Experimental and Numerical Study on the Temperature Elevation in Tissue during Moxibustion Therapy

Abstract

Moxibustion is a thermal therapy in traditional Chinese medicine that relies on the heat from burning moxa to be transferred beneath the skin surface. Although moxibustion has long been in widespread practice, the mechanism of heat transfer modality and temperature distribution during this treatment is not yet well understood. The current paper presents the first examination by magnetic resonance imaging (MRI) of the three-dimensional temperature elevation during moxibustion treatment. A mathematical model for the prediction of temperature elevation during moxibustion therapy has been constructed and compared with the experimental data. Good agreement between the measured temperature and the results of numerical calculations has been found. Tissue up to 3 cm deep can be heated during the treatment. It was revealed that both heat conduction and radiation heat transfer play important roles during the treatment. The results presented in the current paper can be used for understanding the mechanisms of Chinese medicine and developing useful guidelines for Chinese medicine doctors.

Figure 1

(a) Schematic of the treatment; (b) cross section of the moxa and dimensions of the moxa stick. ∗ denotes the location of a thermocouple during the temperature measurements of air.

Figure 2

Temperature as a function of time at the heating position on the pork surface: (a) p1 curve fitting data; (b) the temperature curves fitted from experimental data by the least squares method.

Figure 3

(a) Temperature at two points, as measured by thermocouples during moxibustion treatment without ash cleaning; (b) location of the two points where the temperature was measured.

Figure 4

The measured (MRI) and computed temperature profiles in pork along the y-axis at time t = 1755 sec. (a) Only heat conduction has been considered in the simulations; (b) both heat conduction and radiation were considered during the modeling of moxibustion.

Figure 5

The measured and predicted temperatures at monitoring points in in vitro tissue (a) as the function of time at different depths, h = 0, h = 0.002 m, and h = 0.006 m, and (b) as the function of depth at t = 20 min, 25 min, and 30 min.

Figure 6

The measured temperature profiles in pork at the plane perpendicular to the surface at different time intervals: (a) t = 0 sec; (b) t = 1200 sec; (c) t = 1500 sec; (d) t = 1755 sec.

Figure 7

The (a) measured and (b) simulated temperature profiles in pork at the plane perpendicular to the surface at time t = 1755 sec.

Figure 8

The simulated temperature distribution in porcine muscle at different time intervals: (a) t = 600 sec; (b) t = 1200 sec; (c) t = 1500 sec; (d) t = 1755 sec.

Figure 9

The measured temperature of air between the moxa and pork with and without ash cleaning. The locations of the points at which the temperature measurements were performed can be seen in Figure 1.