Figures & data
Figure 1. Phased array and spherical tumour models. The 1444 element spherical section array is centred at the origin, and the 3 cm diameter spherical tumour model is located 12 cm from the bottom of the array. A square grid of normal tissue control points in quadrant I is positioned between the array and the tumour model to reduce intervening tissue heating.
Figure 2. Simulated temperature (°C) in the y = 0 plane calculated in response to the power deposition obtained with waveform diversity and mode scanning before tumour control points are removed. The centre of the tumour model is located at z = 12 cm, and the 33 initial tumour control points are uniformly distributed throughout the 3 cm diameter tumour in quadrant I. The overall peak temperature in all bioheat transfer simulations is 43°C.
Figure 3. The 3 cm diameter spherical tumour volume and the 42°C isothermal surface calculated in response to the power deposition obtained with waveform diversity and mode scanning, where the initial 33 tumour control points are distributed uniformly throughout the spherical tumour volume in quadrant I. The 42°C isothermal surface, which covers only 16% of the tumour volume, is completely encompassed by the 3 cm diameter spherical tumour model, and no normal tissues are heated above 42°C.
Figure 5. The volume of the normal tissue that exceeds 42°C plotted with respect to the number of tumour control points. When tumour control points are initially removed, the heated normal tissue volume remains small. As additional tumour control points are removed, the heated normal tissue volume increases until the maximum value is reached at 12 tumour control points.
Figure 6. Simulated temperature (°C) in the y = 0 plane calculated from the power deposition obtained with waveform diversity and mode scanning using the 13 optimal tumour control points in quadrant I. This result corresponds to the largest value of the tumour volume heated above 42°C in .
Figure 4. The volume of the tumour that exceeds 42°C plotted with respect to the number of tumour control points. The heated tumour volume obtained with the initial tumour control point distribution is indicated on the far right. As tumour control points are removed, the heated tumour volume increases until the maximum size of the heated tumour volume is achieved with 13 tumour control points.
Figure 7. The 3 cm diameter tumour volume and the 42°C isothermal surface calculated in response to the power deposition obtained with waveform diversity and mode scanning, where the 13 optimal tumour control points are distributed on the back edge of the tumour and laterally about the tumour periphery in quadrant I. The 42°C isothermal surface covers 79% of the 3 cm diameter tumour, and normal tissue heating is observed along the near and far edges of the tumour relative to the centre of the array.
Figure 8. Distribution of tumour control points in quadrant I within the 3 cm diameter spherical tumour model. The points that were removed from the initial control point distribution are indicated by a solid triangle (▾), the 13 optimal points that were retained are represented by a solid square (▪), and the representative point r0 is indicated by a solid circle (•). To maximise 42°C tumour coverage, the tumour control points are located on the far edge of the tumour and laterally around the periphery of the spherical tumour model.
