Biomedical Engineering Reference
In-Depth Information
segmented hand bone radiograph is crucial. A metric that is used to measure the
extent of this agreement expresses the discrepancy level of bones number.
1
1
+ γ |
n
S
−
n
A
|
δ
F R AG
=
(4.10)
where
N
S
denotes the number of bones in segmented hand bone radiograph,
n
A
denotes
the number of bones in actual hand bone radiograph,
α
denotes the parameter
γ
that
determines the impact of small discrepancy between
n
S
and
n
A
whereas the parameter
δ
determines the impact of large discrepancy between
n
S
and
n
A
.
If a portion of bone is
missing, the observer has to decide visually whether the bone has more than 70 % of the
desired region of actual bone to consider that it has been segmented.
Eight hand bone radiographs from each age group ranging from 0 to 18 in dataset
have been tested in which two radiographs are chosen from each population of four
populations in each age group with different gender. Therefore, the experiment com-
prised of 144 radiographs in dataset. This experiment adopted the mean value of 3
metrics above to quantitatively approximate the evaluation of the segmentation accu-
racy with appropriate fixed parameters values:
ω =
0. 8
if the edge pixels in actual
image are belong to ossification sites, else
ω =
1
; α =
0. 8
; β =
0. 9
if the pixels
are belong to ossification sites, else
α =
0.6,
β =
0.8
; γ =
0.9
; δ =
1
if the regions
of b
ones are
belong
to o
ssiicati
on sites, else
γ =
0.3
; δ =
0.5.
The values of 3 met-
rics,
FOM
,
FOC
and
F R AG
are computed as follows:
M
j
N
1
NM
j
1
1
+ ω[
E
(
i
,
j
)]
,
FOM
=
j
=
1,2,3
...
18
(4.11)
j
=
1
i
=
1
where
M
j
denotes the total number of radiographs in
j
th age group;
E
(
i
,
m
j
)
denotes distance between the
i
ith detected edge pixel with its according actual spa-
tial location of radiograph from
j
th age group.
M
j
N
1
NM
j
1
1
+ α |
R
(
i
,
j
) −
S
(
i
,
j
)|
β
FOC
=
(4.12)
j
=
0
i
=
1
where
M
j
denotes the total number of radiographs in
j
th age group;
R
(
i
,
j
)
denotes
the
i
ith actual pixel grey level intensity of radiograph from
j
th age group;
S
(
i
,
j
)
denotes the
i
ith segmented pixel grey level intensity of radiograph from
j
th age
group.
M
j
1
1
+ γ |
n
S
(
j
) −
n
A
(
j
)|
δ
F R AG
=
(4.13)
j
=
1
where
M
j
denotes the total number of radiographs in
j
th age group; where
n
S
(
j
)
denotes the number of bones in segmented hand bone radiograph of
j
th age group,
n
A
(
j
)
denotes the number of bones in actual hand bone radiograph of
j
th age
group.
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