figure 3

(a) Three-dimensional; (b) and two-dimensional schematic views of the cylindrical tissue-mimicking phantom subjected to the insertion of the Ti-coated carbon steel rod. The temperature measuring points are denoted by the red circles.

Figure 4

Computer simulation model of heat transfer drawn (a) three-dimensionally; (b) and two-dimensionally, used in the present study.

Figure 5

Changes in temperature of water (15 mL) for the Ti-coated carbon steel rod at different inclination angles relative to the magnetic flux direction versus the induction time in the high-frequency induction field of 1.69 kA/m at 300 kHz.

Figure 6

Changes in temperature of the tissue-mimicking phantom with different distances from the contact position vs. the induction time at the 10-mm deep cross-section.

Figure 7

Changes in temperature of the tissue-mimicking phantom obtained at the planar surface and the 10-mm deep cross-section after 1,200 s vs. the distance from the contact position.

Figure 8

Heat transfer simulation images showing the temperature distribution at (a) 0 s and (b) after 1,200 s in the longitudinal section of the tissue-mimicking phantom.

Figure 9

Heat transfer simulation images showing the temperature distribution at (a) 0 s and (b) after 1,200 s in the 10-mm deep cross-section of the tissue-mimicking phantom.