Biomedical Engineering Reference
In-Depth Information
Figure 15.
An example of computing shift distance.
5.3.3. Area difference
(
A
d
)
The area difference is used to compare tumor areas between two images, so
that for each breast case the area difference is defined as
Area
I
k
−
Area
I
j
1
N
s
−
1
×
100%
,
A
d
=
(17)
(
k,j
)
where Area
I
k
is the size of the tumor in image
I
k
.
5.3.4. Solidity (
S
o
)
Shape values can be used to distinguish between benign andmalignant tumors.
Benign tumors usually have smooth shapes, whereas malignant tumors tend to be
irregular. The normalized solidity value (see Russ [44]) was used in this study,
and is defined as
Area
C
−
Area
T
sol =
,
(18)
N
s
(Area
C
(
I
k
)
−
Area
T
(
I
k
))
{k}
where Area
C
is the area of the convex hull of a tumor, and Area
T
is the area of
the tumor, as shown in Figure 16.
