CT-resolution regional hyperthermia treatment planning

Abstract

Recent development of quasistatic zooming has enabled the computation of mm-resolution SAR distributions within reasonable computation times. These high-resolution SAR distributions proved to be completely dissimilar from the cm-resolution distributions. To study the impact of high-resolution SAR modelling on regional hyperthermia treatment planning (HTP), a conventional, low-resolution treatment plan is compared to an high-resolution plan. This comparison shows that the high-resolution plan yields totally different SAR and temperature distributions when compared to the conventional plan. Both SAR and temperature maxima predicted by the low-resolution plan are not predicted by the high-resolution plan and, even worse, the low-resolution plan fails to predict maxima that are predicted by the high-resolution plan. Furthermore, it appears that small-scale SAR maxima can result in temperature maxima which may cause treatment-limiting hot spots. These small-scale SAR maxima appear to be highly determined by the dielectric geometry of the patient. This demonstrates the need for an accurate, high-resolution description of this dielectric geometry. Moreover, it suggests that it may be very difficult to reduce potential treatment-limiting hot spots in clinical practice. This study demonstrates the need for high-resolution regional hyperthermia treatment planning.