CA2169338A1

CA2169338A1 - Gamma matched, helical dipole microwave antenna with tubular-shaped capacitator

Info

Publication number: CA2169338A1
Application number: CA002169338A
Authority: CA
Inventors: Eric N. Rudie; Stanley E. Kluge
Original assignee: Individual
Current assignee: Urologix Inc
Priority date: 1993-09-17
Filing date: 1994-08-12
Publication date: 1995-03-23
Also published as: WO1995007730A1; AU7920094A; EP0723468A1; AU678624B2; US5370677A; EP0723468A4; JPH09502630A

Abstract

A catheter shaft carries a coaxial cable (220), the terminal end of which contains a dipole antenna (214) with opposing first and second helical elements (214A, 214B). This first and second helical elements (214A, 214B) originate from a common connection (222) to an outer conductor (224) of the coaxial cable (220). A tubular-shaped capacitor (200) is connected between an inner conductor (218) of the coaxial cable (220) and a point (232) on the second helical element (214B) where the resistive component of the antenna's impedance matches the characteristic impedance of the coaxial cable (220). This match minimizes reflective losses of the antenna (214), thereby maximizing power transfer to the antenna (214). The antenna (214) has an effective electrical length which is equal to one half the wavelength of the radiation emitted, independent of the physical length of the antenna (214).

Description

WO 95/07730 PCT/US94/0914:~

GAMMA MA~ , HELICAL DIPOLE MICROWAVE A~TENNA
WlTH TUBUL~R~SHAPED CAPACITOR
R~ RolrNT) OF T~F. ~VP~lTION
The present invention relates to the field of microw~.c 5 thCI...A~ ela~,~ of tissue. In particular, the ~.~"l imTention relates to an ç.fi;~çnt micr~wa~ C ~ e~ A for ~ C~ o..~ A1 ll,el~ of benign proslatic hyperplasia (BPH).
Thc ~r~s~te ~and is a comple~, rl~rs'~ ~t sl ~pe~l organ which cncircles the ulell~a immeAiAtely below the bl- lder. Nearly one third of 10 the pro~late tissue ~nt~,~ior to the ure~ of fibro ..~ 1A~ tissue that is h..~lo~.l;~lly and filn~tionAlly related to the ulelLa and bl ~lder. Ther~ A;..;.~ two thirds of the ~,ro~la~e is generally posterior to the ulelhla andis ~ .~ ; ed of glAn~llllsr ~ssue.
This relatively small organ, which is thc most frequently 15 ~ d of all intcrnAl orgAn~, is the site of a c~ o-- gff~ n among older men: BPH (benign ~.o~tic L~ ~). BPH is a nnnmAlign~nt bilatcral n~nl~r c~ ;nn of p~ a~c tissue in the tr~n~ih~n zone, a ~liW~ l re~on of the l,ro~ e between the fibro ..~.cc ll~r tissue and the gl~m~ - tissue. The degree of nnAnl~r ~ n within thc tr~n~ition zone 20 tcnds to be greatest ~nterior and lateral to the proslalic urcll~ rclativc to the posterior-most region of the ure~ ~ Left ullllcated, BPH causes obstruction of the wc l~a which usually rcsults in increased Ulll~
frequency, urgency, inr~ntinenr~, noctllri~ and slow or interrupted wi stream~ BPH may also result in more severe compli~tionc) such 8S wina 25 tract infection, acute w~ rete-ntion, ~dlon~lllu~-s and uraemia.
Traditionally, the most frequent L,c-~t~ ~nt for BPH has been sul~el~ sufcl}~l resection). Surgery, ho.._.~r, is often not an available m.~tho~ of If c~ for a variety of re~con~. First, duc to thc advanced agc of many p~t;~'.nt~ with BPH, other health problems, such as cardiovascular WO 95/07730 PCT/US9~/0914;~
.

Aic~c~, can w~ l ag~inct surgical --lel~enLio~ Sec~n~l~ potential oomplir~tionc ~C-coci~te~ with l.~ulc~ l Su~ , such as hemorrhagc, ~nesthetic comrlir~hnnc~ ul~ infçction, dysuria, inr~nffnPnre and rello~ade ej~ tion~ can a.l~ cly affect a patient's willin~cc to undergo 5 such a procedure.
A fairly recent ~lte~ .c tre-~tmPnt mf~.th~ for BPH involves mlCl~wa~., therm~ a~, in which mi uw~_ energy is employed to elevate the te.lll,c-alule of tissue ~ullu""~li~ the l"os~lic UIC~l~d above about 45C, thereby therm~lly A~m~r~ the tumorous ~ssue, as well a~, 10 ~jac~pnt healthy tissue. Delivery of mic.l(lw~C energy to tumorous l,ros~lic tissue is generally ~e~ornrlichp~ by a i.;,uwa~c A.~ CQnt~inil~g applicator, which is positionpll within a body cavity Yq lj~cent the l~roslate gland. The mi.;.ù~.c ~ntennq when c~c.~i~d, heats ~jant tissue due to mole~ll~r ~ s!n The heat generated by the ~ntenn7q is c~-.r~-~l~ated 15 about the ~nt~nnq in a generally ~ylindrically ~.llluctrical pq-ttern which c~ es and lle~l~scs tumorous, aswell as healthy, i..lla~r~lalic tissue.
The necrûsed i~ s~ic tissue is s~lbse(lll~ntly r~l1cd by the body, thereby relieving an individual from the ~ ollls of BPH.
This miCl~ a~ .P.I~ meth~l is derived from a tre~tmen~
20 for prostatic cancer known as llrpc~ ermia~ in which microwa~e energy is supplied by a miCl~)Wa~C. ~nt~nn~ to the ~r~te to elevate the ~ o~ Aing te~lalule to bet~veen about 43C - 45C. Within this te~ el~lule range, healthy, well-vascularized tissue is unharmed be~llse of the circulatory system's ability to effectively carry away the heat. Cancerous tissue, on the 25 other hand, has re~hlce~l vascularity, which restricts its ability to adjust to the heat. Thus, heat con~ntrated in the region of the cancerous tissue is 5-lffiri~nt to necrose the cancerous tissue, yet in~lffi~erlt to harm ~ nt healthy tissue.

WO 95tO7730 PCT/US94/0914~
~ 2 1 6 9338 Micr~Jwa~c~ therrn~l therapy, l~cc~ of its higher tC~Cld~ulCS
(above about 45C), provides the advantage of shortening a tre~tmsnt sesc;~n's duration as c4...l-~red to that of L~ hc,...;~ with its lower t~.~Cralu~CS (bCl~._ell about 43C and 45C). An lm~le~irable c~n~c~lence 5 of micr~)wa~ ",.~1 therapy, hu.._~_r, is the adverse effect the higher tcl.,~r~tures have on healthy tissue ~ nt the ~-e~e~ area of the pros~te. The ~lilemm~ of selectively 1~P2.1;,~g and .,e~osi~g only tumorous ,roslalic tissue by mi.lowa~_ th.orm~ C1a~ has been s ~e~ssfillly addressed in c~ ,g U.S. Patent ~p b~nS Serial No. 07/847,718, 10 çnfftl~d DEVICE FOR ASYMM~RICALT~RMALTHERAPY WlTH
HELICAL DIPOLE MICROWAVE ANT~NNA and Serial No. 0 7/847,894, e-ntithd METHOD FOR TREATING INTERSIITLAL TISSUE
ASSOCLATED WITEI MIC~ROWAVE T~RMAL THERAPY.
~ nter..~c which have been used for h~ c~ have a 15 ~ariety of -~P~v~^ies which preclude their ~pli~tioll to micl~w~e thermal therapy. First, such Dnt~nn?C often g~lle.ale heat in two forms:
~uc~ cnergy and heat energy due to ~L~_ losses of the h.~le~n~l~
The efficien~y of these ~ c hac not been of much a~ r,.. due to the relatively low zmolmt of energy used to generate interst~ti~l temE)e~lures of 20 lbetween about 43C to 45C and the lack of any adverse cffect thece tempelalul c s had on healthy tissue. Ful Ihcllllole, it is lcllown in the art that ~e shape and size of a rZ~ hcn p~tt~prn generated by some micl~,wa~e antennas are in part a fimrtion of how deeply the ~ntçnn~ iS inserted into thc tissue. Prior mici~w~c dipole ~ntçnnzc used for Ly~lhermia have 25 been unable to provide a predictable hPAting patl. ll- within tissue due to the variable cffects caused by the depth of insertion of the ~ntç.nn~c into the tissue. Finally, the rA~ tion length of these Z~ AC ha not been easily variable to ~ mmodate the va~ing sizes of proslates re~niri~ e~t ..P-..
l[he ~ntenn~ dÇci~c of the prior art relating to ~ ermia, lhcrefore~

WO 95/07730 PCTIUS9~/0914~
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6q338 have proven ~ c~t;cl~CtQTy for mic,c,w~c thermal therapy and its ~ttend~nt higher tc~cialurcs.
The objective of mi~ wa~.e the~mal therapy LC to reduce the length of a ~e~ eCcion and to selc~ cly heat and necrosc only S lm~les;~us ti~suc, while ~, to thc grcatest e~ctent possible, adjacent healthy tiscue. In order to avoid tl~m~ge to ti suc. imm~i~tely r lj~e~nt the miel~,w~ c~a~~ ;t~ appli~tor (i.e., the u~cl]n~, the e~ to2y duct and the rcctum), it is ec~-nff~l that ~the rcs~.c losses of the ~ntenn~
be re~ c~ or optim~lly climin~te~ The ability to el;-~ lc rcsi~c losses 10 and utilize only mi~;~u~ energy to heat a targeted tissue arca would permit a coolin~ system, such as that descnbed in the co pen~li~
appli~tinn.C, to ~A;~ safe tc~f-lalur~s ~j3~nt tO the app!i~tQr by absoll,~g and C&ll~ away any excess heat c~nducte~ to thc u~c ~ ssues. In A~flitinn~ the ability to Collst~uct an ~ m~ hle of pro~u~
15 a pret~ blc, yet electively variable size he~ting ~tl~-.. would ud in achieving an effec~ve tre~tn~ent of lm~lc~:. c,us tissue while ...;..;...;~ harmto healthy tissue.
Sl JM~Al~Y OF THF. l~VF~TION
The precent invention is an i~ r~ d helical Antenn~A~ for 20 thermal treAtment of inter~ctitiAl tis ues. The helical ~l~len~A is carried by a coa~aal cable which has an outer in~ qtQr, an outer cQn~ ctor, an inner in.clllAtor and an inner conrlu~Qr. Thc coalaal cablc and A~ n~A are in turn carlied by a catheter. A midpoint of the helical ~nt~nn~ i conn~cted to the outer c~nductor of the coaxial cable so ac to form firct and second helical 25 SGCtiQnc of a~p~ te equal length. A tubular-shaped series cap~çit~n having an outer conductive layer, an inner cQndllctive layer and a lielGctric layer therebetween i. c~nne~te~ between the coaxial cable and the helical ~nt~nn~ The inner cQnductive layer of the series c~r~ n~ is c~ c~led to the inner con~ ctQr of the coaxial cable, while the outer cQn~iuctive layer WO95tO7730 PCT/US91/0914~

2 ~ 6 9338 of the series c~r~ t~n~ is c~ne~ to a point on the second helical se~hnn where a res~Li~e c~ ollent of an in~reA~nce of thc ~ntçnn~
m~trhçs a char~c~eri~tic i~A~-~ of the coa~al cable. This match ...;n;...;-~s rcflective losses of the ~ çnn~ lLcrel~ ...~.;...;-;.~. power ll~rer to the ~nt~nn~
R~2~FF r~FA~ ~oN OF T~F 1)12~ S
Fig. 1 is a vertical section~l view of a male pelvic region showing the u.~ organs affected by benign ~lo~l~lic l.~ lasia Fig. 2A is a side view of the distal end of the ure~ al Mtheter of thc l,.es~ invention.
Fig 2B is an enlarged ~chnn~l view of the ~,r~ al end of the ulc~ al c~hctc~ of the ~lcsclll invention.
Fig. 3 is a cross ~ n~l vicw of the u~c~ .l ~theter of Fig.
2B talcen along line 3-3.
Fig. 4 is a ~ view of a p.~ al rcgion of thc ulctl ~theter with the cnd portion taken in sAcho~ from line ~4 of Fig. 2B.
Fig. S is an cnlarged view of the male pelvic region of Fig. 1 wiag the ur~ al c~thPter of the ~ nt invention p~Citioncd within the l~ro~te region.
Fig. 6 is agraph illusllali~ tel A~lalulc dictributiongenerated by thc catheter of the ~lcscnL invention as a fi-n~iQn of timc.
Fig. 7 is a partial sesti~ n~l view of ~e micl~wa~ ~ntenn~ of t~e Ul'ellli`al e~thPter of t_e present invention.
Fig 8 is an exploded view of the mi~;lOWd~ ntenn~ shown in Fig. 7.
Fig. 9 is a block diagram of the transuret_ral micl.,wa~.c therm~l therapy system of the present invention.
Fig. 10A is an enlarged perspective view of a tubular-shaped r~p~<itQr of an altelnali.,c emboAimpnt of the ~le~lll invention.

WO 95/07730 PCT/US9~/0914~
.

6q33 Fig. 10B is a cross-se~i~n~l view of the tubular-shaped c~pM~tQr of Fig. 10A tal~en along line 10~10B.
Fig. 11 i,c a partial sec~ n~l view of the mi~;luwa~c ~ of the ~iese,.l inve~tion em~loying the tubular-.ch~re~ p~ritclr of Fig. 10~
5 nFT~n Fn nF~ P~ON OF T~F. p~FFFRRFn F~RonlM~s Fig. 1 is a vertical sechQn~l view of a malc pelvic region sl~ow,.~g the effect benignprostatic ~yperplasia (BPH) has on u~ organs.
Urethra 10 is a duct le~ from bl~der 12, through ~r~lc 14 and out orifioe 16 of penis cnd 18. R~c-ni~ lu~ ,us tissue grow~ within ~roslate 14 around u-ell~a 10 causes cQnctri~inn 20 of lllel~ 10, which u~lS the flow of urine from b~ ler 12 to orifice 16. The tumorous ~ssuc of l,roslate 14 which encroaches ule~ 10 and causcs ~nctTichrm 20 can be effectively removed by hP~ng and 1~ the encro~^h OUS tissue. Ideally, with thc ~rc~ l imrcntion, only ~l;We~
15 lull~orous ~dssue of ~i~tc 14 ~ntcnor and lateral to lllc,l]~a 10 is heatcd andnecrosedtoavoid~ P~scc~ and,J~ p~ w~mag~.tou~ 10and to ~ nt healthy tis~es, such as e; ~ to1y duct 24 and rcctum 26.
Selective h~ting of benign luluolous ~dssue of ~lo~L~tc 14 (L[~su~c~
thermal Ihe.ld~) iS made po~ible by mi~;lowd~e ~ntenn~ ;"~ ~theter 20 28 of the present invention, which is shown in Figs. 2A and 2B.
Fig. 2A shows a side view of a distal end of c~theter 28, while Fig. 2B shows an enlarged section~l view of a ~lo~al end of c~theter 28.
As shown in Figs. 2A and 2B, cPtheter 28 generally inr~ e multi-port rnanifold 30, multi-lumen shaft 32, shaft pocition retention balloon 34, 25 conn~o~ion m~nifol(l 35, cooling system 36 and mic~,w~ generating source 38.
~ r~nifold 30 inc~ les infl~tion port 40, urine drainage port 42, miclc,w~e antenna port 44, coo!ing flwd in port 46 and coolillg fluid out port 48. Portc 4~48 co.. ~.. ;r~te with ~llcs~onding hlm-~.n.c within shaft ~ 2 1 69338 32. ~nifs)l~l 30 is l"~fer~bly made of m~ir~1-grade c;lir~nc cold by Dow ~ornir~ under the tr~d~m~lr Sil~cttr Q-74850.
Shaft 32 is cY!nnccted to m~nifold 30 at shaft distal end 50.
Shaft 32 is a multi-lumen, Foley-type ulel~ ~ttheter shaft which is 5 cxtruded from a fl~ t~l~, m~~ -grade ~ili~ne sold by Dow t'~rning under the trS ~l~m~rk- S;l~Chr Q-7-4850. Shaft 32, which has an outer ~iqmcter of between about 16 French to 22 French, inr~ Gs outer sur~ce 52, which is gcnerally elliptical in cross-~ton as shown in Fig. 3. Shaft 32 is long e-nn~lgh to permit insertion of l,r~i.llal sh~ft end 54 through Ulel]lld 10 and into bl~1Acr 12. In one ~le~lled embod;~ r~ , shsft 32 is coatcd with a I~dlo~lilic solvhnn sold by IIydlu~cr, Inc. under the mark IIy~
which lubri~tes outer s~lrf~e 52 of shaft 32 and fiA-~lit~t~ps its adv~nremPnt within ulcl~ a lQ
As shown in Figs. 2B, 3 and 4, shaft 32 in^-ludes te~ldlule IS 5^~C;~ lumen 56, micru~ a~c ~ - - lumen 58, urine L~ai~e lumen 60, b~ll~n infl, tion lumen 62, cooli~ fluid intalcc lllmen~ 64A and 64B, and c~ling fluid ~ ln^.~nc 66A and 66B. ~ ~lm~n.c 56-66B generally extend from dictal shaft end 50 to p~ ..al shaft end 54.
Tc~ ulc s~ lumen 56 is posib~ l near first side 68 20 of shaft 32. Te,ll~ralur~ s~nci~ lumen 56 ~ tes with mic~owa~
~ntenn~ port 44 and ~llLu~ insertion of therm~etry sensor 69 within shaft 32 to mQnitQr tc~ elalulc when shaft 32 is inserted within ulclhla 10.
Sencor 69 exitc through port 44 and is cQnnP~P~ through c~nn~Pction m~nifold 35 to u,et}~l therrllometry unit 178B (shown in Fig. 9). In a 25 preferred embo~lim~nt~ thermomet~y sensor 69 is a fiber optic l~ Psc~n type temperalul e sencor sold by Luxtron Col~oldLion. Telll~lalul e senci~
lumen 56 is sealed at proAilllal end 54 by silic~ne plug 70.
MiCfOwa~ ntenn~ lumen 58 is CCC4~ ;c to thc 1Qr~ 1;n~1 axis of shaft 32, ~ntenn~ lumen 58 being p~citi~)nPd nearer first side 68 of WO 95/07730 PCT/US9~/09145 ~ 6~338 ~

shaft 32 than second sidc 72 of shaft 32. ~nt~nn~ lumcn 58 is scaled at .r~ill.al end 54 by ili~on~ plug 70~ At its distal end, qnt~onnq. lumen 58 c4.. ~.. ;~q-tes with mi~ wa~.~ qnt~.nnq. port 44. Mi~lOwa~_ qnt~nnq 74 is ~.. ~... ~ntly po~iti~n~ within 5 ~.lc ~ lumen 58 ncar ~qlloon 34. .~nt~nnq 5 74 is poition~d within ~ lumen 58 so as to be generally ~ q-te~
~jæ~-nt the benign tumorous ~dssuc of prostate 14 when shaft 32 is ~iopc.ly poitinn~ within urcll~la 10. As shown in Figs. 2A-2B, ~ ...q 74 is bon~l within 9~ --q lumen 58 by adhesive bond 75. ~ntennq 74 is aq-rne~l at the ~c,~al-most cnd of coa~al cable 76. Thc distal-most end of coa~ial cable 76 is c~ c~1s~ to c~ .l ;nn nl~nifnld 35 by a c~ n~l quiclc~ollp~ g fitting 73. rO~ l cablc 76 c~ n;~teS with mic.~wa~_ gc.lel~i~ source 38 by c~ ;nn cable 76A, which is ~ between micl.,w~c ~ ali~ source 38 and ~...P~ m~nif~d 35. In onc embo~limP-nt cp~ ec~ n cable 76A is a ~ rd RG 400 coa~ial cable.
15 Mi~ wa~_ gcllc~aling sourcc 38 produces a .. ~ ... of 100 watts of e1P~;(~1 power at about 915 M~ ~e~ en~s~, +/- 13MHz, which is within the FCC-ISM st~n~zrds. When ~ e.~z 74 is c~e.~d by mic~,w~._ ~,_nclaLil~g source 38, z..lc ...-~ 74 emits clc~ o~.~a~ c energywhich causes hP.~ of tissue within prostate 14.
Urine drainage lumen 60 is pQSitiOTlp~ lj~nt ~ntenn~ lumen 58, between ~ lumen 58 and sccond side 72. Uline d~-nage lumen 60 c~ ..ic~tes with uline drainage port 42 a~d defin-s a drainagc path for urine when ~r~ al end 54 of shaft 32 is inserted within bl~dder 12.
Urine drainage lumen 60 is cc~ e~led to urine drainage lumen e~en.cion 78 25 at pi~ .i~al end 54. Urine drainage lumen eYtenC;on 78 is bonded within al end cap 80. End cap 80 is further bonded over outer surface 52 of shaft 32 at p~oAill,al shaft end 54, with cavi~ 82 ~u~ i~ lnmen eYt~or~;on 78. With end cap 80 and urine drainage lumen ~ ncinn 78 in place, opening 84 to lumen eyten~ion 78 pCl ~ .~ urine to drain from bladder wo 95/07730 2 ~ 6 9 3 3 8 PCT/US9~/0914~

12 through urine drainage lumen 60 and out urine d~7ai~e port 42 when pr~ l shaft end 54 is inserted within bl~dde~ 12. Drainage of urine from bl~ er 12 is neC~c~ due to frequcnt bl 1der cp~cmc which occur during t~ ,.,rc ~ therm~l therapy.
BaUoon infl~tinn lumen 62 is p~cibQlled ncar s~cond side 72, generaUy between urine drainage lumen 60 and sccond side 72. R~lloQn infl~hnn lumen 62 co~ ir~tes with infl~h~ n port 40 and ic sealed at ~r~i~l e~d 54 by silic~nc plug 70B. R~ll~n infl~ht n lumen 62 c4..l...~.~;~te~ with intcrior 86 of b~lloQn 34 by o~ .;..~ 88.
R~lloQn 34, which is formed from a tubular s~ction of a fl~-~ble, m~ gradc silicone sold by Dow Corning under the h?~3çm~rlc Silsch~ ~7 1720, is secured over shaft 32 ~y bQntli~ b~llQon waists 90 and 92 over eYteror snrfs~ 52 of s,haft 32 near ~ ,al shaft end 54. Rqll~Qn 34 is inflste~3 by an inflqhon device 188 (shown in Fig. 9), which is co~ P~
to infl~tion port 40 and which supplies yOSili~_ ~uid ~.e~ure to interior 86 of ~ql~ 34. R~ o- 34 ic defl-q-tecl when inflshorl device 188 supplies a llegaL~c fluid IJl~LUC (i.e., a vacuum) to interior 86 of b-qll~>on 34. Rqlloon 34 serves to retain shaft 32 in a fixed pocition within ule~d 10 when bq-lloon 34 is inflqted within bl~ er 12 near bl~dP-r neclc 22, as shown in Fig. 5.
As shown in Figs. 2~4, cooling fluid intake l~lmpnc 64A, 64B
are position~l c~.- ..-.jqce-nt first side 68, l~-.~n first side 68 and ~ntPnn~
lumen 58. Cooling fluid intake hlmPn~ 64A, 64B extend from distal shaft end 50 to pr~ ,.al shaft end 54 wbere hllm~-nC 64A, 64B are e~posed to cavity 82 of end cap 80. Intake l~-m.on~ 64A, 64B are relatively nall~W in cross-sech~-n and have a relatively small cross-sechon~l s~ ce area Water ~n~ eA within intake l--m.onc 64A, 64B ~ wllls two essential f~mrtiQnc First, water cQnt~ine-d within lnmP,n~ 64A, 64B absorbs some of the miclowa~ energy emitte~l by ~ntPnn~ 74. Tbis assists, in part, in con~rolling WO 95/07730 PCT/US94/0914~i .

~9338 -1~
thc volume of tissue ~ nt first sidc 68 of shaft 32 that is heated above about 45 C. SecQn~l~ the water within lnmenc 64A, 64B absorbs heat energy ~ne-~ted by the miclowa~ ener~y from ~ ~jr~nt tissues (ie., ur~ la 10) ~ia ll~c~ c~nt~ n This ~ ~b the portion of u~ a 10 r~ çnt 5 first sidc 68 from being o._,heated and d5~ a~ A when ~ e~ 74 is energized.
Cooling ~uid ~ l lumenC 66A, 66B are ~ ~-nt second side 72 with lnn Pn~ 66A, 66B generally positi~np~ between second side 72 and ~ lumen 58. Iilce intalce lmnPnC 64A, 64B, ~.l.z..~.l lvm~nc 66A, 66B c~ctend from shaft distal cnd 50 to shaft ~,Ai~l cnd 54 where ~ hlmPn.c 66A, 66B are ~sc~ to cavity æ of end cap 80.
F.Yhqll~t lllmP.nc 66A, 66B arc wider in cross s~ion than intalce hlm~nc 64A, 64B, and have a cross s~hnnql arca ~calcr tban thc cross s~l;nnql arca of intake lnm~Pnc 64A, 64B. Waterwithin ~ l hlmPnc 66A, 66B is therefore r~r~q.~ of al)~o l,mg a ~eatcr ~ of micr~ ener~y when ~.le 74 is cncrgized. As a rcsult, for a given powcr output f~om micl~lwa~
generating source 38, the t~alure of tissue ~j, ~nt second side 72 will remain below about 45C. Water within ~ lm~nc 66A, 66B also absorbs heat energy from adj ^~nl~ tissue (i.c., u~ 10) when ~ntçnn~ 74 is cnergized, which p~ the portion of ufelllla 10 ~ nt second side 72 from being o.ell c~le~ and ~l~mage~l when ~-t~ 74 iS c~c.~cd.
Intake lllmens 64A, 64B and ~ l lnmP.n~ 66A, 66B are supplied with ~lP;oni~ed water from cooli~ system 36. Water from cooling system 36 is chilled to between about 12-15C and ~ ,cd at a rate of between about 100 150 mi~ iteIS per minutc na water feed line 94A to c~ ec1;Qn m~nifold 35. The water flows throu~ conn~ctiQn m~nifold 35 to water feed line 94B and to water intake port 46, which co~ J~.;~tes with water intake lumpn~ 64A, 64B. Under ~uid l)res~ule, tlle water circulates through intake lum~n~ 64A, 64B to ca~ 82 of end cap 80. The water WO 95/07730 PCT/US9~/0914S
~ 2 ~ 69338 reLuu~ to cooling system 36 through ~ cl lllm~nc 66A, 66B to fluid --cl port 48. The water is c~rrie(l from water ~ ..cl port 48 via water return line 96B to CQnneCti~n m~nifolA 35, and ~om C~ r~ ;on ~ifold 35 to cooling system 36 via water return line 96A. Thc water i. then re~hilled 5 and re~irc~ te~1 Water feed line 94B and water retum line 96B are each provided with a cou.~ ;on~l qwck~u~ g fitting 65A and 65B, cs~ .ely, which lJClUli~ theter 28 to bc easily ~ from oooli~ system 36.
Fig. S shows an enlarged view of the male pel~ic region of Fig.
1 with ~th~ter 28 lJlop~lly pociti~ neA within u-ell~a 10. Orient3hon stripe 98 along e~terior surf3ce 52 on first side 68, as shown in Fig. 4, c~uies the proper o ;~ IAIiQn of sh~ft 32 within uuelhla 10. As shown in Fig. 5, shaft 32 is pocitinn~l within uelL~a 10 with second side 72 of shaft 32 ori~o-n~e~
toward rectum 26 Water C ~ llm~nc 66A, 66B are Qriente~ p~teriorly, toward rectum 26 and water intal~e lum~nc 64A, 64B are ol;e~ anteriorly toward fil~ro ~ r tissue 100 of ~,ro ,~te 14. The portion of tr~nciti~n zone 101 anterior and lateral to uretl~a 10 is the most frequent lo~tion of the tumorous tiscue growth which causes BPH. Since water ~ cl lllmenc 66A, 66B are c~r~ble of absorbing more mi.;rowa~e energy than water 20 i;lltalce lllm~n~ 64A, 64B, the r~ tion F~ttern~ created by _ici~owa~ energy elllinell from ~ntenn~ 74 are asymmetrical. Thus, a relatively large volume of tiscue enveloping the anterior portion of tr~nCiti~n zone 101, ~clj~nt fir.ctside 68, is heated to a te u~la~ above about 45C, which ef~ectively necroses the tumorous tissue of prostate 14 which encroaches upon lue~ a 25 10 In CQ l ~ ison, the teuu~Clalure of tissue ~ ce-nt second side 72 rel~ .s below about 45C, thereby e-limin~tin~ the h~rmfill effects of the mi~lowa~c energy to ej~cul~tQ1y duct 24 and rectum 26 Fig 6 is a graph which generally A~m~ ates a mic.~,wa~e thermal ~el~ procedure and a t~ul~cl~ c distribution which was ~ 6q33~

generated by ~theteJ 28 of the ~s~nt invention, with shaft 32 inserted into a polyacl~l~de gel form~ ti~ n which Cimlll~tes biololyc~l tissuc. Thc f~rmnl~ n and ~ ation procedures for the po~ya.;l~l~de gel are ~ir~l~r~ in detail in D. Andrellccetti, M. Bini, ~ ~grP-~i R. Olmi, N.
5 Rubino, and R. Va~ni, Usc of Po~ mi~ c ~ Tic~lle-P~uiv~lerlt M~teri~l in the ~i~ lW~ pe, 35 IEEE TR~CnONS ON BION~DIC~L
ENG~NG 275 (No. 4, A~ril 1988). Fig. 6 shows tc~cl~ c J~ pntc taken from eight tc~lal , s~nconc- Four ~ were nPA at fL~ced tli.ct~rl XS ~ nt first side 68. Sensor LA was pocitiQnpA
imm~oAi~tely ~dj~c~Pnt shaft 32; sensor lB was pQciti~n~ about 0.66 cm from shaft 32; sensor lC wac pocitinnc~ about 133 cm from shaft 32; and sensor lD was positioned about 2.0 cm from shaft 32.
~ our sensors were also alj~ at fixed .l:c~ djP~...~
second side 72. Scnsor 2A was poci~ione~ imlnc~i~tely ~ nt shaft 32;
sensor 2B was p~citic~n~A about 0.66 cm from shaft 32; sensor 2C was p~,ciffnneA about 133 cm from shaft 32; and sensor 2D was poiffc~n~ about 2.0 cm from shaft 32.
The x-axis r~rcscnts a relative period of time over which the mi~lOwa~ethPnn l therapyprocedurewasp~r"~.p~ Thcy-a~srepresents 20 te~cr~ c in degrces C'~lsiu~, with h~ linc H rCprec~ 45 C
(the tempe~ e at or above which cells are necrosed).
As generally shown in Fig. 6, the mi~;lvwa~e thermal therapy procedure of the present invention inCl~dGs five o~laL~g phases, Pl - P5.
~ines lA-lD and 2A-2D col.cs~ond with sensors lA-lD and 2A-2D, 25 respectfully. During f;rst phase Pl, cooling systcm 36 is turncd on and chilled water is pumped through cooli~ lnmPnc 64A, 64B and 66A, 66B.
A drop in te~ clature imme~ tely ~ rent shaft 32 is r~,iescnted by lines lA, 2A At thc cnd of first phasc Pl, coolin~ systcm 36 is ~rncd off. At the be~innin~ of second phase P2, a relatively small amount of power (about 2 1 6~338 S watts) is applied to mi~ wa~C ~ntenn~ 74. The tC~ imm.~ tely ~.nt shaft 32 rises a~ c~lically due to the ~atcr abso,lJti~ilr of water in the larger e~ ucl hlm~n~ 66A, 66B on second side 72, as shown by lines lA, 2A. The power is applied long e-no~ to merely warm ~ ~nt 5 ~ssue to about 40C. By the end of second phase P2, te~ra~ generally return to base line tc,l,~ra~ e.
Ill a ~lef~,l.c,d c ~,~;,,,r.~,l of thc present i~ nlio4 thc tissue res~llses to the rhi during P1 and the l~e~ during P2 aid in ~letel --;--;--~ ~he v~ r ty of the tissue to be treated. This i.~rO~ n aids 10 in ~letc~ the ;""ov"~ of power ,-Gcr~ to treat lu~oruus tissue of OS~ale 14.
At the ~ g of third phase P3, conlj~ ~st~m 36 is again turned on ~llerel~ l,v~ P chilled water I~ u~ g hlmen~ 64A 66B.
The t~,~.a~uic imm~ tely n~ r~nt shaft 32 c~ rgly drops as 15 in~li~te~l by lines lA, 2A. Pre~illiT~g of the tissue ;~ c~:stely adjacent shaft 32 aids in proteGting the tissues im~Yli~tely adjacent shaft 32 (i.c., llre~ d 10) frûm overhe-~h~g due to a ~el~ ely rapid appli~hon of power f~om ~ntenn~ 74.
Mic~ a~c gCnelali~ s~urce 38 is again turned on at the ;ng of fourth phace P4 at a s~ n~d power output of about 20 watts.
As shown in Fig. 6, due to the absol~ti~ cre~lial l~cl-.cc,.- water in the .~wer intake Illm~nc 64A, 64B and water in the wider ~.h~ lllmPn.c 66A, 66B, temperdlurcs ~ r~nt second side 72, r_~rcsçnte~l by lines 2A-2D, are cooler than tempelahllcs ~ c~-nt first side 68, r~rcscntçd by lines lA-25 lD. The tempeld~ulc .lirrcrclllials are most plofoul~d within a target volumecf tissuc 0.66 cm from shaft 32. Within this target volume, as shown by lines lA, 2A and lB, 2B, the di~ercnce in t~ lulc from first side 68 and second side 72 is on the order of about 10C. Thus, by ?~ s~ c4~ ling system parameters or power output from micluwa~e generating source 38, WO 95/07730 PCT/US9-1/0914~
.

2-' 6q33 -1~
tissue within 0.66 cm of first side 68 can be heated to tc~ elalules at or above about 45C, while tissue within 0.66 cm of second side 72 can remain at te~lalulcs svl.~ ly below 45C. In this ...~..er, tissue-l-c~;,os~g te~lures within the target volume are e~ nti~lly rest iete~ only to tissue 5 near first side 68, which is the most frequent l~h~n of ~;u,cll~l tumorous ~-osla~ic tissue. ~1IC!~ C1Y~ by ~ the power ouhput or cooling system par~meter~, a relatively small volume of tissue ~ .nt second side 72 caII be heated above about 45C to l.C~l~C some of the tumorous ~r~l~lic tissue which is posterior and lateral to the u,cll~ In 10 the ~ cd embo~limpns~ during fourth phase P4, microwave gener~Ling source 38 is o~,ated for at least about 45 ...;.. ~c~
As shown by lines lA, 2A, during P4, the tc.,l~lalu~c of tissue imm~li~tçly s~djPcçnt shaft 32 (which is repr~se~ e of te~Cl~LLulcs of hl~ 10), as well as tC~alu~eS of tissue beyond 0.66 cm ~om shaft 32, as shown by lines 1C, 2C and lD, 2D, are .. ~ h!~ well below 45C
This is ~w~ ;chp~ by ~lju~ g cooli~g system ~ ..cters and, if , powcr output from mi.~ .ati~, sourcc 38.
At the end of fourth phase P4 power is turned off. At the b~g;....;.~ of fifth phase P5, rooli-~g system 36 cQ~L;~ s to operate, 20 cir~ll~tin~ water through cooling lnmP.n~ 64A 66B. A tel-l~)clalulc drop imm~ tely ~dj~cent shaft 32 is relatively rapid as shown by lines 1A, 2A
within PS. In a preferred embo~limP-nt of the ~ s~nt invention, cooling system 36 co~ llJes to operate for a period of time (on the order of 10 to 120 mimltes) after the proeedure to cool ulC~ a 10 and reduce edema 25 resllltin~ from the appli~tion of heat to the pel;urct~l tissues of prostate 14. In an alternative embo~lim~-nt~ water feed line 94B, water return line 96B and the-rmr~m~try sensor 69 (as shown in Fig 2A) are tli~conn~ctecl from c(?nnection m~nifold 35. Water feed line 94B and water return line 96B of catheter 28 are then co,l,.c~led to another cooling ~tem similar to cooling WO 95/07730 PCT/US94/0914~
2 1 6 ~338 system 36 and water is then cir~llqt~l ll.lou~ corli~ hlm~P~nc 64A-66B in a ~ cr similar to that previously described. In this fq~hi~n, r~._,~ from the previously ~es~ibeA lJlOC~dul`C can be ~ ;cheA away from the h~ . P~ area thereby en-s-~li~ micl.,w~e gc~cla~i~ source 38 and cooli~
S systcm 36 to be readily available for tre-s-tmr-nt of ~n~ " psti.-.nt Fig. 7 shows a partial s~h~mg~l view of mic.ow~_ qntcnns. 74 of the ~S~nt invention. ~nt~P.nns. 74 is pnCiti~n~l at a ~r~i."al-most end of chielde~l coa~ial cablc 76. Cablc 76 is a s~ d~d RG 178U coa~al cablc and inrlll~les inner r~n~hl~tor 120, inner inClllqtor 122, outer c~n~l~lctor 124, and outer insllstor 126. Outcr in~llstor 126, outcr c~nd~ctQr 124 and inncr in.Clllstor 122 arc sl ~d away to cxposc about 3 m~ ct~ of outcr ~on~ tor 124, about 1 millimPter of inner incnlqtor 122 and about 1 mill;...cteJ of inncr oQn~3llctor 120. Capacitor 128 inrllldes first end 130, which is c4~ ed to inner cQn~lYctor 120 by s~ ~ and second end 132, which Cn~ rA~ to ~ q 74. ~p~citor 128 serves to c~ ct a reactive co~cnl of &~ 9 74, tL_rcl~ providing a 50 ohm match l~h.
co~Yi-q-l cable 76 and micl~.wa~_ ge~lela~ , source 38, and Pnt~nnq. 74.
Iubular eYt~o-nc;~ 134, which is a hollow secti~n of outer in~lllstQr 126 of coaYial cablc 76, is ~ Pd over c~pq-(itQr 128 and thc exposed length of inner in~lllvtQr 122 and sc~ cd by bond 136. Tubular cYtencion 134 inrl~ldes hole 138, which provides an e~t for second cnd 132 of c~r~riter 128. Wound about outer in~ tor 126 and tubular eYtc.n~ion 134 is flat wire 140. Flat wire 140 is a sin~e piece of flat copper wire with ~lim.on~ion~ of about 0.009 inch by about 0.032 inch in cross ~ci:on, which 25 provides a relatively large surface area for ~ Cllt flow while the cross-se~ti~n~l size of ~ntPnn~ 74.
Fig. 8 is an eYplo~led view of a portion of Dnt~nn~ 74 which shows its helical dipole co~h . ction. Gencrally, the effi~ien~y of any dipole ~ntçnn~ iS greatest when the effective electn~l length of the ~ntenns is WO 95tO7730 PCT/US9~/0914~
.

2~933Qo -1~
generally one half the wavelen~th of the rr~ tinn c-..;ll~3 in thc SU11U"n'~
mPdinm Accordi"~y, a relatively effl~Pnt simple dipolc z nt~.nn~, û~la~
at about 915 ~Iz, would r~uire a phy.cical length of about 8 ce-nhmp~ters which, acc~rdil~g to the ~re~.ll invention, would n~ ccly irradiatc and 5 A~magP healshy tissue. Furthermrre, the physical length of a relatively ç-ffi~-nt simple dipole ~nlc~ i~ at about 915 MHz cannot bc varied.
AC shown in figure 8, flat wire 140 is soldered to outer ~n~l-~or 124 at solder point 146. Flat wire 140 is then wound in a distal 10 direction about outer in~ q-tQr 126 and in a ~1 direction about tubular e~en~ n 134, thereby f(s. ~ 8 first wire sechnn 142 and second wire Secti~n 144, both of which are of equal length. In one embo~lim~llt~ first and second wire secti(!nC 142 and 144 are cach ~",~. oJl of cight, equally-spaced win~li~c of flat wire 140. The co~ ~l length of firct and second wire s~ nc 142 and 144, aIld hence the avcrall length of fi~e~ 74, ranges ~omabout1.5cc .I;...eter.toabout4.0~ .~;..rte ~ dvarieca~rdi~to thc length of the area of yl~late 14 which ~u~es t,cD~ A s~-q-n~lq~d m~ -grade ~cili~ne tube (not shown), which has been allowed to soak in a solvent, such as Freon, is pociti~ned over first and second wire ~Ch~!nC 142 20 and 144. As the solvent evaporates, the si~ n~ tube shnnl~c~ thereby sce.,. ;.~ flat wire 140 to outer in.ClllqtQr 126 and tubular e tenC;on 134.
The helical dipole construction of the present inve~tion allows "nt~nnq 74 to range in physical length from about 15 to 4 c~-ntimpter~c~ while electrically behaving lilce an eight centimeter-loDg simple dipole A~le~
25 In other words, ~nt~nn~ 74 has an effective electrical length generally equal to one half of the wavelen~h of the r~ tiQn emitte~ in the S"llu ,.~
m.~-linm, indepen~ent of its physical length. For purposes of de-finitiQn, the g me~ m inrlndes the ~theter shaft and the sullu,~.~ding tissue.
This is P^con~rlished by varying the ~ cr a~d pitch of the win~ of first WO 95/07730 PCTtUS91tO914'i and second wire sectionc 142 and 144. A family of ~AthCterS, which con~A;..
relatively efficient _elical dipole ~ C-~AC of di~crclll physical lc~h~, ....;L~ sclGction of the ~ntcnn~ best suited for the particul_r l-c~ ç-~l area In S~3dib~m, ~ntennA 74 of the present invention is capable of S pro~v~tng a C4~ 1 h~S~tt~ Zl~c".. in tissue, co ~ec^~ ated about ~ntcnnA
74, indepen~ nt of the depth of insertion into the ~ssue.
~ n~ end 132 of cAp~ttor 128, which exits hole 138, is ~ioldered to second wire secttQn 144 at tap point 148, as shown in Fig. 7.
Tap point 148 is a point at which the r~s~ - .l of the comhin~
impeAAn~ of first wire se~n 142 and second wire sechQn 144 .. At~l~Ps the charr~tcri~tt~ imI-e~An~c of coa~cial cable 76. The i..~ ..cc. of either first wire sechon 142 or second wire secti~n 144 is ~lc~s~d as Z, where Z = R
~ ~ The in~I~eAAr~ Z varies from a low value at solder poirlt 146 to a high valuc ae a point ~c~ om soldcr point 146. Thcrc e~cists a tap 15 position where R is equal to 50 ohrns, but an ims~1n~ 1' ~e~l, X is inductive. This inductive c4~.~n~ can bc c~.~l~ by inserting a series c~p~^~t~n~, such as ~r~tQr 128, which has a value of jX ohms. This results in an imr)e~l~nc_, match of 50 ohms real. T~e resulting method of fee~ ntçnn~ 74 is c~ ly called ts~ c~ In one 20 embo~lime-nt of thc present invention, wherc the phycical length of flat wirc140 is about 2.8 cm, tap point 148 is about 3.5 turns from solder point 146 on second wire sect;on 144. In the l,lefe.led embo~ P-nt, thc value of ç~r~ÇitQr 128 is about 2.7pF. Ho.._~,r, as is known in the art, for other fre~l~Pn~es of operation, a~r~liate values of ~p~ritQr 128 can be easily 25 ~etermine~l The helical dipole co~uction of ~ntenn~ 74 achieves a relatively small size, which permits i~ aule~ l app~ tirm The helical dipole ~l~ ction is also responcibk for threc fcaLu.cs which enable ~ntçnn~ 74 to achieve glcater efficiency ~an prior known inlcl~liLial WO 95/07730 PCT/US94/0914~
a /o933 -mi :r~,wa~ ntenn~c- good imre~nce m~t-~hir~g, good ~
~r~l ilit~y and an effective elec~ic~l length which is gcnerally one half of thewave4~h of the r~ hnn emitteA in the sullu~ rling me~ m, in-lep~n~ltont of thc physical length of ~nt~nnsl 74.
S First, the good impe~l~n~ rnatch betwccn Pntçnn~ 74 a~d inner con~ ctor 120 ...;~ ,s reflective losses of ;~ 74, with mP~c~ed reflective losses of less than 1% in a ~-cfellcd em~lim~-n~
Sec~ntl, the use of flat ribbon wire 140 for first wirc seçtinn 142 and sccond wire secb~n 144 ~ S r~li~e losses of ~ e ~ 74 by providing a 10 ~5Icatcr s~l-fq-çe arca upon which RF ~l~ can be c~ l Finally, the helical dipole design of ~ c~ 74 has an ~ ele~c-q-l leng~ which is generally one half of the w~le-*ll. of the radiation çmitte~l in the u~ c ~ d~,pc ~c- ~l of thc physical leng~ of ~ 74.
This ~lll~ib the physical length of ~ 74 to be varied to !qcc~.. ~te 15 v~g sizes of indindu~ prostates while mq;.,~ thc samc effi~
cffec~ve e~e~nC-ql length of z~ 74.
The use of an e-ffi~ent mi~uwa~ is critical to the abi}ity to focus therm~l energy a ~ ce from thc 5~nt.-.nn~ within a target volume. An ineffi~Pnt ~ntPnn~ produces alesser ;~ of mlCl`Ow~C
20 r~ tinn within the target volume than desired. It also produces 1ln~lpcired heat close to the ulct~a~ which will ~l~mage the .,lel~a if not carried away by an increased coQ1~nt flow. This added burden on the coo1ing ~rstem reduces its capacity to protect the urcl~ thereby 1imiting the micluwave power that can be r~di~te~ without ck,~ali~, ulc~ a tc~clalules above 25 safety limits. With mi.;l.~w~re power limited by cooling system capacity, theheat delivered to the desired target area of the prostate will not be s~1ffi~nt for effective therapy. The cfficient helical dipolc design of ~nt~.nn~ 74 of thepresent invention, hu.._~cr, c~ules that almost all heat delivercd during the "~ nl is delivered in the form of mi~lowa~_ encrgy, rather than cc~n~lllctive heat enerD.
Fig. 9 is a block diagram of I ~ulctLal mi~un~a~c thermal thel~ system 170, with which ulellnal c~ etcr 28 is used. System 170 5 intludes conling system 36 micluw~e generat~, source 38, user interface 172, rcal time controller (RTC) 174, direch~r~l coupler 176, I~-c~ cl~
sen~rs 182 and 184, cwl~nt l~ics~ulc sensor 186, ~ o~ n infl~tir~n device 188, and urine collecti~n c~ er 190.
As shûwn in Fig. 9, control of mi~lo..~ ,c.lcra~i~ sourcc 38 and coo~ system 36 is çff~cted by real time contrûller 174, which is in turn controlled by user intPrf~e 172. User interf~ 172 is an IBM co~ l;bl~
machine c~ ;n;.~, two hard drives for data ~l~C; onc for b~ r, and one for n~ l operation of system 170. User interf ^e 172 co~ n;~t~Ps with RTC 174, which is rc~ for all ~losed loop fP~b~^~ to run systcm 170. RTC 174 has direct closed loop control of micr~wa~- power from mi~luwa~._ generating source 38, and COQlC"I flow and coolsnt tc~ _ of cooling system 36. Closcd loop fee~l~æ~ traclcs out v~r ~tionC in gain, drift and cable losses inhcrent in mi~; uwa~_ b_llc~a~g source 38, and variability in pump output and r_L:gel~ion system çffi~en~
20 of cooling system 36. In ~ ition to ...o..;~o. ;.~g mi~uwa~e gene.a~ source 38 and cooling syctem 36, RTC 174 also monitors and contlols several ch~nnPlc of therm~mPtry via inputs from thP,rmr~mPt~r unit 178. ~ooli~
system thermometry 178A mP~cllres the c~ nt and chiller tem~ lu,cs based upon signals from cool~nt t~ ~ldlu~c sensors 182 and 184 and a 25 chiller temperalulc sensor (not shown) of conling system 36. Urethral thermom~tTy 178B m.-.~cnreS ulclhlal tL alurc based upon signals from t~ cldlule sensor 69 within c~theter 28. Rectal thermom~try 178C
mr~C~cs re~ temperature based upon signals rccei~ed from a sensor (not shown) within rectal probe 180.

WO 95/07730 PCTIUS9 1/0914~i .

~oq3 R ~ 174 L" ~ all clos~-loop fe~b~ to user interface 172, which proce-sses the input and ~ ...;L~ co,lc~ions and instluctions back to RTC 174. RTC 174 interprets the instructions given to it by process control l~ngll~ge r~i~cd from user interf:~e 172 and ~P~tes the S instluctions in rcal time. All c~l,e~lions from user interf~ce 172 are made to ..~ ;.. a ~pvcn Ihel",~l profile lluu.~l.ollt the t~ ] the~nn~l the~a~. In ~ ition~ system 170 in~ludes a L~r.lw~re f~il-safe cir~t which shuts down ~ystem 170 should any ~ ter fall ollt~;~e a givcn rangc of values.
Figs. 10A, 10B and 11 show a tubular~ r~tor 200 used in ~oll~cr embo~ .c- ~ of ~ 214. Ant,enn~ 214 is c~uctcd in a m~nn~r similar to ~.le~ 76, which is shown in Figs. 7 and 8. As shown in Figs. 10A-lOB, r~r~tQr 200 co.~ s ~ lechic tube 202 with outer con~ ve layer 204 and inner cQn~vchve layer 206. Outer cQn~lu~tive layer 204 and inner cQn~lv~hve layer 206 form c~n~ntriC plates of ~r3~tor 200.
Metal nng 208, which includes tab 210, fits over outer ~n~h~ ve layer 2(~4.
Ring 208 is pO.citir n~lc along c~r~ it~r 200 so as to locate tab 210 at the desired tap point, similar to tap point 148 of Fig. 7, when c~r~itor 200 is c:Qnno~ to ~nt~nn~ 214 (shown in Fig. 11). Thcr~flcr, nng 208 is soldered to outer c~n~hlctive laycr 204 of c~p~tQr 200.
In one ~lefell~,d emboAim~ont~ ç~r~ritor 200 is ..~ r~ lred by Coors Ceramics Co. of Golden, Colorado, with ~i~lectric tube 202 being formed from ~lllmin~ and with the inner c~n~u~ve layer 206 and outer c~nAUct ve layer 2(}4 being formed by applic~ti~n of a layer of a metal-laced adhesive binder. Ring 208 and tab 210 are ~efcrably formed from any solderable metaL such as brass or copper. r~p~tQr 200 has an outer rli~rneter of about 0.050 inches, which llcl~b ~p~citQr 200 to fit within a rdatively ~exible tubular eYten~ion 216 (shown in Fig. 11). In ~slrlition~
~p?,~itQr 200 has an inner Ai~meter of about .025 inches, which ~llllib -WO 95/07730 2 ~ 6 9 3 3 8 PCT/US9~/0914~

insertion of inner c~nductor 218 of coa~aal cable 220 (shown in Fig. 11) into ç~p~ itQr 200. Like c~pAritor 128 of Fig. 7, cApAGitor 200 has a ~rA~tAnce of about 2.7 pF. C'Ar~Aritor 200 also has a length of about 0.110 inches.
Other ~limPn~ion~ of c~p~ritQr 200 will be ~c,ll to those of ordina~y S electrical sldll.
Fig. 11 is a side view of PntPnn~ 214 with a portion cut away to show a ~""rc!;nn of cArAcito- 200 to Pntenn~ 214 and coanal cablc 220.
~n~ennA~ 214 is c~ e~1P~ to coa~al cable 220 in a ..~...er similar to that previously ~ cucc-p~ with lCi~c~l to ~ C I~A 74 and coal~ial cable 76 (Fig. 7).
As shown in Fig. 11, metal band 222 (which is similar to ring 208) is positinrp~ over inner inclllAs~r 223 and outer o~n~lllGtQr 224 and ~.~.ected by solde~in~ to outer con~lu~tor 224 of coa~dal cable æo. Metal band 222 inrlucles tab 226, which is c~ ,cte~ by sold~ to ~at wire 228 so as to produce first S~ A s~o~r~n 214A and second Pnt--nn~ ~hon 214B. Iilce first and second wire sech~nC 142 and 144 of Pnt~nn~ 74 (shown in Fig. 8), fir,ct ~ntenns- sectiQn 214A and second ~ ffQn 214B are a~prn. ;~ tely equal in length. Metal band m is sized to be l~teA within tubular ~Ytencion 216 when tubular e~te~ n 216 is pos;~ l over inner inc~ tQr 2~ and outer c~n~luctnr 224. A groove in tubular eytencion 216 (not shown) enables the CQ~ e~ ;r)n of tab 226 of metal band ?~7 to flat wire 228.
Prior to the positionin~ of tubular ~-~encion 216, c~r~- itor 200 is slipped over inner c~n~lllrtor 218. Inner con~lllctive layer 206 of c~r~ci~Qr200 is thereafter c~nnecte~l to inner cor~dllcto~ 218 by soldering. r~r~tQr 200 is preferably spaced apart from outer con~lllctor 224 by at least about 0.050 inches to avoid a short between outer con(luctQr 224 and outer cond~lctive layer 204 of ~p~ tor 200. With c~r~c~tor 200 c~ r~1e~l to inner con~llctor 218, the relatively flexible tubular eYtencion 216 is slipped over c~r~tQr 200, ring 208, inner inClll~tQr 2~ and outer c~n~lnrtor 224 WO 95/07730 PCTIUS94/Q914;~
q33~ ~

uIItil tab 210 of ring 208 engages hole 230 of tubular e-t~n~;~n 216. Holc 230 is loc~te~l so as to expose tab 210 for sol lP~ri~ to sec~nd ~
se~ n 214B at tap point 232. Tap point 232, IL~ce tap point 148 of Fig. 7,`
is the point at which the rci,isli~c component of the s~ .P~ impe~an~ of first ~.le~ se~ir~n 214A a~d second ~ntenn9~ sechnn 214B m~trhp~c the char~cteri~tic in~retl~nre of coa~nal cablc 220.
The tubular shape of ~p~tor 200 provides for a highly reliable co....ec1;on to inner con~luctQr 218 and ta~ point 232. In ~ iih~n, r~p~itQr 200 ~C~ ib ~ljv~ t of tap point 232 by virtue of the ~ ct~hility of ring 208. Thus, c~p~ritor 200 is able to be adapted for use with various ~ntenn~ nc ~lths~gh the plcscnl invention has been described with fcfcrc~ce to ~lc~.-ed çmhorlimentc, Wul}Cl~ slc;lled in the artwill rcc~g~
that ~ s may be made in form and dchil ~ i~oul dep~ from thc spirit and scope of the invention. For G~l)lc, while the b~-~e-firi~l uses of thc mi~ow~c ~nt~.nn~ ~theter of the ~rcsenl inven~don have been des~ibed with rci,~c~ to thc ulc~ a, other intra~ app!i~- nc are implied.

Claims

WHAT IS CLAIMED IS:

1. A device for thermal therapy, the device comprising:
a catheter;
a coaxial cable carried by the catheter having an outer insulator, an outer conductor, an inner insulator and an inner conductor;
a helical antenna having a first location connected to the outer conductor of the coaxial cable; and a tubular capacitor having an inner conductive layer, an outer conductive layer and a dielectric layer between the inner conductive layer and the outer conductive layer, the inner conductive layer being electrical connected to the inner conductor of the coaxial cable and the outer conductive layer being electrically connected to a second location of the helical antenna.

2. The device of claim 1 and further comprising adjustable connector means associated with the outer conductive layer for electrically connecting the outer conductive layer to the second location of the helical antenna.

3. The device of claim 2 wherein the adjustable connector means is positioned so as to define a connection point between the tubular capacitor and the helical antenna which permits the tubular capacitor to match an impedance between the helical antenna and the coaxial cable.

4. The device of claim 1 and further comprising a conductive sleeve which is positionable over and electrically connectable to the outer conductive layer of the tubular capacitor.

5. The device of claim 4 wherein the conductive sleeve is connected to the outer conductive layer of the tubular capacitor and the helical antenna at a location which permits the tubular capacitor to match an impedance between the helical antenna and the coaxial cable.

6. The device of claim 1 and further including a tubular extension having outer and inner dimensions approximating those of the outer insulator of the coaxial cable, the tubular extension being positioned over the outer conductor, the inner insulator and the inner conductor of the coaxial cable, wherein the helical antenna is position over the outer conductor of the coaxial cable and the tubular extension, and wherein the tubular capacitor is positioned within the tubular extension, the tubular extension being configured to permit the helical antenna to be connected to the outer conductor of the coaxial cable and the outer conductive layer of the tubular capacitor.

7. The device of claim 1 wherein the tubular capacitor has a capacitance of about 2.7pF.

8. The device of claim 1 wherein the helical antenna is a helical dipole antenna.

9. The device of claim 1 wherein the helical antenna further comprises a first section and a second section connected to the first section, the first and second sections being of approximately equal, wherein the first location is centered between the first and second sections.

10. A radiating device comprising:
a catheter;
a coaxial cable, carried by the catheter, having a first end, a second end, an outer insulator, an outer conductor, an inner insulator and an inner conductor;
an antenna having a first section and a second section connected to the first section, the first and second sections being of approximately equal length, a midpoint of the antenna being electrically connected to the outer conductor;
a capacitor including a tubular-shaped dielectric having an outer surface and an inner surface, a first conductive layer on the outer surface and a second conductive layer on the inner surface;
an adjustable connector contacting the first conductive layer;
wherein the second conductive layer is connected to the inner conductor of the coaxial cable, and wherein the adjustable connector is connected to the antenna and the first conductive layer at a point which allows the capacitor to match an impedance of the coaxial cable and the antenna.