<s>
In	O
radiography	O
,	O
focal	B-Algorithm
plane	I-Algorithm
tomography	I-Algorithm
is	O
tomography	B-Algorithm
(	O
imaging	O
a	O
single	O
plane	O
,	O
or	O
slice	O
,	O
of	O
an	O
object	O
)	O
by	O
simultaneously	O
moving	O
the	O
X-ray	B-Library
generator	O
and	O
X-ray	B-Algorithm
detector	I-Algorithm
so	O
as	O
to	O
keep	O
a	O
consistent	O
exposure	O
of	O
only	O
the	O
plane	O
of	O
interest	O
during	O
image	O
acquisition	O
.	O
</s>
<s>
This	O
was	O
the	O
main	O
method	O
of	O
obtaining	O
tomographs	B-Algorithm
in	O
medical	B-Application
imaging	I-Application
until	O
the	O
late-1970s	O
.	O
</s>
<s>
Focal	B-Algorithm
plane	I-Algorithm
tomography	I-Algorithm
’s	O
development	O
began	O
in	O
the	O
1930s	O
as	O
a	O
means	O
of	O
reducing	O
the	O
problem	O
of	O
superimposition	O
of	O
structures	O
which	O
is	O
inherent	O
to	O
projectional	O
radiography	O
.	O
</s>
<s>
Focal	B-Algorithm
plane	I-Algorithm
tomography	I-Algorithm
generally	O
uses	O
mechanical	O
movement	O
of	O
an	O
X-ray	B-Library
source	O
and	O
film	O
in	O
unison	O
to	O
generate	O
a	O
tomogram	B-Algorithm
using	O
the	O
principles	O
of	O
projective	O
geometry	O
.	O
</s>
<s>
The	O
blurring	O
provided	O
by	O
focal	B-Algorithm
plane	I-Algorithm
tomography	I-Algorithm
is	O
only	O
marginally	O
effective	O
,	O
since	O
it	O
only	O
occurs	O
in	O
the	O
X	O
plane	O
.	O
</s>
<s>
Moreover	O
,	O
since	O
focal	B-Algorithm
plane	I-Algorithm
tomography	I-Algorithm
uses	O
plain	O
X-rays	B-Library
,	O
it	O
is	O
not	O
particularly	O
effective	O
at	O
resolving	O
soft	O
tissues	O
.	O
</s>
<s>
The	O
increased	O
availability	O
and	O
power	O
of	O
computers	O
in	O
the	O
1960s	O
and	O
70s	O
gave	O
rise	O
to	O
new	O
imaging	O
techniques	O
such	O
as	O
CT	O
and	O
MRI	O
which	O
use	O
computational	O
(	O
in	O
addition	O
to	O
or	O
in	O
lieu	O
of	O
mechanical	O
)	O
methods	O
to	O
acquire	O
and	O
process	O
tomographic	B-Algorithm
image	O
data	O
,	O
and	O
which	O
do	O
not	O
suffer	O
from	O
the	O
limitations	O
of	O
focal	B-Algorithm
plane	I-Algorithm
tomography	I-Algorithm
.	O
</s>
<s>
Initially	O
focal	B-Algorithm
plane	I-Algorithm
tomography	I-Algorithm
used	O
simple	O
linear	O
movements	O
.	O
</s>
<s>
This	O
is	O
the	O
most	O
basic	O
form	O
of	O
conventional	O
tomography	B-Algorithm
.	O
</s>
<s>
The	O
X-ray	B-Library
tube	O
moved	O
from	O
point	O
"	O
A	O
"	O
to	O
point	O
"	O
B	O
"	O
above	O
the	O
patient	O
,	O
while	O
the	O
detector	O
(	O
such	O
as	O
cassette	O
holder	O
or	O
"	O
bucky	O
"	O
)	O
moves	O
simultaneously	O
under	O
the	O
patient	O
from	O
point	O
"	O
B	O
"	O
to	O
point	O
"	O
A	O
"	O
.	O
</s>
<s>
Rarely	O
used	O
,	O
and	O
has	O
largely	O
been	O
replaced	O
by	O
computed	O
tomography	B-Algorithm
(	O
CT	O
)	O
.	O
</s>
<s>
This	O
was	O
achieved	O
using	O
a	O
more	O
advanced	O
X-ray	B-Library
apparatus	O
that	O
allows	O
for	O
more	O
sophisticated	O
and	O
continuous	O
movements	O
of	O
the	O
X-ray	B-Library
tube	O
and	O
film	O
.	O
</s>
<s>
This	O
is	O
a	O
variant	O
of	O
linear	B-Algorithm
tomography	I-Algorithm
,	O
where	O
a	O
limited	O
arc	O
of	O
movement	O
is	O
used	O
,	O
resulting	O
in	O
less	O
blurring	O
than	O
linear	B-Algorithm
tomography	I-Algorithm
.	O
</s>
<s>
Panoramic	O
radiography	O
is	O
the	O
only	O
common	O
tomographic	B-Algorithm
examination	O
still	O
in	O
use	O
.	O
</s>
