HRP990351A2

HRP990351A2 - Medical ultrasonic localizer of ultrasound source

Info

Publication number: HRP990351A2
Authority: HR
Inventors: Branko Breyer
Original assignee: Branko Breyer
Priority date: 1999-11-15
Filing date: 1999-11-15
Publication date: 2001-06-30

Description

Područje tehnike The field of technology

Izum spada u područje medicinske tehnike, a posebno u područje ultrazvučne kontrole i vođenja medicinskih postupaka. The invention belongs to the field of medical technology, and especially to the field of ultrasound control and management of medical procedures.

Tehnički problem Technical problem

Ovim se izumom rješava problem lokalizacije izvora ultrazvuka u tijelu pomoću ultrazvučnog ehoskopa, a posebno označivačkog-marker odašiljača ultrazvuka montiranog na medicinsku napravu uvedenu u tijelo. Posebno je riješen problem rečene lokalizacije bez potrebe za sinkronizacijom sa radom rečenog ehoskopa. This invention solves the problem of localization of the ultrasound source in the body by means of an ultrasound echoscope, and in particular an ultrasound marking-marker transmitter mounted on a medical device introduced into the body. In particular, the problem of said localization was solved without the need for synchronization with the operation of said echoscope.

Stanje tehnike State of the art

Ultrazvučna pretrage ja jeftina efikasna metoda medicinske dijagnostike i odslikavanja. Ne upotrebljava ionizirajuće zračenje. Osim toga ta metoda funkcionira u stvarnom vremenu i pogodna je za prikaz mekih tkiva. Prikaz u stvarnom vremenu omogućuje vođenje medicinskih postupaka poput kateterizacije i endokirurgije. Međutim, ove su prednosti djelomično umanjene činjenicom da su naprave koje valja prikazati slabo vidljive u nekim važnim situacijama. Na primjer, savitljiva naprava može biti jasno vidljiva kad je u ravnini pretrage postavljena okomito na ultrazvučni snop. Naprotiv, ako ona ulazi u ravninu pretrage pod 90 stupnjeva ili je u ravnini pretrage ali pod oštrim kutom, vidljivost jedva ili nikako ne zadovoljava za vođenje postupka. Ultrasound examinations are a cheap and efficient method of medical diagnostics and imaging. It does not use ionizing radiation. In addition, this method works in real time and is suitable for imaging soft tissues. The real-time display enables the management of medical procedures such as catheterization and endosurgery. However, these advantages are partially diminished by the fact that the devices that need to be displayed are barely visible in some important situations. For example, a flexible device can be clearly visible when placed perpendicular to the ultrasound beam in the plane of examination. On the contrary, if it enters the plane of the search at 90 degrees or is in the plane of the search but at a sharp angle, the visibility is hardly or not at all sufficient for conducting the procedure.

Problem vođenja pomoću ultrazvuka postupaka u kojima se upotrebljavaju fleksibilne naprave, predmet je više patentiranih rješenja. The problem of ultrasound guidance of procedures in which flexible devices are used is the subject of several patented solutions.

Posebni problem ultrazvučnog prikaza fleksibilnih katetera postavljenih u ljudsko tijelo je činjenica da ove naprave nisu uvijek u potpunosti u ravnini pretrage tako da se bez posebnog rješenja ne može znati koji se dio katetera vidi na ultrazvučnoj slici. Ovo je izrazito težak problem ako je kateter u srcu pa se miče i povremeno ulazi i izlazi iz ravnine pretrage. Sličan se problem javlja kad se prikazuje kateter koji prolazi kroz dijelove tijela ispunjene plinom poput crijeva i pluća. Ovo je posebno težak problem kad je kut pod kojim se kateter prikazuje bitno različit od 90° prema osi katetera. A special problem of ultrasound imaging of flexible catheters placed in the human body is the fact that these devices are not always completely in the plane of examination, so without a special solution it is not possible to know which part of the catheter is visible in the ultrasound image. This is an extremely difficult problem if the catheter is in the heart and moves and periodically moves in and out of the plane of examination. A similar problem occurs when a catheter is shown passing through gas-filled parts of the body such as the intestines and lungs. This is a particularly difficult problem when the angle at which the catheter is displayed is significantly different from 90° to the axis of the catheter.

Postojeća rješenja, USA patenti 4,697,595 i 4,706,681 (Breyer et al.), te 5,076,278 (Vilkomerson et al.) zasnivaju se na slijedećem principu: Existing solutions, US patents 4,697,595 and 4,706,681 (Breyer et al.), and 5,076,278 (Vilkomerson et al.) are based on the following principle:

Na dijelu katetera koji želimo lokalizirati (npr. vrh) montiran je piezoetektrični pretvarač. Vodiči položeni uzduž katetera povezuju rečeni pretvarač sa priključnicama na proksimalnom kraju katetera. Kad taj piezoelektrični pretvarač uđe u ravninu pretrage ultrazvučnog aparata, ultrazvučni impulsi koje on odašilje pogađaju rečeni marker pretvarač pa se na rečenim priključnicama pojave signali koji označavaju da je označeni dio katetera u ravnini pretrage. Takvi signali mogu se, na razne načine upotrijebiti za generiranje vidljivih oznaka na ekranu ultrazvučnog aparata. Reprezentativni način upotrebe opisane metode je rad sa transponderom koji je vezan na rečene priključnice. Transponder se odaziva svakom dolazećem ultrazvučnom impulsu koji dolazi iz ultrazvučnog aparata karakterističnim nizom impulsa koji generiraju seriju ultrazvučnih impulsa a koji na ekranu rečenog aparata stvaraju vidljive oznake. Postoje i drugi, složeniji, načini upotrebe ove informacije, ali to ne mijenja osnovnu ideju sistema. A piezoelectric transducer is mounted on the part of the catheter that we want to localize (eg the tip). Conductors laid along the catheter connect said transducer to connectors at the proximal end of the catheter. When this piezoelectric transducer enters the search plane of the ultrasound machine, the ultrasonic pulses it emits hit said marker transducer, so signals appear on said connectors indicating that the marked part of the catheter is in the search plane. Such signals can be used in various ways to generate visible marks on the screen of the ultrasound machine. A representative way of using the described method is to work with a transponder connected to said connectors. The transponder responds to every incoming ultrasonic pulse coming from the ultrasound device with a characteristic series of pulses that generate a series of ultrasonic pulses that create visible marks on the screen of said device. There are other, more complex, ways of using this information, but this does not change the basic idea of the system.

Posebna tema tehnoloških kompromisa je odnos osjetljivosti detekcije i širine funkcije usmjerenosti odziva. Naime, ako se upotrijebi cilindrični ili pločasti pretvarač, povećanje površine povećava osjetljivost, ali čini marker pretvarač usmjerenijim i time težim za otkriti iz elevacijskih kutova bliskih osi katetera. Funkcija usmjerenost se može proširiti smanjenjem visine cilindričnog pretvarača. Druga metoda proširivanja funkcije usmjerenosti je opisana u USA patentu 5,076,278 gdje se upotrebljava pretvarač zakrivljene vanjske površine. Druge primjene medicinskih naprava koje se ugrađuju u tijelo opisane su u USA patentu 5,840,030 (Breyer et al.) gdje je za detekciju ugrađenog izvora ultrazvuka potreban transponder ili neki drugi sinkronizirani elektronički sklop. A special topic of technological trade-offs is the relationship between detection sensitivity and the width of the response directionality function. Namely, if a cylindrical or plate transducer is used, the increase in surface area increases sensitivity, but makes the marker transducer more directional and thus more difficult to detect from elevation angles close to the catheter axis. The directivity function can be extended by reducing the height of the cylindrical transducer. Another method of extending the directivity function is described in US Patent 5,076,278 where a curved outer surface transducer is used. Other applications of implantable medical devices are described in US Patent 5,840,030 (Breyer et al.) where detection of the implanted ultrasound source requires a transponder or other synchronized electronic circuit.

U svim rečenim metodama lokalizacije funkcija ovisi o brzom ili striktno definiranom odašiljanju ultrazvučnih valova ili sinkronizaciji elektroničkih sklopova sa radnim ciklusom ultrazvučnog aparata (npr. pasivni sistem iz USA patenta 4,697,595, Breyer et al. ili 5,076,278, Vilkomerson et al). Takva konstrukcija postavlja striktne zahtjeve na elektroničke sklopove koji upravljaju odašiljanje lokalizacijskog signala. U slučaju transpondera vidljivost i kvaliteta signala za vođenje na ekranu aparata kritično ovisi o transponderskim impulsima i jedini način poboljšanja je upotreba TGC pojačala, što zahtijeva direktnu sinkronizaciju sa ultrazvučnim aparatom koji se rabi. In all said localization methods, the function depends on fast or strictly defined transmission of ultrasound waves or synchronization of electronic circuits with the working cycle of the ultrasound apparatus (eg passive system from US patent 4,697,595, Breyer et al. or 5,076,278, Vilkomerson et al). Such a construction places strict requirements on the electronic circuits that control the transmission of the localization signal. In the case of transponders, the visibility and quality of the guidance signal on the screen of the device depends critically on the transponder pulses, and the only way to improve it is to use a TGC amplifier, which requires direct synchronization with the ultrasound device being used.

Ovaj izum rješava problem ultrazvučnog označavanja na novi način koji u realizaciji sa kontinuiranim valom ne zahtijeva sinkronizaciju a u realizaciji s impulsnim valom može trebati samo vrlo primitivnu i jednostavnu sinkronizaciju. Prednost ovog izuma je da je oblik odaslanog vala gotovo irelevantan, što ovu metodu čini mnogo otpornijom na smetnje i mnogo fleksibilnijom u implementaciji. This invention solves the problem of ultrasonic marking in a new way, which in the implementation with a continuous wave does not require synchronization, and in the implementation with a pulse wave may only need a very primitive and simple synchronization. The advantage of this invention is that the form of the transmitted wave is almost irrelevant, which makes this method much more resistant to interference and much more flexible in implementation.

Suština izuma The essence of the invention

Na mjestu na kateteru ili drugoj medicinskoj napravi koje želimo lokalizirati montiran je jedan ili više markerskih utrazvučnih pretvarača koji odašilju kontinuirani, stohastički ili impulsni ultrazvučni signal. Vremenski oblik tih valova je u osnovi irelevantan ako se poštuju ograničenja u pogledu frekvencijskih i repeticijskih granica. Rečeni markerski odašiljači ultrazvuka su smješteni na mjesta od interesa uzduž katetera, npr. blizu terapijskih ili dijagnostičkih elektroda. Takvi se ultrazvučni izvori detektiraju pomoću sonde ultrazvučnog aparata. Ta sonda je građena kao niz pretvarača. Parametri lokalizacije, tj. udaljenost izvora i linija gledanja uzduž koje se nalazi izvor ultrazvuka se zatim upotrebljavaju u sistemu za odslikavanje za generiranje vidljive oznake koja pokazuje mjesto rečenog marker pretvarača. Na taj se način jednoznačno određuje položaj označenih naprave (terapijskih ili dijagnostičkih elektroda ili drugih naprava) u čijoj su neposrednoj blizini ugrađeni rečeni odašiljači ultrazvuka. At the point on the catheter or other medical device that we want to localize, one or more marker ultrasound transducers are mounted that emit a continuous, stochastic or pulsed ultrasound signal. The time shape of these waveforms is basically irrelevant if the restrictions on frequency and repetition limits are respected. Said ultrasound marker transmitters are placed at places of interest along the catheter, eg near the therapeutic or diagnostic electrodes. Such ultrasound sources are detected using the probe of the ultrasound machine. That probe is built as a series of transducers. The localization parameters, ie source distance and line of sight along which the ultrasound source is located, are then used in the imaging system to generate a visible marker indicating the location of said marker transducer. In this way, the position of the marked devices (therapeutic or diagnostic electrodes or other devices) in the immediate vicinity of which the said ultrasound transmitters are installed is unambiguously determined.

- Princip lokalizacije može se objasniti kako slijedi: - The localization principle can be explained as follows:

- Valovi odaslani iz marker pretvarača stižu na prijamni niz pretvarača i mogu se jednoznačno lokalizirati na osnovi rješavanja jednadžbe širenja vala. Specifični je parametar fazna brzina valne fronte koja dolazi do prijamnog niza pretvarača. Fazna brzina ovisi o udaljenosti između izvora vala i prijamnika na način koji se može analitički izračunati. Točka prvog kontakta valne fronte ukazuje na lateralni položaj uzduž prijemnog niza pretvarača. Prema tome moguća je jednoznačna lokalizacija. Točka prvog kontakta može se odrediti usporedbom trenutaka kad razni članovi rečenog niza pretvarača detektiraju dolazak vala. Obje te operacije, tj. usporedba trenutaka dolaska vala i rješenje jednadžbe vala obavljaju se u glavnom računalu rečenog ultrazvučnog aparata. - Waves sent from the marker transducer arrive at the receiving array of transducers and can be unambiguously localized based on solving the wave propagation equation. A specific parameter is the phase speed of the wavefront that reaches the receiving array of the converter. The phase velocity depends on the distance between the wave source and the receiver in a way that can be calculated analytically. The point of first contact of the wavefront indicates the lateral position along the receiving array of the transducer. Therefore, unambiguous localization is possible. The point of first contact can be determined by comparing the moments when various members of said array of transducers detect the arrival of the wave. Both of these operations, i.e. the comparison of the moments of arrival of the wave and the solution of the wave equation, are performed in the main computer of the said ultrasound device.

Analitičke jednadžbe koje opisuju fazu odnosno kašnjenje dolaznog vala date su u detaljnom opisu izvedbi izuma. Ipak, intuitivno razumijevanje principa može se postići razmatranjem dviju ekstremnih situacija, tj. situacije kad je marker pretvarač u beskonačnoj udaljenosti i slučaja kad je izvor na nultoj udaljenosti od prijamnog niza pretvarača. Analytical equations that describe the phase or delay of the incoming wave are given in the detailed description of the embodiment of the invention. However, an intuitive understanding of the principle can be achieved by considering two extreme situations, i.e. the situation when the marker transducer is at infinite distance and the case when the source is at zero distance from the receiving array of transducers.

Ako je izvor vala na beskonačnoj udaljenosti, val koji stiže do prijamnog niza pretvarača je u osnovi ravni val, pa stiže na cijeli linearni niz pretvarača istovremeno. Fazna brzina je beskonačna a kašnjenje između trenutka prijama na raznim članovima niza je jednako nuli. Što je izvor zvuka bliži to je valna fronta savinutija i to je dulje kašnjenje između trenutaka prijama vala na raznim članovima prijamnog niza. If the wave source is at infinite distance, the wave arriving at the receiving array of transducers is essentially a plane wave, so it arrives at the entire linear array of transducers simultaneously. The phase speed is infinite and the delay between the moment of reception on the various members of the array is equal to zero. The closer the sound source is, the more curved the wavefront is and the longer the delay between the moments of reception of the wave at the various members of the receiving array.

Ako se izvor vala naslanja na prijamni niz, tj. udaljenost je nula, brzina kojom se ultrazvučni val širi uzduž prijamnog niza jednaka je brzini zvuka u tijelu. If the source of the wave rests on the receiving array, i.e. the distance is zero, the speed with which the ultrasound wave propagates along the receiving array is equal to the speed of sound in the body.

Svi slučajevi između ta dva ekstrema daju kašnjenja koja su između nule i kašnjenja koje odgovara propagaciji brzinom zvuka uzduž prijamnog niza. Točne jednadžbe 1 i 2 koje opisuju ove pojave date su u detaljnim opisima izvedbi izuma. All cases between these two extremes give delays that are between zero and the delay corresponding to propagation at the speed of sound along the receiving array. The exact equations 1 and 2 that describe these phenomena are given in the detailed descriptions of the embodiments of the invention.

Ako se upotrebljavaju kontinuirani valovi, članovi prijamnog niza detektiraju maksimume i minimume ultrazvučnog tlaka. Za impulsni ultrazvuk mora vrijeme repeticije impulsa biti dulje od vremena potrebnog da ultrazvuk prijeđe duljinu rečenog prijamnog niza. Ekvivalentno tome, u režimu rada s kontinuiranim valom, gornja granica frekvencije koja osigurava jednoznačnost određivanja udaljenosti je frekvencija čiji je period vala dulji od vremena potrebnog da val prijeđe preko duljine rečenog prijamnog linearnog niza pretvarača. To znači da je najkraći period jednak duljini rečenog prijamnog niza podijeljenog sa brzinom ultrazvuka. Ovo su jedina osnovna ograničenja na vrst lokalizacijskih valova. If continuous waves are used, the members of the receiving array detect the maxima and minima of the ultrasonic pressure. For pulsed ultrasound, the pulse repetition time must be longer than the time required for the ultrasound to cross the length of said receiving array. Equivalently, in the operating mode with a continuous wave, the upper limit of the frequency that ensures the unambiguity of the distance determination is the frequency whose wave period is longer than the time required for the wave to pass over the length of said receiving linear array of converters. This means that the shortest period is equal to the length of said receiving sequence divided by the ultrasound speed. These are the only basic restrictions on the type of localization waves.

Rečene jednadžbe su dovoljno jednostavne da se mogu rješavati u stvarnom vremenu za vrijeme procesa lokalizacije. Alternativno se te jednadžbe mogu unaprijed riješiti za oblik prijamnog niza te se njihova rješenja mogu očitavati iz tablice. U svakom slučaju se kašnjenja detektiraju prijamnim nizom a postupak lokalizacije je dodatni program u glavnom računalu ultrazvučnog aparata. Stoga se ovaj lokalizacijski sistem može primijeniti u svim postojećim digitalnim ultrazvučnim aparatima relativno jednostavnim softverskim dodatkom. Said equations are simple enough to be solved in real time during the localization process. Alternatively, these equations can be solved in advance for the shape of the receiving sequence and their solutions can be read from the table. In any case, delays are detected by the receiving array, and the localization procedure is an additional program in the main computer of the ultrasound machine. Therefore, this localization system can be applied in all existing digital ultrasound machines with a relatively simple software add-on.

Prednost ove metode lokalizacije pred ostalim postojećima je u tome da je valni oblik ultrazvučnog signala gotovo irelevantan, što metodu čini otpornijom na smetnje i jednostavnijom za implementaciju. The advantage of this localization method over other existing ones is that the waveform of the ultrasound signal is almost irrelevant, which makes the method more resistant to interference and simpler to implement.

Daljnji ciljevi, svojstva i prednosti ovog izuma postat će jasni detaljnim razmatranjem izvedbi iz upotrebu slijedećih slika: Further objects, features and advantages of the present invention will become clear upon a detailed consideration of embodiments from the use of the following figures:

Kratki opis slika Short description of the pictures

Slika 1 je opća ilustracija principa lokalizacije pomoću marker pretvarača. U slučaju jednodimenzionalnog niza prijemnih pretvarača, informacija o greški zbog izlaska iz ravnine pretrage se ignorira, ali je kod dvodimenzionalnih prijamnih nizova (matričnih nizova) moguća lokalizacija i tri dimenzije na jednak način kako je to opisano u dvije dimenzije. Figure 1 is a general illustration of the principle of localization using a marker transducer. In the case of a one-dimensional array of receiving transducers, information about the error due to departure from the search plane is ignored, but with two-dimensional receiving arrays (matrix arrays) localization is possible in three dimensions in the same way as described in two dimensions.

Slika 2 je shematski prikaz ultrazvučnih valova koji padaju na linearni prijamni niz pretvarača. Figure 2 is a schematic representation of the ultrasonic waves incident on the linear receiver array of the transducer.

Slika 3 je shematska ilustracija sistema za lokalizaciju koji upotrebljava kontinuirane valove ultrazvuka za lokalizaciju, uključujući i detaljniju blok shemu ili dijagram toka proračuna za obradu signala iz rečenog niza prijamnih pretvarača. Figure 3 is a schematic illustration of a localization system using continuous waves of ultrasound for localization, including a more detailed block diagram or flow diagram of the calculation for processing signals from said array of receiving transducers.

Slika 4 je shematska ilustracija sistema za lokalizaciju koji upotrebljava impulsne valove ultrazvuka za lokalizaciju, uključujući i detaljniju blok shemu ili dijagram toka proračuna za obradu signala iz rečenog niza prijamnih pretvarača. Figure 4 is a schematic illustration of a localization system using pulsed ultrasound waves for localization, including a more detailed block diagram or flow diagram of the calculation for processing signals from said array of receiving transducers.

Slika 5 je blok shema sklopova ili dijagram toka proračuna određivanja kašnjenja detekcije između raznim članovima prijamnog niza pretvarača uz upotrebu proračuna unakrsne korelacije. Figure 5 is a circuit block diagram or flow diagram of the calculation of the determination of the detection delay between the various members of the receiver array of transducers using the cross-correlation calculation.

Detaljni opis izvedbi izuma Detailed description of embodiments of the invention

Prema ovom izumu je na mjestu od interesa uzduž u tijelo uvedene ili ugrađene medicinske naprave montiran jedan ili više ultrazvučnih odašiljača koji odašilju kontinuirane, stohastičke i impulsne ultrazvučne signale. Ultrazvučni aparat za odslikavanje se upotrebljava za dobivanje slika područja u tijelu gdje je rečena naprava smještena. Ultrazvučni aparat ima prijamnik ultrazvuka u obliku niza pretvarača. Lokalizacija rečenog odašiljača ultrazvuka se izvodi na prijamnoj strani rješavanjem jednadžbe koja opisuje vremenski slijed prijama odaslanog vala na rečenom nizu ultrazvučnih prijamnika. Sonde tipa niza su najuobičajeniji tip ultrazvučnih pretvaračkih sklopova u modernim ultrazvučnim aparatima. Oni se sastoje od više pretvarača (obično između 32 i 200) ugrađenih u obliku linearnog ili zakrivljenog niza. Postoje i dvodimenzionalni nizovi. Takva množina pretvarača omogućuje upravljanje i fokusiranje snopa kao i raznolike manipulacije karakteristikom usmjerenosti. U posljednje vrijeme se najčešće za obradu signala upotrebljavaju digitalna računala pa su analogne linije za kašnjenje i preklopnici sve manje u upotrebi. Takva sposobnost brze obrade podataka omogućuje implementaciju novog principa detekcije ultrazvučnog izvora koji ne zahtijeva dodatni TGC sistem i omogućuje izbor svojstava ultrazvučno markiranih naprava jednostavnim reprogramiranjem postojećeg procesora. Tako je uvođenje novih generacija poboljšano i olakšano. U više detalja raznih ostvarenja ovog principa lokalizacije možemo ući ako podijelimo ostvarenja prema tipu odašiljanja ultrazvučnih markera, i to: According to this invention, one or more ultrasound transmitters are mounted at the point of interest along the body of the introduced or implanted medical device, which emits continuous, stochastic and pulsed ultrasound signals. An ultrasound imaging device is used to obtain images of the area in the body where said device is placed. The ultrasound machine has an ultrasound receiver in the form of a series of transducers. Localization of said ultrasound transmitter is performed on the receiving side by solving the equation that describes the time sequence of reception of the transmitted wave on said series of ultrasound receivers. Array probes are the most common type of ultrasound transducers in modern ultrasound machines. They consist of multiple transducers (typically between 32 and 200) installed in a linear or curved array. There are also two-dimensional arrays. Such a plurality of transducers enables control and focusing of the beam as well as various manipulations of the directivity characteristic. Recently, digital computers are most often used for signal processing, so analog delay lines and switches are less and less used. This ability to quickly process data enables the implementation of a new principle of ultrasonic source detection that does not require an additional TGC system and enables the selection of properties of ultrasonically marked devices by simply reprogramming the existing processor. Thus, the introduction of new generations is improved and facilitated. We can go into more details of various implementations of this localization principle if we divide the implementations according to the type of transmission of ultrasonic markers, namely:

1. Odašiljanje kontinuiranih valova 1. Transmission of continuous waves

2. Odašiljanje determinističkih impulsnih valova 2. Transmitting deterministic pulse waves

3. Odašiljanje stohastičkih valova 3. Sending stochastic waves

Lokalizacija pomoću odašiljanja kontinuiranih valova kao marker signala zasniva se na faznoj razlici između valova koje primaju različiti članovi prijamnog niza. Može se smatrati da fazna razlika ovisi o zakrivljenosti dolaznih valova kako je to ilustrirano na slici 2. Localization using the transmission of continuous waves as a signal marker is based on the phase difference between the waves received by different members of the receiving array. It can be considered that the phase difference depends on the curvature of the incoming waves as illustrated in Figure 2.

Razumijevanje principa može se postići razmatranjem dviju ekstremnih situacija, tj. situacije kad je marker pretvarač u beskonačnoj udaljenosti i slučaja kad je izvor na nultoj udaljenosti od prijamnog niza pretvarača. An understanding of the principle can be achieved by considering two extreme situations, i.e. the situation when the marker transducer is at infinite distance and the case when the source is at zero distance from the receiving array of transducers.

Ako je izvor vala na beskonačnoj udaljenosti, val koji stiže do prijamnog niza pretvarača postaje u osnovi ravni val pa stiže na cijeli linearni niz pretvarača istovremeno. Fazna brzina je beskonačna a kašnjenje između trenutka prijama na raznim članovima niza je jednako nuli. Što je izvor zvuka bliži to je valna fronta savinutija i to je dulje kašnjenje između trenutaka prijama vala na raznim članovima prijamnog niza. If the source of the wave is at infinite distance, the wave arriving at the receiving array of transducers becomes essentially a plane wave and arrives at the entire linear array of transducers simultaneously. The phase speed is infinite and the delay between the moment of reception on the various members of the array is equal to zero. The closer the sound source is, the more curved the wavefront is and the longer the delay between the moments of reception of the wave at the various members of the receiving array.

Svi slučajevi između te dva ekstrema daju kašnjenja koja su između nule i kašnjenja koje odgovara propagaciji brzinom zvuka uzduž prijamnog niza. Sad ćemo opisati principe kad se upotrebljavaju kontinuirani, impulsni i stohastički valovi kao marker signali. All cases between these two extremes give delays that are between zero and the delay corresponding to propagation at the speed of sound along the receiving array. Now we will describe the principles when continuous, impulse and stochastic waves are used as marker signals.

1. U slučaju kontinuiranog vala, izvor električkog signala koji stvara ultrazvučnu emisiju s marker pretvaračem, može se smjestiti unutar sklopa marker pretvarača ili izvan njega a povezan njime vodičima koji su ugrađeni uzduž tijela katetera. Ako marker odašiljač odašilje kontinuirani postojati će fazna razlika između signala koji se pojavljuju na članu prijemnog niza pretvarača koji se nalazi direktno nasuprot izvoru t bio kojeg drugog člana niza pretvarača. Ako je udaljenost tih dvaju članova niza a, frekvencija vala ??? a fazna razlika između ta dva signala je ω onda je udaljenost D (v. sliku 2) jednaka: 1. In the case of a continuous wave, the source of the electrical signal that creates an ultrasound emission with the marker transducer can be located inside the marker transducer assembly or outside of it and connected to it by conductors that are installed along the body of the catheter. If the marker transmitter transmits continuously there will be a phase difference between the signals appearing at the receiving member of the transducer array located directly opposite the source t or any other member of the transducer array. If the distance between those two members of the series is a, the frequency of the wave ??? and the phase difference between those two signals is ω, then the distance D (see figure 2) is equal to:

[image] [image]

jednadžba 1 equation 1

Fazni demodulator kakav je poznat u elektronici može mjeriti Δϕ, tako da se D može izračunati gornjom jednadžbom za određeni a. Položaj nasuprotnog člana niza može se odrediti mjerenjem fazne razlike među susjednim članovima niza. Traženi nasuprotni član je onaj gdje su najmanje razlike u fazi susjednih pretvarača u nizu. Prema tome, moguće je lokalizirati izvor kontinuiranog ultrazvučnog vala mjerenjem fazne razlike signala dobivenih od dolaznog kontinuiranog vala na pretvarački niz. A phase demodulator as known in electronics can measure Δϕ, so that D can be calculated by the above equation for a given a. The position of the opposite array member can be determined by measuring the phase difference between adjacent array members. The desired opposite term is the one where the phase differences of the adjacent inverters in series are the least. Therefore, it is possible to localize the source of the continuous ultrasonic wave by measuring the phase difference of the signals obtained from the incoming continuous wave to the transducer array.

To je ilustrirano na slici 3 uz razumijevanje da konkretna realizacija može biti u obliku analognih ili digitalnih sklopova sa odgovarajućim programima (softverom). This is illustrated in Figure 3 with the understanding that the concrete realization can be in the form of analog or digital circuits with appropriate programs (software).

2. U slučaju sistema sa determinističkim impulsima ultrazvuka, izvor električnih impulsa inducira ultrazvučne impulse u marker pretvaraču. Taj izvor električnih impulsa može biti unutar sklopa marker pretvarača ili izvan njega a povezan s njime putem vodiča koji teku unutar i uzduž kateterskog tijela (7). Ultrazvučni impulsi se šire i obliku praktički kuglastih "ljusaka" od marker pretvarača. Takvi sferni valovi stižu do različitih članova prijemnog niza pretvarača u razna vremena. Naime, udaljenosti od marker pretvarača do raznih članova prijamnog niza su različite. Ovaj se problem može riješiti geometrijskim odnosima. Ti se geometrijski odnosi mogu riješiti za sve poznate oblike i forme prijamnih nizova. Za slučaj linearnog niza imamp izraz za udaljenost D kako slijedi: 2. In the case of a system with deterministic ultrasound pulses, the source of electrical pulses induces ultrasound pulses in the marker transducer. This source of electrical impulses can be inside the marker transducer assembly or outside it and connected to it through conductors running inside and along the catheter body (7). Ultrasonic pulses spread and form practically spherical "shells" from the marker transducer. Such spherical waves arrive at different members of the transducer receiving array at different times. Namely, the distances from the marker converter to the various members of the receiving array are different. This problem can be solved by geometric relations. These geometric relationships can be solved for all known shapes and forms of receiving arrays. For the case of a linear sequence imamp the expression for the distance D as follows:

[image] [image]

jednadžba 2 equation 2

gdje je Δt vrijeme propagacije između elementa prijamnog niza najbližeg marker pretvaraču i člana niza na udaljenosti a od njega. Brzina ultrazvuka je označena sa c. Za zakrivljene nizove pretvarača sa zakrivljenostima tipa čunjosječica, ovaj se problem može riješiti analitički. U drugim se slučajevima odnos udaljenosti prema širenju valne fronte uzduž niza pretvarača može se modelirati digitalnim računalom. Zapravo može biti praktično da se blok 94 na slici 4 ostvari kao program sa utabličenim podacima, bez obzira da li su podaci dobiveni analitičkim proračunom ili numeričkim modeliranjem. Kako bi se izbjegla višeznačnost frekvencija repeticije impulsa iz marker pretvarača mora biti manja od c/L, gdje je L duljina prijamnog niza a c je brzina ultrazvuka. where Δt is the propagation time between the element of the receiving array closest to the marker transducer and the array member at a distance a from it. The speed of ultrasound is indicated by c. For curved converter arrays with cone-type curvatures, this problem can be solved analytically. In other cases, the relationship of distance to wavefront propagation along the array of transducers can be modeled by a digital computer. In fact, it may be practical to implement block 94 in Figure 4 as a program with tabulated data, regardless of whether the data is obtained by analytical calculation or numerical modeling. In order to avoid ambiguity, the pulse repetition frequency from the marker transducer must be less than c/L, where L is the length of the receiving array and c is the ultrasound speed.

3. Odašiljanje stohastičkih valova je još jedna moguća realizacija opisanog principa. Naime, dosad opisane izvedbe zahtijevaju dobar i stalan ultrazvučni kontakt između aktiviranih članova niza pretvarača i pacijentove kože. Ako taj kontakt nije optimalan, rezultat proračuna prema jednadžbama 1 i 2 će davati promjenjive rezultate. Kako bi se ta poteškoća riješila u slučaju imputenih valova moguće je poboljšanje upotrebom proračuna unakrsne korelacije za određivanje Δt. Poznati princip stohastičke matematike je da je kašnjenje Δt maksimuma funkcije unakrsne korelacije za vrlo slične, ali za Δt u vremenu pomaknute procese jednako Δt. Dakle blok 94 na slici 4 može računati funkciju unakrsne korelacije signala iz raznih članova niza pretvarača, te na osnovi kašnjenja maksimuma te funkcije mjeriti kašnjenja signala čak i u prisustvu šuma i smetnji. Ovaj je proces ilustriran na slici 5. 3. Sending stochastic waves is another possible realization of the described principle. Namely, the versions described so far require good and constant ultrasonic contact between the activated members of the array of transducers and the patient's skin. If this contact is not optimal, the result of calculations according to equations 1 and 2 will give variable results. In order to solve this difficulty in the case of imputed waves, an improvement is possible by using the cross-correlation calculation to determine Δt. A well-known principle of stochastic mathematics is that the delay Δt of the maximum of the cross-correlation function for very similar but Δt-shifted processes is equal to Δt. Thus, block 94 in Figure 4 can calculate the cross-correlation function of signals from various members of the array of converters, and based on the delay of the maximum of that function, measure signal delays even in the presence of noise and disturbances. This process is illustrated in Figure 5.

Razmatrajući sliku 1 vidimo da je ultrazvučni aparat (ehoskop) koji se upotrebljava za odslikavanje unutrašnjosti pacijentova tijela 3 građen od sonde 4 u kontaktu s kožom preko koje odašilje i prima ultrazvučne impulse iz tijela 3. Rečena sonda pretražuje sloj 5 tijela 3. Medicinska naprava 1, koja može biti dijagnostički ili terapijski kateter ili neka druga naprava uvedena u pacijentovo tijelo u medicinske svrhe. Medicinska naprava 1 ima aktivni član 8 koji je označen sklopom 2 marker piezoelektričnog pretvarača. Sklop piezoelektričnog pretvarača 2 je smješten u neposrednoj blizini ili na položaju aktivnog člana 8 medicinske naprave 1. Rečeni aktivni član može biti dijagnostička ili terapijska elektroda, izvor za davanje lijekova, otvor za uzimanje uzoraka krvi ili neki drugi aktivni dio medicinske naprave. Aktivna funkcija medicinske naprave ostvaruje sa dijelom 9 koji, npr. može biti dijagnostičko EKG pojačalo, izvor energije za elektroterapiju, infuziona pumpa, itd. Sredstvo 7 za generiranje električkih impulsa može biti spojeno na rečeni sklop piezoelektričnog pretvarača 2. S druge strane, sklop piezoelektričkog pretvarača 2 može i sam sadržavati dio za generiranje električnih impulsa, u kojem slučaju impulsni generator 7 nije potreban. Električni impulsi se generiraju u rečenom impuls generatoru ili u specifičnom dijelu sklopa piezoelektričnog pretvarača. Ovi impulsi nisu na nikakav način sinkronizirani sa ultrazvučnim impulsima koje generira i odašilje u tijelo sonda ultrazvučnog aparata (4). Lokalizacija marker pretvarača vrši se na prijemnoj strani ultrazvučnog pretvarača i njegove sonde 4 po principima opisanim slikom 2. Looking at picture 1, we see that the ultrasound machine (echoscope) used to image the inside of the patient's body 3 is made up of a probe 4 in contact with the skin through which it transmits and receives ultrasound pulses from the body 3. Said probe searches the layer 5 of the body 3. Medical device 1 , which can be a diagnostic or therapeutic catheter or some other device introduced into the patient's body for medical purposes. The medical device 1 has an active member 8, which is marked by a piezoelectric transducer marker circuit 2. The piezoelectric transducer assembly 2 is located in the immediate vicinity or at the position of the active member 8 of the medical device 1. Said active member can be a diagnostic or therapeutic electrode, a source for administering drugs, an opening for taking blood samples or some other active part of the medical device. The active function of the medical device is realized with the part 9 which, for example, can be a diagnostic ECG amplifier, an energy source for electrotherapy, an infusion pump, etc. The means 7 for generating electrical impulses can be connected to said piezoelectric transducer assembly 2. On the other hand, the piezoelectric transducer assembly converter 2 can itself contain a part for generating electrical pulses, in which case the pulse generator 7 is not needed. Electric pulses are generated in said pulse generator or in a specific part of the piezoelectric transducer circuit. These pulses are not in any way synchronized with the ultrasound pulses generated and transmitted to the body by the probe of the ultrasound machine (4). Localization of the marker transducer is performed on the receiving side of the ultrasonic transducer and its probe 4 according to the principles described in Figure 2.

Razmatrajući sliku 2 vidimo situaciju sa slike 1 potpuno shematiziranu u svrhu objašnjenja matematičke obrade i objašnjenja principa. Marker pretvarač je ovdje označen sa 2, a on odašilje ultrazvučne valove prikazane u ovoj slici valnim frontama 10,11,12 koje se udaljavaju od pretvarača 2 kao sferni valovi. Rečeni valovi stižu do pretvaračkog niza 40 koji je aktivni dio sonde 4 sa slike 1. Niz pretvarača je ovdje ilustriran kao linearni niz koji se sastoji od odvojeno spojenih članova niza, tj. pretvarača tr(1) - tr(n). U praksi, niz može biti ravan ili zakrivljen. Valna fronta iz ultrazvučnog odašiljača 2 prvo stiže do najbližeg člana rečenog niza pretvarača, ovdje označenog tr(n). Dakle lateralni položaj odašiljača ultrazvuka - marker pretvarača uzduž prijemnog niza pretvarača 40 sadržan je u podatku o tome koji pretvarač prvi detektira val. Valna fronta 11 je prikazana kako upravo dotiče član niza tr(n). Taj član niza ćemo ubuduće nazivati referentnim (centralnim) članom niza. Kako se val dalje širi, on dalje dotiče slijedeće članove niza pretvarača na obje strane. Brzina ostvarivanja ovog kontakta je zapravo fazna brzina i ona ovisi o udaljenosti D između odašiljača 2 i niza 40. Tva ekstrema se mogu odmah evaluirati, tj. slučaj kad je D jednak nuli i slučaj kad je udaljenost D beskonačna. Za udaljenost D=0 fazna brzina je c. Ako je udaljenost beskonačna onda valne fronte 10,11,12.... degeneriraju u ravne valove a fazna brzina je beskonačna. Brzina valne fronte 11 koja dodiruje niz 40 može se mjeriti jer je moguće odrediti njeno dodirivanje svakog od članova niza pretvarača. Ako je, npr., udaljenost između članova niza tr(n) i tr(n+4) jednaka a a vremenska razlika doticanja tih članova niza valnom frontom 11 je Δt, onda se udaljenost D može izračunati jednadžbom 1 za kontinuirane valove a jednadžbom 2 za impulsne ili stohastičke valove. Ove metode bit će detaljnije opisane pomoću slika 3, 4 i 5. Looking at Figure 2, we see the situation from Figure 1 completely schematic for the purpose of explaining the mathematical processing and explaining the principles. The marker transducer is marked here with 2, and it transmits the ultrasonic waves shown in this figure as wavefronts 10,11,12 that move away from transducer 2 as spherical waves. The said waves reach the transducer array 40 which is the active part of the probe 4 of Figure 1. The transducer array is illustrated here as a linear array consisting of separately connected array members, i.e. the tr(1) - tr(n) transducers. In practice, the string can be straight or curved. The wavefront from ultrasonic transmitter 2 first reaches the nearest member of said array of transducers, denoted here tr(n). Thus, the lateral position of the ultrasound transmitter - transducer marker along the receiving array of the transducer 40 is contained in the information about which transducer detects the wave first. Wavefront 11 is shown just touching the string term tr(n). In the future, we will call this member of the series the reference (central) member of the series. As the wave continues to propagate, it further touches the next members of the transducer array on either side. The speed of making this contact is actually the phase speed and it depends on the distance D between the transmitter 2 and the array 40. Two extremes can be immediately evaluated, i.e. the case when D is equal to zero and the case when the distance D is infinite. For the distance D=0 the phase speed is c. If the distance is infinite, then the wave fronts 10,11,12... degenerate into flat waves and the phase speed is infinite. The velocity of the wavefront 11 touching the array 40 can be measured because it can be determined as it touches each of the members of the transducer array. If, for example, the distance between the members of the series tr(n) and tr(n+4) is equal to a and the time difference between the touching of these members of the series by the wave front 11 is Δt, then the distance D can be calculated by equation 1 for continuous waves and by equation 2 for impulse or stochastic waves. These methods will be described in more detail using Figures 3, 4 and 5.

Ostvarenje s upotrebom odašiljanja kontinuiranih valova Realization using continuous wave transmission

Razmatrajući sliku 3 vidimo ilustraciju metode gdje se lokalizira marker pretvarač 21 korištenjem kontinuiranih valova koje odašilje taj pretvarač. Unutar naprave za generiranje signala 22 ili vanjskog generatora signala 7 generira se kontinuirani signal koji se vodi na marker pretvarač 21, koji, sa svoje strane odašilje kontinuirani, u biti sferni, ultrazvučni val. Taj val dostiže sondu 4 ultrazvučnog aparata. Sonda sadrži niz pretvarača (40 na slici 2) od kojih je svaki povezan s jednom jedinicom za obradu signala (61 do 6n na slici 3). Detektor fazne razlike 83 detektira razliku u fazi primljenog vala između rečenih članova pretvaračkog niza i računa udaljenost D od sonde do marker pretvarača. Ova se informacija vodi u jedinicu za obradu slike koja generira vidljivu oznaku na ekranu 602 ultrazvučnog aparata za odslikavanje. Referentni (centralni) prijamni član niza je onaj gdje je fazna razlika između susjednih članova najmanja. Drugi način određivanja referentnog (centralnog) člana niza je da se nađe centar simetrije faznih razlika koje se mijenjaju u suprotnim smjerovima počevši od tog člana. Valja primijetiti da blokovi 61 do 6n, te blokovi 83 i 84 mogu biti ostvareni kao dijelovi kompjuterskog programa. U potpuno digitaliziranim ultrazvučnim aparatima se operacije ilustrirane na slici 3 i jednadžbom 1 izvode kao dijelovi obrade signala u aparatu. Interferencija impulsne ehoskopije aparata 6 i ovog lokalizacijskog sistema može se spriječiti na dva načina. Jedan je ilustriran blokom 603 koji paralizira rad lokalizacijskog sistema za vrijeme rada eho sistema. Lokalizacijski sistem funkcionira "krađom ciklusa", tj. uzimaju se ciklusi-vremenski odsječci kad ehoskop ne radi te se taj za lokalizaciju marker pretvarača. Druga mogućnost je upotreba dvaju oštrih frekvencijskih filtera na frekvenciji marker pretvarača, gdje je jedan od njih pojasni propust a signal te frekvencije se vodi na lokalizacijske sklopove sa slike 3 dok drugi frekvencijski filter sprječava lokalizacijsku frekvenciju da interferira s radom ehoskopa. Looking at Figure 3 we see an illustration of the method where the marker transducer 21 is localized using the continuous waves emitted by that transducer. Inside the signal generating device 22 or the external signal generator 7, a continuous signal is generated which is fed to the marker transducer 21, which, in turn, emits a continuous, essentially spherical, ultrasonic wave. This wave reaches the probe 4 of the ultrasound machine. The probe contains a series of transducers (40 in Figure 2), each of which is connected to one signal processing unit (61 to 6n in Figure 3). The phase difference detector 83 detects the difference in the phase of the received wave between said transducer array members and calculates the distance D from the probe to the transducer marker. This information is fed to the image processing unit which generates a visible mark on the screen 602 of the ultrasound imager. The reference (central) receiving member of the array is the one where the phase difference between adjacent members is the smallest. Another way to determine the reference (central) member of the series is to find the center of symmetry of the phase differences that change in opposite directions starting from that member. It should be noted that blocks 61 to 6n, and blocks 83 and 84 can be implemented as parts of a computer program. In fully digitized ultrasound machines, the operations illustrated in Figure 3 and Equation 1 are performed as part of the signal processing in the machine. The interference of the pulsed echoscopy of the device 6 and this localization system can be prevented in two ways. One is illustrated by block 603 which paralyzes the operation of the localization system during the operation of the echo system. The localization system works by "stealing cycles", i.e. cycles are taken when the echoscope is not working, and this is used for localization of the transducer marker. Another possibility is the use of two sharp frequency filters on the frequency of the marker converter, where one of them is a band pass and the signal of that frequency is led to the localization circuits from Figure 3, while the other frequency filter prevents the localization frequency from interfering with the operation of the echoscope.

Ostvarenje sa odašiljanjem impulsnog ultrazvuka Realization with the transmission of pulsed ultrasound

Razmatrajući sliku 4 vidimo da se u slučaju odašiljanju impulsnog vala iz marker pretvarača 21, signal koji primi prijamni niz 40 sa slike 2 može obraditi kako je to prikazano na slici 4. Marker pretvarač 21 odašilje ultrazvučne impulse kad mu se dovede impulsni električki signal iz vanjskog generatora signala 7 (slika 1) ili iz unutrašnjeg signal generatora 22. Ograničenje postavljeno na rečene impulsne signale je da njihova frekvencija repeticije mora biti manja od kvocijenta brzine širenja ultrazvuka i duljine čela sonde (4) ultrazvučnog pretvarača. Frekvencija repeticije se ne mora precizno kontrolirati, u stvari, ona može biti stohastička. Signali dobiveni na rečenim članovima prijamnog niza se vode do okidnih sklopova 71 do 7x. Signali iz tih sklopova se vode do bloka za mjerenje vremena (elektronički sklop ili dio softvera), gdje se mjere i uspoređuju vremena dolaska valova. Tako izmjerena kašnjenja trenutaka dolaska se upotrebljavaju za proračun udaljenosti D izvora ultrazvuka (v. sliku 2) uz upotrebu jednadžbe 2. Referentni pretvarač u prijemnom nizu pretvarača se određuje tako da se nađe onaj pretvarač do kojega val prvo stigne ili pak tako da se odredi od kojeg se pretvarača kašnjenja šire simetrično u suprotnim smjerovima. Evaluacija rečene jednadžbe se obavlja u bloku 94, a rezultati proračuna se vode u sistem za odslikavanje u ultrazvučnom aparatu. Ta informacija se vodi u procesor slike koji generira vidljivu grafičku oznaku na mjestu koje dogovara položaju marker pretvarača na ekranu 602 ultrazvučnog aparata. Lokalizacijski aparat može raditi "krađom ciklusa", tj. radni ciklusi se upotrebljavaju kad ehoskop ne radi (ima pauzu), te se taj vremenski interval koristi za lokalizaciju marker pretvarača. Alternativno se frekvencijski spektar odaslanog marker signala može učiniti vrlo uskim i to znatno užim od spektra frekvencija ehoskopskih impulsa. U tom se slučaju lokalizacijski signal može izdvojiti filtriranjem i tako izbjeći interferenciju sa signalom za odslikavanje. Looking at Figure 4, we see that in the case of sending a pulse wave from the marker transducer 21, the signal received by the receiving array 40 of Figure 2 can be processed as shown in Figure 4. The marker transducer 21 transmits ultrasonic pulses when a pulsed electrical signal is supplied to it from an external of the signal generator 7 (figure 1) or from the internal signal generator 22. The limitation placed on said pulse signals is that their repetition frequency must be smaller than the quotient of the ultrasound propagation speed and the length of the probe head (4) of the ultrasound transducer. The repetition frequency does not have to be precisely controlled, in fact it can be stochastic. The signals received on the said members of the receiving array are led to the trigger circuits 71 to 7x. The signals from these circuits are led to the timing block (electronic circuit or part of the software), where the arrival times of the waves are measured and compared. The arrival time delays measured in this way are used to calculate the distance D of the ultrasound source (see Figure 2) with the use of equation 2. The reference transducer in the receiving array of transducers is determined by finding the transducer to which the wave reaches first or by determining from of which converter the delays spread symmetrically in opposite directions. The evaluation of the said equation is performed in block 94, and the results of the calculation are fed into the imaging system in the ultrasound machine. This information is fed to an image processor that generates a visible graphic marker at a location corresponding to the location of the transducer marker on the ultrasound machine screen 602 . The localization device can work by "stealing cycles", i.e. work cycles are used when the echoscope is not working (it has a break), and that time interval is used to localize the marker transducer. Alternatively, the frequency spectrum of the transmitted marker signal can be made very narrow, significantly narrower than the frequency spectrum of echoscopic pulses. In this case, the localization signal can be isolated by filtering and thus avoid interference with the imaging signal.

Razmatrajući sliku 5 vidimo realizaciju kojom se rješava problem povremenih prekida ultrazvučnog kontakta sonde 4 sa tijelom pacijenta 3 prema slikama 1, 2, i 3. U takvom se slučaju može deterministička metoda mjerenja kašnjenja opisana u vezi sa slikom 4 zamijeniti sistemom prikazanom na slici 5. Na toj slici se kašnjenja između vremena dolaska impulsa na razne članove prijamnog niza pretvarača određuju računanjem funkcije unakrsne korelacije između signala koje primaju pojedini članovi niza. Ova funkcija unakrsne korelacije ima maksimum na kašnjenju koje je jednako stvarnom kašnjenju signala između članova niza koji su u pitanju. Razlika u usporedbi sa determističkim sistemom sa slike 4 je u tome da je sistem sa slike 5 mnogo manje osjetljiv na smetnje. Looking at figure 5, we see a realization that solves the problem of occasional interruptions of the ultrasound contact of the probe 4 with the patient's body 3 according to figures 1, 2, and 3. In such a case, the deterministic delay measurement method described in connection with figure 4 can be replaced by the system shown in figure 5. In this figure, the delays between the arrival times of the pulses at various members of the receiving array of converters are determined by calculating the cross-correlation function between the signals received by individual members of the array. This cross-correlation function has a maximum at a delay equal to the actual signal delay between the array members in question. The difference compared to the deterministic system from Figure 4 is that the system from Figure 5 is much less sensitive to disturbances.

Period vremenske repeticije lokalizacijskih impulsa mora biti dulji od vremena potrebnog da ultrazvuk prijeđe duljinu rečenog prijamnog niza pretvarača. Ekvivalentno tome je gornja granica frekvencije koja se može upotrijebiti bez višeznačnosti, ona frekvencija čiji je period dulji od vremena potrebnog da val prijeđe duljinu rečenog prijamnog niza pretvarača. To znači da je najkraći period vala jednak duljini rečenog niza pretvarača podijeljenog s brzinom zvuka. Ovo su jedina bitna ograničenja na frst lokalizacijskih valova. The time repetition period of the localization pulses must be longer than the time required for the ultrasound to pass the length of said receiving array of transducers. Equivalently, the upper limit of the frequency that can be used without ambiguity is that frequency whose period is longer than the time required for the wave to travel the length of said receiving array of transducers. This means that the shortest period of the wave is equal to the length of said string of transducers divided by the speed of sound. These are the only significant limitations on first localization waves.

Način primjene izuma Method of application of the invention

Ovaj izum predstavlja bitno poboljšanje postojećih lokalizatora marker pretvarača u smislu znatno veće otpornosti na smetnje i odsustva potrebe za sinkronizacijom sa ehoskopom s kojim se zajedno upotrebljava. U tom se smislu izum može upotrijebiti za povećanje proizvodnje ultrazvučno markiranih medicinskih naprava koje se uvode u tijelo poput katetera, endoskopa i slično. Posebno se ovim izumom otvaraju mogućnosti izrade ultrazvučno markiranih medicinskih naprava i izvan zemalja koje imaju proizvodnju ultrazvučnih ehoskopa. This invention represents a significant improvement of existing localizer marker transducers in terms of significantly greater resistance to interference and the absence of the need for synchronization with the echoscope with which it is used together. In this sense, the invention can be used to increase the production of ultrasound marked medical devices that are introduced into the body such as catheters, endoscopes and the like. In particular, this invention opens up the possibility of manufacturing ultrasound-marked medical devices even outside of countries that produce ultrasound echoscopes.

Claims

1. Medical ultrasound localizer of the ultrasound source characterized by the fact that it consists of: - An ultrasound pulse echoscope capable of searching and imaging the inside of the body and creating images or a series of images of a section or volume of said body - where said pulse echoscope consists of a search probe and localization circuits and software - where said search probe consists of a series of ultrasound receivers of known geometry - where said ultrasound receivers are each individually connected to said localization circuits - where the localization circuits, in addition to the mirroring function, are capable of detecting and measuring the phase difference of their input signals - where localization circuits, in addition to the mirroring function, are capable of detecting and measuring the time delay of their input signals - where said localization electronic circuits measure the phase or difference in arrival times between signals arriving at different members of said array of transducers and calculate the distance of said means for transmitting ultrasonic waves based on said phase difference or difference in arrival times of pulses using the equation of wave propagation in the body - where said localization electronic circuits or software identifies the member to the smallest neighboring members, and determines the line of sight that goes out perpendicular to the baked day ma as the direction in which said distance is measured - Medical devices introduced into said body - At least one localized and autonomous means for transmitting ultrasound, located on said medical device - Devices capable of generating a continuous electrical signal or a series of pulses connected to said means for transmitting ultrasound - where said impulse echoscope contains circuits or software that converts said data about the distance to said ultrasound source and said line of sight along which said distance is measured into a visible mark on the screen of the ultrasound echoscope and which shows the position of said means for transmitting ultrasound waves within said searched section or volume.

2. Medical ultrasound localizer of an ultrasound source, according to claim 1 characterized by the fact that said localization circuit is in fact an electronic circuit or software capable of measuring the phase difference of signals that appear on various members of the receiving array of transducers according to claim 1.

3. Medical ultrasound localizer of an ultrasound source, according to claim 1 characterized by the fact that said localization circuit is an electronic circuit capable of measuring the difference in the arrival times of pulse signals that occur on various members of the receiving array of transducers according to claim 1.

4. Medical ultrasound localizer of the ultrasound source, according to claims 1, 2 and 3 characterized by the fact that said localization circuit is connected to the circuit for image generation on the monitor of the ultrasound echoscope according to claim 1.

5. Medical ultrasound localizer of an ultrasound source, according to claims 1, 2, 3 and 4 characterized by the fact that said localization circuit is connected to a circuit or software for solving the equation of wave propagation in the body according to claim 1 using measured data according to claims 2 and 3.

6. Medical ultrasound localizer of the ultrasound source, according to claims 1, 2 and 3 characterized by the fact that said circuitry for generating an image on the monitor of the ultrasound echoscope according to claim 1 is constructed so that it converts the data obtained according to claims 2, 3, 4 and 5 into a visible memory address marks in the echoscope image memory from claim 1, and according to the solution of the wave equation in accordance with claim 5.

7. Medical ultrasound localizer of the ultrasound source, according to claims 1 to 6 characterized by the fact that its part is a medical device introduced into the body according to claim 1

8. Medical ultrasound localizer of the ultrasound source, according to claims 1 to 7, characterized in that the medical device according to claim 7 is mounted with an ultrasound transmitter converter - means for transmitting ultrasound.

9. Medical ultrasound localizer of the ultrasound source, according to claims 1 to 7 characterized by the fact that an electrical signal source of sufficient energy is connected to the ultrasound transmitter of ultrasound according to claim 8 to cause ultrasound vibrations of the ultrasound transmitter transducer - means for transmitting ultrasound.