The second international conference of medical physics

t i s s u e which m a y b e i n t e r p r e t e d as i n c r e a s e d s y n t h e s i s of DNA, as well as of p r o t e i n a n d / o r m u c o p o l y s a c c h a r i d e . The o t h e r p a p e r of t h i s p a i r , by J. B. Pond and R. Warwick, d e a l t with t e s t s for p o s s i b l e i n j u r y p r o d u c e d by u l t r a s o u n d a s e m p l o y e d in diagnostic p r o c e d u r e s , e s p e c i a l l y with p r e g nant women. Mice, in v a r i o u s s t a g e s of p r e g n a n c y , have b e e n i r r a d i a t e d e m p l o y i n g d i f f e r e n t f o r m s of p r o j e c t o r and g e n e r a t o r s to give widely d i f f e r e n t f o r m s of dose at 1, 2 and 3MHz.

P r o g e n y and t h e i r d e s c e n d a n t s w e r e e x a m i n e d for a b n o r m a lity in g r o s s s t r u c t u r e and in the c h r o m o s o m e p i c t u r e s f r o m dividing c e l l s . R e s u l t s so f a r a r e negative, a finding that is of s o m e c o m f o r t . However, it was w a r n e d that m o r e studies and b e t t e r s t a t i s t i c s a r e r e q u i r e d b e f o r e safe l e v e l s can be s t a t e d with c e r t a i n t y . W. L. Nyborg

Boston, 11-16 August 1969

The Second International Conference of Medical Physics f r o m Dean F r a n k l i n who a l s o i s c o n n e c t e d with O c e a n o g r a p h y at La J o l l a C a l i f o r n i a . He helped p i o n e e r Doppler m e t h o d s of flow m e a s u r e m e n t , and e l i c i t the p h y s i c s behind the e a r l y J a p a n e s e publications. On t h i s o c c a s i o n he r e v i e w e d Doppler m e a s u r e m e n t s in r e l a t i o n to ' u p - s t r e a m d o w n - s t r e a m ' t r a n s i t t i m e d i f f e r e n c e m e t h o d s and i n t r o d u c e d a new m o d i f i c a t i o n well suited to t e l e m e t e r i n g blood flow f r o m moving s u b j e c t o r m a r i n e a n i m a l s . In t h i s a continuous f r e q u e n c y modulated 10MHz s o u r c e i s u s e d and the p h a s e d i f f e r e n c e of up-down s t r e a m s i g n a l s a r e c o m p a r e d . The v e r y neat t r a n s d u c e r s have to be i m p l a n t e d n e a r to the a r t e r y . F . M . e l i m i n a t e s the m u l t i p l e path s i g n a l s t h a t tend to confuse fixed f r e q u e n c y o p e r a t i o n of the s y s t e m .

T h i s well o r g a n i z e d c o n f e r e n c e a t t r a c t e d m o r e than 600 p a r t i c i p a n t s and t h r o u g h the g e n e r o s i t y of United States G o v e r n m e n t D e p a r t m e n t s and the A m e r i c a n C a n c e r Society, e x p e r t s in a n u m b e r of s u b j e c t s w e r e invited a s g u e s t s with t h e i r t r a v e l l i n g s u b s i d i z e d . T h e t h e m e of the c o n f e r e n c e w a s R a d i a t i o n but not e x c l u s i v e l y ionizing b e a m s ; U l t r a s o n i c s and L a s e r p h y s i c s and I n s t r u m e n t and C o m p u t e r d e s i g n and T h e r m o g r a p h y had well filled s e s s i o n s too. Medical P h y s i c s now r e p r e s e n t s m u c h t h a t w a s r e g a r d e d a s Medical E l e c t r o n i c s and p e r h a p s for t h i s r e a s o n the ' m o t i f ' of the c o n f e r e n c e p r o g r a m m e was modified f r o m the ' m a r k ' of the ten y e a r old I n t e r n a t i o n a l F e d e r a t i o n of Medical E l e c t r o n i c s by the addition of an e x t r a snake! C e r t a i n l y t h e r e i s m u c h o v e r l a p b e t w e e n the two s o c i e t i e s a s the r e v i e w s of t h e s e two c o n f e r e n c e s show. It i s to be hoped that in f u t u r e t h e r e will be m o r e c o - o r d i n a t i o n b e t w e e n p h y s i c i s t s and e n g i n e e r s and t h a t v i s i t o r s to both will not h a v e a t h r e e week wait between the two p r o g r a m m e s if they should o c c u r a g a i n in the s a m e land. In the 236 c o n t r i b u t i o n s the p h y s i c i s t s r o l e in i n t r o d u c i n g new t e c h n i q u e s and an e n q u i r i n g a p p r o a c h to b a s i c p r i n c i p l e s w a s e m p h a s i z e d . In two s e s s i o n s devoted to 'New Frontiers' subjects discussed were 'Holography'; 'The scanning e l e c t r o n m i c r o s c o p e ' ; and ' C a r d i a c a s s i s t a n c e by an i n t r a - a o r t i c balloon', which, on r e p e a t e d inflation f r o m a pump, m o v e s blood along the a o r t a and allows the h e a r t to ' t a k e i t e a s y ' while r e c o v e r i n g f r o m an i n f a r c t o r o t h e r d i s o r d e r . (The balloon had t h r e e s e p a r a t e c o m p a r t m e n t s , and w a s i n s e r t e d t h r o u g h the f e m o r a l a r t e r y by a m i n o r s u r g i c a l p r o c e d u r e ) . The o t h e r 'New F r o n t i e r ' s e s s i o n w a s devoted to ' T h e p h o t o c h e m i s t r y of excited s t a t e s of DNA c o m p o n e n t s ' ; ' T h e l i m i t s of m a n n e d u n d e r w a t e r a c t i v i t y ' , which s u g g e s t e d t h a t we s h a l l p r o b a b l y l e a r n how to b r e a t h e w a t e r supplied f r o m a n a r t i f i c i a l gill and b e able to dive to the bed of the d e e p e s t s e a s without any of the p r e s e n t h a z a r d s . 'Marts r o l e on the o c e a n f l o o r ' sounds i n t e r e s t i n g once we c a n a r r i v e t h e r e . The C h a i r m a n of the S e s s i o n on U l t r a s o n i c s , R. S, Mackay, e n l a r g e d on the u s e of u l t r a s o n i c s a s a c o m m u n i c a tion m e d i u m u n d e r w a t e r and a s a m e a n s of v i s u a l i z i n g and m e a s u r i n g and t e l e m e t e r i n g s i g n s of bubble f o r m a t i o n in the blood b e f o r e they lead to a t t a c k s of the d a n g e r o u s ' b e n d s ' which d i v e r s get on a s c e n t f r o m high p r e s s u r e work. No c o n f e r e n c e on a d v a n c e s in m e t h o d s of m e a s u r i n g blood flow u l t r a s o n i c a l l y would b e c o m p l e t e without a c o n t r i b u t i o n

A n o t h e r two Doppler s t u d i e s f r o m the U n i v e r s i t y of W i s c o n s i n (Kelsey et al) w e r e c o n c e r n e d with s p e e c h s t u d i e s and phonation. P o o r c o r r e s p o n d e n c e was found between Doppler and d i r e c t p h o t o g r a p h i c r e c o r d i n g of l a r y n x m o v e m e n t s due to a s s o c i a t e d m o v e m e n t s of s u r r o u n d i n g t i s s u e s . On the o t h e r hand the Doppler method c o n f i r m e d that c o - a r t i c u l a t i o n m o v e m e a t s of the p h a r y n x s u p p o r t l a r y n x action, e s p e c i a l l y when high and low pitched vowel sounds a r e p r o d u c e d s i m u l taneously. On the a p p l i c a t i o n s side one o t h e r r e p o r t f r o m Q u e e n s U n i v e r s i t y , Ontario, c o n t r i b u t e d to the m y s t e r y , o r solution, s u r r o u n d i n g the s i g n i f i c a n c e of p u l s a t i n g e c h o e s obtained f r o m i n s i d e the head. White and m a n y c o l l e a g u e s a r e making e c h o e n c e p h a l o g r a m s :and s i m u l t a n e o u s a r t e r i a l p r e s s u r e wave, r e s p i r a t i o n and e l e c t r o c a r d i o g r a p h i c r e c o r d i n g s . The p u l s a t i o n s a p p e a r to affect quite l a r g e a r e a s of the b r a i n . In s o m e i n s t a n c e s they m a y a r i s e f r o m blood flow p u l s a t i o n s in the skull bones. In the f u t u r e t h e s e o b s e r v a t i o n of p u l s a tion m a y a s s u m e d i a g n o s t i c i m p o r t a n c e for p a t i e n t s with s t r o k e s o r b r a i n injury. The quality of b o n e s and conditions leading to r i s k of f r a c t u r e w e r e r e p o r t e d f r o m the U n i v e r s i t y of W i n c o u s i n (Kelsey et al). T h e s e t e s t s a r e sonic r a t h e r than u l t r a s o n i c . The n a t u r a l f r e q u e n c y of the long b o n e s and the jaw can b e d e t e r m i n e d by applying t r a n s d u c e r s n e a r the ends, and e x t e r n a l to the skin. The r e s p o n s e to i m p u l s e s , a n d to sine w a v e s i s studied. R e s o n a n t f r e q u e n c y and d a m p i n g coeff i c i e n t s a r e d e t e r m i n e d . When the r e s u l t s a r e grouped f o r s e x and age d i f f e r e n c e s a b n o r m a l i t i e s can b e d e t e c t e d c h a r a c t e r i s t i c for e x a m p l e of d i a b e t e s , o r of d e c a l c i f y i n g d i s e a s e s . In a s u p p o r t i n g p a p e r by C a m e r o n the effects of age and a c t i v i t y and r a c e a r e included and sonic findings c o m p a r e d with m o n o e n e r g e t i c photon a b s o r p t i o n c h e m i c a l a n a l y s i s m e a s u r e m e n t s . C o r r e l a t i o n s between the m e t h o a s and bone s t r e n g t h a r e p r o m i s i n g f o r t h i s c o n v e n i e n t technique. T h e sounds a r e in the 500Hz region. Bone length t i m e s r e s o n a n t f r e q u e n c y f o r the ulna i s 4 5 5 0 H z - c m for w o m e n of 30 to 50 y e a r s of age a f t e r which it d e c r e a s e s about 1.1°~ p e r y e a r . Diabetic w o m e n exhibited a change of 25% a g a i n s t t h e i r age m a t c h e d c o n t r o l s . 80% of o s t e o p o r o t i c women, a s e v i d e n c e d s p o n t a n e o u s f r a c t u r e s , w e r e 30°~ down by t h i s c r i t e r i o n . On the r e s e a r c h side t h e r e w e r e two p a p e r s c o n c e r n e d with a c o u s t i c holography, (Stroke, New York State U n i v e r s i t y ) (Smyth, City U n i v e r s i t y ) . Stroke d e a l t with h o l o g r a p h i c p r i n c i p l e s g e n e r a l l y , f o r a c o u s t i c i m a g e s and a l s o f o r 3D m i c r o scopy and p o s s i b i l i t i e s f o r 3D i m a g i n g of p r o t e i n s t r u c t u r e s ULTRASONICS J a n u a r y 1970

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by X - r a y s . Smyth c o m p a r e d u l t r a s o n i c i m a g e s p r o d u c e d by l e n s e s with t h o s e p r o d u c e d by h o l o g r a p h y at 4MHz u s i n g the u l t r a s o n i c i m a g e c a m e r a . The l e n s p i c t u r e s w e r e b e t t e r and p r o v i d e d m u c h m o r e i n f o r m a t i o n in a g i v e n space, the 3D quality of h o l o g r a m s w a s not a c h i e v e d b e c a u s e of the s o n i c optic w a v e l e n g t h d i s p a r i t y and the difficulty of r e d u c i n g p h o t o g r a p h s by a f a c t o r of 500 t i m e s without l o s i n g p h a s e i n f o r m a t i o n in e m u l s i o n i m p e r f e c t i o n s . Some new d e s i g n s f o r u l t r a s o n i c c a m e r a s w e r e p r o p o s e d which would e n a b l e holog r a m s o r i m a g e s to be r e c o r d e d f r o m a s i n g l e p u l s e . The v a l u e of c o l o u r f o r p h a s e i n f o r m a t i o n u s i n g the J a c o b s t e c h n i q u e and a c o l o u r t e l e v i s i o n s e t f o r the i m a g e s was briefly reviewed. On the t e c h n i c a l side E r i c k s o n , B r i l l and Cook (Nashville) p r o v i d e d e l a b o r a t e d e t a i l of t h e i r m e t h o d s of d i g i t i s i n g 'A' and ' B ' s c a n s s t o r i n g i n f o r m a t i o n and c o m p u t e r p r o c e s s i n g to give i s o - a m p l i t u d e c o n t o u r d i s p l a y s . The c o m p u t e r h a s a 4096 word m e m o r y , if I r e m e m b e r c o r r e c t l y ! Spactal g r a d i e n t s of the e c h o - a m p l i t u d e d i s t r i b u t i o n can a l s o be plotted. M a l l a r d and C h r i s t i e (Aberdeen) have studied the f a c t o r s r e l a t e d to i m a g e quality, not only p h y s i c a l p a r a m e t e r s but a l s o the s c a n n i n g p r o c e d u r e s . They r e c o m m e n d e d t h a t a s in t e l e c o m m u n i c a t i o n s , r a d i o l o g y and isotope s c a n n i n g the concept of m o d u l a t i o n t r a n s f e r function and i t s p a t t e r n of v a r i a tion with s p a c i a l f r e q u e n c y had p r o v e d useful it should a l s o be applied to u l t r a s o n i c e c h o - s c a n n e r s . The p e r f o r m a n c e

of the ' B ' type s c a n n e r , s e n s i t i v i t y and r e s o l u t i o n , w e r e p r e s e n t e d in t e r m s of point and line s p r e a d funcl2ons and m o d u lation t r a n s f e r functions. To many, t h e s e p h r a s e s need e x pounding and t h i s type of c o n t r i b u t i o n will be a p p r e c i a t e d m o r e fully when the c o n f e r e n c e p r o c e e d i n g s a r e published. The s a m e m i g h t be said of r e l a t e d p a p e r s f r o m the J o h n Hopkins U n i v e r s i t y (Rao) and f r o m The U n i v e r s i t y of Chicago ( R o s s m a n n ) which d e a l t f o r m a l l y with the p a r a m e t e r s which r e g u l a t e i m a g e quality in u l t r a s o n i c a s well a s o t h e r s y s t e m s . Work s t i l l n e e d s to b e done on the n e c e s s a r y r e l a t i o n of i m a g e quality to d i a g n o s t i c a c c u r a c y . The c o n f e r e n c e would not have been c o m p l e t e without a cont r i b u t i o n f r o m the Health p h y s i c i s t s . R. O l i v e r ( C h u r c h i l l , Oxford) d i s c u s s e d m e t h o d s of health p h y s i c s c o n t r o l which could be applied to l a s e r s , u l t r a s o n i c s and o t h e r f o r m s of n o n - i o n i s i n g r a d i a t i o n even b e f o r e the exact n a t u r e of the biological h a z a r d s a r e known. R e s e a r c h into the n a t u r e of h a z a r d s and the p a r t i c u l a r d a n g e r s of long t e r m e x p o s u r e and e n v i r o n m e n t a l m o n i t o r i n g t e c h n i q u e s w e r e d e s c r i b e d . It i s u n d e r s t o o d the c o n f e r e n c e p r o c e e d i n g s a r e being publ i s h e d and will contain t h e m a i n c o n t r i b u t i o n in full. Copies of a b s t r a c t s and f u r t h e r i n f o r m a t i o n a r e a v a i l a b l e f r o m the s e c r e t a r y : D r E d w a r d W. W e b s t e r , M a s s a c h u s e t t s G e n e r a l Hospital, Boston, M a s s . USA C. N. Smyth

Winnipeg, Canada, 6-10 O c t o b e r 1969

American Institute of Ultrasound in Medicine 14th annual s c i e n t i f i c c o n f e r e n c e

The f i r s t two d a y s of the C o n f e r e n c e w e r e devoted to s o c a l l e d ' w o r k s h o p ' s e s s i o n s f o r t h o s e s t a r t i n g to u s e u l t r a sonic t e c h n i q u e s and w e r e g i v e n at Winnipeg G e n e r a l Hospital by a p a n e l of e x p e r t s in the d i f f e r e n t fields. T h e r e w e r e o p p o r t u n i t i e s f o r the t r a i n e e s to e x a m i n e p a t i e n t s u n d e r supervision. T h i s a d m i r a b l e a r r a n g e m e n t e n s u r e d that the p a p e r s r e a d on the t h r e e d a y s of Scientific S e s s i o n s in the Hotel F o r t G a r r y , w e r e r e s t r i c t e d to t e c h n i c a l d e t a i l s and the r e p o r t i n g of r e s u l t s and did not involve continual r e p e t i t i o n of the b a s i c p r i n c i p l e s by s p e a k e r a f t e r s p e a k e r . As the A m e r i c a n I n s t i t u t e of U l t r a s o u n d in M e d i c i n e had b e e n the j o i n t s p o n s o r of the F i r s t World C o n g r e s s of U l t r a sonic D i a g n o s i s held in Vienna in the f i r s t week of June, it w a s p e r h a p s s u r p r i s i n g that only a q u a r t e r of the p a p e r s showed l a r g e o v e r l a p s with t h o s e r e a d in Vienna. It i s p e r h a p s s i g n i f i c a n t t h a t the f i r s t full s e s s i o n w a s devoted to the b i o l o g i c a l e f f e c t s of u l t r a s o u n d and the p h y s i c s of the t r a n s m i s s i o n of u l t r a s o u n d t h r o u g h d i f f e r e n t t i s s u e s . T h e r e w a s a g e n e r a l feeling t h a t the r a p i d e x t e n s i o n of the u s e of Doppler instruments using continuously energized crystals on the foetus, r e q u i r e d a m u c h g r e a t e r c e r t a i n t y in the c o n t r o l of i n t e n s i t y and in the f a c t o r of safety than a r o s e in adult e c h o - e n c e p h a t o g r a p h y f o r e x a m p l e . In p a r t i c u l a r the d e v e l o p m e n t of s p e c i a l e q u i p m e n t i n t e n d e d f o r the continuous m o n i t o r i n g of the foetal h e a r t with wide b e a m s that would include the foetal b r a i n , m a d e it e s s e n t i a l f o r the biological e f f e c t s to be studied m o r e s y s t e m a t i c a l l y . The s e c o n d full s e s s i o n w a s devoted to both p u l s e - e c h o and D o p p l e r o b s t e t r i c a l and g y u a e c o l o g i c a l a p p l i c a t i o n s . C l a i m s m a d e f o r the i n t r a - u t e r i n e m e a s u r e m e n t of the foetal skull w e r e d i s p u t e d u n l e s s the e x a c t skull p o s i t i o n w e r e f i r s t e s t a b l i s h e d with a compound B - m o d e s c a n t h a t d e m o n s t r a t e d the m i d - l i n e of the c r a n i a l c o n t e n t s a s well a s the bony outline. The l o c a t i o n of the p l a c e n t a w a s shown to be m o r e a c c u r a t e l y d e m o n s t r a t e d by B - m o d e t h a n by D o p p l e r in the 62

ULTRASONICS J a n u a r y 1970

v e r y i m p o r t a n t group of c a s e s w h e r e the p r e s e n c e of a p a r tial p l a c e n t a p r a e v i a had to be c o n f i r m e d o r excluded. D o p p l e r d e m o n s t r a t e s the p o i n t of i n s e r t i o n of the u m b i l i c a l c o r d but i s u n a b l e to d e m o n s t r a t e the edge of the p l a c e n t a . The s e s s i o n of n e u r o l o g y and n e u r o s u r g e r y was l a r g e l y d e voted to conflicting v i e w s on the a c c u r a c y with which the c e r e b r a l v e n t r i c l e s c a n be m e a s u r e d in the adult. The w o r k e r s f r o m Kingston, O n t a r i o p r o d u c e d f u r t h e r d e t a i l e d e v i d e n c e f r o m in v i t r o s t u d i e s of the s e r i o u s l i m i t a t i o n s on a c c u r a t e m e a s u r e m e n t and it i s only in h y d r o c e p h a l u s that t h e r e was by g e n e r a l a g r e e m e n t an a c c e p t a b l e a c c u r a c y in the r e s u l t s . An i n t e r e s t i n g f e a t u r e w a s a p a p e r on the i n t r a - o p e r a t i v e b r a i n s c a n i n t r o d u c e d by Wild and r e v i v e d by M~iller. N e u r o s u r g e o n s have shown a n i n t e r e s t in t h i s which c o n t r a s t s with the long y e a r s of waiting b e f o r e e c h o - e n c e p h a l o g r a p h y b e c a m e accepted. T h e r e was a s h o r t s e s s i o n of u l t r a s o u n d in p h y s i c a l m e d i c i n e and s u r g e r y which showed a m a r k e d falling off in the i n t e r e s t in M e n l ~ r e ' s D i s e a s e and r h e u m a t i s m w h i c h f o r m e r l y d o m i nated t h i s field but a g r o w t h in i n t e r e s t for p i t u i t a r y and brain surgery. Cardiology had a full s e s s i o n , m o s t of the p a p e r s being d e v o ted to p u l s e - e c h o t e c h n i q u e s with a s u r p r i s i n g l y high p r o p o r tion using i n t r a - c a r d i a c p r o b e s and v e r y s o p h i s t i c a t e d r e c o r d i n g and i n t e r p r e t a t i o n s y s t e m s often r e q u i r i n g a c o m p u t e r . D o p p l e r s t u d i e s of the h e a r t and v a s c u l a r s y s t e m a r e m a k i n g s l o w e r p r o g r e s s than e x p e c t e d c o m p a r e d with the p r o g r e s s in o b s t e t r i c s . Ophthalmology was m u c h r e d u c e d d o u b t l e s s due to the r e c e n t SIDUO in Vienna. Of the final m i s c e l l a n e o u s p a p e r s , one on the r e c o r d i n g of the m o v e m e n t of the p h a r y n g e a l wall in v e l o p h a r y n g e a l i n s u f f i c i e n c y showed that a c o m p l e t e l y new field i s opening up. Douglas G o r d o n