RF MODULE

1 Click the Plot Parameters button on the Main toolbar.
2 Click the Surface tab. From the Unit list select o C, then click Apply.
The following steps describe how to visualize the resistive heating of the tissue:
1 In the Predefined quantities list select TM Waves (rfwh)>Resistive heating, time
average. In the Unit edit field type W/cm^3, then click Apply.
Heating decreases rapidly in the liver tissue, resulting in an almost uniformly blue
plot. To get a better feeling for the heating at a distance from the antenna, do as
follows:
2 In the Expression edit field type min(Qav_rfwh,1[W/cm^3]), then click OK.
In the resulting plot, which reproduces that in Figure 3-23, the region around the
antenna in which the time-averaged resistive heating exceeds 1 W/cm 3 has a
uniform, deep red color. Outside this region, you can read off the heating
distribution from the color legend on the right.
To compute the total heating power deposited in the liver, follow these steps:
1 From the Postprocessing menu open the Subdomain Integration dialog box.
2 Select Subdomain 1. From the Predefined quantities list select
TM Waves (rfwh)>Resistive heating, time average.
3 Select the Compute volume integral (for axisymmetric modes) check box. Click OK.
The result appears in the message log at the bottom of the user interface. The value
of approximately 9.37 W indicates that the tissue absorbs most of the 10 W input
power at stationary conditions.
These steps reproduce the plot in Figure 3-24, displaying the normalized SAR value:
1 From the Postprocessing menu open the Cross-Section Plot Parameters dialog box.
2 On the Line/Extrusion page, type Qav_rfwh/3.01[W/cm^3] in the Expression edit
field. In both the r0 and r1 edit fields type 2.5e-3; in the z0 edit field type 0.08;
and in the z1 edit field type 0.
3 Click the General tab, then click the Title/Axis button. In the Title/Axis Settings dialog
box, select the option button next to the Title edit field, then enter the title
Off-axis SAR values (distance = 2.5 mm).
4 In a similar way, enter the first axis label Insertion depth [m] and the second axis
label SAR (normalized), then click OK to close the Title/Axis Settings dialog box.
5 Click OK to generate the plot.
MICROWAVE CANCER THERAPY | 141