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7/26/2019 Bai Bao Desing Pacs
1/13
Jou rnal o f ig ita l Im aging
V O L 9 , N O 2
M A Y 9 9 6
D e s i g n a n d I m p l e m e n t a t i o n o f a P i c t u r e A r c h i v i n g a n d
C o m m u n i c a t i o n S y s te m T h e S e c o n d T i m e
H .K . H u a n g , K a t h e r i n e A n d r i o l e , T o d d B a z z il l, S .L . L ou , A l b e r t W . K . W o n g , a n d R o n a l d L. A r e n s o n
T h i s re p o r t d e s c r i b e s t h e a u t h o r s e x p e r i e n c e in t h e
d e s i g n a n d i m p l e m e n t a t i o n o f t w o l a r g e s c a l e p i c t u r e
a r c h i v i n g a n d c o m m u n i c a t i o n s y s t e m s ( P A C S ) d u r i n g
t h e p a s t 1 0 y e a r s . T h e f i r s t s y s t e m , w h i c h i s i n d a i l y
c l in i c al o p e r a t i o n w a s d e v e l o p e d a t U n i v e r s i t y o f C a l i -
f o r n i a , Lo s A n g e l e s f r o m 1 9 8 3 t o 1 9 9 2 . T h e s e c o n d
s y s t e m , w h i c h c o n t i n u e s e v o l v i n g , h a s b e e n i n d e v e l o p -
m e n t a t U n i v e r s i t y o f C a l i f o r n ia , S a n F r a n c i s c o ( U C S F )
s i n c e 1 9 9 2 . T h e r e p o r t h i g h i i g h t s t h e d i f f e r e n c e s b e -
t w e e n t h e t w o s y s t e m s a n d p o i n ts o u t th e g r a d u a l
c h a n g e i n t h e P A C S d e s i g n c o n c e p t d u r i n g t h e p a s t 1 0
y e a r s f r o m a c l o s e d a r c h i t e c t u r e t o a n o p e n h o s p i t a l -
i n t e g r a t e d s y s t e m . B o t h s y s t e m s f o c u s o n s y s t e m
r e l i a b i l i t y a n d d a t a i n t e g r i t y , w i t h 2 4 - h o u r o n - l i n e
s e r v i c e a n d n o I o s s o f i m a g e s . T h e m a j o r d i f f e r e n c e
b e t w e e n t h e t w o s y s t e m s i s t h a t t h e U C S F P A C S
i n f r a s tr u c t u r e d e s i g n i s a c o m p l e t e l y o p e n a r c h i t e c t u r e
a n d t h e s y s t e m i m p l e m e n t a t i o n u s e s m o r e a d v a n c e d
t e c h n o l o g i e s in c o m p u t e r s o f t w a r e , d i g i ta l c o m m u n i c a -
t i o n , s y s t e m i n t e r f a c e , a n d s t a b l e i n d u s t r y s t a n d a r d s .
S u c h a P A C S c a n w i t h s t a n d f u t u r e t e c h n o l o g y c h a n g e s
w i t h o u t r e n d e r i n g t h e s y s t e m o b s o l e t e , a n e s s e n t i a l
c r i t e r i o n i n a n y P A C S d e s i g n .
C o p y r i g h t 9 1 9 9 6 b y W . B . S a u n d e r s C o m p a n y
K E Y W O R D S : p i c tu r e a r ch i vi n g a n d c o m m u n i c a t i o n
s y s t e m { P A C S ) , c o m m u n i c a t io n n e t w o r k s , i n f r a st r u c -
t u r e d e s i g n , o p e n a r c h i t e c t u r e , d i s p la y w o r k s t a t i o n .
H E R E A R E g e ne ra ll y t h re e m e t h o d s o f
a p p r o a c h t o d e si g n a nd i m p l e m e n t a t i o n o f
a p i c t u r e a r c h i v i n g a n d c o m m u n i c a t i o n s y s t e m
P A C S ) . ~ I n t h e f i rs t a p p r o a c h , s y s t e m s i n t e g r a -
t i o n , a m u l t i d i s c i p l i n a r y t e a m w i t h t e c h n i c a l
k n o w - h o w is a s s e m b l e d b y t h e r a d i o l o g y d e p a r t -
m e n t o r t h e h o s p i t a l . T h e t e a m b e c o m e s a
s y s t e m i n t e g r a t o r , s e l e c t i n g P A C S c o m p o n e n t 5
f r o m v ar i ou s m a n u f a c t u r e r s . T h e t e a m d e v e l o p s
s y s te m i n t e r f a c e s a n d w r i t e s th e P A C S s o f t w a r e
a c c o r d i n g t o t h e c l in i ca l r e q u i r e m e n t s o f t h e
h o s p i t a l . I n t h e s e c o n d a p p r o a c h , r e q u i r e m e n t s
s p e c i f i c a t i o n a n d c o n t r a c t i n g , a t e a m o f e x p e r t s ,
f r o m b o t h o u t s i d e a n d i n s i d e t h e h o s p i t a l , is
a s s e m b l e d t o w r i t e d e t a i l e d s p e c i f i c a t i o n s f o r
t h e P A C S f o r a c e r t a i n c li n ic a l e n v i r o n m e n t . A
m a n u f a c t u r e r i s c o n t r a c t e d t o i m p l e m e n t t h e
s y s t e m . I n t h e t h i r d , o r t u r n k e y a p p r o a c h , t h e
m a n u f a c t u r e r d e v e l o p s a t u r n k e y P A C S a n d
i n s t a l l s i t i n a d e p a r t m e n t f o r c l i n i c a l u s e . E a c h
o f t h e s e a p p r o a c h e s h a s a d v a n t a g e s a n d d i sa d -
v a n t a g e s . O n e a d v a n t a g e o f t h e f ir st , o r s y s t em s
i n t e g r a t i o n a p p r o a c h , i s t h a t t h e r e s e a r c h t e a m
c a n c o n t i n u o u s l y u p g r a d e t h e s y s t e m w i th s t a t e -
o f - t h e - a r t c o m p o n e n t s a n d t h e r e f o r e , t h e s y s -
t e m w i l l n o t b e c o m e o b s o l e t e . T h e s y s t e m s o
d e s i g n e d is ta i l o r e d t o t h e c l in i ca l e n v i r o n m e n t
a n d c a n b e u p g r a d e d w i t h o u t d e p e n d i n g o n t h e
s c h e d u l e o f t h e m a n u f a c t u r e r . O n e d i sa d v a n-
t a g e is t h a t i t r e q u i r e s a s u b s t a n t i a l c o m m i t m e n t
b y t h e h o s p i t a l t o a s s e m b l e a m u l t i d i s c i p l i n a r y
t e a m . I n a d d i t i o n , t h e s y s t e m d e v e l o p e d w ill b e
o n e o f a k i n d , a n d t h e r e f o r e , s e r v ic e a n d m a i n t e -
n a n c e w i ll b e d i f f i cu l t b e c a u s e i t c o n s i s t s o f
c o m p o n e n t s f r o m d i f f e r e n t m a n u f a c t u r e r s .
T h e p r i m a r y a d v a n t a g e o f t h e s e c o n d a p -
p r o a c h r e q u i r e m e n t s sp e c i fi c a ti o n a n d c o n t r a c t -
i n g ) i s t h a t t h e P A C S s p e c i f i c a t i o n s a r e t a i l o r e d
t o a c e r t a i n c l in i c al e n v i r o n m e n t , y e t t h e r e s p o n -
s ib i li ty f o r i m p l e m e n t i n g t h e P A C S is d e l e g a t e d
t o t h e m a n u f a c t u r e r . T h e d e p a r t m e n t a c t s a s a
p u r c h a s i n g a g e n t a n d d o e s n o t h a v e t o b e
From the Laboratory for Radiological Informatics, Depart-
m ent of Radiology, University of Califomia, San Fran cisco
94143-0628.
Part ial ly supported by PH S grant RO l CA 51198, Nat ional
Librar) ' of Medicine contract NO1-LM-4-3508, Cal RE N grant
ATMN-O07, Fuj i Medical Systems USA, Lumisys, and Abe
Sekkei.
Address reprint requests to H.K . Huang, DSc, Laboratory for
Radiological lnformatics, Department of Radiology, Un iversity
of California, San Francisco, CA 94143-0628.
R.L .A. contributes to the design of the U CS F PA CS.
Copyright 9 1996 by H 91 Saunders Com pany
0897-1889 / 96 / 0902-000153. O0 0
Journa/ofDigita//maglng Vol 9, No 2 May ), 1996: pp 47-59 47
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8 HUANG ET AL
c o n c e r n e d w i t h t h e i n s ta l l at i o n . T h e d i s a d v a n -
t a g e s a r e t h a t t h e s p e c i f i c a t i o n s t e n d t o b e
o v e r l y a m b i t i o u s . T h e e x p e r t s m a y n o t b e f a m i l -
i a r w i t h t h e c l i ni c al e n v i r o n m e n t , a n d t h e y m a y
u n d e r e s t i m a t e t h e t e c h n i c a l a n d o p e r a t i o n a l
d i ff ic u lt y . T h e d e s i g n a t e d m a n u f a c t u r e r , w h o
m a y l a c k cl in i ca l e x p e r i e n c e , t e n d s t o o v e r e s t i -
m a t e t h e p e r f o r m a n c e o f e a c h P A C S c o m p o -
n e n t . A s a r e su l t, t he c o m p l e t e d P A C S m a y n o t
m e e t t h e o v e r a l l s p e c i f i c a t i o n s . T h e c o s t o f
c o n t r a c t i n g t h e m a n u f a c t u r e r t o d e v e l o p a s p e c i-
f ie d P A C S is a l so h i g h b e c a u s e o f th e m a n u f a c -
t u r e r s n a r r o w p r o f i t m a r g i n i n b u il d i n g o n l y
o n e s y s te m .
T h e a d v a n t a g e o f t h e t h i r d o r t u r n k e y a p -
p r o a c h i s t h a t i t i s a g e n e r a l i z e d p r o d u c t i o n
s y s t e m , t h e r e f o r e , t h e c o s t t e n d s t o b e l o w e r .
H o w e v e r , i n t h is a p p r o a c h , t h e m a n u f a c t u r e r
n e e d s a c o u p l e o f y e a r s to c o m p l e t e t h e p r o d u c -
t i o n c y cl e . B y th e t i m e t h e s y s te m i s c o m m e r -
c i al ly a v a i la b l e , s o m e c o m p o n e n t s m a y h a v e
a l r e a d y b e c o m e o b s o l e t e b e c a u s e o f t h e f a s t
m o v i n g c o m p u t e r a n d c o m m u n i c a t i o n te c h n o l o -
g i e s . A l s o , i t i s d o u b t f u l w h e t h e r a g e n e r a l i z e d
P A C S c a n b e u s e d b y e v e r y s p e c i a lt y in a
d e p a r t m e n t a n d b y e v e r y r a d io l o g y d e p a r t m e n t .
I n t h e p a s t s e v e r a l y e a r s , t h e s e t h r e e a p -
p r o a c h e s g r a d u a l l y m e r g e a s a d d i t i o n a l c l i n i c a l
d a t a i n P A C S b e c o m e a v a il a b le . A s a r e s u lt , t h e
d i s ti n c ti o n a m o n g t h e m h a s b e c o m e b l u r r e d .
T h i s r e p o r t d e s c r i b e s t h e a u t h o r s e x p e r i e n c e
o f d e s ig n a n d i m p l e m e n t a t i o n o f tw o P A C S , o n e
a t U n i v e r s i t y o f C a l i f o r n i a a t L o s A n g e l e s
( U C L A ) a n d t h e o t h e r a t U n i v e r s i ty o f C a l i f o r-
n i a at S a n F r a n c i s c o ( U C S F ) d u r i n g t h e p a s t 1 0
y e a r s . T h e f i r s t s y s t e m w a s b a s e d o n t h e f i r s t
a p p r o a c h a n d t h e s e c o n d w a s b a s e d o n c o m b i n -
i n g t h e f i r st a n d s e c o n d a p p r o a c h e s . S e c t i o n s 2
a n d 3 d e s c r ib e th e U C L A a n d t h e U C S F P A C S ,
r e s p e ct i v e ly . S e c t i o n 4 c o m p a r e s t h e d i f f e r e n c e s
b e t w e e n t h e s e t w o s y s te m s .
T H E F IR S T P C S S Y S T E M T U C L
W e b e g a n t h e d e s ig n o f t h e U C L A P A C S in
1 98 3. 2 I ts i m p l e m e n t a t i o n w e n t t h r o u g h t h r e e
p h a s e s . P h a s e 1 , f r o m 1 9 84 t o 1 9 9 0, e n c o m -
p a s se d t h e d e m o n s t r a t i o n o f t h e c o n c e p t o f
P A C S a n d t h e d e s i g n o f t h e P A C S i n f r a s tr u c -
t u r e . P h a s e 2 , f r o m 1 9 9 0 t o 1 9 9 1 , c o m p r i s e d
c l in i ca l i m p l e m e n t a t i o n o f s e v e r a l P A C S m o d -
u l e s . P h a s e 3 , f r o m 1 9 9 2 o n , i n c l u d e d t h e
s y s t e m s r e f i n e m e n t , m a i n t e n a n c e , a n d a p p l i c a -
t io n s . T h i s P A C S w a s d e s i g n e d f o r t h e r a d i o l o g y
d e p a r t m e n t o p e r a t i o n w i t h o u t c o n s i d e r a t i o n o f
a h o s p i t a l i n t e g r a t e d P A C S .
Phase 1: Demonstration o f Concept and Design
o f PA CS Infrastructure
T o s h o w t h e c o n c e p t o f P A C S t o p h y s i c i a n s ,
i n 19 87 w e i m p l e m e n t e d t w o P A C S m o d u l e s ;
o n e i n t h e p e d i a t r i c r a d i o l o g y s e c t i o n w i t h i n t h e
d e p a r t m e n t , 3 a n d t h e o t h e r i n th e c o r o n a r y c a r e
u n i t . 4 T h e p e d i a t r i c r a d i o l o g y s e c t i o n w a s s e -
l e c t ed b e c a u s e i t o p e r a t e s i n d e p e n d e n t l y f r o m
o t h e r r a d i o l o g y s p ec i a l ti e s a n d r e s e m b l e s a m i n i
r a d i o l o g y d e p a r t m e n t . I r is a n e x c e l le n t m o d e l
t o s tu d y th e i m p l e m e n t a t i o n o f a P A C S f o r t h e
e n t i r e r a d i o l o g y d e p a r t m e n t . I n t h is m o d u l e ,
i m a g e s w e r e d i s p l a y e d o n t w o 2 , 0 4 8 - 1 i n e m o n i -
t o r s. T h e m o d u l e w a s u s e d f o r d ai ly c o n f e r e n c e s
a n d c a s e r e vi ew s . T h e c o r o n a r y c a r e u n i t w as
c h o s e n f o r t h e s e c o n d P A C S m o d u l e b e c a u s e it
e x p l o r e d t h e a p p l i c a t i o n o f P A C S o u t s i d e o f t h e
r a d i o l o g y d e p a r t m e n t . I n th i s m o d u l e , i m a g e s
w e r e d i s p l a y e d o n t h r e e 1 , 0 2 4 - 1 i n e m o n i t o r s .
B o t h m o d u l e s w e r e i n c l i n i c a l o p e r a t i o n 2 4
h o u r s a d a y , 7 d a y s a w e e k . T h e r e a c t i o n s f r o m
b o t h r a d i o l o g i s t s a n d c l i n i c i a n s w h o u s e d t h e s e
t w o s y s t e m s w a s v e r y p o s i ti v e .
F r o m 1 98 8 t o 1 99 0, 5 w e c o n c e n t r a t e d o n t h e
d e s ig n o f t h e P A C S i n f r a s t r u c t u r e . T h e c r i ti c al
c o m p o n e n t s i n t h e i n f r a st r u c t u re w e r e t h e c o m -
m u n i c a t i o n s y s te m , P A C S c o n t r o l l e r s , d a t a b a s e
d e s i g n , f a u l t t o l e r a n c e c o n s i d e r a t i o n , a n d s y s -
t e t a i n t e g r a t i o n s o f t w a r e . T h i s i n f r a s t r u c t u r e
s u p p o r t e d a d i g it a l -b a s e d r a d i o l o g y o p e r a t i o n .
T h e i n f r a s t r u c t u r e w a s i m p l e m e n t e d f r o m
1 9 90 t o 1 9 91 . 6 T h e r e w e .r e 64 m u l t i m o d e a n d 4 8
s i n g l e - m o d e f i b e r o p t i c c a b l e s c o n n e c t i n g t h e
t h r e e b u i l d i n g s ( C e n t e r f o r t h e H e a l t h S c i e n c e s
[ C H S ] , M e d i c a l P l a z a , a n d T a p e r B u i l d i n g )
h o u s in g t h e r a d i o to g y d e p a r t m e n t . T h e r e w e r e
t w o P A C S c o n t r o l l e r s , o n e a t t h e C H S a n d o n e
a t t h e M e d i c a l P l a z a . T h e i n f r a s t r u c t u r e w a s
o n - l i n e i n t h e b e g i n n i n g o f 1 9 91 .
Communica t ion sys tem W e d e s i g n e d a
t h r e e - t i e r e d f i b e r o p t i c c o m m u n i c a t i o n s y s t e m
w i t h E t h e r n e t , F D D I ( f ib e r d i s t r i b u t e d d a ta
i n t e r f a c e ) , a n d U l t r a n e t ( a p r o p r i e t a r y 1 g b i t /
s e c n e t w o r k ) . 7 E t h e r n e t w a s u s e d t o t r a n s m i t
i m a g e s f r o m a c q u i s i t i o n d e v i c e s t o t h e a c q u i si -
t i o n c o m p u t e r . B e c a u s e t h e a c q u i s i t i o n d e v i c e
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PACS SECOND TIME 49
w a s s l o w i n g e n e r a t i n g i m a g e s , t h e t r a n s m i s s i o n
s p e e d b e t w e e n t h e s e t w o n o d e s w a s n o t c r u c ia l .
I m a g e s w e r e r e f o r m a t t e d a t t h e a c q u i s i t i o n
c o m p u t e r a n d s e n t t o th e P A C S c o n t r o l l e r b y
m e a n s o f F D D I . I m a g e s w e r e a r c h iv e d o n t o
o p t i c a l d i s k s a n d d i s t r i b u t e d t o t h e i m a g e d i s -
p l a y s t a ti o n s w i th t h e U l t r a n e t . T h e t h r e e c o m -
m u n i c a t i o n n e t w o r k s w e r e c o e x i s t e n t i n t h e
i n f r a s t r u c t u r e a n d s e r v e d a s b a c k u p s f o r e a c h
o t h e r .
PACS con t ro l l e r s .
T h e r e w e r e t w o P A C S
c o n t r o l l e r s i n t h e i n f r a s t r u c t u r e . 8 E a c h c o n t r o l -
l e r w a s c o m p o s e d o f a n i m a g e s e r v e r 4 / 4 9 0
S P A R C ; S u n M i c r o s y s t e m s , M o u n t a i n V i e w ,
C A ) w i t h 4 - G b y t e m a g n e t i c d i s k s t o r a g e , a
1 Tbyte
o p t i c a [ d i sk l i b r a r y w i t h w r i t e o n c e r e a d
m a n y W O R M ) d i s ks f o r a r c h iv i n g i m a g e s , a n d
a S un 4 / 4 9 0 S P A R C s e r ve r r u n n i n g t h e d a t a
b a s e S y b a s e , E m e r y v i l l e , C A ) f o r p a t i e n t d i r e c -
t o r y a n d t e x t i n f o r m a t i o n . T h e a r c h i t e c t u r e o f
e a c h c o n t r o l l e r w a s i d e n ti c a l a n d c o u l d b e u s e d
a s t h e b a c k u p f o r t h e o t h e r . T h e P A C S c o n t r o l -
l e rs w e r e c o n n e c t e d w i th t h e U l t r a n e t . I m a g e s
c o u l d b e t r a n s m i t t e d b e t w e e n t h e P A C S c o n t r o l -
l e r s a n d d i s p l a y w o r k s t a t i o n s a t 4 t o 8 M b y t e s /
s ec
Data base .
T w o i d e n t i c a l S y b a s e d a t a b a s e s
e x i s te d i n e a c h P A C S c o n t r o l l e r a n d s e r v e d a s a
m i r r o r e d s y st em . C u r r e n t p a t i e n t i m a g e i n f o r m a -
t i o n w a s u p d a t e d c o n t i n u o u s l y o n t h e d a t a b a s e
o f e a c h c o n t r o l l e r .
Fault tolerance consideration.
I n t h e i n f r a -
s t r u c t u r e , e v e r y c r i ti c a l c o m p o n e n t h a d a b a c k u p .
T h e r e w e r e t w o id e n t i c a l d a t a b a s e s o n e i n e a c h
P A C S c o n t r o l le r . E a c h P A C S c o n t r o l l e r w a s
l o c a t e d i n a s e p a r a t e b u i l d i n g t o a v o i d p o t e n t i a l
d i s a s t e r . T h e t h r e e c o m m u n i c a t i o n n e t w o r k s
b a c k e d u p e a c h o t h e r , a n d a ll a c ti v e fi b e r o p t i c
c a b le s h a d s p a re s . E a c h P A C S c o n t r o l l e r w a s
p o w e r e d b y an u n i n t e r r u p t a b l e p o w e r s u p p l y
w i t h u p to 20 m i n u t e s o f u n i n t e r r u p t e d p o w e r .
Systems integration sof tware.
T h e p r e v i o u s l y
d e s c r ib e d c o m p o n e n t s w e r e i n t e g r a t e d a s t h e
P A C S i n f r as t r u c tu r e b y m e a n s o f an e l a b o r a t e
s y s te m s o f t w a r e . T h e s y s te m s o f t w a r e w a s w r i t -
t e n in C p r o g r a m m i n g l a n g u a g e a n d r a n u n d e r
t h e U N I X o p e r a t i n g s ys te m .
Phase 2 : Implementa tion o f PA CS Modules
T o i m p [ e m e n t P A C S m o d u l e s i n t h e c l i n i c a l
e n v i r o n m e n t , tw o a d d i t i o n a l ta s k s w e r e n e e d e d .
T h e f i r s t t a s k , c o m p l e t e d i n P h a s e 2 , w a s t o
c o n n e c t i m a g e a c q u i s i t i o n d e v i c e s t o t h e P A C S
c o n t r o l l e r t h r o u g h t h e i n f r a s t r u c t u r e . T h e s e c -
o n d w a s t o d e si g n a n d i m p l e m e n t d i s p l a y w o r k -
s t a t i o n s i n t h e d e p a r t m e n t a n d c l i n i c s i n t h e
t h i r d p h a s e . I n i m a g e a c q u i s it i o n , w e c o n n e c t e d
t h r ee c o m p u t e d to m o g r a p h y C T ) a nd t hr e e
m a g n e t i c r e s o n a n c e M R ) s c a n n e r s w i t h d i r e c t
d i g i t a l i n t e r f a c e s , a s w e l l a s t h r e e c o m p u t e d
r a d i o g r a p h y C R ) u n i t s a n d tw o fi lm di g i ti z e rs
t o t h e i n f r a s t r u c t u r e .
Pha se 3: Systems Refinemen t Training
Maintenance and App lications
P h a s e 3 w a s c o m p r i s e d i n t w o s t a g e s. 9 S t a g e 1
w a s t h e d e v e l o p m e n t o f d i s p la y w o r k s t a t i o n s
a n d t h e i r c l i n i c a l i m p l e m e n t a t i o n . S t a g e 2 c o n -
s i st e d o f re f i n in g t h e P A C S ; u p g r a d i n g t h e
d i s p l a y w o r k s t a t i o n s o f t w a r e ; a n d e s t a b l i s h i n g
t r a in i n g , m a i n t e n a n c e , a n d s e r v i c e.
Stage 1: Display stations an d clinical implernen-
tation.
I n t h i s s t a g e , f o u r s t a t i o n s , e a c h w i t h
t w o 2 , 0 4 8 - 1 i n e m o n i t o r s , w e r e d e p l o y e d i n t h e
p e d i a t r i c ra d i o l o g y t w o st a t io n s ) , n e u r o r a d i o l -
o g y , a n d g e n i t o u r i n a r y r a d i o l o g y s e c t io n . A l s o ,
o n e l a s e r i m a g e r p r i n t i n g s t a t i o n w a s i n s t a l l e d
a s a h a r d c o p y de v i c e . I n a d d i t i o n , t w o t h r e e -
m o n i t o r s t a ti o n s w i t h 1 K m o n i t o r s w e r e i n -
s t a ll e d i n th e c o r o n a r y c a r e u n i t a n d p e d i a t r i c
i n t e n s iv e c a r e u n it I C U ) . F i g u r e 1 s h o w s t h e
U C L A P A C S i n f r a s tr u c t u r e a n d i m a g e a cq u is i-
t i o n a n d d i s p l a y s ta t i o n s a s o f O c t o b e r 1 99 2.
Stage 2: Systems ref inem ent and training m ain-
tenance andservice.
D u r i n g c l in i ca l i m p l e m e n -
t a t io n , w e s e t u p p r o c e d u r e s f o r t r a in i n g , s y s t e m
m a i n t e n a n c e , a n d s e rv i ce . T h r e e g r o u p s o f p er -
s o n n e l w e r e t r a i n e d . T h e f ir st g r o u p w a s r a d i o l o -
g i s t s a n d c l i n i c i a n s t o u s e t h e d i s p l a y s t a t i o n s .
T h e s e c o n d g r o u p i n c lu d e d t h e P A C S c o o r d i n a -
t o r , t e c h n o l o g i s t s , a n d c l e r i c a l p e r s o n n e l . T h i s
t r a i n i n g w a s e x t e n si v e a n d c o v e r e d i m a g e q u a l -
i ty a s s u r a n c e , u p d a t i n g t h e p a t i e n t d i r e c t o r y ,
a n d f i r s t - l i n e t r o u b l e s h o o t i n g . T h e t h i r d g r o u p
w a s t h e P A C S e n g i n e e r s . T h i s tr a i n i n g w a s m o s t
e l a b o r a t e . I t i n c l u d e d a l l o p e r a t i o n a l a s p e c t s o f
t h e P A C S .
I n S e p t e m b e r 1 9 9 2 , t h e a u t h o r s t r a n s f e r r e d
t h e r e s p o n s i b i l i t y o f d a i l y o p e r a t i o n t o a n e w
P A C S m a n a g e m e n t t e a m a t U C L A , a n d w e
r e l o c a t e d t o U C S F t o d e v e lo p a s e co n d g e n e r a -
t i o n P A C S . T h i s r e p o r t o n l y s u m m a r i z e s t h e
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Global Ethernet
9 s ,
Central Node CHS)
I__
PACS
Con~oller
PACS
Damb~ Se~er
FDDI
To Medical Plaza
Advanced MR
Imaging Center
20~)
UltraNet
B
Global Ethernet
E t ~ ~
To CHS
FDD1
n
al Node Medical Plaza)
UltraNet
T
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PACS-SECOND TIME 51
UCLA system up to September 1992. Further
development of the UCLA system has since
been done by the new management team.
THE SECOND TIME UCSF
We started to plan the second generation
PACS at UCSF in October 1992. In addition to
following our previous PACS design philosophy
at UCLA, we have redesigned the PACS asa
hospital-integrated system, o and built the frame-
work in the infrastructure for future PACS-
based radiology research, la
There are several major differences between
the UCSF and the previous UCLA PACS de-
sign, among them intelligent image archiving
and distribution; integration of hospital informa-
tion system (HIS), radiology information system
(RIS), 12 and other manufacturer s PACS compo-
nents; new network architecture and technol-
ogy; and collaboration with manufacturers to
develop new display workstations. This section
describes these major features.
Intelligent Im age Arc hive an d D is tr ibution
The UCLA PACS was designed with focus on
system reliability and data integrity, promising
24-hour on-line service and no loss of images.
Images were managed in the individual PACS
component on a first come-first serve basis,
which resulted in inefficient image distribution
and retrieval.
The second generation UCSF PACS design
includes more intelligent and thereby minimizes
access time for both current and historical
images. The system is hospital-integrated and
based on a composite staging mechanism using
multiple storage media, HIS and RIS, and the
client server concept.
Two major aspects are considered in the
implementation of the second-generation UCSF
PACS: data integrity, which promises no loss of
images once the PACS receives the images from
Fig 1. A) U C L A P A C S n e t w o r k a t t h e C e n t e r f o r H e a l t h
S c ie nc e s , a nd r e m ot e M R s i t e . ( B ) U C LA P A C S ne t wor k a t
M e dic a l P la z a . The y a r e c onne c t e d t oge t he r . C H S , C e nt e r f o r
t he H e a l t h S c ie nc e s ; Ge nU n , ge n i t our ina r y r a d io logy ;
PCR,
P hi lips c om put e d r a d iogr a phy ; P e ds , pe d ia t r i c r a d io logy ; RIS,
r a d i o l o g y i n f o rm a t i o n s y s te rn ( R e p r i n te d f r o m C o m p u t e r i z e d
M e d ic a l Im a g ing Gr a ph ic s ,
V o l 17 , Huang HK , T a i r a RK , Lou
SL, e t a l , Im p le m e nt a t ion o f a la r ge s ca le p ic t u r e a r ch iv ing a nd
comrnunicat ion sys tem, pp 1-11, 1993, w i t h p e r m i s s i o n f r o m
E ls ev ier S c ie nc e L t d , The B ou le v a r d , La n gf or d La ne , K id l ing t on
OX 5 1GB, UK. 9)
the radiologic imaging system and system effi-
ciency, which minimizes access time for images
at the display stations. The following describes
some major components.
L o ca l stor ag e ma n a g eme n t v ia P A CS in ter co m
p o n en t co mmu n ica t io n .
To ensure data integ-
rity, the UCSF PACS always retains two copies
of an individual image on separate storage
devices until a successful archive of the image to
the long-term optical disk library has been
made. This backup scheme is achieved via the
PACS intercomponent communication:
(1) At the radiologic imaging system: Images
are not dele ted from the imaging devices unless
technologists have verified the successful archiv-
ing of individual images via the PACS terminals.
Should any failure of the acquisition process or
the archival process occur, images can be resent
from these imaging systems to the PACS; (2) At
the acquisition subsystem: Images acquired in
the acquisition subsystem remain on its local
magnetic disks until the archive subsystem ac-
knowledges back to the acquisition subsystem a
successful archive. These images are then de-
leted from the magnetic disks so that storage
space from these disks can be reclaimed; (3) At
the archive subsystem: Images received in the
archive server from various acquisition nodes
are not deleted before their successful archiving
to the optical storage. On the other hand, all
archived images are stacked in the archive
server s cache magnetic disks and will be de-
leted based on their aging criteria (eg, number
of days an examination is performed, discharge
or transfer of a patient, etc).
Mu ltiple s torage m edia.
The storage manage-
ment system features three levels of user-
accessible storage media: (1) redundant array of
inexpensive disks (RAID) in the display station
for immediate access for current images; (2)
magnetic disks in the archive server for fast
retrieval of cached images; and (3) erasable
magneto-optical disks and WORM disks in the
optical disk library for retrieval of any historical
images. On the other hand, all local magnetic
disks in the radiologic imaging systems and the
acquisition subsystem are used for storing newly
acquired images. These images are deleted once
they have been successfully archived to the
optical disks. Table 1 illustrates the configura-
tion of these multiple level storage media.
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52 HUA N G E T A L
T a b t e 1 M u l t i p l e S t o r a g e D e v i c e s f o r I m a g e s in t h e S t o r a g e M a n a g e m e n t S y s t e m
Storage Media Location Purpose
Level 1
Level 2
Level 3
Redundan t a r r ay o f i nexpens i ve d i sks
t e m p o r a r y s t o ra g e )
Ma gne t i c d i sks t emp or a r y s t o r age )
Ma gne to - o p t i ca l d i sks I onge r - t e r m
s to r age )
W O R M d i sk s p e r m a n e n t s t o ra g e )
D isp lay subsys tem d i sp lay hos t )
A r ch i ve subsys tem a r ch i ve se r ve r )
A r ch i ve subsy s tem op t i ca l d i sk l ib r a r y )
A r ch i ve subsys tem op t i ca l d i sk l i b ra r y )
P r ov ides imme d ia te access to bo th
cu r r en t and se lec ted h i s t o r i ca l images
P r ov ides f as t r e t r ieva l o f cu r r en t images
P r ov ides r e t r i eva l o f h i s t o r i ca l images
P r ov ides r e t r i eva l o f h i s t o r ica l im ages
RAI D t ech n o l o g y a p p l i ed t o PACS s t o r a g e .
All h igh- reso lu t ion (2 ,048 x 2 ,048 p ixe l s ) d i s -
p l a y s t a ti o n s i n t h e U C S F P A C S a r e c o n f i g u r e d
w i t h 5 - G b y t e h i g h - p e r f o r m a n c e R A I D . W i t h
th i s co nf ig ura t ion , a 2 ,048 2 ,048 x 10-b it
( 8 - M b y t e ) C R i m a g e c a n b e d i s p l a y e d i n l e s s
t h a n 2 s e c o n d s .
Fo l d er ma n a g er .
T h e s t o r a g e m a n a g e m e n t
s y s t e m i s c h a r a c t e r i z e d b y i t s o n - l i n e p a t i e n t
f o l d e r m a n a g e m e n t . 13 W h e n t h e f ir st r a d i o l o g i-
c a l e x a m i n a t i o n i s s c h e d u l e d , a p a t i e n t f o l d e r i s
c r e a t e d i n t h e P A C S c o n t r o l l e r f o r t h e g i v e n
p a t i e n t . D u r i n g t h e p a t i e n t s h o s p i t a l s ta y , t h i s
f o l d e r r e m a i n s i n t h e d i s p l a y s t a t i o n ( s ) f o r
i m m e d i a t e a c c e s s u n t i l t h e p a t i e n t i s d i s -
c h a r g e d , t r a n s f e r r e d , o r o t h e r a g i n g c r i t e r i o n
( e g , t w o d a y s a f t e r a n o u t - p a t i e n t v i s i t ) i s m e t .
T h e p a t i e n t s a d m i s s i o n , d i s c h a r g e , a n d t r a n s f e r
( A D T ) i n f o r m a t i o n i s o b t a i n e d d i r ec t ly fr o m
t h e H I S a n d R I S . I m a g e s a n d a s s o c i a t e d d a t a
f r o m a n y n e w e x a m i n a t i o n s o f t h e p a t i e n t a r e
c o n t i n u a l l y a d d e d t o t h e e x i s t i n g f o l d e r s o t h a t
n o r e d u n d a n t p r e f e t c h i n g p r o c e d u r e s w i l l b e
p e r f o r m e d . B y a p p l y i n g t h e f o l d e r m a n a g e r
c o n c e p t , t h e p r e f e t c h m e c h a n i s m is o n l y p e r -
f o r m e d o n c e p e r h o s p i t a l s t a y o f a n i n d i v i d u a l
p a t i e n t .
Im p lem en ta t io n o f the In te l ligen t Arc h ive Server
H I S / R I S / P A C S i n t e r f a c i n g . I n t e r f a c i n g t h e
H I S a l l o w s t h e s t o r a g e m a n a g e m e n t s y s t e m t o
r e c ei v e p a t ie n t A D T m e s s a g e s. I n t e r f a c i n g th e
R I S , o n t h e o t h e r h a n d , a l l o w s t h e s t o r a g e
m a n a g e m e n t s y s t e m to r e c e iv e i n f o r m a t i o n s u c h
a s p a t i e n t a r r i v a l , e x a m i n a t i o n s c h e d u l i n g , e x -
a m i n a t i o n c a n c e l l a t i o n , e x a m i n a t i o n c o m p l e -
t i o n , e t c . T h e s e e v e n t s t r ig g e r t h e s t o r a g e m a n -
a g e m e n t s y s t em t o p e r f o r m t h e p r e f e t c h , s t u d ie s
g r o u p i n g , a n d p l a t t e r m a n a g e m e n t m e c h a -
n i sm s . E x c h a n g e o f m e s s a g es a m o n g t h e s e h e t -
e r o g e n e o u s c o m p u t e r s y s t e m s i s c o n d u c t e d i n
t h e H e a l t h L e v e l S e v e n ( H L 7 ) s t a n d a r d d a t a
f o r m a t 14 w i t h t h e u s e o f T r a n s m i s s i o n C o n t r o l
P r o t o c o l / I n t e r n e t P r o t o c o l ( T C P / I P ) p r o t o c o l s
o n a c l i e n t / s e r v e r b a s i s .
I n teg r a ti o n w i t h o t h er ma n u f a c t u r er s P A C S
co mp o n en t s .
T h e U C S F s e c o n d g e n e r a t i o n
P A C S c a n i n t e g r a te w i t h o t h e r m a n u f a c t u r e r s
P A C S c o m p o n e n t s u s i n g t h e D i g i t a l I m a g i n g
a n d C o m m u n i c a t i o n s i n M e d i c i n e ( D I C O M )
3 . 0 s t a n d a r d . A n e x a m p l e i s t h e A e g i s u l t r a -
s o u n d P A C S ( A c u s o n , M o u n t a i n V i e w , C A ) . 15
I n th i s c a se , P A C S t r e a ts t h e A e g i s a s a P A C S
a c q u i s i t i o n d e v i c e a n d c o o r d i n a t e s t h e U S i m -
a g e s th e s a m e w a y a s C T a n d M R i m a g e s in t h e
p a t i e n t s i m a g e f o l d e r .
Image rout ing. B e f o r e s u c c e s s f u l a r c h i v i n g
t o l o n g - t e r m o p t i c a l s t o r a g e , a ll c u r r e n t i m a g e s
a r r i v e d a t t h e a r c h i v e s e r v e r f r o m v a r i o u s a c q u i -
s i ti o n n o d e s a r e i m m e d i a t e l y r o u t e d t o t h e i r
d e s t i n a t i o n d i s p l a y s ta t i o n ( s ) . T h i s r o u t i n g m e c h -
a n i s m m i n i m i z e s a c c e ss t i m e f o r c u r r e n t i m a g e s
a t t h e d i s p l a y s t a t i o n s . T h e r o u t i n g p r o c e s s i s
d r i v e n b y a p r e d e f i n e d r o u t i n g t a b l e c o m p o s e d
o f p a r a m e t e r s i n c l u d i n g e x a m i n a t i o n t y p e , d i s -
p l a y s t a t i o n s i t e , ra d i o l o g i s t , a n d r e f e r r i n g p h y s i -
c i a n . T h e r o u t i n g a l g o r i t h m p e r f o r m s t a b l e
l o o k - u p b a s e d o n t h e s e p a r a m e t e r s a n d d e t e r -
m i n e s w h e r e a n i m a g e s h o u l d go .
Image s tacking.
S t a c k i n g c u r r e n t i m a g e s i n
t h e a r c h i v e s e r v e r s c a c h e m a g n e t i c d i s k s a ll o w s
t h e s e i m a g e s t o b e r e t r i e v e d f r o m t h e h i g h -
s p e e d m a g n e t i c d i s k s i n s t e a d o f t h e l o w - s p e e d
o p t i c a l d i s k s . T h e a r c h i v e s e r v e r h o l d s a s m a n y
i m a g e s i n i t s m a g n e t i c d i s k s a s p o s s i b l e a n d
m a n a g e s t h e s e i m a g e s o n t h e b a s is o f t h e i r a g i n g
c r i t e r i a . D u r i n g a h o s p i t a l s t a y , f o r e x a m p l e ,
i m a g e s b e l o n g i n g t o a g i v e n p a t i e n t r e m a i n o n
t h e m a g n e t i c d i s k s o f t h e a r c h i v e s e r v e r u n t i l t h e
p a t i e n t i s d i s c h a r g e d o r t r a n s f e r r e d .
I m a g e a g i n g .
A g i n g c r i t e r i a s u c h a s n u m b e r
o f d a y s s i n c e a n e x a m i n a t i o n w a s p e r f o r m e d ,
d i s c h a r g e o r t r a n s f e r o f a p a t i e n t , o r c l as s o f t h e
p a t i e n t ( i n - p a t i e n t o r o u t - p a t i e n t ) a r e u s e d b y
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PACS SECOND TIME 53
t h e s t o r a g e m a n a g e m e n t s y s t e m t o c o n t r o l t h e
m i g r a t i o n o f im a g e s f r o m o n e s t o r a g e d e v i c e to
a n o t h e r ( e g , f r o m a m a g n e t o - o p t i c a l d i s k t o a
W O R M d is k) o r th e d e l e t i o n o f i m a g e s f r o m
t h e i r r e s i d e n t s t o r a g e d e v i c e s .
Image prefetching
T h e p r e f e t c h i n g m e c h a -
n i s m 16 is t r i g g e r e d b y m e a n s o f a p a t i e n t a r r i v a l
m e s s a g e f r o m t h e R I S . S e l e c t e d h i s t o r i c a l i m -
a g e s a r e r e t r i e v e d f r o m t h e l o n g - t e r m o p t i c a l
s t o r a g e . T h e s e i m a g e s a r e t h e n d i s t r i b u t e d t o
t h e d e s t i n a t i o n d i s p l a y s t a t io n ( s ) b e f o r e c o m p l e -
t i on o f t h e p a t i e n t s c u r r e n t e x a m i n a t i o n .
P r e f e t c h i n g h i s t o r i c a l i m a g e s t o t h e d i s p l a y
s t a t io n s m i n i m i z e s o n - l f n e i m a g e r e t r i e v a l , h e n c e
r e li e v in g p e a k - h o u r w o r k l o a d o f th e a r c h i v e
s u b s y s te m a n d t h e n e t w o r k s . T h e p r e f e t c h a l go -
r i t h m is b a s e d o n p r e d e f i n e d p a r a m e t e r s s u c h a s
e x a m i n a t i o n t y p e , d i s e a s e c a t e g o r y , r a d i o l o g i s t ,
r e f e r r i n g p h y s i c i a n , l o c a t i o n o f d i s p l a y s t a t i o n ,
a n d t h e n u m b e r a n d a g e o f t h e p a t i e n t s a r -
c h i v e d i m a g e s . T h e s e p a r a m e t e r s d e t e r m i n e
w h i c h h i s t o r i c a l i m a g e s s h o u l d b e r e t r i e v e d
f r o m t h e l o n g - t e r m a r c h iv e .
Studies grouping
D u r i n g a h o s p i t a l s t a y , a
p a t i e n t m a y u n d e r g o d i f fe r e n t e x a m i n a t io n s o n
d i f f e r e n t d a y s. I m a g e s f r o m t h e s e e x a m i n a t i o n s
a r e a r c h i v e d t o t h e e r a s a b l e m a g n e t o - o p t i c a l
d is ks , w h e r e t h e y a r e s c a t t e r e d a c r o s s d i f f e r e n t
p l a t te r s . W h e n a p a t i e n t i s d i s c h a r g e d o r t r an s -
f e r r e d , t h e s e i m a g e s a r e t h e n g r o u p e d f r o m t h e
m a g n e t o - o p t i c a l d i s k s a n d c o p i e d c o n t i g u o u s l y
t o a s in g le W O R M d i sk o r t o c o n s e c u t i v e
W O R M d is ks f o r p e r m a n e n t s to r a ge . O n c e
t h e s e i m a g e s h a v e b e e n a r c h i v e d p e r m a n e n t l y ,
t h e y a r e r e m o v e d f r o m t h e m a g n e t o - o p t i c a l
d i s k s s o t h a t s t o r a g e s p a c e i n t h e m a g n e t o -
o p t i c a l d i s k s c a n b e r e c l a i m e d . S t u d i e s g r o u p i n g
a l l o w s a l l i m a g e s f r o m a p a t i e n t d u r i n g a h o s p i -
t a l s t a y t o b e a r c h i v e d c o n t i g u o u s l y t o o p t i c a l
d i s k ( s ) , h e n c e o p t i m i z i n g f u t u r e r e t r i e v a l o f a
p a t i e n t s i m a g e s fr o m m u l t i p l e e x a m i n a t i o n s .
Plattermanagement P l a t t e r m a n a g e m e n t a l -
l o c a te s t h e s t o r a g e s p ac e r e s e r v e d in t h e W O R M
d i sk s f o r f u t u r e i m a g e s i n c a s e a p a t i e n t r e v is i ts
o r i s r e a d m i t t e d t o t h e h o s p i t a l . I n t h i s w a y ,
i m a g e s o f a p a t i e n t f r o m m u l t i p l e h o s p i t a l v i s i t s
c a n b e a c c u m u l a t e d i n a s in g le W O R M d i s k o r
i n c o n s e c u t i v e d i s ks , r e d u c i n g e x c e s s d i sk s w a p -
p i n g a n d c o n s e q u e n t l y m i n i m i z i n g r e t r ie v a l t i m e
f o r t h e se i m a g e s. H o w e v e r , p r e a l l o c a t i n g s t o r -
a g e s p a c e i n a n o p t i c a l d i s k f o r a p a r t i c u l a r
p a t i e n t i s e x p e n s i v e . L o g i c a l ly g r o u p i n g c o n s e c u -
t iv e o p t ic a l d i sk s i n t o o n e v o l u m e , o n t h e o t h e r
h a n d , c a n r e d u c e d i s k s w a p p i n g t i m e a n d h e n c e
m i n i m i z e s t h e r e t r i e v a l t i m e f o r i m a g e s s t o r e d
i n d i f f e r e n t di sk s w i t h i n t h e s a m e v o l u m e .
Networking
O n e d i s ti n c t d i f f e r e n c e in n e t w o r k i n g b e -
t w e e n th e U C S F a n d th e U C L A P A C S is t h e
a v a i la b i li ty o f a s y n c h r o n o u s t r a n s f e r m o d e
( A T M ) t e c h n o l o g y in th e U C S F s y st em . T h e
U C L A n e t w o r k s w e r e m a i n l y a l o c a l a r e a n e t -
w o r k ( L A N ) w i t h E t h e r n e t , F D D I , a n d U l t ra -
n e t. I n t h e U C S F P A C S n e t w o r k s , A T M is u s e d
b o t h in w i d e a r e a n e t w o r k ( W A N ) a n d L A N
w i t h t h e c o n v e n t i o n a l T - 1 a n d E t h e r n e t a s
b a c k - u p , r e s p e c t i v e l y . 17 F i g u r e 2 s h o w s t h e l o gi -
c a l n e t w o r k c o n n e c t i o n a n d F i g 3 s h o w s t h e
p h y si c al A T M c o n n e c t i o n .
Image Display
T h e U C S F P A C S i m a g e d is p la y s ys t em is
b a s e d o n t h r e e i m p l e m e n t a t i o n m e t h o d s : u s i n g
e x i s t i n g i n - h o u s e w o r k s t a t i o n s , w o r k i n g w i t h
m a n u f a c t u r e r s t o d e v e l o p n e w w o r k s t a t i o n s ,
a n d d i s t r i b u t in g i m a g e s a n d p a t i e n t t e x t u a l d a t a
t o e xi s ti n g l o w - e n d d e s k t o p M a c i n t o s h c o m p u t -
e r s ( A p p l e C o m p u t e r s , C u p e r t i n o , C A ) . I n t h e
f ir st t y p e , w e m o d i t h e t w o - m o n i t o r 2 K
d i sp l ay w o r k s ta t i o n s d e v e l o p e d a t U C L A b y
a d d i ng t h e H I S / R I S i n t e r f a c e a n d s o m e e x t r a
d i s p l a y f u n c t i o n s . A n e x a m p l e i s t h e M o n t a g e
f u n c t i o n t h a t a l lo w s t h e a s s e m b l y o f im a g e s
f r o m d i f f e r e n t e x a m i n a t i o n s i n t o o n e f il e. T h e s e
w o r k s t a t i o n s a r e u s e d in t h e n e u r o r a d i o l o g y a n d
p e d i a t r i c r a d i o l o g y s e ct i o ns . S e c o n d , w e w o r k e d
F ig 2 . D e p a r t m e n t o f R a d i o l o g y U C S F L o g i ca l N e t w o r k
A r c h i t e c tu r e w h i c h i n c l u de s W A N a n d L A N . T h e e x t e rn a l
n e t w o r k i s o p e n w h e r e a s t h e i n t e rn a l n e t w o r k h a s a f i r e w a l l
p r o t e c t i o n .
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54 HUANG ET AL
I ~ I u ''~ 17 6x~0.ioh
, OM ~ , , ,- - ~ , ./ /I \ \ \
A T M S w i t c h
A S X 2 0 0
UCSF
Siemens
G E 5X G E S X G E 5X G E 5X I m a tr onGE9800
G E S p i r a f G E S p i r a l G E S p i r a l I m p ac t
LP P I M RS C UCI C1 UC lC2 Lo ng Long Long UC lC CT M ZH M ZH
~CQ
U V U T P
I LAN Acr I
S w i t c h
LAX 20
Mt. Z i o n
Sing~ e Mode Fibers
Switch
O a k l a n d
F i g 3 . F i rs t p h a s e A T M c o n n e c t io n b e t w e e n U C S F a n d M t Z i o n H o s p i t al ; - - ) c o m p l e t e d , . . . . . ) s e c o n d p h a s e . W A N a n d L A N A T M
155 m b i t s / s e c ) N e t w o r k P h y s ic a l C o n n e c t i o n a t U C S F . F o r t h o s e o l d e r c o m p o n e n t s t h a t d o n o t support ATM, a n A T M t o L A N s w i t c h
i s u s e d w h i c h
supports 10
m b i t s / s e c f o r e v e r y n o d e c o n n e c t e d t o t h e s w i t c h .
with ISG Technologies Inc Toronto, Ontario,
Canada) to develop the two-monitor 1,600-1ine
display stations for ICU applications. Figure 4
shows such a workstation.
The third method is to develop a file server to
distribute integrated PACS images and textual
data to the Macintosh desk top computers for
individual review, teaching, and research.~8 Fig-
ure 5 shows the distributed network and Fig 6
depicts a page on the Macintosh screen.
M J O R D I F FE R E N C E S B E T W E E N T H E U C S F
N D T H E U C L P C S
This section summarizes some major differ-
ences between the UCSF and the UCLA PACS.
P C S C o n t r o ll e r
The PACS controller is an intelligent ma-
chine that controls the flow of data within the
entire PACS from acquisition data input) to
archiving long-term and short-term storage)
and display data output) . The primary func-
tions of the PACS controller include: 1) accept-
ing images from acquisition nodes; 2) accept-
ing HIS /RIS data; 3) updating global PACS
data base; 4) archiving images to optical disks;
5) routing images and HIS/RIS data to display
workstations; 6) handling retrieval requests
from display stations.
The PACS controller implemented in the
UCLA PACS was a single-processor Sun
SPARCserver 490 computer, from which a one
terabyte optical disk library based on 14 inch
platters was attached. A three-tiered communi-
cation network comprising Ethernet, FDDI,
and the proprietary fiber-optic UltraNet net-
work was used to provide independent paths for
data transmission between the PACS controller
and other PACS computers. Images acquired
from radiologic imaging devices were trans-
ferred from various acquisition nodes to the
PACS controller, where they were then routed
to destination display stations and were ar-
chived chronologically on WORM optical disks.
With its fault-tolerant design, the PACS control-
ler focused on system reliability and data integ-
rity, promising 24-hour on-line service and no
loss of images.
The PACS controller developed at UCSF
includes more intelligence and thereby mini-
mizes access time for both current and previous
imaging studies. The computer system is based
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PACS-SECOND TIME 55
Fig 4. A 1,600-1ine tw o moni tor wo rkst ati on fo r ICUs. This station consists of a SPARC 20 with 128 Mbytes m emory and two
TurboGXplus cards, all off-the-shelf components. The display soft ware w s d e v e l o p e d by ISG Technologies Inc based on UCSF
specific ations The communication interface between workst atio ns and the PACS contro ller was codeveloped by both parties b s e d
on the DICOM standard.
on the SUN 690 Sun Microsystems) with four
central processing units CPUs), which allows
multiple processes to run simultaneously with
minimal shared CPU time. Two standard net-
work interfaces, the Ethernet and the 155-bit
~ ~ ~ . ~
~ V
Fig 5. Distributed image file servers connected to the PACS
controller. Eac h server provides specific applications for a
given cluster of users. One of this clusters is to serve the
Macintosh users in the department to access PACS data.
sec bandwidth ATM, OC 3 networks, are used
for receiving and distributing images. The opti-
cal disk library attached to the PACS controiler
supports both erasable magneto-optical disks
and WORM disks. A composite staging mecha-
nism is implemented in the PACS controller to
manage images stored in its multiple storage
media: magnetic disks immediate-access tempo-
rary storage), crasable magneto-optical disks
Ionger-tcrm archive data cache), and WORM
disks permanent storage). This second-genera-
tion PACS controller differs from the first-
generation system in severai of its new features:
multiple storage media, image stacking, auto-
mated image prefetching, studies grouping, plat-
ter management, and HIS/RIS/PACS interfac-
ing. Table 2 shows the major differences in the
infrastructure design between the two systems.
In Table 2 there are several items that were
not considered in the original UCLA design, for
example, integration to the HIS/RIS and other
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5 6 H U A N G E T A L
v e n d o r s P A C S . T h e r e a s o n w a s b e c a u s e t h e
h o s p i t a l -i n t e g r a te d c o n c e p t w a s n o t i n t r o d u c e d
u n t il 1 99 2. A l so , t h e A m e r i c a n C o l l e g e o f R a d i -
o l o g y - N a t i o n a l E l e c t r i c a l M a n u f a c t u r e r s A s s o -
c ia ti on ( A C R - N E M A ) a n d D I C O M w e r e n o t
r e a d y f o r i m p l e m e n t a t i o n i n 19 91 . O n t h e o t h e r
h a n d , t h e U C S F P A C S d o e s n o t h a v e a d u p l i -
c a t e P A C S c o n t r o l l e r a n d a l l a r c h i v i n g i s d o n e
w i t h i n o n e s i t e a r e b e c a u s e o f l im i t e d s p a c e a n d
f i n a n c i a l r e s o u r c e .
T a b l e 2 . D i f f e re n c e s i n t h e I n f r a s t r u c t u r e D e s i g n
UCLA
as of
September
1992) UCSF
O p e n a r ch i t e c t u re l i m i t e d Y
C o n n e c t i v i t y l ir n i te d Y
S t a n d a r d i z a t i o n
A C R - N E M A , D I C O M N Y
H L 7 N Y
T C P / I P Y Y
I n t e r f a ce t o H I S / R I S N Y
I n te r f a c e t o o t h e r v e n d o r P A C S
m o d u l e s N Y
M i r r o r e d d a t a b a s e Y Y
D u p l i c a te P A C S c o n t r o l a n d a r c h i v i n g Y N
D i f f e re n t s i te s f o r a r ch i v i n g Y N
A u t o r o u t i n g u Y
I m a g e p r e f e t c h i n g N Y
I m a g e s e q u e n c i n g N i n p r o g r e s s
A b b r e v i a t i o n s : Y , Y e s ; N , N o .
Fig
6. A
p a g e o n t h e M a c i n
tosh screen. T he user can
d i -
r e c t l y
access both images and
t e x t u a l
i n f o r m a t i o n i n c l u d i n g
d i -
a g n o s t i c
r e p o r t s f r o m P A C S . T h e
' T o o l s ' k i t
a l l o w s u s e r t o m a
n i p u l a t e i n d i v i d u a l i m a g e s w h i c h
inc ludes programs l ike Na t iona l
I n s t i t u t e s o f H e a l t h I m a g e , e t c.
Networking
T a b l e 3 s h o w s t h e m a j o r d i f f e r e n c e s in n e t -
w o r k d e s i g n b e t w e e n t h e s e t w o s y s t e m s . T h e
U C L A n e t w o r k w a s m a in l y a L A N w i th v e ry
l o n g f ib e r o p t i c c a b le c o n n e c t i o n s b e t w e e n b u i ld -
i n g s , w h e r e a s t h e U C S F s y s t e m i n c l u d e s b o t h
W A N a n d L A N .
I t i s s e e n i n T a b l e 3 t h a t t h e U C S F n e t w o r k
d e s i g n i s m o r e s o p h i s t i c a t e d w i t h u p - t o - d a t e
n e t w o r k t e c h n o l o g y . O n t h e o t h e r h a n d , t h e
U C L A s y s te m h a d t h e h i g h e r s p e e d p r o p r i e t a r y
U l t r a n e t f o r h i g h s p e e d i m a g e c o m m u n i c a t i o n s .
T h e U C L A s y st e m h a d n o f i re w a ll p r o te c t i o n
f o r d a t a i n t e g r i t y a n d s e c u r i t y , w h i c h w a s a m a i n
d r a w - b a c k in n e t w o r k d e s ig n .
lmage Acquisition Component
CT a n d M R T h e U C L A C T / M R im a g e
a c q u i s it i o n s y s te m s w e r e a l l m a d e b y G e n e r a l
E l e c t r i c M e d i c a l S y s t e m s ( M i l w a u k e e , W I ) . I n
t h i s r e g a r d , t h e G E 9 , 8 0 0 C T s c a n n e r s u s e d G E
I D N E T - 1 c o n f i g u r a t i o n f o r i n t e rf a c i n g , a n d t h e
i m a g e a c q u i s i t io n p r o c e s s e s o f G E h i g h - s p e e d
C T s c a n n e r s a n d S ig n a 5 x M R s c a n n e rs w e r e
b a s e d o n G E p r o p r i e t a r y c o m m u n i c a t i o n p ro t o -
c o ls . T h e a c q u i s i ti o n p r o c e s s e s i n t h e P A C S d i d
n o t h a v e p a t i e n t I D v e r i f i ca t i o n a l g o r it h m , n o
a u t o m a t i c p r o c e s s r e c o v e r y m e c h a n i s m , a n d n o
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PACS-SECOND TIME 57
T a b l e 3 D i f fe r e n c e s B e t w e e n t h e T w o N e t w o r k s
UCLA* UCSF
9 Fibers were used to connect remote buildings, but the back-
bone primarily consisted of Thicknet Ethernet (copper) that
stretched through multiple buildings and levels.
9 Clinical acquisition, Research, and Distr ibut ion networks
were all physically connected to the same subnet. Ultranet
used for 2K distribution only.
9 AUI cables were connected d irectly to the backbone as
opposed to CAT 5 UTP cables. Radiology Dept did not have
a direct connection to the Internet.
9 Ultranet was used fo r transfer of images from the PACS Con-
trolle r to the 2K display stations at a tate of 125 Mb/s. The
transfer of information between the two Ultranet hubs in
CHS and Medical Plaza was striped between fou r 250 Mb/s
fibers giving a total transfer rate of 1,000 Mb/s or 1 Gb/s.
9 No routers or firewa lls were used.
9 No WAN connections.
9 Only Med Plaza hada UPS.
9 The backbone consists of primari ly fibe r optics, but CAT 5
UTP is the media used for station connections.
9 ATM via fiber used for acquisition and distribution.
9 The design is a distributed star configu ration with multiple
subnets. For examples, Genesis ne twork is used to connect
the digital modalities le, CT, MR to the PACS controller. The
departmental network is used to distribute images to Macin-
tosh's users, etc.
9 PACS External network is used fo r transferring image data
from the imaging modalities to the acquisition computers.
The internal network, with a firewall protection is used to
transfer data from the acquisition computers to the PACS
Controller.
9 The External ne twork is also used asa backup network for
the display systems.
9 Distribution to the 1K stations is done via ATM, which uses a
dedicated 155 MB/s fiber optic connection directly to the
PACS Controller.
9 Distribution to the 2K systems is done through an ATM to
Ethernet switch, which has dedicated 10 Mb/s connections
to each station.
9 Radiology has direct connections to the Internet via the
departmental network which has over 100 connections to
faculty and staff offices.
9 Routers and gateways are used to divide subnets and insure
security among the networks.
9 The network has T1 and ATM WAN connections to two aff ili-
ated hospitals. Network hubs are backed up by UPS's.
*As o f September 1992.
Abbrevia tions: AUI, attachment unit interface; CAT UTP, category 5 unshielded twis t pair; UPS, uninterrupted power supply.
a u t o m a t i c p a g i n g s y s t e m f o r e n g i n e e r i n g s e r -
v i c e . T h e i m a g e h e a d e r f o r m a t w a s b a s e d o n a
U C L A i n te r n a l d e s ig n a n d w a s n o t st a n d a rd .
T h e U C S F C T / M R i m a g e a c q u i s it i on sy s-
t e m s c o n s is t o f m u l t iv e n d o r e q u i p m e n t i n c lu d -
i n g G E , S i e m e n s E r l a n g e n , G e r m a n y ) , a n d
I m a t r on S o u t h S a n F r a n c i sc o , C A ) . T h e G E
9 8 0 0 C T s c a n n e r u s e s G E I D N E T - I I c o n f ig u r a -
t i o n f o r i n t e r f a c i n g , a n d i m a g e a c q u i s i t i o n p r o -
c e s s e s o f G E s p ir a l C T s c a n n e r s a n d S i g n a 5
M R s c a n n e rs a re b a s e d o n D I C O M s ta n d a rd
c o m m u n i c a t i o n p r o t o c o l u p p e r le v e l f o r T C P /
I P ). T h e S i e m e n s a n d I m a t r o n u s e t h e ir o w n
p r o p r i e t a ry i n t e r f a c e p r o t o c o l s .
T h e P A C S a c q u i s i t i o n c o m p u t e r s h a v e a
p a t i e n t I D v e r i f i c a t i o n a l g o r i t h m t o c o r r e c t
t y p o g r a p h i c a l e r r or s b y im a g i n g m o d a l i t y t e c h n i -
c i an s , a m e c h a n i s m t o a u t o m a t i c a l l y r e c o v e r
i m a g e a c q u i s i t i o n p r o c e s s e s , a n d a c e n t r a l p a g -
i n g s c h e m e t o a u t o m a t i c a l l y p a g e s e r v i c e e n g i -
n e e r s f o r s y s te m f a t a l e r r or s . T h e P A C S u s e s
b o th A C R / N E M A 2 .0 a s w e l l as D I C O M 3 .0
h e a d e r i n f o r m a t i o n f o r m a t .
CR The UCLA PACS used earlier versions
of CR technology: Philips 901 and two Philips
7000 laser plate readers Philips Medical Sys-
tems, Shelton, CT), and ST-III type photostimu-
lable phosphor plates; while the UCSF PACS
incorporates the latest in CR technology: Fuji
FCR AC2 and FCR 9,000 plate readers Stam-
ford, CT), and ST-V standard) and HR-V
high-resolution) photostimulable phosphor
plates. The interfacing of the CR devices to
PACS required three different methods: two
different methods for the two different models
of Philips CRs and one method compatible with
both Fuji CRs. The Philips 901 digital interface
consisted of a RS-422 connection to a Data
Interception Circuitry buffer) board and a
DR-11W link over which the image data was
transmitted to the SUN acquisition computer;
textual information demographic and image
header data) carne over an RS-232 cable connec-
tion. The Philips 7,000 interface device included
a PCR interface processor PIP) which con-
tained an auto data transfer board, memory
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5 8 H U A N G E T A L
b u f f e r b o a r d a n d E t h e r n e t b o a r d a n d t r a n sm i t -
t e d b o t h i m a g e s a n d t e x t t o t h e S U N a c q u i s i ti o n
c o m p u t e r o v e r E t h e r n e t . T h e d ig it al i n t e r fa c e
t o P A C S f o r b o t h t h e F u j i A C 2 a n d t h e 9 ,0 0 0
c o n s i st s o f a D M S B u s w i t h a R S - 4 8 5 c a b l e
( w h i c h i s a c o m b i n a t i o n R S - 2 3 2 s e r i a l b u s f o r
m e s s a g e s a n d t e x t u a l i n f o r m a t i o n a n d a n R S -
4 2 2 p a r a l l e l b u s f o r i m a g e d a t a ) c o n n e c t i o n t o
t h e d a t a a c q u i si t io n s y s te m m a n a g e r ( D A S M ) .
T h e D A S M i s b a s i c a l l y a r i n g - b u f f e r e d s m a l l
c o m p u t e r s y s t e m i n t e r f a c e ( S C S I ) d i s k t h a t
t r a n s m i t s b o t h t e x t u a l a n d i m a g e d a t a t o t h e
S U N a c q u i s i t i o n c o m p u t e r o v e r S C S I c a b l e .
T a b l e 4 s u m m a r i z e s t h e d i f f e r e n c e s i n C R
b e t w e e n t h e s e t w o P A C S s y s t e m s .
The Display ornponent
T h e U C L A P A C S d is pl ay c o m p o n e n t c o n-
s i s te d o f t h e 2 K d i s p l a y s ta t i o n s , 1 K d i s p la y
s t a ti o n s , a n d a f il m p r i n t i n g s ta t i on . T h e U C S F
d i s p l a y c o m p o n e n t i s c o m p r i s e d o f 2 K d i s p l a y
s t a t i o n s , 1 K d i s p l a y s t a t i o n s , a n d M a c i n t o s h
s t a ti o n s . B o t h 2 K s t a ti o n s i n t h e U C L A a n d
U C S F P A C S a r e o f t h e s am e h a r d w a r e p l a t-
f o r m . W e d e v e l o p e d t h e s o f t w a r e i n - h o u s e a t
U C L A , a n d c a r r i e d i t o v e r t o U C S F . C e r t a i n
e n h a n c e m e n t s h a v e b e e n a d d e d t o t h e s o ft w a r e
a t U C S F b a s e d o n u s e r s f e e d - b a c k . I n p a r t i c u -
l a r , t h e r e i s a l o c a l m o n t a g e f e a t u r e f o r u s e r s t o
s e l e c t i m a g e s f r o m d i f f e r e n t f i l e s f o r d i s p l a y . A
f e a t u r e w i t h 1 o n 1 f o r c u r r e n t i m a g e s a n d 4 o n 1
f o r h i s t o r i c a l i m a g e s w a s s p e c i f i c al l y d e s i g n e d
f o r p e d i a t r i c C R i m a g e v i e w i n g . T h e s t u d y l i s t
a u t o m a t i c u p d a t e f e a t u r e a l e r t s u s e r s t h a t t h e
a c t i v e ( s e l e c t e d ) p a t i e n t h a s a n e w i m a g e f i l e
j u s t a r r i v e d . A n o t h e r n e w f e a t u r e i s a w o r k s t a -
t i o n u s a g e s t a t i s t i c s o f t w a r e p a c k a g e t o t r a c k
s y s t em u s a g e . T h i s p a c k a g e a l lo w s r e f i n e m e n t o f
w o r k s t a t i o n s o f t w a r e b a s e d o n u s e r s w o r k i n g
h a b i t s .
T h e U C L A 1 K s y st e m w a s d e v e l o p e d b a se d
Table 4 Differences Between the CR Acquisition
Components
UCLA* UCSF
De vices Ph i l i ps 901 Fu ji AC 2
Phi l i ps 7 ,000 tw o) Fu ji 9 ,000
Ph os ph or p la te t yp e ST- II I ST-V , HR-V
I n te r f a ce D R -1 l W b o a r d t o D A S M t o A C 2 a n d
901 9 ,000
PIP to 7 ,000
* A s o f S e p t e m b e r 1 99 2 .
Table 5 Ma jor Differences in the Display Component
Between the Two PAC Systems
Types of
Workstat ion UCLA * UCSF
2 K S U N 4 / 4 7 0 , M e g a - S a m e w i t h n e w
s c a n d i s p l a y b o a r d s e n h a n c e m e n t
w i t h t w o m o n i t o r s s o f t w a r e 4 )
4)
1 K S UN 4 , i n -h o u se d i s - S P A RC 2 0 , T u b o r
p l a y b o a r d w i t h G X + b o a r d s s u p -
t h re e 1 , 0 2 4 m o n i - p o r t i n g 2 , 3 , o r 4
t o r s 2 ) m o n i t o r s 5 )
F i lm p r i n t i n g Y N
PC sta t ion N 100
* A s o f S e p t e m b e r 1 9 96 .
o n a n i n - h o u s e d e s i g n e d d i s p la y b o a r d w h i c h
s u p p o r t e d t h r e e 1 ,0 24 m o n i t o rs . T h e U C S F 1 K
s y s t e m i s d e v e l o p e d i n c o l l a b o r a t i o n w i t h I S G
T e c h n o l o g i e s I n c b a s e d o n o f f - th e - s h e lf c o m p o -
n e n t s . T h i s 1 K s y s te m c a n s u p p o r t e i t h e r 2 , 3 , o f
4 1 , 6 00 li n e m o n i t o r s , a n d h a s v e r y e a sy to u s e
u s e r i n t e r f a c e .
T h e U C S F s y st e m c u r re n t l y d o e s n o t s u p p o r t
a fi lm p r i n t i n g s t a t i o n , i n s t e a d , i t s u p p o r t s o v e r
1 0 0 M a c i n t o s h u s e r s t o r e t r i e v e i m a g e s a n d
r e l a t e d P A C S d a t a f o r re s e a r c h , t e a c h in g , a n d
c a s e r e v i e w . F r o m t h e s e M a c i n t o s h c o m p u t e r s ,
t h e u s e r s c a n s e l e c t o t h e r p r i n t i n g r e s o u r c e s i n
t h e d e p a r t m e n t f o r h a r d c o p y o u t p u t . T a b l e 5
s u m m a r i z e s t h e m a j o r d i f f e r e n c e s in t h e d i sp l ay
c o m p o n e n t s b e t w e e n t h e s e tw o P A C s y st em s .
D l S C U S S l O N
B o t h t h e U C L A a n d t h e U C S F P A C S a r e
d e s i g n e d i n - h o u s e b a s e d o n t h e S U N w o r k s t a -
t i o n p l a t f o r m . B e c a u s e o f t h e e v o l u t i o n o f t h e
P A C S c o n c e p t , t h e U C S F s y s t e m i s d e s i g n e d a s
a h o s p i t a l - i n t e g r a t e d P A C S w i t h t h e A C R -
N E M A a n d D I C O M a n d H L 7 s ta n da rd s . R e l-
e v a n t d a t a f r o m H I S a n d R I S i s a u t o m a t i c a l l y
i n c o r p o r a t e d i n t h e P A C S . O t h e r m a n u f a c t u r -
e r s P A C S c o m p o n e n t s t h a t c o n f o r m w i th t h e s e
s t a n d a r d s c a n b e e a s i l y i n t e g r a t e d i n t o t h e
s y s t e m . T h e U C S F s y s t e m a l s o t a k e s a d v a n t a g e
o f n e w e r c o m m u n i c a t i o n , s t o r ag e , a n d s o f tw a r e
t e c h n o l o g i e s i n A T M , m u l t i p l e s t o r a g e m e d i a ,
a n d a u t o m a t i c p r o g r a m m i n g f o r a b e t t e r c o st -
p e r f o r m a n c e s y st em .
T h e n e w c o n c e p t s o f a u t o - r o u t i n g , p r e f e t c h -
i n g , a n d a u t o - s e q u e n c i n g h a v e i n f l u e n c e d o u r
d e s i g n in t h e U C S F P A C S c o n t r o l l e r , w h i c h is
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PACS SECOND TIME 59
q u i te a d ra s t ic d i f fe r e n c e f ro m t h e U C L A P A C S
c o n t r o l le r . W i t h t h e c l i e n t - s e r v e r c o n c e p t w e
a r e a b le t o i m p l e m e n t t h e M a c i n t o s h s e r v e r t o
d i s t r ib u t e P A C S i m a g e s a n d p a t i e n t t e x t u a l
d a t a t o e v e ry M a c i n t o s h u s e r i n t h e d e p a r t m e n t .
T h i s f e a t u r e w a s n o t a v a i l a b l e i n t h e U C L A
s y s t e m b e c a u s e o f a l a c k o f su c h k n o w l e d g e o n
o u r p a r t a s w e l l a s n o t u n d e r s t a n d i n g t h e
i m p o r t a n c e o f d a t a d i s t r ib u t i o n t o e v e r y r a d i o l o -
g i s t a n d c l i n i c ia n a t t h a t t i m e .
T o o u r d i s a p p o i n t m e n t w e h a v e n o t s e e n a n y
i m p r o v e m e n t i n t h e 2 K d i s p l a y t e c h n o l o g y i n 5
y e a rs . B o t h th e U C L A a n d U C S F 2 K d is p la y
s y s t e m s a r e p r a c t i c a l l y t h e s a m e i n t e r m s o f
h a r d w a r e p l a t f o r m a n d d i s p l a y s o f tw a r e . O n t h e
o t h e r h a n d 1 K d i s p l a y h a s i m p r o v e d in b o t h
p e r f o r m a n c e a n d c o s t .
T h e U C S F h o s p i t a l i n t e g r a t e d P A C S h a s
b e e n d e v e l o p e d t o s u c h a s t a g e t h a t t h e i n f r a -
s t r u c t u r e w i ll n o t b e c o m e o b s o l e t e a n d i t c a n
s u p p o r t a n y n e w P A C S c o m p o n e n t s a s w e l l a s
a d d i t i o n a l a c q u i s i t i o n m o d a l i t i e s a n d d i s p l a y
w o r k s t a t i o n s . P A C S s y s t e m r e f i n e m e n t w i ll c o n -
t i n u e e v o l v i n g f o r h i g h e r r e li a b il it y b e t t e r p e r -
f o r m a n c e a n d n e w a p p l i c a t i o n fu n c t i o n s a s i ts
d e v e l o p m e n t i s a c o n t in u o u s d y n a m i c p r o c e s s .
R E F E R E N E S
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