<s>
Single	B-Algorithm
photon	I-Algorithm
absorptiometry	I-Algorithm
is	O
a	O
measuring	O
method	O
for	O
bone	O
density	O
invented	O
by	O
John	O
R	O
.	O
Cameron	O
and	O
James	O
A	O
.	O
Sorenson	O
in	O
1963	O
.	O
</s>
<s>
Single	B-Algorithm
photon	I-Algorithm
absorptiometry	I-Algorithm
(	O
SPA	O
)	O
was	O
developed	O
in	O
1963	O
by	O
Steichen	O
et	O
al	O
.	O
</s>
<s>
The	O
expensive	O
and	O
potentially	O
dangerous	O
radioactive	O
sources	O
used	O
in	O
SPA	O
and	O
DPA	O
have	O
been	O
replaced	O
by	O
single	O
X-ray	O
absorptiometry	O
(	O
SXA	O
)	O
and	O
dual-energy	B-Algorithm
X-ray	I-Algorithm
absorptiometry	I-Algorithm
(	O
DXA	B-Algorithm
)	O
since	O
the	O
late	O
1980s	O
.	O
</s>
<s>
Similar	O
to	O
DPA	O
,	O
the	O
basic	O
principle	O
of	O
DXA	B-Algorithm
is	O
to	O
measure	O
the	O
high	O
and	O
low	O
energy	O
X-ray	O
transmission	O
of	O
stable	O
X-ray	O
sources	O
.	O
</s>
<s>
With	O
the	O
increasing	O
popularity	O
of	O
DXA	B-Algorithm
,	O
its	O
application	O
in	O
pediatric	O
research	O
and	O
clinical	O
practice	O
has	O
increased	O
significantly	O
.	O
</s>
<s>
In	O
the	O
past	O
10	O
years	O
,	O
measuring	O
forearm	O
bone	O
mass	O
by	O
single	B-Algorithm
photon	I-Algorithm
absorptiometry	I-Algorithm
measurement	O
has	O
become	O
one	O
of	O
the	O
most	O
widely	O
used	O
methods	O
for	O
evaluating	O
cortical	O
bone	O
.	O
</s>
<s>
Single	B-Algorithm
photon	I-Algorithm
absorptiometry	I-Algorithm
is	O
the	O
first	O
quantitative	O
analysis	O
method	O
used	O
in	O
the	O
diagnosis	O
of	O
osteoporosis	O
.	O
</s>
<s>
These	O
125I-based	O
instruments	O
(	O
now	O
known	O
as	O
single	B-Algorithm
photon	I-Algorithm
absorptiometry	I-Algorithm
)	O
have	O
been	O
widely	O
used	O
for	O
many	O
years	O
,	O
and	O
their	O
medical	O
applications	O
have	O
been	O
well	O
established	O
.	O
</s>
<s>
The	O
US	O
multicenter	O
trial	O
showed	O
that	O
SPA	O
forearm	O
measurements	O
were	O
as	O
good	O
as	O
SPA	O
heel	O
or	O
dual-energy	B-Algorithm
X-ray	I-Algorithm
absorptiometry	I-Algorithm
(	O
DEXA	B-Algorithm
)	O
spine	O
or	O
hip	O
measurements	O
and	O
could	O
be	O
used	O
to	O
predict	O
future	O
overall	O
fractures	O
in	O
elder	O
women	O
.	O
</s>
<s>
The	O
amount	O
of	O
bone	O
mineral	O
content	O
,	O
bone	O
structure	O
,	O
and	O
bone	O
strength	O
can	O
be	O
reflected	O
better	O
by	O
velocity	O
and	O
amplitude	O
attenuation	O
and	O
has	O
a	O
good	O
correlation	O
with	O
DEXA	B-Algorithm
.	O
</s>
