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PACSMIILI Refresher Software Retrieval1 Sridbar
The
Suite
for
MSEE
#{149} Sheel
B. Sesbadri,
efficient
system
operation
(PACS)
not only concert
with
a fully
to store
software
throughout
the
PACS.
improve the flow The software was
and
Archiving
Image Kisbore,
of a clinical
requires
be able
Course
MS
picture
functional
retrieve
that
optimizes
The
authors
#{149} Ronald
image the
L. Arenson,
archiving
images devised
and
MD
communication
archive.
reliably
flow
and
The
archive
but should
of image-related
a software
should
also work
in
information
suite
that
serves
to
of information and the integrity of the data. by translating the functions performed by a conventional film library. Types of transactions possible with this system indude scheduling, canceling, rescheduling, and prestaging examinations; changing demographic information; merging patient information; and gencrating reports. The authors believe such a software suite is essential for a clinically useful PACS. U
and content developed
INTRODUCTION
Computer-based
systems for the acquisition, communication, storage, and display of medical images within a health care institution are expected to be in clinical use within the next decade. These systems, widely known as picture archiving and communication systems (PACS), are expected to improve the radiologist’s and clinician’s management
of the case. In addition,
has yet to emerge. for the efficient In addition to being
age-related
data,
information library and
across discuss
Index
term:
1
1992;
the Department
From
From
the
Vortech 0
PACS Picture
RadioGraphlc.s
RSNA,
1991 Data.
the image
RSNA Address
facility
picture
archive
archiving
archiving and
managing
operation of a clinical able to reliably store
must
the PACS. In this how this function
=
by better
be capable
information.
the
implementation of these complex systems is in its infancy. Although a few systems are under clinical trials at academic radiology centers, a fully digi-
Abbreviations:
care
substantially
the actual prototype
age archive.
health
to reduce
costs
tal department A prerequisite
of the
PACS are expected
operating
PACS is a fully functional and retrieve images and
of efficiently
communication
communication
system
system,
IllS
=
radiology
imim-
disseminating
article, we describe the working can be achieved with software.
and
However,
the
of a typical
information
film
system
(PACS)
12:357-363
ofRadiology, scientilic reprint
assembly. requests
University Received
ofPennsylvania November
Medical 18,
1991;
Center, accepted
3400
Spruce
November
St, Philadelphia, 19.
Supported
PA 19104. in part
by
to S.B.5.
1992
357
in Con ventional
of Functions
Handling
PACS-based
and
Function
Image
Conventional
Libraries
System
PACS Message
Supervisor All personnel
Image
All personnel
RIS/PACS Data base
File clerks Supervison*
Image Patient
management
Image storage Optimization *
Occasionally
handled
by othe
activities:
the
coordination,
radiology
management,
image
tion. Coordination supervisor tions,
film resolving
overall flow IllS-related library
the
IllS
ing
the
film
storage,
film
library
with
image
ance
by the
includes
and
and
their
monitoring
in the performed involve
certain
management,
out
and
personnel
of information functions,
HIS about library.
(1115),
carried
problems,
the
data and informactions
taken
also handled
by the
by all
personnel, involves communicating with the HIS and subsequently carrying out specific tasks, such as pulling film-jackets and storing films.
storage
ac-
department. by all film querying
library
Image
is typically
handled
by the
film library clerks. It includes the actual archiving and retrieval of patient folders from both shortand long-term storage.
of the film library
of the digital workstation. In the following section, ample signed ciently U
of a PACS-based to perform the and automatically.
THE
The folder
FOLDER manager
integrating
fully
data
the
et al
an cxis deeffi-
software
various
sources,
of data
by validating
and
to
information against the RIS. manager was developed by care-
translating
pares the conventional
Seshadri
we provide
analogue that above functions
MANAGER is a distributed
from
integrity
the conventional grated software
U
Motivated
suite that acts as an information router within the PACS and is more fully described elsewhere (1). The three major tasks of the folder manager are to improve the flow of information by predicting image retrieval characteristics, to improve the content of information by
PACS-derived The folder
RadioGrapbics
supervisor.
film library personnel may perform these functions on their own accord. Various other functions of the film library, including the loading and unloading of multiviewers, are not included here. In the PACS, these functions are usually the responsibility
improve
U
archive manager
The optimization aspect of film library management includes such activities as retrieving a patient’s old (comparison) examinations in anticipation of his on her arrival and tuning the size of the active film library to optimize storage space. These functions are typically performed on an ad hoc basis under the guid-
and optimiza-
library
personnel, usually for examination-level
Image film
system
is typically of the
managing
communication
information
manager manager
r personnel.
U THE FILM LIBRARY The organization of operations of a conventional film library provides a framework for understanding the requirements of a PACSbased digital image library. The conventional film library essentially performs the following
358
manager
Coordination RIS communication
handling and
the
functions
film library architecture. ofvarious PACS-based
performed
by
into an inteThe Table comfunctions scenarios.
Volume
in the
12
Number
2
DisplayNodes
1k
a 1k,
2k x 2k
Lass
Printer
Other
Workszauons
[abaeD
Figure folder
Acquisition
.
-
Figure 1 is a schematic of the folder ager. The heart of the folder manager intelligent
data
base
that
level and examination-level
maintains
man-
is an patient-
data. A linking
process
maintains two-way communication the HIS and the PACS. A message manager layer permits various processes to communicate according to the message protocol devised by the committee of the American between
College of Radiology and National Electrical Manufacturers Association (ACR-NEMA). These aspects ther described sions
of the
sition
and
of the folder manager are furelsewhere (2). Minimal verfolder
display
to as the acquisition
March
1992
manager nodes.
and
operate These
on are
workstation
acqui-
Structure of the The
folder
man-
ager comprises an intelligent data base and the RIS-PACS manager encapsulated by a message manager layer. The folder manager communicates with the RIS, image archive, acquisition nodes, and display nodes. Note the
Nodes
smaller
[RIsi
managers,
1.
manager.
MRI
folder
manager
at the acquisition nodes (denoted
segments
and display by Database).
We have identified seven significant transactions between the 1115 and the PACS that can be employed to improve the flow and integrity of the image and image-related information within the PACS. These transactions include the receipt of the following notices by
the PACS: tion
examination
cancels,
nation
prestages
manager),
(3).
The
next
reports. are fully section
examina-
reschedules,
(generated
demographic
merges, and transactions plc
schedules,
examination
by the changes,
exami-
folder patient
The details described
of these elsewhere
discusses
selected
sam-
transactions.
referred
folder
respectively.
Seshadri
et al
U
RadioGrapbics
U
359
Figure 2. Examination schedule. This transaction is initiated by the RIS and is the beginning of the data flow process. After processing the information, the
folder
manager
passes
the infor-
mation to the image archive and acquisition nodes. The demographics sent to the acquisition
nodes
are used
to identify
the
images when they are input the PACS. Open-architecture quisition devices that permit
PACS communication increase dously.
U
data
HIS-
sizer . .
tremen-
Figure
TRANSACTIONS
in more
.
Examination
Figure
curs
after
who tion
Schedule
2 shows
the
transaction
flow
an examination
(generated
Nodes
Acquisition
ac-
would
integrity
SAMPLE
into
that
oc-
schedule
notice
by the HIS) is received
by the
3 illustrates detail.
the
Often,
will view and when,
prestaging
MRI
process
it is possible
the radiologic permitting
to predict
image informathe PACS to send
the required images to the display node in advance of the viewing session. To enable this
PACS. The receipt of the notice results in three significant events. First, the PACS data base processes the appropriate demographic information and sends it to the acquisition node. This is done to minimize operator keyboard entry at the acquisition console. 5ccond, as a result of a data base trigger, an cx-
function, the folder manager has been designed to operate with a heuristic rule base that is capable of generating triggers and sending a comparison folder to the appropri-
amination
ceiving
“prestage”
image
archive.
downloading data from
working the
transaction
of previous optical storage
stone.
Finally,
appropriate
examination
pniate
notice
This
display
to the
initiates
generates and
sends
base,
a comparison it to the
node.
appro-
and
folder manager. Display stathe control of a workstation which is responsible for re-
managing
a local
folder
data
base
for a display station and fetching images from the image archive. At its convenience, the
examination pixel to the (magnetic)
the PACS data
time, folder
is sent
ate workstation tions are under folder manager,
at
workstation fetches the
interrogates the folder required pixel information
the image archive. folder is, of course, chive
so that
tical
to magnetic
A copy also
it may
stage
media.
and from
of the comparison sent to the image the
images
In our
from
model,
arop.
display
devices, by the addition of a workstation folder manager, are transformed into intelli-
360
U
RadioGrapbics
U
Seshadri
et al
Volume
12
Number
2
Figure 3. Examination prestage. Upon receipt examination schedule
folder
Database
Acquisition
Digitizer
sult
sion,
size
the
tated
ager
results
report)
and
(which
are
then,
sent
if so
may
to the desired,
include
data
base
to the
man-
HIS.
aminations
local
at the
storage folder
of the manager
manager
notices
that
the
1992
on for
examinations
.
indirect bandwidth
For procx-
the
optical
fetching
more
is, of course,
(and,
therefore,
archive.
The
comparison
dependent
transmission
on time)
the
of
examination.
Examination
Cancel
a variety
of reasons, scheduled it is processed
workstacan
to delete
relevant
user
. The
notice which
Examination
HIS may
is received
by the
and
takes
the
cancel Once
logged
a the
folder in the
appropriate
action
entries.
Reschedule
examination
essentially
the
examination.
cancellation manager, data base,
has called up E2, it sends a notice to the archive, asking for a prestage and transfer of E.A to the workstation. This “background” fetching of pixel data also improves the perceived bandwidth of the PACS. We do not send all the previous examinations, since this may ne-
March
point
previously
workstation
folder
in “thrashing”
trigger
each
optimize the retrieval of the required examinations. For example, assume that the rule base has composed a folder comprising the current examination (E.0) and three previous examinations (Ri, E.2, and 3). Ifthe workstation
appropriate time retrieves the required images from the magnetic storage system of the archive.
This
fetch heuristics do not number of comparison
the
the
dic-
intelligent control result of increasing of the network. If the automatic vide the sufficient tion,
strategy has the perceived
the
the
a list of
box. The workstation inspects the comparison folder and at the
Nodes
MRI
gent devices thatpull the images off the archive rather than having pixel data pushed from the image archive. After the viewing ses-
generates
comparison examinations. This list is rule-base driven and can be easily modified. The comparison folder is sent to the image archive and the workstation. The image archive downloads the required images from the juke-
II [RIS
manager
of the notice,
reschedule
transaction
a combination
of an
is
examination
cancel transaction followed by an examination schedule transaction. This change is propagated to the appropriate acquisition node.
Seshadri
et
al
U
RadioGraphics
U
361
.
.
DisplayNodes
.
lkxlk.lkx2k Workstations
-
L*serPrinter
Other
: Changes
4.
Figure
Demographic
changes. This transaction is initiated by the HIS. Note the flow of information via the RIS-PACS manager through the data base and onto the display and acquisition
nodes.
mented
In a fully
Acquisition
changes
to flow
Security
cessed changes
are
display
nodes.
Change
number.
by the and
:-
to multiple
.
generates demographic as a change in date of birth
such
received
When
folder
entered
such
manager, into
propagated
the
to the
It is critical
or
a notice
is
base
and
acquisition
to perform
the
(Fig
5).
notice
U
Seshadri
et a!
is one
of the
processed On that
by
more the
complex
folder
manager
film library personnel HIS has two patients who
occasion, the
are
the
seemingly
and
cal record number) but in actuality are the same person. The resolution of this error is not trivial, since the PACS archive would have
last
different
indexed under must dation priate
image
(eg,
information
different
name,
mcdi-
for this situation
two different patients. The data sets be merged (including possibly a consoliof data on optical platters), and appronotices must be sent to the display and
acquisition
RadioGraphics
MRI
Merge merge
transactions
it is prodata
Patient
Patient
step, as it directly contributes to the integrity of the data on the PACS. Figure 4 shows a schematic of this event.
U
Nodes
imple-
. Demographic The HIS periodically
362
DataJ]
PACS, this information
may have nodes.
Social
I
nodes.
Volume
12
Number
2
DisplayNodes
Ikxlk.lkx2k Workstations
-
Other
LaserPrinter
II
Database Merge
Patient
\
Acquisition
tagtiw
. Reports The folder
is capable
of passing variHIS (eg, ‘stat
ous forms of reports from the readings,” preliminary findings, and final neports) to the display node. For data integrity reasons, reports always travel to the image archive first, are logged, and then are sent to the workstation. The folder manager permits the reports to “mature” for a short period of time (to handle addendums or editions, for
1.
‘
example)
and
the
platter
same
then
attempts
as the
image
library.
like
clinically
March
1992
the
useful
folder
3.
on
folder manager has control the flow information in a
It is possible
operational efficiency by translating ing of a conventional film library based heuristics. In our opinion, suite
them
2.
images.
U SUMMARY A software suite called the been developed to optimally of image and image-related digital
to place
manager
Nodes
MRI
U
manager
Figure 5. Patient merge. This is a complex transaction involving the merging of patient and examination data in the image data base. Pixel data may need to be consolidated and reorganized onto different platters. The resuit of the merge operation must be propagated to the acquisition and display nodes.
REFERENCES Seshadni SB, Kishore 5, Khalsa 5, Arenson Functional design of a folder manager on image archive. In: Arenson RI, Fniedenberg RM, eds. Proceedings of Computer Applications to Assist Radiology. Carlsbad, Calif: posia Foundation, 1990; 242-248. Kishore 5, Khalsa 5, Seshadri SB, Arenson A digital film library implementation. Proc February 1991 (in press). Arenson RI, Seshadri SB, Stevens FJ, van Voorde F. The overlapping domains and
RI. an
SymRI. SPIE der in-
terface between radiology information systems and medical image management systems (PACS). In: Lemke HU, Rhodes ML,Jaffee CC, Felix R, eds. Proceedings ofcomputer assisted radiology. Berlin: Springer-Verlag, 1987; 855865.
to achieve
the workinto rulea software
is essential
for
a
PACS.
Seshadri
et a!
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