Note: Descriptions are shown in the official language in which they were submitted.
21~3487
!
EIIG~ N91:TY ~TRA91;~UMD l~PY J~ETEOD AND l~PAR~TIJS
W~ I CO~!R9I.~13D CieLVITA~IO~ ~:~J~5:CT AND REDIJCl~ SID~: I.OBE8
. ",.. .....
5T~e p~e~ent inventio~ rela~es to a th~rap~ method and
apparatus ~or ~enerating high-int~n~lty ultra~ound with
control of cavitation e~e~t, and to the u~e ~f thl8
method and apparatu~ for reducing ~econdary lobea ~et up
by a periodic-type ~tructure.
10It is k~ow~ ~hat ultra~ound ~he~apy, u~in~ a
: piezoelectric transducer driv~n b~ sin~wav~-typ~
~ el~ctronic signal~ m~k~s it pos~i~le to create tl~sue
:: le~ion~ through tisau~ hoating du~ to ultrasound
ahsorption. Fur~he~m~re, ~u~h ti88U~ le ion~ c~ be~
limited to a ~peci~io ~olume by ~arry~ng out thorapy
u~ing fo~used ultr~ound, which i8 par~lcula~ly valuable
~or achieving ~ff~ctive t~e~tme~t in cancer therapy ~uch
a~, for examplo, canc~r o~ the pro~tat~, bre~st, ~rain,
et~.
20Bxi~ing ~yp~rthermia apparatus ~Bin~ ultr~ound
heat~ tumor~ to a moderate temp~rature o~ the order ~f
42.5C ~or a tim~ of the o~der of one h~ur.
Sinc~ hy~erth~rmia trcatment may be ln~ufflci~nt, lt
can he~ ad~anta~eou~ ta att~pt to obtain much highsr
t~mpera~ures, ~or exa~le of around 80C, with a view to
~en~lti~lng cell~ or completely d~troying them. To
~chie~ thi~, lt i~ nece~sary to ~upply acou~tic en~rgy
to the ti#~Ue ovor a bri~ period, ~enerally o~ the ord~r
- o~ a fe~ ~acond3, in~ orde~, notably, to avoid h~at loss
~y natural tr~ns~er, notably due to blond circulation,
throughout ~he ti~su~. Sufficient n~rgy needs ~o be ~ d
' !'i I ~ ~ and thi~ i,mplia~ u~ing hl~h ultrasound in~ensity.
Thi~ how~v~r bringo one up against th~ tachnical
problem~ re~ulting :~rom czlvi'cation p~enomena which b~come
3S even mor~ acc~ntuat~d a~ acou~tic int~nsi~y increa~e~,
h~ b~e~ de~crib~d i~ de~all ~y ~. Hynyne~ in " The ; : .
threshold for thermally ~i~n~icAnt ca~i~a~ion ln dog~
C001~ ~S~ cr o~ cz L~ I SS~, 9Z:IT sa.
2~3487
` ..
thigh muscle in ~ivo" publish~d in Ultra~ound In Medlcine
and Biology, vol. 17, No.~, p~ge~ 157-171, (1991).
Acou~tic ca~it~tion co~er~ any.phy~ical phenomena i~-
vol~lng ~h~ activity o~ bubble~ o~ micro-bubbles o~ ~as
und~rgoing mo~emen~ as a re~ul~ o an acou~tic ~leld.
Tw~ typa8 C~ cavltat~on can generally be dl~ting-
ui~hed:
- st~ble ca~it~tion where ~he walls of the b~bble~
are os~illating at the ~requency of the ultra~ound ~ield
without too great a conse~uence ~or the surrounding
c~ , but which con~id~rably di~turbs ultra~ound
transmi~ion by reflecting or ~aatt~rlng incldant wave~.
Thi~ phenom~non can appear ~t ~ery ~ow ~e~ure lev~l~ a~
300n aa bubble3 ar~ pre~e~t in th~ medium;
~ transitory cavit~tlon where bubble~ e~pand up eo
their re#onant ~ize, and than implode viol~ntly. In this
ca~o, tha ~n~r~y accumulated by the bubble3 i~ ~imul-
ta~eou~ly r~laa~d in the form o~ a shock wa~e, with
inten~e heat (generally from 1 ooO ~o 20 000K) and
microj~t~ that can ~each ~pee~ o~ loo m/q. All thi~
laad~ to th~ creation o~ ~ree radicals and mechanical
de~truQtlon of ~urrounding ~ ue. Generally, this
phonomenon a~pe~r~ st~rting ~rom high incident pres~ures
which thu~`defi~e~ the cavitation thr~hold~
Every living medium contains ~ ~ertain amount.of di~
~ol~ed gas present in tha form of h~bbl~ mlcronuclai
Uhd~r th~ e~ect of an ultr3sound ~ield, the ~ucle~
axpand thr~u~h ~ phy~ic~l phenomenon know~ a~ ~ecti~ied
diffuc~on to rea~h ~ cr4tical ~iz~ known ~a th~ ~laka
~hr~shold.
The inventor show~d a while ag~ ln an ar~cle
. ientltled ~'Effect_ of cavita~ion in high i~ten~ity
therap~utic ultrasound" publi~hed o~ pa~eq 1357 to 13~0
of volum~ 2 (l991) of "Ultra~onic~ Sympo~ium Proc~ding~"
~published by ~.R. ~cAvoy) that thc us~ o~ intensiti~s
that were too~ high, gen~rally abo~ 3 000 W~cm2 reduced
the therapeu~ic effects of thermal tre~tment involving
tis6ue de~tructlon. Thi~ phenomenon can be ~xplain~d by
1~00[21 H~SYI~ Z L~ 1 C~12, 9Z ~ .
' "' ~
~ 2~3~7
~upposing that at the~ inten3i~ie~, cavitatlon bub~las
which may a~ear ahead o~ the ~ocal Ypot ~ct ~ a screen f - .
for in~ident ultr~ou~d wa~e~. Mor~ov~r, with th~
8p~0i~iC aim o~ reducin~ cavitatio~ cffect~, F.J. Fry~
5 stated ln Inter~at~on~l Patent a~llcation Wo-A-8~/0790~ -
that it i~ nece~æary to inhibit produation of micro-
bubble~ in th~ primary ~ocal ~i~e to a~oid le~ion~
appea~ing out3ide said ~ite (~e~ pa~e 15 of ~aid PAtent
application). Under ~hese conditlon~, lt iR ~tated that - :
~e lnten~ity ~hould not exceed 300 w/cm~ at a 1 MHz
fraque~cy, o~ Z,10~ WJ~m2 at 4 MHz.
K. ~ynynen al90 ~howed in the above-cited articl~
that an intensity of 700 ~/cm2/MHz ahould ~e con~idered ~b
as a ~aximum valu~ ta be u~ed in hyp~rthenmi~ treatment
~, at high~r lev~ vl~ation leads to unpr~dictable
ener~y ab60rption.
To ~um up th~ ~tat~ of ~h~ art, cavitation hind~r~
penetration o~ aaousti¢ wave~ into tissue thu~ pre~entlng :~ :
treatme~t fro~ following pred~ctabla lin~s~ Moreov~r,
20 ~a~ltation can lead to uncontroll~d ti~ue de~truction, ~.
outslde the target ~olume. It is thu~ appropriate, ..
regardles~ o~ the applieation envisaged ~in oth~r word~
thermal tre~tm~nt at high tempexature for tis~u~ de- ~:
~truction, ar at mo.d~r~t~ ta~aperature or hyperth~3rm~a), ~ - .
: ~ to increase cavitation onoet thre~hold~
To avoid cavl~ation, the only recomm~ndation~ that
can be f ourld in the p3~ior art consist eith~ ln reducirlg ~`~
acou~tic lnten~lty, or em~ ttlng in a di~con~cinuous
~ann~x, u~ing ~a~e trai~ of de~ermined duratlon, and.
30 respectin~ A waiting ti~e betwe~n th~ tr~in~, or, yet
a~ain, increa6ing ~mis~ion ~requency.
However, rqducing a~oustic iate~ity or u~ing di~con- ;
tinuous emi~ion lead~ to a los~ o~ ac~ustic ener~y ~.
tran~mitted t~ the medium, which llmi~a temporatur~ rise
35 or increa~a tr~a~ment duration. Furthermore, in~reasing ~.
em~sion freguency limlts the depth o~. treat~e~t~
absorption by ti~ue being directly proportlo~al to
~requenc~, a~ d~s~ribed by Daniel3 et al., in the journ~l
sno~~S~ Cl 8~ CZ L~ I 6~ ~Z:II S~. Zo~bZ ;
,'':'~
~`:` 21~3~87 :
"Ultrasound in Medicine and Blology" ~rol . 13, No. 9,
~19~7) in th~ articl~ ~ntitled "Ultra~onically induced
ga~ bubble~ producti~ in ag~r bas~d gel~n. I~ ~hould
~lso be noted th~t, in th~ prior art, continuou~
sinewav~s are ~mployed ~or ti~u~ heating, and thu~
emis~ion du~atio~ i~ far higher than ~ignal period.
U~ually, in~onification of ti~ue ~or ~e~eral ~econ~ at
a fres[uency c:omprlsed between 1 and 5 MHz l~ envisaged.
Certain authors h~re, on the other hand, consid~red
10 u61ng acou~tlc waves o~ a pul~ed typ~s, with a duration of
the order of se~rer~l perio~, in other word~ ~veral
rnlcrosecond~;, but for a complet~ly dif ~erent pu~pose,
~pec:i~ically eith~r the c~e~truction o~ concretlon~
~li tho~rl~t~tlc~n), or for diagnc~ (DQPP1er ultra~;ound : . .
~canning).
The ca~itation phenomena produced by such pul~es have
bee~ ~tudied. For example, ~owlh!~ and Crum in an
articl~ entitled " Cavitation thre~hold measurementa ~or
microsecond langth pu~ 8 of ultrasound~ publi~hed i~ J.
20 Acou~tic 90c. A~. 83 ~ un~ 1988, inv~a~tigat~s th~
evolution o~ c~itatlon thrc~hol~ as a ~unctiQn o~ pu180 ,'
widt~ and pul~e fr~qu~ncy. ~imilarly, Deliu8, while
studying ~a~ltation pr~duced by lithotripter~ reaommended
~educing acou~tic wav~ repctition ra~e~ (see "~f~ects of
lithotripter ~hoak wave~ on ti~u~ and mat~rial~
Frontier3 on non-lin~ar acoustic~, ~dited by M.F. ~amil- ~;
ton and D.T. ~ k~tock, Ele~vlor Scienc~ Publishers,
London lg90).
How~er,. puLae ~thods. do not make it po~siblo to ` ~::
produco ~ temper~tu~e rl~e in tis~uo since e~ch pul~e
o~ly tr~nsports small amount of cner~y, and the pulses
n~ed to be spaced. It i~ thu~ not possible to asslmilate
work don~ with the~e wave~ with thq work at the basis of
thi~ pre~ent in~ntion.
T~u~r the. prl~ciple aim o~ th~ prc~ent invention is ;~
to resolve the new tochnical problom of pro~i~ing a
~olution enablln~ maximum energy to be supplied to the
~00~1 EI~S~ ST ~ CZ L~ I CC~ Z:TI S~. ZO~Z
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21~3~87
. . .
medium, pref~rably ~he ti~ue o~ a livln~ ~ing, in ;~
particular an a~imal or huma~ being, ln the ~hortest
possibl~ time and p~ef erD~ly reducing or preventing the
oc~urr~nce o~ ea~itation ~henome~a .
A further aim ~ the in~ention i~ to re301ve the n~w
t~chni~al p~o~lem o~ providlng a solution enabling
maximum ~rgy to be ~upplled to th~ m~ium, pr~arably
~he tia~ue of ~ li~ing baing, in par~icular an animal or
huma~ bei~g, in the ~horte~t possible time, whil~
simult~ously enæuring ~a~e a~d ef~ec~ive control Of
heat de~o~it, thu~ making lt po~ le eithsr to provi~e
mod~rat~ ther~al ~reatm~nt in ~he ~ramewor~ of hyper-
thexmla, or to carry out thermal tr~atmont at high
tcmpcrature~ tQ achi~Ye tis~u~ de~tructiQn, pre~era~ly . .;~
15 reducing or llmiting ca~ita~ion phenomen~. -- .-~
Moreo~er, the in~ention r~sol~es th~ ~ew p~oblem of
3ec~ndary focusing whieh can occur wben perlodic ~r ~-`
qu~ai-periodic ~tructures are pre~ent on the path betw~Qn
the emi~sion de~ice and the re~ion to be treated. ::
~0 The preæent inv~ntibn h~s the ~urther aim o :~
re~olvlng th~ abo~e technical probl~mg in ~ ~imple,
r~liabl_, inexpen~lve mann~r makin~ widespread indu6trial
~nd madical uae ~os~lble. : :.:
The pre~ent invention provides a ~tl~iactory
~5 901ut~0n ~or th~ firs~ time to the technic~l problems ~.
defin~d abo~e, and has ~urth~ir tcchnical Advantagee which ~ ::
wlll hecome more clear ~rom tho det~iled de~cription
which ~ollow~, including the attach~d drawing~ which
con~tttute an integral p~rt thereo~. :
Thu~, ~cc~rding to a flrst as~ect ~ there i~ provided
a method ~0~ ~enerat~ng ultrasound waves i~ a ~opagation
!` mediu~ comp~i~ln~ acti~ating at least one ul~ra~ound
~ransducer ~lement by an elec~ronic signal ~upplied by a ::
sign~l generator and xedu~l~g or pre~enting c~Yltation :
35 ph~nomon~ re~ulting from ths propaga~ion of ultra~ound ::
wave~ emi:tted by the ul~rasound tranedu~ier element wlthin.
the pxopa~a~ion m~dium by the u~e of a siynal ~n~r~to~
supplying a wid~band elect~onlc signa~
L00~ H~S~IH ~ CT or ~Z L~ T S6~ LZ:TI 9fl, zo~z
2~3~87
~i , ! .
rn thi~ tnvention~ in oth~r words in the de~cription
and claim~, ths oxpre~ion "wideband" ~or th~ epectrum o~
an eLectronic ~ign~l m~an~ that ~ignal sp~ctrum bandwidth
i~ a~out 50~ of ~he central fr~-quoncy. For ~xnmpl~, for
a ~ignal of central frequenc~ 2 M~z, bandwidth will b~
around 1 M~ and will thu~ co~r ~requensieY ~a~y~ rom
abou~ 1. 5 MH3 to about 2.5 M~z.
I~ ~ pref~rred em~odlment, a ~ignal generator ~:.
supplying a continuou~ rand~m or ~eudo-random electronic
~ignal i~ em~loyed.
Throughout this speci~catio~, the term ~con~inuous"
should be tak~n to msan that th~ duratlon of emlsslon o~
the ~ignal i~ ~ery much long~r than t~ period of the
slgn~l, a~ ha~ al~ead~ been sald in the introductlon
15 abov~. ~
Acco~ding to on~ preferred feature, the a~ovesaid .~:;
ignal gen~rator s~upplies a p~e:udo-ra2~dom electronic
~i~nal o~ th~ Gau~sian or Poi~onian d~tributio~ t~pe.
Su~h ~ignal can t~ l~ally be obtained fro~ a sourc~ a ~.
20thormal noi~e ampllfi~3d by e~le~ronic ampllfication. .~
According to a further advantageous ~eature, the ~aid .:~ .. o
~igne.l t3en~3rator ~upplie~ a l?oeudo random electronic
c~ignal using G~lay coding. ~ -
~ccording ~t~:a ~u~er ad~antagOEtaus fe~ture, the 6aid
ZS~i~rnal g~nerator ~upplieY a }~eudo-random el~ctronic
si~n~l using Barktr coding.
Ac~ os:din~ to still a ~urthex ~dvantagtaou~ ft3ature of
thti~ in~r~ntlon~ ~he E3aid signAl generator ~u~pli~ a c:oded
el.qctronic ~ sign~l o~ M-s~t~ut3nce pseudo-randc~m type .
30M-~e~ena~ signal~ also referred to ac maximum l~ngth - :: -
binary acquence~ are of th~ typ~ de~ribed b~ Jeasl-Y~e~
Chapelon in Chapter 6, on pag~ 225 to 23~, partlcularly .
page 230 onwards of the ~oc~k "Progr~:ss in medic~
imaging" edit~d by Profeasor Newhou~e arld pu~ hed by .
3SSpring~r Vexlag, New Yorlc, 1988 whlch i3 incorporated ~ * :~
her~i~ by. ~e~renc~
Such M-~equ~n~ or ~olay or Bark(3r pl3~udo-random ~ .
cod~d signal~ can be employed directly or can pha3e- or
800~ H~S~IH ~ Sl ~ SZ ~ I SS~3 LZ:~T g~, ZOi~Z .'~
7 `~
frequency-modula'ce an electronic eignal thc carrier
f requ~ncy of whlch correspond~ eo the tr~n~ducer '
nominal- op~r~:n~ Sr~uen~.
Coded signals of the M-3equence p~eudo-random type
5 are pa~icularly pre~erred. Such slgnalE~ are prf3c~ sely
de~cribed in ~Progre~ med~e~ glngn. ~riep~
they co~i~t of b.inary 8ignal~ buil~ up by p~oudo-random
repetitio~ of J?ul~^~ of elem~ntary duration E:Ach of
said sequ~nc~ss is xe~p~ated with a ;repetition p~riod T
lO 'chat i8 chara~terl~tic of the M ~equonce.
A more~ pr~ci~ deacription of an M s~quonc~ ~ignal
c~n be pro~ided with referenc~ to FIG. 4 attached, ~ ~
- element~ry pulse duration 11011 O.l ~L9 C: u ~ 100 ~3, '.
ideally akou~ ~ fL3,
- re~p~ti~ion period T: 1 ~9 c T c l~ ~, ideally com-
prl~ed b~ws~n ~.5 and 5 ~
The p~eudo-ra~dom typ~ cod~d signal~, parti~ularly
the currently pre~erred M ~equenc~ p~eudo-rando~ type
sllgnals can readily be obtained usin~ el~c:tx~onie circuita
zo well lcnown to tho~ ~killsd in th~ art.
Th~ u~ o~ l3uch wideband electronic E;i~als, ~ ~
pref~rably random or p~eudo-random, mak~s it pos~ibls to :: :
ac~iav~ b~tter c~ntrol o~ heat depo~ition and to a~oid
tempe~atu~e. inc~ease di~turbancc by ~econdary e~e~t~
25 such as ca~lt~ion, ~hu~ e~abling spontaneous tissue ::
dsstruction to ~e a~olded part~cularly in the ~aee o~
~oder~t.~ he~tlng used ln hyperthe~mla..
9ooondly, conaidering hlgh-intensity u~, the
invention ~k~ . po~ible/ to employ high~r intensiti~s :
3nd to redu~, for a given ultrasound dose, firing
duration and, con6equently, the dur~tion of creatment,
whils a~oi~ing cavltation phenomena ~hus m~king iC
po~ible to carry out treat~ent of tumore in living
b~ing3, in particular animals or human beings, ~ith
~5 higher l~vel o~ ~a~ety whil~ reducing the risk o~ damage
at ~ari~us.in~r~e~:.
From a ~econd a~pect, the present in~cntion also pro-
vides a therap~ apparatu~ comprising an ac~ual therapy
600 SHIH ~ ) Sl ~ CZ L~ T CC~ 8Z:IT S6. Z0~2
2~3~87
device eo~prising at lea~t on~ ultra~ound therapy
tran~duecr Ql~nt and ~ ~ignal ~cner~tor ~upplylng an
~lectro~ic signal to said u}tra~ound tran~ducex elem~nt,
in whieh the ~i~nal g~neratDr ~upplies a wideband
~lectro~ic ~lgnal o~ th~ random or pseudo-r~ndom typo.
ln on~ pr~ferred embodiment, the ~ignal ~enerator . ::
.supplie~ a ~aua~lan or Poi8~0nlan di~tri~ution type
random ~ignal. ::
~n another pre~erred embodim~nt, the ~ignal generator
supplie~ a ~olay coded or a Barker Goded pseu~o-~andom
~ignal. ~;
In ~nother pre~err~d embodiment, the ~ignal ~e~erator
~upplie~ ~n M-sequ~nce paeudo-random type coded :~
elec~rontc si$~al................................................... , -~ Thl~ M-s~quence p6eudo-~andom type coded ~lectronic
3~nal p~e~erably has an elementary pul~e d~ration ~e) .
theta comp~i~e~ between 0.1 ~ and 100 ~ and 1~ ld0ally
of About 1 ~ nd a period of repet$tion T ao~pri~ed
~etween 1 ~ and 10 ~ and ~deally compri~ed bRtween 0.58
and 5 ~
In eithar a~pect o~ th~ invention, to increase the
ef~ectiven~ of ca~it~ effec~ x~duction or preYention,
a~ ultraso.und tran~ducer which pre~erably i~ it~el$ ~ ` ?`,
w.ideban~, 18' u~d, in o~hc~ words the ultrasound ;:`~
transducer gener~te~ ultra~ound wa~es when excited by a
8~ ~nal th~ reque~cy of w~ich ie qubstantially di~erent
~ro~ its nomlnal ~requQnay.
U~ually, tWo type~ of tran~duc~r can b~ u~ed for gen~
er*ttn~ ~ontinuou~ ultra80und waves ~or. th~rapeutic. ::~
30 purposes. ~he~e comprise, f~r~tly, conv~ntional -~
ult~asoun~ tran~ducors e~se~eially consl~ing o~
piezoelectric ceramia. Such ceramlc~ ha~ an acou~tic
impedance whlch i~ v~ry differene ~rom that of the ;~
propagation medlum and, as a re8ul~ o~ ~hi~, ~hei~
35 coupling with ~ald medium i~ poor. Thi~ re~ult~ in .
s.trong.vibration3 ~f the ceramic when it i~ ~xcit~d hy ~n
elect~lc ~ig~al, the re~ulting ~ra~ound transduccr ~:
havlng a narrow ~re9uency bandwidth. ~`
OTO~ H~S~ Cl 0~ ~Z L~ T ~C~ qZ:TT S~. ZO~PZ ~ -;
3~87 `;
g I .....
,
For ther~py ~arrled out ~o d~te u31~g ul~r~ound
waves ~ ouch tran~ducer~ are suitable a~ the control
~ignalg ~r~ ~hemsclve~ of tha ~arrow ba~d ty~e.
In ~he fr~mework o~ this lnv~ntlon, the ~requency
band of the ultra~ound tran~ducer~ i~ widened ~y the
ap~lic~tlon o~ dif~erent type~ of tr~atment to the
ceramic surf~c~, th~se modifying ultra~ound coupliny with
the propagAtlon madiu~ Particularly) a layer o~
matexial~ haYing an Acoustic ~mpedance lntermedlate ` `:
betw~en that of ceramic and the propagation m~dium of
ap~roprlate thickne~ i8 d~posit~d in this cas~ on th~
ceramic, such a layer being re~rr~d to ~ a quarter-wav~
l~yer. A 30~called backin~ layer c~uld aleo be depo~ited ` :: :
on the back o~ the c~ramic between the latter and the :`
15 air. The~e two ty~e~ of treatment of the ceramic enabl~ :
a wideb~nd ultra~ound transducer to be obt~ined. ::
Another ~ype o~ wideba~d tran8duco~ can b~ obtaiuod ;~
u~ing composite type materials, thi~ being particularly ; ~-
suitable for impl~m~ntation in the present invention ~or
ao reducing or pr~v~nting ca~itation e~fect~
Thi~ make~ 1~ po~3ibl~ to obtain the de~termining
technical ad~ant~ges stated aboYe.
AccordlnS~ to a further ~pect, the invention
di~close~ the use, i~: a therapy apparatua comprising at
2 5lcaJt o~e ultrasound trarl~duc~r and .D ~ l gen~rzltor
supplyin~ an electro~i~ signal to ~aid tr~n~ducor, of a
wid~band ~lectr~nle ~l~nal f~r r~duciny or preventing
s2condary fo~uein~ phenomena bqhind ~ perlodic or
qu~ per~ Qdic ~;truc:ture~
30Th~ ~or ex~m~le mak~a it po~sibl~ to tre~t the li~er
be~l~d the rib cag~i by reducing or prev~nting le~ion~ due
~o seconda~y facu~ing or side lobe phenomena.
In one eimbodlm~nt o~ this third a~ect of the
inv~ntion, the wide~and ~l~ctroni~ nal i9 0~ the
35 random or p~eudo-random typo. ::
The ~ideband RlQctronic ~ignal ca~ he a Gauss;~ian or ~ :
Poi~sonian di~trlbutlon typ0 random ~ign~
. .
............. . .... ~ .... .... . ~
TT~ H~S~ Cl ~ CZ L~ I SS~ aZ:TI S~. ZO~Z ~ -:
:.
- '
~ ~ .
-- 21~3487
1 0
' ' ':
The wideband e~l~ctronic ~i~nal can al~o be a Barker
coded ~r Golay cod~d ps~udo-random slgnal.
Fo~ t~e wideband elec~tronic ~ignal, one c~n u~3e a -:
M- se~ue~ce pseudo-random typ~ coded el~ctronic si~nal
5 of a ~r~ue~cy havin~ a~ elementary pul~e du~at ion
compri~ed be~twQ~n 0.1 ,us3 and 100 ~ and ideally o~ about :~
3, and ~ p~rlo~l o~ repet~ tion T com~ri~3~3d between 1
and 10 E~ and id~ally comprised between 0.5e and 5 8. : ::;~
The ele~ronic wideband ~3ignal may also ha~e an
lo autocorrelation function apl?ro~chlng a Dirac functlon. .
~ urther characte~ri~;tiaæ of the invention will ~ecome
cl~3ar rom ~he detail~3d de6cription that i~ollows,
including the dra~ing~ which ~onstitut0 an integral part
th~r~a. and:th~ cl~im~ ~ccompa~yi~ thia deecription
1 5 -
Th~ in~rention will now b~ d~cribed on the basis o~ a : -
currently pr~~rred ~mbodlme~t thereo~ slmply by way o~
illu8tr~tlon whlch in no m~nn~r ~hould be con~dered a~
::~: .,:: -: . :::
limiting the scope on the lnvention, with rQ~Qr~nc~ to ;.. ~.--
thc attached d~aw~n~s.
FI~ a h~ghly ~chematic r~pr_sentatiqn of a ~:.; :"
known therapy dovic~ for per~ormln~ t~srapy o~ the ti39U~
of ~ llYin~ ~lng, compri~ing a sinyle- or multl-tran~
d~a~r d~ e ha~l~g on~ or ~v~ral piezoelec~ic tran~
25 du~rs, in th~ ~oxm of a 0am~-~ph~rical cup ~llowing :'. :
~eo~etrlcal ~ocusin~ on the proRagation axis Vi9~ bl~ in
FI~. 2~ : `
FIG. 2 ~hows a curve in the form of a 6inewa~e a~ a
functlon o~ ~ime; t on th~ x-axi~ and.a~plituda A on the
y-axl~, according to the prlor art as ~mployed in an
ultra~ound wav~ yen~rating device o~ FIG. l; ,~
. i FI~.... 3 i~ a highly ~chcm~tic ~iew of ~ therapy devicq "`~
according to the pres~nt invcntiorl for carryin~ out ;~
th~rapy of li~ing bel~g ti~ue, comprising a wid~band ..
35 elec~ronic ~ignal g~neratlng device, ~aid signal being
pr~f~r~bly rand~m ar p~ud~-randcm, delivered to the .
piezoele~tric transducer devlc~ ~or generating an
ultraaound wave, the r~ndo~ or pseudo-random ~ignal being
,.:
ZTo~ ~S~IH ~ CT ~t cz L~ I cc~ ~Z:TT 9~. zof~z ~ -
:, -. :.,
; ~ - ~ : .
~ 21~3~87
.. . ..
11 ' - '
shown diagramma~cally in FIG. 3, ~nd in det~il ln Fr~. 4
~ a 4~nctlon of ~ime expressc~ in microseconds on the
x-axi~, with ~mplitude on thc y-axi~;
FI~. S i~ ~ block di~gram of a ~ctup making it
5 possi~le ~o claarly bring to light reduction in cavita-
tio~ by u~lng a random or ~eudo-random ty~e electronic
signal for axciting the ultra~ound tran~ducer;
FIG. ~ show~ r~ult~ obtainca with the apparatua in
~IG. 5 ln ~he ~orm of a graph ln whlch the l~ne : :
identiied by the reference 2 corrc~ondo to the random
or p~eudo-r~ndo~ ~i~nal accordin~ to the in~ention of
FIG~. 3 and 4 joining the points ~how~ by the - o -
~ign~, ~nd th~ llne be~ring the re~er~nca 1 re~ul~ ~xom
th~ u~ o~ ~ ~inew~v~ ~ig~al according to ~hc prior art :~:
employed in FI~5. 1 and 2, and ~o~in~ the ~olnt~
a~ a ~unc~ion ~ pow~r tran~mltted by the ~ran~duc~r
expre~ed in Watt~ on the x-axi~, the valu~ in nano-
ampere~ pro~ided by an ammeter inte~ra~ln~ the total
amount of light cmit~ed ~y ch~ luMinol ernployed ~eing
~o indi~ated on the y-axiB;
- FI~. 7 ~how~ ~chematically the operation o~ a p~io~
art device in tho pr~senc~ o~ a periodic or
quasi-pe~lodi~ atructur~; and
- FIa. 8 is a isichematic re~ei~i~tatlon ~imilar to
that in FI~. 7 in a d~ice imPlem~n~ins ~he in~ntion.
Wi~h r~fer~n~ to FIQ. 1, th~re i~ i~hown dlagram~ati-
cally a known therapy d~vic~ g~n~rially idonti~i~d by
re~ere~ce numeral lO, ~or carryir~ out th~rap~ o~ ~he
ti~ue o~'ia llving being.
Thi~ tharapy apparatus 10 compriae~ an actual theripy
device whlch here takes the form o~ a 3~mispherical cup ~ :~
22 using natural focusing compri~iing one or se~eral
piczoeloctric trAnsducer element~, in pii~rticular a :~
singl~ m~nt piezoelec~ric trani~d~er i~entified hy
~e~erencR 23 haYlny iuhstantially th~ same d~me~i~ion~ as
the semi-~pherical cup 22 a~ i~ well known to tho~e
skillsd in the art, no supplementary dascription thsr~o~
SlO~ H~S~I~ l,~SI~r~ ~T ~ CZ LP T SS~ ûZ:IT SO. ZO~Z
~ 2~3487 ~
appearing neGe~sary. One exa~ple o~ an embodiment o~
such a th~rapy device is, for example, one in the ~orm o~
a ~mi-spherical cup 2~ of 100 m~ diameter, u~ing natural .
focusing a~ a ~ocal leng~h o~ 100 mm, with an o~erating
frequen~y of ~bout 1 MHz, uslng on~ sin~l~ piezoelectric
transducer elemen~ 23. :~
Tra~sducer element 23 is linked, via a~ ~mpli~ier de~
vice 30, to a si~nal generator 40 which can it~lf b~
controlled by a ~o~trol unit 50. ,:.
~t should be noted tha~, in accord~ce with an~th~r
pos~ible embodimen~, ~emi-~pherlcal cup 22 u~ing ~atural
focusing can be subdlvided into a~ annula~ a~ay, well
kn~wn t~ t.hose ~killed in Sh~ art, ~r l~to a mo~aic al~o :~
known to tho~e ekil~ed ln th~ ~rt, and no supplementary
description th~r~o~ ~ppear~ nece~a~y. In chi~ c~
each i~div~dual annular or mosaic-like ~ran~duc~r element
i~ linked via ~n ampliSle~ device ~om~ri~i~g ~nd~vidual
ampll~iar~ and a d~lay line de~ice ~omprislng individual
d~lay lineY, to a common signal gen~ratox ~uch a~ sig~al
20 gen~rator 40 controll~d i~ ~t~ tu~ by control unit ~uch :
a~ con~rol unit so. Th~ control unit th~n controls th~
delay line~ 4~ upplying the delay value nceded by each
for ~t~i~g ~oc~l~lng a~ the desired focal len~h.
rh~r~cs to ~hi~; de~ign o~ the apparatu~, clynamlc elec-
25 tronic fc~cuE3islg with focal len~th being varied at willcan be Achlq~red.
Con~i~lering the ~?rior art apparatu~ of FI~. 1, w}~en a - :9
convontio~al electronic signal i9 ge~e~ated by generator
40 of, th~: sin~wa~ type ~ shown schamatic~lly at the
ou~pu~ ~om ampl~ier 30 and, in mor~ ds~il, ln FIG. 2,
for ~xample ~k a frequency of around 1 MHz, n~tural
:~focu~ing i8 obtain~d in ~hc foc~l re~ion F dc~inin~ the
tr~atment volume T.V~
With ~3uch a con~inuous sinew~ve ~ al, in other - ~
35 words one having a du:ration di~tinctly hiyhe~r than tho . ~ . .
~r~quer~cy~ ~alue per period, which in g~neral ia ~everal
second~ compared to a 1 ME~z fre~uer~cy, bubble~ of ga~ : ~
pre~ent in ti~sue or which are 1pontaneou~ly gen~rated by ; ; ~ .
~T0~ H~S~ Cl a~ ~z L~ I C~ 0~:TT S~, Z0~Z .~
"' ~"',
~ 2~43~87
13 :
ultrasound ~av~, id~nti~ied by re~e~ence B, whlch ar~ :
pr~0~nt ahea~ of the ~rious intex~aces, ~or ~xamplo o~
fo~al region F or th~ inter~ac~ with the ~kin S o~ th~
pati~nt P, will ~tart ascillating aft~r ~eYeral pul8e8 at
5 ~requency ~p, called the pumE)ing ~recauer~cy. The dlameter
o the ~a~ bubble~ B will incro~6~ ~t e~ch pu16~ duc to
the ~o-called recti~ied dlffuslon phe~omenon, to reach a
maximu~ value that i~ ch~ract~ristic o~ th~ ~r~quency fp,
or Blake thseshold. When the acoust~c field inten~ity
lo exceeds th~ ~avi~ation threshold, whl~h pxactically
alway~ i9 th~ cafie in th~r~p~uti~ tre~tment, Chc bubble~
~ill implode releasing energy. Thi~ cavitation ~hreshold
is identified by the general re~eren~e charact~r C on
E'IG. :~ ~o~ ~i~ewa~re signal ir ten~iti~3~ o~ relatively hislh
amplitude. ~.
This constituteÆ a ~na~or disad~antag~ in th~s tats ~f
the art.
Under th~e aondltions, and with r~f~renc~ to F~G. 3,
an apparatu~ ac~ording to t~e ~recent ~nvention iR ~hown
20 generally identi~ied by re~erence numeral 100. The ~ame :
r~f~r~nce nu~eral~ increaeed by lO0 ha~e be~n u~ed to ~::
identl~y tho6~ part~ that are ldentlcal, or operate : ' `
iden~icallr, to ~ho~e in th~ prior art apparatu~. Thus,
the actual: ther~py devlce ~ her~ ldanti~ d ~y the ::
25 ~eference 120, th~ semi-~pheslcAl cup by 122 and th~~:
piezoelectric tran8ducer element b~ 123, the a~plifi~r -;~::
device by 130 a~d the el~ctronic ~nal ~enerA~o~ dev~ce
and control unit by 140 and 150 respectlvely.
In the ~ramework of the apparatu~ accordl~g t~ the
invcntion, the ~i~nal generator devicc 140 s~pplies a
wideb~nd electronic ~ignal, identlfied ~y the ra~erence
, A.S. ~how~ on FIG. 3, at the output rom ampli~ier device~
130, thi~ belng show~ in mor~ d~tail on FI~. 4. ~.
For thi~ invention, thq ultra~oun~ tran~duc~r can ~ t- ;
3~ ~elf b~ a wideband device, impl~mented as de~cribed
pr~iou~ly~
In the inv~ntion and ~or p~ovidin~ an endor~ctal
prob~ fo~ pro~tate treatment, it is pre~erred to u~e a
Slo~ S~IH ~ CT ~ ~Z L~ I C~ o~:IT S~, Zo~Z
~3~8~
:; ,,, ~",...
14 `; ~
~ ~: ,: :::;
tran~ducer in the form of ~ ~mi-~pherlcal cup of about .~ .
35 mm diame~ex usin~ natural ~ocusing at the focal length
of 35: mm, ~h~le, pre~rably, ~ ~ignal h~lng a ce~-ral
~requency of about 2.25 M~z is employed.
5A~ has bee~ ld abo~e, the term wid~b~n~ ~p~ctrum in
thi~ pre~ent description and claim~ ~hould b~ takQn to
mean that the bandwidth o~ the ~ignal spectrum ie about ~:
50~ o~ the central ~requency. For example, ~or a signal ;~
having a co~tral frequency of 2 MHz, bandwidth wlll be
abou~ 1 M~z and will thu~ comprl~e frequencie~ from about
1.5 M~Z to a~out 2.5 M~z. ;
In the invontion, more particularly for the purposo
o~ ~edu~ing Qr preve~ting cAvita~ion phenomena re~ulting
~rom the propagation o~ ultrasound wav~ emitted by th~
lS ultrasound tran~ducer element 12~ in the prop~gation-` `
medium PMl, PM2, signal ge~erator 140 ~upplie~ a random
or p~e~do-random wide~and elect~onic sign~l, id~t~ d
by rof~re~ce A.~. in FI~. 3 And 4. The central ~requen~
cy is genar~lly comp~i3ed be~wee~ 20 MHz a~d 0.5 MH
20It will~ be noted th~t, in tho ~r~m~work o~ tho in~ton~
n, ~e u~e o~ random or pseudo-random slg~al pra~id2~
an ~xcitation ultxa~ound fi~ld ~pectrum consi~ting of a
multiple-~r.e~ ncy ~e~t~um, the rand~m app~ara~ e
chara~teristic o;E whic~h limits bu~hl~: growth, 80 tha~ the ` ``
l~tter ~arely attal~ the c~l~ical diameter abo~e which
cavitation effect~ occur. :: :
Thue, th~ invention makes lt poc~l~le to llmit or
prevent cavita~lon phenomena.
Th~ random or p~e~do-ran~om signal ~upplled by.~ignal
gcner~to~ 140 i9 o~ th~ type described abov~ and can, ~or
examplQ, be a Golay or ~arker coded p~eudo-random
' lelectronic signal, the~e ~eing. w~ll know~ to ~hose
skilled in th~ art, paxticularly ~rom th~ pr~ce~ing
d~cription.
35An M-~quenc~ p~eudo-ra~dom coded aleatronia 8ignal
ca~ a~a. ba employed, this. ~re~erably ha~in~ a~ '
~lamentary pul~e duration (9) ~heta, compri~ed betw~en ~ .
~' ~'`' ,'
~TOI~I R~)S~IR ~3NIf~ CT ~ CZ L~ T CC~ TC:IT sa. zo~z ~ ~
21~3~8~
0.1 ~s and 1~0 ~, and a repetit~on period T compri~ed
~tw~en 1 ~8 and ~0 ~. -
A random ~ignal o~ a Gaua~ia~ o~ Poi~so~ian di~trib-
ution type can also be employed.
It ~hould be noted that th~ ctronic 3ignal ~hown
in FIG. 3 and in d~tail in FIG. 4 i~ an M-s~que~c~ : .
p~eudo-random al~ctronic ~lgnal the ~eri~d o~ wh~c~ T i~ .
compri~ed between 1 ~g and 10 8, th~ blem~ntary pul~
duration theta (~) being comprlsed betwee~ 0.1 ~ and 100
~
With re erence to FIG. s, there i8 h¢re shown an
apparatu~ making it po9~ible to demon~trate reduction in
cavitation when ~l~c~ro~ic signals, or pseudo-random : :
cod~s ~ecordin~ to th~ pros~nt in~ntion ~rc emplo~ed,
~hank~ to the u~e of a luminol. Thia chemical compound
i~ known to emit photon~ (~luo~e~c~nce~ when ln th~
presencc oE ca~itation, a~ described in th~ article ~y
Fo~lke~ et al, in J. ~coust Soc. ~m. vol 83 of June 88
page 2190-2200 ~ntit,led nCa~itation threRhold
mea~ur~m~nts for microcecond leng~h p~l~es o
ult.ra~ound~.
Thl~ apparatu~ compri~e~, in the ~chematlc fo~m of: ::
FIG. 5, a fr~quen~y generator 160 a~ociat.ed with a code :
generator l-lQ, the. combinatio~ of: th~ ~w~ g~nerator~ 1~0
25 and 170 ~orre~pondin~ to th~ alectronic signal ~enerator~ ~.
140 ~f FIG. 3, coupled to an amplifier device l~0 ~or . :
~upplyi~ a p~udo-random or ~andom type ele~tronic .:-:.
signal according to the pr~sent inven~ion, for ~xample an :.
: M-6equanc~ ~ignal, ~o tran~duc~r elcment 12~3 placed i~ a - ::
~0 tank 180 containin~ a solution of luml~ol 1~2. In the : ;
luminol ~olution 182, not only i~ tran~ducer lZ3 : :`
i~mer~ed, but a photomultlpli~r 184 device i~ ~ al~o
pres~nt, conn~c~ed to a moving-n~edle nanoa~meter 186
pro~iding a mea~u~e~nt in nanoampere~ proportional to
35 the photoluminei~cence obtal~d using th~ luminol. :~ :
The luminol~ ~lution ~82 ~B obta~ned~ro~ a s~lution~ .
of deminerallz~d di~tilled water, isaturatod with air a~
atmo~ph~ric pre~r~, and o~ l~minol
L T O [21 ~)S~ C Z L~ I C ~ IS: II S~ . Z O ~ ~ Z
`-~ 21~3~7 ~ ~
..
; ~ . .", .
(a~inophtalhydxazide, 1.4 mmol previou61y dissol~d in
hplc-~rade dim~thylsul~oxide ~DM~O)). Th~ ~olution was
buf~ered with CAPS ~3-yclohex~lAmino l-propan~ ~ul$onic
acid), 25 mmal and balanaed to ~ p~ o~ lO with o.l M :
5 ~oda. .~ ~
For thi~ experiment, the ultra~ou~d tran~ucer :;--. :
elem~nt 123 ~mploy~d had a di~meter of 5 cm, and fo~us~d
to 97 mm. The tank wa~ a cylind~ical 40 ml contalner -~
arrang~d horlzontally, with a length of 5 cm in which ~ :
0 foc~in~ e~fect did not partici~ate, th~ energy being : ~p
distr~u~ed throughout the t~nk. Tran~ducer re~nant
frequency ~as l.ll M~z, ~aid ~alue bei~g obtained at the
80nolumin~cence maximum o$ the wat~r.
The photamultiplier is ~or example ~amamat~u type -~
~74 comprising a len~ optical ~y~tem ~or receiv~ng the
fluorescence emltted by the luminol. Tan~ 180 wa~
optically lsola~ed to avoid ~ny light ~nte~S~rence.
Photom~ltlpliar 184 wa~ pow~red by a 6mall g~n~rator not
~hown he~e and the light ~ignAl wa~ read on the ammeter
~0 18~ that integrated th~ total amou~t of l~ht emi~ted by
the luminol.
Transducer 123 wa~ conne~eed to power ampll$ier 130,
which~ for example~ ~ of ~he Ampar 801, Prana, type
ha~ing ~ pa~band ra~glng from o.l to l.a MHz. The
electronic ~ignal or M-~equence p~eudo-random code
generator w~a m~n~fact-lxod by the INSERM havi~g a period ;; :
T of about 60 m~, and an indivldual pul~ duratlon ~) o~
~ , and W~ s~n~hronlz~d by a HP ~116 A type function
generator~. Wattmet~r 132 wa~ a Rhods ~ S~hwarz dlgital
30 watt~et~r refer~nc~ NAP whlch allowed lncident and r~- ;
flected pow~r to ~e mea~urQd. . .
Re~ardi~g wattmeter 132 re~ding~, th~ r~rences ;. .;.
indicated o~ FIG. 5 have the following meaning~
- "2dNC'I = direct puw~r fro~ ~n ~ncoded aignal, in ,;
35 oth~r word~ a si~ewa~e si~nal of the prio~ art; `.; ~.
- PrNS" = r~ ~ect~d power from an uncoded ~ig~al, in ::
other words a ~inewave eignal o~ the prior art~ : .
,:,
''' " ' ' .''
, , ,:,
8To~ ~S~IH ~ cT ~ CZ L~ l s~ ZC:TI 9~. zo~Z .:
'
2143487 ~ -`
17
- "PdC" - direct power ~rom a coded signal, in other
words a random or p~eud~^random type ~ignal o~ th~
l~e~ion;
- "Pr~l' = power r~f l~c~d wt th a coded ~i~nal, in
o~her word~ a random or ps~do-random type signal o~ the
inv~ntiOn. `
Me~ureme~t were mad~ at di~r~nt power~, ~irs~ly :~ .
with an u~codod ~ignal ~NC) (monochromati~ ~ignal at 1.11
MHz~ o~ contln~ou~ ~inewave o~ the p~ior art, ~u~h as
10 ~i~nal ~1 o~ FI~S. 1 a~d 2, which enabled llne 1 to b~
obtain~d shown by th~3 circle~3 or dot~ in FIG. 6 ~or
comparativ~ purpo~e~. Secondly, this ~ame signal :~
: modulated with a p~oudo-random cod~ made it pos~ible to
obtai~. ~n M-~eque~c~ p6cudo~random electronic 3ignal
accordin~ to the in~ention, a~ shown in Fl~S. 3 ~nd
be~ing the re~erence AS, which p~ovided the line
identifiad by the diamo~d-~haped point~ on FI~. 6. :~
In both Ca8~8, the ~ignal generated wa~ maintained
until a luml~eacence plateau was achieved. The ~olution
20 was i~ct~d lnto the ~anlc m~nually with A 50 ml 3yringe, :; . .
~hi~ alway~ ~in~ done in the same way.
Fo~ ea~h power teeted, m~as~r~ment was r~p~tod
time8 wit~ th~ same ~olution. Between ths~ ~aur
m~a~ureme~t~., the ~olution wa~ dr~wn o~f ~rom the tii~nk
25 a~d reinj~cted in o~der to ma~ntain a ~on~t~nt de~ree of ~ ;~
saturation. On th~ other hand however, when there was a
aP.ang~ iram one power to th~ other, the solution was
th~own away and r~newed. .
~ . Temperatur~ w~ r~lat~ely stable (23-2~c), radia-
: 30 tion time ~eing ~hort and the tran~ducer beiny only
cQ~led rom the back with a cold watex cixc~it (not
shown) on its me~al part.
The re~ult~ obtained are gi~en in tabls I ~elow.
Vin ~m~ the lnput voltag~ at the Prana ~ype power
amplifier 130. Pd and Pr are, r~a~pectively, the dl~ect
r~leat~d.po~rs ~o~d~on w~tt~eter 132, PT~ans bein~
the power tran~mitt~d b~ ~he tr~nsducer ~PTr~ Pd-Pr).
L~lrn i6 thQ luminescenc2 valu~a r~ad on na~oammeter 18~.
0il0~ H~S~ 3~ Ct ~ CZ Lr T CC~ ZC:TT S~i. Zo/~Z
i , .
~$
,j .
; 2~3~87 `
18 ~`:
, ~'
The indice~ C and NC r~p~ctlvely ~harac~erize a random
or pseud~-random ~A.S.) type coded sl~nal according to
~h~ inv~ntion ~FIG~. 3 and 4~ and an ~ncod~d signal, in
other words ln sl-type ~in~wav~ according t~ th~ pr~or ~ :
art (FIGS. 1 ~nd 2~.
The lumin~sc~nc~ value~ ob~ain~d from a ai~nal coded
according to the inv~ntion are ~h4wn by li~e ~ with
diamond-3haped poi~t~ in FI~. 6, line 1 joinin~ the cir~
cle~ or dots ~i~ing the ~igu~e~ or ~ sinewa~ uncoded ~ -
~lgnal ac~ording to th~ prior art in FIG. 6, a~ a
function of ~ignal powçr tran~mltted by t~e tran~ducer,
in Watt~. ~or valu~s b~low lO W, th~ lum~n~scence
mea3ur~d for the two ~i~n~ls corresponds to the ~atural
lumln~3ce~ce ~ wate~
The cavitation threshold wa~ obt~ined around 12 to
15 W for the uncod~d signal of the continuou~ sinswave
type of th~ prior art wh~r~a~ thl~ was n~vor r~ach~d in
~he ~n~ç of power ~mploy~d with ra~dom or pseudo-r~ndom
~pe coded sig~al ~ording t~ ~he pre~ent ~nventio~.
It was no~ po~ble to m~ke tne~suresre~t$ above 40 w
without putting the ul~ra~ound trani~ducer 123 at ri~k.
uln P~c~rNa dC ~.5 T,~ un~ _~NC ~Tr~
~4 1~, ~ 0, i. 31. 5lg, 0 2ig 49 12, ~ 12, 5 ~ ~ ~
3g ~,S,3 0,~ 3ig,524,1 130 61 14,7 15,4 ~: '`
44 Z0,0 0,i9 S0,831,1 ~00 ?1 lg,l g,~
. ., :: ..
49 26,3 1,5 6:L,2 37,~ 1400 78 2~,8 24,0
S3 3~,1 1,7 77,8 ~7,~ 2600 ~5 30,4 30,0
62 41,0 2,~ S9,6 ~325 89 ~8,8 3~
~' :....
~huo, it ci~n be aeen that, unexpoctcdly, by using a ; ~
wideband ~lectro~ic ~l~al according t~ the present :~ :
~5 inv~ntion and, ~or example, a p~eudo-random or random :;
typ~ cod~d ~lectronic sl~nal, no cavitation phenomena: -:
a~pear in the rango o~ pow~rs used ~or the exp~im~t,
t~ heing.~ re~l~ct~id by the s~it Q~ isteaidy valuois ~or ~:
lumin~scenc~ as a ~unc~ion oE power, in con~raist to line
l obtai~ed with a ~inewa~e si~nal o~ the prior art.
, :,,. "
ozn~ H~S~ INI~ Cl ~ CZ L~ I SC~ ~C:TI S~. ZOi~Z
21~3~87
This constitutes a ~urpri~ing result of the pre~3ent
in~en~ion
FIG. 7 is a his~hly ~;chel~latic repre~entation of th~
opera~cion o a dev1 ce acc~rdln~ to the prior ar'c, in the
S pre~l~nc~ of a per~ odlc or ~uaai-perioc3.lc s~'cruc'curel; in
FIG. 7, a therapy de~ic~ 200 link~d via an amplifie~ 203 :
to a ~3ignal g~n~rator 204 c~n ~ s~an. ; .
~ me~tioned above, th~ th~rapy devic~ i~ for exampl~ -
a ~3emi-spherical cup with natural ~ocu~ing, comprising
10 one or se~reraL transducer element~3 (a single tran~duc~r,
or a ge~ of annular ~r mo~aic cer~mic element~
The therapy device ~3etEI up an ultra~ound field 20S
directed towards th~ tr~tment region 2~6. A periodic or
~uasi-periodic ~rUCtUr~ 207 1B dlfipO5~d in th-3 ultra-
15 ~ound fi~ld aos between a therapy de~ice ;~00 ar~d thet~eatment reglon ~!0~, r~erence 210 ldentlfying the ~oc~l
spo~:. This s~tructllre can i~or example be the rib cage, in
the ca~3 of e~xt~rnal l:reatment o~ tumor~ of the l~ver. : ~ .
In devic~s o~ th~3 ~r~o~ ~rt driven by a ao~fentional
20 ~inewave type~ 9igr~al or, more generally, excited by
periodlc ~lgnal~, ~uah a p~riodic structure lead~; to the
appear~nc~ o~ secondary poirlt~ of ~ocu~ 208, ~0~ ~or ~ida
labei~) outisid63 th~ tr~atm~t regio~ as a result of
dira~tion ~f ~h~ ultrasQun~ waveY pa~in$ through
~S ~tructure 207. Th~ appearance of ~uch secondary points
o~ ~ocu~ ha~ obvious cons~quences ~r the ~f~ty o~
tr~at~ent. Moreover, radiation o~ energy ta the~
secondary points decreai~ee the power radiated to ~ocal
point 2~0, and can compromi~e the e~ecti~e~e~3 of
30 treatment. On~ can cay that in this c~n~ig~ation, soc-
ondary focusing ph~nomena occur b~hind the p~riodic or
f . quaei-periodic structure. In thl~ ispecl~icatlon,l th~,
expre~i~ion "behind th~ periodic or qua~i-peri~di~ struc-
turc 207" ~hould be tak~n to mean ~down~tream, r~g~r~ing
35 thc propa~ion path of ultrasound wave~, of th~ p~riodic
or.qua~ paria~ic structur~ 207~
FI~. 8 ~how0 the ~amo arr~nsement as as in FI~. 7 in
a device implementin~ the invention. The i~vention ::
IZ0~ ~S~ CT o~ SZ L~ I SC8 CC :TI S0. ZOi~Z ~ : ~
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di~clo~e~ the use of a ~iynal gen~ratOr ~upplyi~l~ a
wideband electronlc signal for exciting the therapy
device. A~ d~cribed above, ~h~ ~ign~l generator may
~upply a random or pseudo-random ~l~ctronlc ~ignal and,
more particul~rly, a Golay or Barker coded paeuda-random
elactronlc ~i~nal or an M-~quence pseudo-random coded
type electronic signal (of the typ~ dexcribed ab4ve for
exampl~
The inv~ntion can also ba cha~terized ln that the
therapy devic~ i~ excl~ed b~ a signal h~ving ~n auto~
correlation ~unctlon th~t i~ ~ clo~e ~s possible to a
Di~ac ~unction. The signal~ a~o~o have an a~to-
correlatlon ~unctio~ w~ich approache~ tha~ of ~ Dirac
func~ion.
F~G. ~ lllustrate~ the result6 o~ the invention: the
~econdary point~ o focu~ caused by the periodic or
qu~ periodic ~tructu~e have dl~app~ared; the position
o~ such ~ocal point~ doe~ ~n fact cs~entially de~end o~
the periodicity of the ~trU~tu~e 207 and the ultrasound
frequency. The use o~ wideban~ nal~ cAu~e~ ~he
posltion of the ~econdary point o~ focu6 to ~ary d~ring
th~ cour~e o~ treatment. In thi~ way, there i~ no longer
B local ~uild-up of enersy~outsid~ ~he txeatment region
in. ~e ax~ea. surrqur~ding the priD,cipal pQi~t oi~ i~o(~uq 210..
2 ~ l~h~ inv~ntion thus mak~s ~t posslble to decrease the ri~k
of producing secondar~ le~lons out~ide the treatment
rc~ion, even in the pre~ence of a periodic or qua~
p~riodic struct~re.
. - .
Th~ in~e~tion mak~s it pos~ibl~ t~ achieve ~ccurat~
30 and loc~ ed ~reatme~t, ~n behind a periodic or ;~
, . .. .
guasi-p~riodl~ st~UCture ~uch ~S, for example, treatment
! . 0~ tho llv~r b~hind the rlb cage.
The varlou~ embodiment~ of the in~ention deacribed -~
with re~er~nce to the p~eceding figures can obviously be ~
35 combined. ..
The: pr~ent ln~ention ob~ioui~ly i~clude~ all ~e~ns
constituting tschnical e~ui~lents of the ~eans ~:
de~cribed, a~ well aa various co~binations thereo~
:. .
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Moreo~re~, FIt~;S. 3 to ~ constitu~e an lnte5~ral part of
thi~ invention ~nd thu~ o~ tha deEIcription.
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