normal segment at a certain point A on the envelope
surface. By analogy, taking all the points on the tumor
envelope as the starting point, each point on the
envelope surface is made perpendicular to the normal
segment of the tangent plane Σi at the point, the length
of the normal segment is set as 1cm per unit length,
and finally a new convex surface composed of the end
point of the unit length normal segment is obtained,
so that the new convex surface is defined as a tangent
edge surface 1cm away from the tumor outer network,
and its principle is regarded as the uniform expansion
deformation of the tumor model. In summary, the
outward expansion deformation is based on all the
points on the envelope surface, and the convex
surface that expands and deforms by 1 cm is defined
as the tangent edge surface of the tumor. The distance
from any point on the cut edge surface to the tumor
should be no less than 1 cm, as shown in Fig. 2(a).
Finally, based on the envelope surface isometric
expansion to obtain a plurality of convex surfaces,
consisting of a plurality of progressively deformed
and expanded convex surfaces of the field, we define
it as the margin field of the tumor, wherein the
interval between each surface of the margin field is 1
cm, as shown in Figure 2 (b), the distance from the
above-mentioned cut edge surface to the tumor
surface contour is 1 cm, the cut edge surface is the
tumor 1 cm margin field.
(a) (b) (c)
Figure 2: The outer contour surface, envelope surface, and marginal field of the tumor.
3.2 Distance Calculation Application
Between Scalpel and Tumor Based
on Margin Margin Field
In the future minimally invasive liver tumor resection,
robot technology will be continuously introduced for
the requirements of accurate removal of liver tumors,
and under the motion simulation model based on
robot surgical action, the definition and visualization
of the margin field provide the robot with distance
parameters to know the distance d of the scalpel and
the tumor boundary. According to the distance
between the margin field and the envelope surface, it
is named, as shown in Fig. 2(c). Such as 1cm margin
field, 2cm margin field and 3cm margin field, etc.
Assuming that the scalpel head is located between the
2cm to 3cm margin field in the simulation model of
robot motion, it is obvious that the distance from the
scalpel head to the tumor is 2 to 3cm. In summary, the
definition of marginal field can be used in future
robotic minimally invasive surgery to measure the
distance between the scalpel and the intrahepatic
tumor, providing auxiliary guidance for physicians
when removing the tumor during surgery, and
avoiding the risk of surgery caused by the scalpel
touching the tumor.
3.3
Establishment System for Marginal
Fields
Fig. 3 Further provides an establishing module for
tumor margin margin field, comprising: establishing
module 1, determining module 2, envelope creation
module 3 and determining module 4. Wherein, the
establishment of module 1 for obtaining the patient's
imaging data, through the three-dimensional
reconstruction of the body data to obtain a model of
the relative position relationship between the tissues;
judgment module 2, for calling the relative position
information between the tumor and other tissues to
determine the resectability of the tumor, if yes
(intrahepatic tumor has resectability), into the
envelope creation module 3, if not, end; the envelope
creation module is used to establish an envelope
surface according to the external contour information
of the tumor surface, the envelope surface is the
convex envelope of the tumor; determine module 4, It
is used to determine the tumor 1 cm margin and
margin
field based on the envelope surface of the