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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!

U

RadioGrapbics

U

363

Software suite for image archiving and retrieval.

The efficient operation of a clinical picture archiving and communication system (PACS) requires a fully functional image archive. The archive should ...
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