<s>
A	O
Vendor	B-Algorithm
Neutral	I-Algorithm
Archive	I-Algorithm
(	O
VNA	O
)	O
is	O
a	O
medical	B-Application
imaging	I-Application
technology	O
in	O
which	O
images	O
and	O
documents	O
(	O
and	O
potentially	O
any	O
file	O
of	O
clinical	O
relevance	O
)	O
are	O
stored	O
(	O
archived	O
)	O
in	O
a	O
standard	O
format	O
with	O
a	O
standard	O
interface	O
,	O
such	O
that	O
they	O
can	O
be	O
accessed	O
in	O
a	O
vendor-neutral	O
manner	O
by	O
other	O
systems	O
.	O
</s>
<s>
This	O
terminology	O
is	O
used	O
as	O
distinct	O
from	O
a	O
traditional	O
Picture	B-Application
Archiving	I-Application
and	I-Application
Communications	I-Application
Systems	I-Application
(	O
PACS	B-Application
)	O
,	O
although	O
there	O
is	O
debate	O
about	O
where	O
the	O
boundary	O
between	O
a	O
VNA	O
and	O
a	O
PACS	B-Application
lies	O
along	O
the	O
continuum	O
of	O
their	O
common	O
features	O
.	O
</s>
<s>
The	O
simplest	O
definition	O
is	O
"	O
a	O
medical	O
device	O
that	O
stores	O
medical	B-Application
images	I-Application
in	O
a	O
standard	O
format	O
with	O
a	O
standard	O
interface	O
,	O
such	O
that	O
they	O
can	O
be	O
accessed	O
in	O
a	O
vendor-neutral	O
manner	O
by	O
other	O
systems	O
"	O
.	O
</s>
<s>
So-called	O
"	O
vendor	O
neutrality	O
"	O
is	O
implied	O
by	O
the	O
standard	O
format	O
and	O
interface	O
,	O
and	O
the	O
neutrality	O
is	O
with	O
respect	O
to	O
vendor-specific	O
devices	O
that	O
produce	O
or	O
consume	O
those	O
images	O
(	O
e.g.	O
,	O
for	O
display	O
,	O
distribution	O
or	O
analysis	O
,	O
with	O
or	O
without	O
specific	O
workflows	O
,	O
such	O
as	O
for	O
radiology	O
reporting	O
,	O
i.e.	O
,	O
a	O
PACS	B-Application
)	O
.	O
</s>
<s>
Traditionally	O
,	O
the	O
need	O
to	O
store	O
medical	B-Application
images	I-Application
has	O
been	O
most	O
common	O
in	O
the	O
radiology	O
and	O
nuclear	O
medicine	O
departments	O
,	O
and	O
has	O
been	O
implemented	O
in	O
the	O
form	O
of	O
sub-specialty	O
and	O
departmental	O
(	O
PACS	B-Application
)	O
,	O
which	O
have	O
combined	O
the	O
functions	O
of	O
image	O
management	O
and	O
image	O
archiving	O
into	O
a	O
single	O
solution	O
.	O
</s>
<s>
Whilst	O
such	O
systems	O
all	O
have	O
standard	O
interfaces	O
(	O
DICOM	B-Algorithm
and	O
IHE	O
)	O
for	O
ingestion	O
and	O
distribution	O
of	O
images	O
over	O
the	O
network	O
and	O
on	O
physical	O
media	O
(	O
like	O
CD	O
)	O
,	O
typically	O
the	O
workflow	O
and	O
optimal	O
performance	O
for	O
display	O
are	O
achieved	O
using	O
proprietary	O
software	O
and	O
protocols	O
.	O
</s>
<s>
Further	O
,	O
the	O
persistent	O
storage	O
"	O
inside	O
"	O
a	O
proprietary	O
PACS	B-Application
may	O
not	O
be	O
in	O
a	O
standard	O
form	O
,	O
the	O
PACS	B-Application
may	O
not	O
update	O
the	O
stored	O
files	O
with	O
the	O
latest	O
study	O
and	O
demographic	O
updates	O
and	O
annotations	O
stored	O
in	O
the	O
database	O
,	O
and	O
it	O
may	O
extend	O
,	O
abuse	O
or	O
depend	O
on	O
specific	O
standard	O
and	O
non-standard	O
(	O
private	O
)	O
DICOM	B-Algorithm
attributes	O
in	O
the	O
stored	O
files	O
.	O
</s>
<s>
Over	O
time	O
,	O
in	O
many	O
implementations	O
,	O
the	O
underlying	O
storage	O
infrastructure	O
has	O
been	O
"	O
factored	O
"	O
out	O
of	O
the	O
traditional	O
(	O
PACS	B-Application
)	O
at	O
the	O
hardware	O
and	O
file	O
system	O
(	O
DAS	B-General_Concept
,	O
NAS	B-Application
,	O
SAN	O
)	O
level	O
,	O
and	O
are	O
supplied	O
instead	O
by	O
non-domain-specific	O
computer	B-General_Concept
data	I-General_Concept
storage	I-General_Concept
vendors	O
.	O
</s>
<s>
A	O
complicating	O
factor	O
is	O
that	O
the	O
(	O
PACS	B-Application
)	O
offerings	O
are	O
in	O
a	O
constant	O
state	O
of	O
flux	O
with	O
respect	O
to	O
features	O
and	O
quality	O
of	O
service	O
,	O
and	O
traditionally	O
users	O
will	O
abandon	O
one	O
vendor	O
and	O
replace	O
their	O
product	O
with	O
another	O
's	O
every	O
3	O
–	O
5	O
years	O
.	O
</s>
<s>
An	O
alternative	O
term	O
for	O
a	O
VNA	O
is	O
a	O
"	O
PACS	B-Algorithm
Neutral	I-Algorithm
Archive	I-Algorithm
"	O
,	O
which	O
perhaps	O
better	O
conveys	O
the	O
original	O
intent	O
,	O
but	O
this	O
term	O
is	O
rarely	O
used	O
,	O
and	O
for	O
better	O
or	O
for	O
worse	O
,	O
VNA	O
has	O
become	O
the	O
buzzword	O
of	O
choice	O
amongst	O
customers	O
and	O
salesmen	O
.	O
</s>
<s>
From	O
the	O
early	O
days	O
of	O
PACS	B-Application
,	O
it	O
was	O
expected	O
that	O
standard	O
interoperability	O
boundaries	O
would	O
need	O
to	O
be	O
defined	O
.	O
</s>
<s>
The	O
ACR-NEMA	O
,	O
and	O
later	O
DICOM	B-Algorithm
,	O
standards	O
arose	O
to	O
address	O
not	O
only	O
the	O
need	O
for	O
a	O
standard	O
file	O
format	O
but	O
also	O
protocols	O
for	O
storage	O
of	O
images	O
from	O
acquisition	O
modalities	O
to	O
archives	O
,	O
and	O
to	O
query	O
and	O
retrieve	O
images	O
from	O
the	O
archive	O
.	O
</s>
<s>
The	O
first	O
DICOM	B-Algorithm
demonstrations	O
at	O
RSNA	O
beginning	O
in	O
1992	O
made	O
use	O
of	O
a	O
so-called	O
"	O
central	O
test	O
node	O
"	O
,	O
which	O
arguably	O
was	O
one	O
of	O
the	O
first	O
DICOM-based	O
vendor	B-Algorithm
neutral	I-Algorithm
archives	I-Algorithm
,	O
though	O
that	O
label	O
was	O
not	O
in	O
use	O
at	O
the	O
time	O
.	O
</s>
<s>
Homegrown	O
PACS	B-Application
or	O
mini-PACS	O
typically	O
described	O
the	O
archive	O
and	O
workstation	O
as	O
separate	O
entities	O
.	O
</s>
<s>
Many	O
,	O
but	O
not	O
all	O
,	O
monolithic	O
commercial	O
PACS	B-Application
continued	O
to	O
make	O
use	O
of	O
proprietary	O
protocols	O
between	O
their	O
integrated	O
workstations	O
and	O
archives	O
,	O
but	O
the	O
need	O
to	O
support	O
separate	O
third-party	O
workstations	O
for	O
specialized	O
work	O
,	O
such	O
as	O
3D	O
processing	O
and	O
radiotherapy	O
planning	O
,	O
was	O
always	O
recognized	O
,	O
and	O
implemented	O
using	O
the	O
DICOM	B-Algorithm
protocol	O
.	O
</s>
<s>
In	O
1998	O
,	O
Erickson	O
and	O
Hangiandreou	O
discussed	O
the	O
advantages	O
of	O
once	O
again	O
separating	O
the	O
archive	O
functionality	O
from	O
the	O
conventional	O
monolithic	O
PACS	B-Application
and	O
making	O
use	O
of	O
pre-fetching	O
to	O
populate	O
the	O
"	O
interpretation	O
storage	O
device	O
"	O
.	O
</s>
<s>
The	O
article	O
noted	O
some	O
of	O
the	O
practical	O
challenges	O
at	O
the	O
time	O
,	O
such	O
as	O
the	O
relative	O
inefficiency	O
of	O
doing	O
DICOM	B-Algorithm
queries	O
against	O
such	O
multiple	O
archives	O
and	O
separating	O
out	O
those	O
responses	O
relevant	O
for	O
pre-fetching	O
,	O
as	O
well	O
as	O
challenges	O
of	O
patient	O
identifiers	O
.	O
</s>
<s>
In	O
one	O
of	O
many	O
blog	O
entries	O
on	O
the	O
subject	O
,	O
Michael	O
Gray	O
makes	O
a	O
reference	O
to	O
an	O
early	O
description	O
of	O
the	O
concept	O
of	O
separating	O
the	O
front-end	O
clinical	O
applications	O
from	O
the	O
back-end	O
storage	O
function	O
,	O
in	O
an	O
article	O
by	O
Nadim	O
Daher	O
,	O
a	O
Medical	B-Application
Imaging	I-Application
Market	O
Analyst	O
at	O
Frost	O
&	O
Sullivan	O
.	O
</s>
<s>
A	O
long	O
running	O
Aunt	O
Minnie	O
PACS	B-Application
Forum	O
thread	O
digressed	O
to	O
discuss	O
the	O
issue	O
of	O
neutral	O
archives	O
amongst	O
a	O
broader	O
audience	O
after	O
a	O
response	O
from	O
Michael	O
Gray	O
.	O
</s>
<s>
Herman	O
Oosterwijk	O
provides	O
a	O
more	O
recent	O
description	O
on	O
behalf	O
of	O
Teramedica	O
,	O
in	O
his	O
white	O
paper	O
,	O
in	O
which	O
he	O
offers	O
a	O
more	O
detailed	O
definition	O
:	O
"	O
A	O
Vendor	B-Algorithm
Neutral	I-Algorithm
Archive	I-Algorithm
(	O
VNA	O
)	O
is	O
a	O
medical	O
device	O
that	O
provides	O
scalable	B-Architecture
image	O
and	O
information	O
and	O
life	O
cycle	O
management	O
so	O
that	O
images	O
and	O
related	O
information	O
can	O
be	O
queried	O
,	O
stored	O
,	O
and	O
retrieved	O
in	O
a	O
manner	O
that	O
is	O
defined	O
by	O
open	O
standards	O
at	O
multiple	O
department	O
,	O
enterprise	O
,	O
and	O
regional	O
level	O
while	O
maintaining	O
patient	O
privacy	O
and	O
security	O
.	O
</s>
<s>
The	O
relationship	O
of	O
VNA	O
to	O
storage	O
of	O
medical	B-Application
images	I-Application
in	O
the	O
cloud	O
is	O
also	O
nebulous	O
,	O
though	O
offers	O
high	O
potential	O
for	O
buzzword	O
compliance	O
,	O
and	O
Michael	O
Gray	O
provides	O
some	O
clarity	O
in	O
his	O
paper	O
commissioned	O
by	O
EMC	O
.	O
</s>
<s>
Most	O
internal	O
systems	O
(	O
and	O
most	O
PACS	B-Application
)	O
do	O
not	O
manage	O
the	O
existence	O
of	O
multiple	O
identity	O
domains	O
,	O
and	O
if	O
identifiers	O
are	O
used	O
across	O
domains	O
then	O
collisions	O
and	O
ambiguity	O
occur	O
.	O
</s>
<s>
Thus	O
each	O
identifier	O
needs	O
to	O
either	O
be	O
qualified	O
by	O
its	O
"	O
assigning	O
authority	O
"	O
when	O
used	O
(	O
the	O
approach	O
taken	O
by	O
the	O
DICOM-based	O
IHE	O
Multiple	O
Image	O
Manager	O
Archive	O
(	O
MIMA	O
)	O
profile	O
)	O
or	O
coerced	O
into	O
a	O
single	O
"	O
canonical	O
"	O
identifier	O
that	O
spans	O
the	O
scope	O
of	O
the	O
larger	O
domain	O
that	O
includes	O
all	O
integrated	O
cross-enterprise	O
systems	O
(	O
the	O
approach	O
taken	O
by	O
IHE	O
Cross	B-Device
Enterprise	I-Device
Document	I-Device
Sharing	I-Device
.	O
</s>
<s>
When	O
importing	O
outside	O
images	O
into	O
the	O
local	O
archive	O
,	O
this	O
matter	O
also	O
has	O
to	O
be	O
addressed	O
,	O
usually	O
by	O
mapping	O
the	O
outside	O
identifier	O
into	O
an	O
internal	O
identifier	O
and	O
re-encoding	O
the	O
information	O
(	O
coercion	O
)	O
in	O
the	O
DICOM	B-Algorithm
"	O
header	O
"	O
or	O
other	O
meta-data	O
(	O
such	O
as	O
by	O
the	O
manner	O
specified	O
in	O
Import	O
Reconciliation	O
Workflow	O
)	O
.	O
</s>
<s>
One	O
purpose	O
of	O
a	O
VNA	O
is	O
to	O
store	O
information	O
and	O
serve	O
it	O
to	O
multiple	O
systems	O
that	O
may	O
have	O
different	O
requirements	O
for	O
its	O
use	O
and	O
expectations	O
for	O
very	O
specific	O
characteristics	O
of	O
the	O
DICOM	B-Algorithm
attributes	O
and	O
values	O
stored	O
in	O
them	O
,	O
both	O
standard	O
and	O
private	O
.	O
</s>
<s>
"	O
Tag	O
morphing	O
"	O
refers	O
to	O
changing	O
the	O
values	O
in	O
one	O
or	O
more	O
attributes	O
(	O
usually	O
DICOM	B-Algorithm
data	O
elements	O
in	O
this	O
context	O
)	O
.	O
</s>
<s>
In	O
its	O
degenerate	O
form	O
,	O
the	O
ability	O
to	O
map	O
any	O
tag	O
and	O
value	O
to	O
any	O
other	O
is	O
inherently	O
dangerous	O
and	O
undermines	O
the	O
value	O
of	O
attempting	O
to	O
standardize	O
attributes	O
in	O
the	O
first	O
place	O
,	O
and	O
the	O
efforts	O
by	O
modality	O
and	O
PACS	B-Application
vendors	O
to	O
use	O
them	O
"	O
properly	O
"	O
.	O
</s>
<s>
A	O
typical	O
use	O
case	O
is	O
to	O
change	O
the	O
values	O
in	O
Series	O
Description	O
supplied	O
by	O
acquisition	O
modalities	O
,	O
in	O
order	O
to	O
allow	O
two	O
different	O
PACS	B-Application
sharing	O
the	O
same	O
data	O
to	O
use	O
different	O
hanging	O
protocol	O
rules	O
based	O
in	O
Series	O
Description	O
.	O
</s>
<s>
Dynamic	O
tag	O
morphing	O
is	O
distinct	O
from	O
the	O
specific	O
attribute	O
changes	O
related	O
to	O
Cross-domain	O
Identity	O
and	O
Code	O
Resolution	O
(	O
what	O
DICOM	B-Algorithm
in	O
PS	O
3.4	O
refers	O
to	O
as	O
"	O
coercion	O
"	O
)	O
,	O
for	O
which	O
there	O
are	O
standards	O
defined	O
for	O
what	O
to	O
change	O
,	O
when	O
and	O
how	O
,	O
and	O
which	O
often	O
involve	O
additional	O
actors	O
such	O
as	O
a	O
Master	O
Patient	O
Index	O
,	O
though	O
some	O
proponents	O
lump	O
these	O
together	O
and	O
some	O
products	O
implement	O
them	O
using	O
the	O
same	O
mechanism	O
.	O
</s>
<s>
VNAs	O
should	O
have	O
no	O
difficulty	O
storing	O
DICOM	B-Algorithm
content	O
such	O
images	O
and	O
associated	O
information	O
such	O
as	O
presentation	O
states	O
and	O
so-called	O
"	O
evidence	O
documents	O
"	O
,	O
such	O
as	O
DICOM	B-Algorithm
Structured	O
Reports	O
containing	O
such	O
things	O
as	O
measurements	O
recorded	O
by	O
the	O
modality	O
,	O
or	O
post-processing	O
results	O
such	O
as	O
from	O
CAD	O
.	O
</s>
<s>
Most	O
PACS	B-Application
take	O
the	O
approach	O
of	O
converting	O
these	O
to	O
DICOM	B-Algorithm
,	O
in	O
some	O
cases	O
using	O
objects	O
intended	O
to	O
"	O
encapsulate	O
"	O
another	O
type	O
of	O
object	O
.	O
</s>
<s>
The	O
classic	O
example	O
is	O
a	O
scanned	O
document	O
stored	O
as	O
a	O
PDF	O
file	O
and	O
encapsulated	O
in	O
a	O
DICOM	B-Algorithm
PDF	O
object	O
along	O
with	O
sufficient	O
metadata	O
to	O
identify	O
it	O
and	O
manage	O
it	O
,	O
as	O
if	O
it	O
were	O
an	O
image	O
.	O
</s>
<s>
VNAs	O
should	O
support	O
these	O
type	O
of	O
encapsulated	O
DICOM	B-Algorithm
objects	O
and	O
the	O
DICOM	B-Algorithm
"	O
header	O
"	O
provides	O
a	O
means	O
to	O
obtain	O
the	O
metadata	O
for	O
indexing	O
to	O
support	O
query	O
and	O
retrieval	O
.	O
</s>
<s>
For	O
other	O
object	O
types	O
,	O
or	O
when	O
there	O
is	O
no	O
DICOM	B-Algorithm
encapsulation	O
object	O
available	O
,	O
or	O
when	O
there	O
is	O
no	O
need	O
to	O
interface	O
with	O
DICOM	B-Algorithm
systems	O
,	O
as	O
long	O
as	O
there	O
is	O
a	O
standard	O
means	O
of	O
providing	O
the	O
necessary	O
metadata	O
for	O
indexing	O
,	O
such	O
as	O
by	O
using	O
HL7	O
version	O
2	O
messages	O
or	O
XDS	B-Device
registry	O
services	O
,	O
then	O
in	O
theory	O
a	O
VNA	O
could	O
store	O
anything	O
.	O
</s>
<s>
Specific	O
types	O
of	O
non-DICOM	O
content	O
,	O
such	O
as	O
an	O
HL7	O
CDA	O
document	O
instance	O
containing	O
,	O
for	O
example	O
,	O
a	O
radiology	O
report	O
,	O
could	O
be	O
stored	O
either	O
as	O
a	O
XDS	B-Device
,	O
or	O
first	O
encapsulated	O
in	O
a	O
DICOM	B-Algorithm
Encapsulated	O
CDA	O
object	O
and	O
stored	O
using	O
DICOM	B-Algorithm
services	O
,	O
or	O
its	O
content	O
and	O
header	O
could	O
be	O
transcoded	O
into	O
a	O
DICOM	B-Algorithm
Structured	O
Report	O
instance	O
.	O
</s>
<s>
A	O
description	O
of	O
Wayne	O
Dejarnette	O
's	O
approach	O
to	O
non-DICOM	O
object	O
storage	O
in	O
his	O
product	O
is	O
described	O
in	O
his	O
2009	O
white	O
paper	O
.	O
</s>
<s>
There	O
is	O
general	O
agreement	O
that	O
the	O
use	O
of	O
the	O
DICOM	B-Algorithm
file	O
format	O
is	O
required	O
for	O
images	O
,	O
and	O
that	O
where	O
images	O
are	O
compressed	O
for	O
archival	O
or	O
transport	O
,	O
standard	O
,	O
not	O
proprietary	O
,	O
compression	O
schemes	O
(	O
transfer	O
syntaxes	O
)	O
need	O
to	O
be	O
used	O
.	O
</s>
<s>
Indeed	O
,	O
a	O
distinguishing	O
feature	O
of	O
most	O
VNAs	O
as	O
opposed	O
to	O
many	O
traditional	O
PACS	B-Application
is	O
the	O
avoidance	O
of	O
proprietary	O
internal	O
formats	O
ostensibly	O
used	O
in	O
the	O
past	O
for	O
"	O
performance	O
"	O
reasons	O
,	O
whilst	O
still	O
obtaining	O
good	O
performance	O
across	O
the	O
interfaces	O
.	O
</s>
<s>
Implementations	O
also	O
vary	O
in	O
the	O
range	O
of	O
modality-specific	O
image	O
types	O
that	O
they	O
support	O
;	O
though	O
many	O
archives	O
will	O
support	O
all	O
DICOM	B-Algorithm
image	O
information	O
objects	O
in	O
principle	O
,	O
some	O
extreme	O
cases	O
,	O
like	O
whole	O
slide	O
pathology	O
images	O
and	O
long	O
videos	O
may	O
not	O
be	O
supported	O
.	O
</s>
<s>
A	O
general	O
feature	O
of	O
VNAs	O
is	O
to	O
attempt	O
to	O
preserve	O
all	O
attributes	O
as	O
originally	O
supplied	O
,	O
including	O
private	O
(	O
proprietary	O
)	O
attributes	O
whether	O
from	O
the	O
acquisition	O
modality	O
or	O
added	O
by	O
other	O
intervening	O
applications	O
(	O
such	O
as	O
QC	O
workstations	O
or	O
PACS	B-Application
)	O
.	O
</s>
<s>
DICOM	B-Algorithm
describes	O
many	O
different	O
"	O
Information	O
Object	O
Definitions	O
"	O
and	O
"	O
SOP	O
Classes	O
"	O
for	O
storage	O
of	O
images	O
with	O
specific	O
metadata	O
related	O
to	O
particular	O
modalities	O
and	O
applications	O
,	O
and	O
the	O
list	O
of	O
these	O
grows	O
as	O
technology	O
evolves	O
.	O
</s>
<s>
Since	O
the	O
DICOM	B-Algorithm
format	O
is	O
inherently	O
extensible	O
,	O
and	O
all	O
new	O
objects	O
build	O
upon	O
a	O
common	O
encoding	O
and	O
pattern	O
,	O
a	O
VNAs	O
should	O
be	O
able	O
to	O
store	O
any	O
DICOM	B-Algorithm
image	O
object	O
,	O
regardless	O
of	O
whether	O
the	O
SOP	O
Class	O
is	O
recognized	O
or	O
new	O
.	O
</s>
<s>
This	O
may	O
be	O
achieved	O
through	O
the	O
use	O
of	O
field-modifiable	O
configuration	O
to	O
add	O
new	O
SOP	O
Classes	O
,	O
or	O
by	O
analysis	O
of	O
the	O
contents	O
of	O
the	O
objects	O
"	O
header	O
"	O
,	O
or	O
by	O
the	O
simple	O
of	O
approach	O
of	O
accepting	O
,	O
storing	O
and	O
regurgitating	O
anything	O
transferred	O
via	O
a	O
DICOM	B-Algorithm
C-STORE	O
operation	O
.	O
</s>
<s>
Support	O
of	O
the	O
basic	O
DICOM	B-Algorithm
C-STORE	O
,	O
C-FIND	O
,	O
C-MOVE	O
and	O
preferably	O
C-GET	O
are	O
fundamental	O
and	O
not	O
debated	O
.	O
</s>
<s>
Most	O
would	O
agree	O
that	O
an	O
important	O
VNA	O
interface	O
is	O
the	O
original	O
version	O
of	O
Web	O
Access	O
to	O
DICOM	B-Algorithm
Persistent	O
Objects	O
(	O
WADO	O
)	O
,	O
which	O
allows	O
single	O
images	O
to	O
be	O
retrieved	O
with	O
an	O
HTTP	B-Protocol
URL	O
in	O
either	O
DICOM	B-Algorithm
file	O
format	O
or	O
pre-rendered	O
into	O
a	O
consumer	O
format	O
like	O
JPEG	O
.	O
</s>
<s>
The	O
SOAP	B-Application
Web	O
Service	O
based	O
transactions	O
of	O
the	O
IHE	O
Cross	B-Device
Enterprise	I-Device
Document	I-Device
Sharing	I-Device
for	O
Imaging	O
are	O
also	O
generally	O
considered	O
a	O
prerequisite	O
for	O
a	O
claim	O
to	O
be	O
a	O
VNA	O
.	O
</s>
<s>
The	O
grayscale	O
or	O
color	O
rendering	O
transformation	O
applied	O
to	O
images	O
for	O
display	O
should	O
be	O
stored	O
as	O
a	O
DICOM	B-Algorithm
Presentation	O
State	O
object	O
.	O
</s>
<s>
These	O
objects	O
support	O
grayscale	O
and	O
true	O
color	O
images	O
,	O
as	O
well	O
as	O
the	O
application	O
of	O
a	O
pseudo-color	O
lookup	B-Data_Structure
table	I-Data_Structure
to	O
grayscale	O
images	O
.	O
</s>
<s>
Since	O
many	O
modern	O
PACS	B-Application
can	O
also	O
store	O
image	O
annotations	O
using	O
DICOM	B-Algorithm
Presentation	O
State	O
objects	O
,	O
a	O
VNA	O
needs	O
to	O
support	O
these	O
,	O
including	O
not	O
just	O
storage	O
and	O
regurgitation	O
,	O
but	O
also	O
selection	O
and	O
display	O
in	O
any	O
viewer	O
supplied	O
as	O
a	O
VNA	O
component	O
.	O
</s>
<s>
The	O
preferred	O
format	O
for	O
storage	O
of	O
annotations	O
,	O
regions	B-Algorithm
of	I-Algorithm
interest	I-Algorithm
,	O
and	O
measurements	O
is	O
the	O
DICOM	B-Algorithm
Structured	O
Report	O
(	O
SR	O
)	O
object	O
,	O
which	O
allows	O
structure	O
,	O
coded	O
and	O
semantic	O
information	O
to	O
be	O
persisted	O
,	O
rather	O
than	O
just	O
presentation	O
.	O
</s>
<s>
DICOM	B-Algorithm
SR	O
objects	O
may	O
also	O
be	O
produced	O
in	O
the	O
context	O
of	O
the	O
IHE	O
specifies	O
these	O
in	O
the	O
Simple	O
Image	O
and	O
Numeric	O
Report	O
(	O
SINR	O
)	O
profile	O
.	O
</s>
<s>
For	O
specific	O
domains	O
,	O
such	O
as	O
Radiotherapy	O
,	O
an	O
older	O
format	O
,	O
the	O
DICOM	B-Algorithm
RT	O
Structure	O
Set	O
,	O
which	O
can	O
encode	O
3D	O
patient	O
relative	O
coordinate	O
isocontours	O
(	O
only	O
)	O
is	O
used	O
,	O
and	O
some	O
non-RT	O
workstations	O
produce	O
these	O
as	O
well	O
instead	O
of	O
SRs	O
.	O
</s>
<s>
A	O
common	O
concept	O
in	O
a	O
PACS	B-Application
is	O
for	O
the	O
user	O
(	O
such	O
as	O
a	O
modality	O
operator	O
or	O
interpreting	O
radiologist	O
)	O
to	O
flag	O
some	O
images	O
(	O
or	O
other	O
objects	O
)	O
as	O
being	O
"	O
key	O
"	O
,	O
i.e.	O
,	O
of	O
particular	O
interest	O
for	O
some	O
reason	O
.	O
</s>
<s>
Though	O
obsolete	O
PACS	B-Application
may	O
only	O
record	O
this	O
as	O
a	O
flag	O
in	O
an	O
internal	O
database	O
,	O
modern	O
PACS	B-Application
use	O
the	O
DICOM	B-Algorithm
Key	O
Object	O
Selection	O
object	O
(	O
a	O
specialized	O
form	O
of	O
SR	O
)	O
to	O
export	O
this	O
information	O
.	O
</s>
<s>
Since	O
many	O
medical	B-Application
imaging	I-Application
techniques	I-Application
deliver	O
non-trivial	O
amounts	O
of	O
ionizing	O
radiation	O
to	O
the	O
patient	O
,	O
the	O
dose	O
exposure	O
needs	O
to	O
be	O
tracked	O
,	O
and	O
in	O
some	O
jurisdictions	O
this	O
must	O
be	O
recorded	O
by	O
law	O
.	O
</s>
<s>
DICOM	B-Algorithm
defines	O
a	O
specialized	O
form	O
of	O
Structured	O
Report	O
,	O
the	O
Radiation	O
Dose	O
Structured	O
Report	O
(	O
RDSR	O
)	O
to	O
encode	O
this	O
.	O
</s>
<s>
In	O
radiology	O
and	O
nuclear	O
medicine	O
applications	O
,	O
the	O
practice	O
of	O
dictating	O
and	O
transcribing	O
(	O
or	O
using	O
speech	B-Application
recognition	I-Application
)	O
is	O
well	O
entrenched	O
and	O
the	O
output	O
of	O
these	O
is	O
typically	O
unstructured	O
or	O
minimally	O
structured	O
prose	O
,	O
encoded	O
as	O
plain	O
text	O
and	O
distributed	O
by	O
fax	O
or	O
HL7	O
version	O
2	O
messages	O
or	O
some	O
equally	O
primitive	O
mechanism	O
.	O
</s>
<s>
The	O
same	O
principles	O
apply	O
as	O
for	O
the	O
storage	O
of	O
any	O
non-DICOM	O
content	O
,	O
including	O
the	O
use	O
of	O
HL7	O
version	O
2	O
messages	O
or	O
XDS	B-Device
to	O
provide	O
metadata	O
in	O
lieu	O
of	O
a	O
structured	O
"	O
header	O
"	O
,	O
such	O
as	O
in	O
the	O
case	O
of	O
reports	O
rendered	O
as	O
PDF	O
,	O
when	O
they	O
have	O
not	O
been	O
encapsulated	O
in	O
DICOM	B-Algorithm
or	O
CDA	O
objects	O
.	O
</s>
<s>
DICOM	B-Algorithm
defines	O
templates	O
for	O
the	O
encoding	O
of	O
human-generated	O
reports	O
as	O
DICOM	B-Algorithm
Structured	O
Report	O
(	O
SR	O
)	O
objects	O
,	O
and	O
IHE	O
specifies	O
these	O
in	O
the	O
Simple	O
Image	O
and	O
Numeric	O
Report	O
(	O
SINR	O
)	O
profile	O
.	O
</s>
<s>
In	O
addition	O
to	O
DICOM	B-Algorithm
RT	O
Structure	O
Sets	O
,	O
for	O
a	O
VNA	O
to	O
be	O
usable	O
in	O
an	O
enterprise	O
that	O
performs	O
Radiotherapy	O
,	O
the	O
entire	O
family	O
of	O
DICOM	B-Algorithm
RT	O
objects	O
for	O
beam	O
,	O
ion	O
and	O
brachytherapy	O
need	O
to	O
be	O
stored	O
and	O
regurgitated	O
.	O
</s>
<s>
DICOM	B-Algorithm
defines	O
a	O
Raw	O
Data	O
object	O
that	O
is	O
essentially	O
a	O
conventional	O
DICOM	B-Algorithm
composite	O
instance	O
header	O
with	O
patient	O
,	O
study	O
,	O
series	O
and	O
instance	O
information	O
,	O
but	O
no	O
payload	O
.	O
</s>
<s>
It	O
was	O
intended	O
for	O
the	O
storage	O
of	O
the	O
raw	O
data	O
that	O
is	O
not	O
easily	O
represented	O
as	O
an	O
image	O
or	O
image-like	O
object	O
,	O
such	O
as	O
the	O
raw	O
views	O
obtained	O
from	O
the	O
detectors	O
of	O
a	O
CT	O
scanner	O
,	O
or	O
the	O
k-space	B-Algorithm
data	O
from	O
an	O
MRI	O
scanner	O
,	O
but	O
can	O
be	O
used	O
to	O
encode	O
anything	O
.	O
</s>
<s>
A	O
VNA	O
that	O
wants	O
to	O
support	O
these	O
needs	O
to	O
have	O
a	O
means	O
of	O
providing	O
such	O
information	O
,	O
such	O
as	O
submission	O
using	O
XDS	B-Device
.	O
</s>
<s>
DICOM	B-Algorithm
does	O
define	O
a	O
Basic	O
Audio	O
object	O
,	O
and	O
though	O
it	O
does	O
not	O
support	O
the	O
plethora	O
of	O
audio	O
codecs	O
available	O
in	O
the	O
consumer	O
world	O
,	O
some	O
PACS	B-Application
do	O
produce	O
them	O
,	O
so	O
a	O
VNA	O
should	O
support	O
these	O
.	O
</s>
<s>
Time-based	O
waveforms	O
(	O
such	O
as	O
ECGs	O
)	O
may	O
be	O
stored	O
as	O
DICOM	B-Algorithm
or	O
in	O
a	O
multitude	O
of	O
other	O
formats	O
,	O
and	O
the	O
same	O
principles	O
apply	O
as	O
for	O
audio	O
;	O
i.e.	O
,	O
if	O
the	O
format	O
is	O
a	O
medically	O
oriented	O
one	O
,	O
use	O
the	O
header	O
meta-data	O
for	O
indexing	O
during	O
ingestion	O
,	O
if	O
not	O
,	O
use	O
XDS	B-Device
to	O
register	O
it	O
.	O
</s>
<s>
A	O
DICOM	B-Algorithm
MR	B-Algorithm
Spectroscopy	I-Algorithm
object	O
is	O
defined	O
,	O
and	O
since	O
some	O
modalities	O
produce	O
it	O
,	O
a	O
VNA	O
should	O
be	O
able	O
to	O
store	O
and	O
regurgitate	O
instances	O
of	O
it	O
.	O
</s>
<s>
DICOM	B-Algorithm
allows	O
for	O
the	O
concept	O
of	O
Private	O
SOP	O
Classes	O
,	O
which	O
use	O
the	O
DICOM	B-Algorithm
encoding	O
and	O
transfer	O
mechanisms	O
but	O
whose	O
content	O
is	O
opaque	O
.	O
</s>
<s>
The	O
size	O
of	O
the	O
global	O
VNA	O
market	O
is	O
small	O
relative	O
to	O
the	O
PACS	B-Application
market	O
,	O
but	O
is	O
purported	O
to	O
be	O
growing	O
.	O
</s>
