<s>
Dual	B-Algorithm
X-ray	I-Algorithm
absorptiometry	I-Algorithm
and	I-Algorithm
laser	I-Algorithm
technique	O
(	O
DXL	O
)	O
in	O
the	O
area	O
of	O
bone	O
density	O
studies	O
for	O
osteoporosis	O
assessment	O
is	O
an	O
improvement	O
to	O
the	O
DXA	B-Algorithm
Technique	I-Algorithm
,	O
adding	O
an	O
exact	O
laser	O
measurement	O
of	O
the	O
thickness	O
of	O
the	O
region	O
scanned	O
.	O
</s>
<s>
The	O
addition	O
of	O
object	O
thickness	O
adds	O
a	O
third	O
input	O
to	O
the	O
two	O
x-ray	B-Library
energies	O
used	O
by	O
DXA	B-Algorithm
,	O
better	O
solving	O
the	O
equation	O
for	O
bone	O
and	O
excluding	O
more	O
efficiently	O
these	O
soft	O
tissues	O
components	O
.	O
</s>
<s>
These	O
different	O
components	O
have	O
different	O
x-ray	B-Library
attenuating	I-Library
properties	O
.	O
</s>
<s>
The	O
standard	O
in	O
bone	O
mineral	O
density	O
scanning	O
developed	O
in	O
the	O
1980s	O
is	O
called	O
Dual	B-Algorithm
X-ray	I-Algorithm
Absorptiometry	I-Algorithm
,	O
known	O
as	O
DXA	B-Algorithm
.	O
</s>
<s>
The	O
DXA	B-Algorithm
technique	I-Algorithm
uses	O
two	O
different	O
x-ray	B-Library
energy	O
levels	O
to	O
estimate	O
bone	O
density	O
.	O
</s>
<s>
DXA	B-Algorithm
scans	I-Algorithm
assume	O
a	O
constant	O
relationship	O
between	O
the	O
amounts	O
of	O
lean	O
soft	O
tissue	O
and	O
adipose	O
tissue	O
.	O
</s>
<s>
To	O
reduce	O
soft-tissue	O
errors	O
in	O
DXA	B-Algorithm
,	O
DXL	O
technology	O
was	O
developed	O
in	O
the	O
late	O
1990s	O
by	O
a	O
team	O
of	O
Swedish	O
researchers	O
led	O
by	O
Prof	O
.	O
Ragnar	O
Kullenberg	O
.	O
</s>
<s>
With	O
DXL	O
technology	O
,	O
the	O
region	B-Algorithm
of	I-Algorithm
interest	I-Algorithm
is	O
scanned	O
using	O
low	O
and	O
high	O
energy	O
x-rays	B-Library
as	O
with	O
a	O
DXA	B-Algorithm
scan	I-Algorithm
.	O
</s>
<s>
The	O
improvement	O
to	O
DXA	B-Algorithm
with	O
DXL	O
is	O
that	O
,	O
for	O
each	O
pixel	O
scanned	O
by	O
DXA	B-Algorithm
,	O
the	O
exact	O
thickness	O
of	O
the	O
measured	O
object	O
is	O
also	O
measured	O
using	O
lasers	O
.	O
</s>
<s>
The	O
DXL	O
results	O
allow	O
for	O
a	O
more	O
accurate	O
estimation	O
of	O
bone	O
density	O
by	O
using	O
three	O
separate	O
inputs	O
(	O
low	O
and	O
high	O
x-ray	B-Library
energies	O
plus	O
thickness	O
)	O
rather	O
than	O
two	O
for	O
each	O
pixel	O
in	O
the	O
measuring	O
region	O
.	O
</s>
<s>
N1	O
and	O
N2	O
are	O
the	O
detected	O
x-ray	B-Library
counts	O
after	O
passing	O
through	O
the	O
region	B-Algorithm
of	I-Algorithm
interest	I-Algorithm
.	O
</s>
<s>
N01	O
and	O
N02	O
are	O
the	O
detected	O
x-ray	B-Library
counts	O
taken	O
from	O
the	O
internal	O
phantom	O
.	O
</s>
<s>
νb1	O
,	O
νs1	O
and	O
νf1	O
are	O
the	O
x-ray	B-Library
attenuation	O
coefficients	O
for	O
each	O
component	O
at	O
the	O
low	O
x-ray	B-Library
energy	O
level	O
.	O
</s>
<s>
νb2	O
,	O
νs2	O
and	O
νf2	O
are	O
the	O
x-ray	B-Library
attenuation	O
coefficients	O
for	O
each	O
component	O
at	O
the	O
high	O
x-ray	B-Library
energy	O
level	O
.	O
</s>
<s>
The	O
DXL	O
technique	O
is	O
used	O
in	O
the	O
bone	B-Algorithm
densitometry	I-Algorithm
system	O
DXL	B-Algorithm
Calscan	I-Algorithm
,	O
manufactured	O
and	O
marketed	O
by	O
the	O
company	O
Demetech	O
AB	O
,	O
Täby	O
,	O
Sweden	O
.	O
</s>
<s>
Many	O
published	O
studies	O
have	O
evaluated	O
the	O
DXL	O
technique	O
using	O
the	O
DXL	B-Algorithm
Calscan	I-Algorithm
system	O
,	O
which	O
scans	O
the	O
subject	O
's	O
heel	O
.	O
</s>
<s>
Several	O
published	O
fracture	O
studies	O
have	O
shown	O
that	O
heel	O
scans	O
using	O
DXL	B-Algorithm
Calscan	I-Algorithm
have	O
an	O
ability	O
to	O
predict	O
fractures	O
as	O
well	O
or	O
better	O
than	O
the	O
DXA	B-Algorithm
technique	I-Algorithm
scanning	O
the	O
hip	O
.	O
</s>
