Numerical study on thermal field of microwave ablation with water-cooled antenna

Figures & data

Figure 1. Ablation antenna geometry.

Figure 2. Antenna and thermocouple (TC) in the phantom.

Table I.  Fitted coefficients of Equation 2.

a	b	c	d	e
14.23	0.05	0.19	−0.28	0.53

Figure 3. Geometric modeling. A coaxial slot antenna was inserted in the phantom along the z-axis. The radius of the antenna was 0.95 mm. The dimension was directly labeled and every boundary condition was named as L1 ∼ L5.

Table II.  N_u and h of the different velocities.

Cooling water velocity(m/s)	Nu	h(W/m^2°C)
0.22	5.935	1876
0.44	7.682	2430
0.66	8.665	2741

Table III.  Phantom ingredients (%).

Carboxymethyl cellulose sodium	Polyethylene	Water	Sodium chloride
3.5	27.15	69	0.35

Table IV.  Physical parameters of the phantom.

Temperature (°C)	Specific heat (J/kg°C)	Thermal conductivity (W/m°C)
20–70	3700	0.535
80	2413	0.607
90	2597	0.653
100	2852	0.682
110	3454	0.868
120	4043	1.017
130	28444	6.311
140	6762	1.499

Figure 4. Transient temperatures for monitoring points 3, 4, 5, 12 in the simulation.

Figure 5. Ablation pattern at 54°C in the simulation.

Figure 6. Transient temperatures for monitoring points 3 (A), 4 (B), 5 (C), 12 (D).

Table V.  R-sq between simulation and experiment.

Monitoring point	3	4	5	12
R-sq value	94.4 %	95.3 %	96.7 %	97.6 %

Figure 7. Ablation patterns at 54°C contours in the simulation (A) and the experiment (B).

Table VI.  Comparison of the coagulation region.

Energy	Ablation pattern of experiment (r × z) mm	Thermal field of simulation (r × z) mm
60 W 120 s	11.8 × 28.8	11.4 × 29.3

Figure 8. Ablation lesions (54°C contours) at 60 W and 120 s in the simulation (A) and experiment (B) at the cooling water velocity of 0.22 m/s, 0.44 m/s, 0.66 m/s.

Figure 9. Comparison of numerical results (original parameters and revised parameters) with experimental results at the flow velocity of 0.22 m/s (monitoring point 3)).