NEUROTHERM RADIO FREQUENCY LESION GENERATOR
10-16
MODEL NT1100
®
OPERATORS MANUAL
Document 109.00
10September2012 Issue 06
Typical heat lesion sizes
Typical lesion sizes are categorized below in figures 10.11, 10.12, and 10.13, for different tip
temperatures, tip exposures and needle gauges. Though lesion size can vary considerably
depending on tissue electrical and thermal conductivity, presence of heat sinking by blood, and
thermal insulation such as the presence of bone, some qualitative observations can be made. It
is clear that the lesion shape is that of prolate spheroid where the major axis is always along the
needle shaft, and whose length is virtually the length of the tip exposure. Note that the lesion
extends very little beyond the electrode tip thus indicating that a tangential approach to the target
is warranted. The minor axis becomes larger with increasing temperatures and electrode
diameters. Typical sizes for common needles and temperatures are given below. It is worth
noting that these sizes represent equilibrium volumes (greater than 60 second treatment). After
this time the lesion volume ceases to increase.
Figure 10.11
Figure 10.12
Figure 10.13