CLEANING SYSTEM AND METHOD FOR OPERATING THE CLEANING SYSTEM

Abstract

The application relates to a cleaning system configured for cleaning of cavities filled with a liquid, including fragmentation, debridement, material removal, irrigation, disinfection, and decontamination. The cleaning system includes an electromagnetic radiation system and a liquid. A treatment handpiece irradiates the liquid within a cavity with a radiation beam, producing a first vapor bubble using first pulse, and, at a different location, a second vapor bubble using a second pulse. The pulse repetition time is adjusted to ensure efficacy, for example such that an onset time of the second vapor bubble is within the first contraction phase of the first vapor bubble, when the first vapor bubble has contracted from its maximal volume to a size in a range from about 0.7 to about 0.1 of the maximal volume.

Claims

1-24. (canceled)

25. A cleaning system configured for cleaning cavities filled with a liquid, the cleaning system comprising: an electromagnetic radiation system comprising a radiation source for generating a radiation beam and an optical delivery system for delivering the radiation beam, wherein the delivery system includes a treatment handpiece and an exit component, wherein the treatment handpiece and the exit component are configured to irradiate the liquid within the cavity with the radiation beam, wherein a wavelength of the radiation beam is chosen for significant absorption of the radiation beam in the liquid, wherein the electromagnetic radiation system is adapted to be operated in pulsed operation with at least one pulse set containing at least two individual pulses, wherein a first pulse of the pulses is followed by a second pulse of the pulses with a pulse repetition time, wherein the electromagnetic radiation system is adapted to generate a first vapor bubble within the liquid by delivery of the corresponding first pulse such that the first vapor bubble oscillates in an expansion phase from a minimal volume to a maximal volume and in a subsequent contraction phase from a maximal volume to a minimal volume, wherein the electromagnetic radiation system is adapted to generate a second vapor bubble within the liquid by delivery of the corresponding second pulse at a location different to the location where the first vapor bubble is present at the time of generating the second vapor bubble, and wherein the pulse repetition time is configured such that an onset time of the second vapor bubble is within the first contraction phase of the first vapor bubble, when the first vapor bubble has contracted from its maximal volume to a size in a range from about 0.7 to about 0.1 of the maximal volume.

26. The cleaning system according to claim 25, wherein the electromagnetic radiation system is a laser system, wherein the radiation source is a laser source, wherein the radiation beam is a laser beam, and wherein the wavelength of the laser beam is in a range from above 0.4 m to 11.0 m inclusive.

27. The cleaning system according to claim 25, wherein the pulse repetition time is configured such that the onset time of the second vapor bubble is within the first contraction phase of the first vapor bubble, when the first vapor bubble has contracted from its maximal volume to a size in a range from about 0.5 to about 0.1 times the maximal volume.

28. The cleaning system according to claim 25, wherein within one pulse set the pulse repetition time is configured to be in a range from about 50 s to about 900 s.

29. The cleaning system according to claim 25, wherein the electromagnetic radiation system further comprises a feedback system, wherein a bubble oscillation intensity of at least one vapor bubble generated within the liquid when irradiated with the irradiation beam is determined by the feedback system, and wherein cleaning system is configured to adjust the pulse repetition as a function of the determined bubble oscillation intensity.

30. The cleaning system according to claim 29, wherein the feedback system is configured within the cleaning system as a closed loop control system to automatically adjust the temporal pulse period.

31. The cleaning system according to claim 29, wherein the feedback system comprises an acoustical, a pressure, or an optical measurement sensor for sensing the bubble oscillation intensity.

32. The cleaning system according to claim 25, wherein the clean system is configured to generate multiple pairs of first and second bubbles such that the time difference between the onset time of the second vapor bubble and the onset time of the related first vapor bubble is repeatedly varied in a sweeping manner.

33. The cleaning system according to claim 32, wherein the cleaning system is configured to generate and deliver multiple pulses within one pulse set at a sweeping pulse repetition time, and wherein from pulse to pulse the pulse repetition time is varied in a sweeping manner.

34. The cleaning system according to claim 32, wherein the cleaning system is configured to generate and deliver multiple pulse sets, and wherein each pulse set contains at least two pulses, and wherein from pulse set to pulse set the repetition time between two subsequent pulses is varied in a sweeping manner.

35. The cleaning system according to claim 32, wherein the cleaning system is configured to generate and deliver multiple pairs of two pulses, and wherein from pair of pulses to pair of pulses the pulse energy of each second pulse is varied in a sweeping manner.

36. The cleaning system according to claim 25, wherein the cleaning system is configured to provide two or more pulse sets, and wherein a temporal separation between the pulse sets is 10 ms.

37. The cleaning system according to claim 25, wherein one pulse set consists of two to twenty individual pulses.

38. The cleaning system according to claim 26, wherein the wavelength of the laser beam is chosen to be in a range from about 1.3 m to about 11.0 m for the laser beam to be highly absorbed in the liquid, and wherein a pulse duration of one individual laser pulse is in the range of 1 s and <500 s.

39. The cleaning system according to claim 38, wherein a laser source is one of an Er:YAG laser source having a wavelength of 2940 nm, an Er:YSGG laser source having a wavelength of 2790 nm, an Er,Cr:YSGG laser source having a wavelength of 2780 nm or 2790 nm, or a CO.sub.2 laser source having a wavelength of 9300 to 10600 nm, and wherein a pulse energy of one individual laser pulse is in the range from 1 mJ to 1000 mJ.

40. The cleaning system according to claim 39, wherein the laser source is an Er:YAG laser having a wavelength of 2940 nm, wherein the pulse energy of one individual laser pulse is in a range from 1.0 mJ to 40.0 mJ, wherein the temporal separation between two consecutive pulse sets is <0.5 s, and wherein the cumulative delivered energy during one treatment is <150 J.

41. The cleaning system according to claim 38, wherein the handpiece and its exit component are adapted to be adjusted for both a contact or a non-contact delivery of laser energy to the liquid within the cavity, and wherein the exit component has a flat output surface providing a generally parallel exiting beam portion of the laser beam.

42. The cleaning system according to claim 38, wherein the handpiece and its exit component are adapted to be adjusted for a contact delivery of laser energy to the liquid within the cavity, and wherein the exit component has a substantially conically shaped output surface providing a generally circumferentially spread exiting beam portion of the laser beam.

43. The cleaning system according to claim 38, wherein the delivery system comprises an articulated arm through which the laser beam is delivered from the laser source to the exit component.

44. The cleaning system according to claim 38, wherein the delivery system further comprises a scanner for scanning one of a flat shaped output surface and a conically shaped output surface of the exit component with the incoming laser beam.

45. The cleaning system according to claim 38, wherein the handpiece and its exit component are adapted to be adjusted for a non-contact delivery of laser energy to the liquid within the cavity, and wherein a lens system is provided to focus the exiting beam portion of the laser beam within the volume of the liquid.

46. The cleaning system according to claim 26, wherein the wavelength of the laser beam is chosen to be in a range from about 0.4 m to about 1.3 m for the laser beam to be weakly absorbed in the liquid, and wherein the pulse duration of one individual laser pulse is in the range of 1 fs and <100 ns.

47. The cleaning system according to claim 46, wherein the laser source is one of a Q-switched Nd:YAG laser source having a wavelength of 1064 nm, a Q-switched ruby laser source having a wavelength of 690 nm, or an alexandrite laser source having a wavelength of 755 nm, including laser sources with frequency doubled wavelengths of these laser sources, and wherein a pulse energy of one individual laser pulse is in the range from 0.05 mJ to 1000 mJ.

48. The cleaning system according to claim 27, wherein the cleaning system is adapted to adjust the pulse repetition time such that the onset time of the second vapor bubble is within the first contraction phase of the first vapor bubble, when the first vapor bubble has contracted from its maximal volume to a size in a range from about 0.5 to about 0.2 times the maximal volume.

49. The cleaning system according to claim 37, wherein one pulse set consists of two to eight individual pulses.

50. The cleaning system according to claim 49, wherein one pulse set consists of three to six individual pulses.

51. The cleaning system according to claim 38, wherein the pulse duration of one individual laser pulse is in the range of 10 s and <100 s.

52. The cleaning system according to claim 39, wherein a pulse energy of one individual laser pulse is in the range from 1 mJ to 100 mJ.

53. The cleaning system according to claim 40, wherein the pulse energy of one individual laser pulse is in a range from 5.0 mJ to 20.0 mJ.

54. The cleaning system according to claim 46, wherein the pulse duration of one individual laser pulse is in the range of 1 ns and <25 ns.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Embodiments of the invention will be explained in the following with the aid of the drawing in more detail. With reference to the following description, appended claims, and accompanying drawings:

[0040] FIG. 1 illustrates an exemplary inventive laser system with both an optical fiber laser delivery system and an articulated arm laser delivery system;

[0041] FIG. 2a illustrates an exemplary treatment handpiece fed by an articulated arm in contact operational mode;

[0042] FIG. 2b illustrates an exemplary treatment handpiece fed by a delivery fiber in contact operational mode;

[0043] FIG. 3a illustrates an exemplary treatment handpiece fed by an articulated arm in non-contact operational mode;

[0044] FIG. 3b illustrates an exemplary treatment handpiece fed by a delivery fiber in non-contact operational mode;

[0045] FIG. 4a illustrates an exemplary optical exit component of a treatment handpiece fed by an articulated arm, having a flat tip geometry, and showing the resultant laser beam path;

[0046] FIG. 4b illustrates an exemplary optical exit component of a treatment handpiece fed by an articulated arm, having a conical tip geometry, and showing the resultant laser beam path;

[0047] FIG. 5a illustrates an exemplary vapor bubble in generally spherical form;

[0048] FIG. 5b illustrates an exemplary vapor bubble in generally elongate form;

[0049] FIG. 6 illustrates an exemplary vapor bubble oscillation sequence under influence of one short laser pulse;

[0050] FIG. 7 illustrates the difference in single laser pulse vapor bubble oscillation sequence in an infinite and confined cylindrical liquid reservoir;

[0051] FIG. 8a illustrates an exemplary collapse and shock wave emission of a vapor bubble under the influence of an expanding subsequent bubble in confined reservoir, according to the present invention;

[0052] FIG. 8b illustrates an exemplary sequence of laser pulses, and exemplary development of vapor bubbles and emission of a shock wave, according to the present invention;

[0053] FIG. 9 represents a diagrammatic illustration of the temporal course of pulse sets in accordance with various embodiments of the invention;

[0054] FIG. 10 represents an enlarged diagrammatic illustration of a detail of a pulse set according to FIG. 9 with the temporal course of individual pulses with sweeping pulse repetition rates from pulse to pulse within one pulse set;

[0055] FIG. 11 represents an enlarged diagrammatic illustration of a detail of the temporal course of pulse sets according to FIG. 9 with the temporal course of individual pulses with sweeping pulse repetition rates from pulses to pulse set; and

[0056] FIG. 12 represents an enlarged diagrammatic illustration of a detail of an alternative pulse set according to FIG. 9 with the temporal course of individual pulses with sweeping pulse energy from pulse to pulse within one pulse set.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0057] With reference now to FIG. 1, in various embodiments, an electromagnetic radiation system comprising a radiation source for generating a radiation beam is shown. In the following, both the inventive electromagnetic radiation system and an inventive method of operating said electromagnetic radiation system are described. In the shown preferred embodiment, the electromagnetic radiation system is a laser system 1, wherein the radiation source is a laser source 4, and wherein the radiation beam is a laser beam 5. The shown medical treatment laser system 1 comprises at least one laser source 4 for generating a laser beam 5 (FIGS. 4a and 4b), and an optical delivery system 6 for the laser beam 5. The laser system further comprises a schematically indicated control unit 22 for controlling the laser beam 5 parameters, wherein the control unit 22 includes again schematically indicated adjusting means 10 for adjusting the laser beam 5 parameters as described below. The optical delivery system 6 preferably includes an articulated arm 14 and a treatment handpiece 7, wherein the laser beam 5 is transmitted, relayed, delivered, and/or guided from the laser source 4 through the articulated arm 14 and the handpiece 7 to a target. The articulated arm 14 might preferably be an Optoflex brand articulated arm available from Fotona, d.o.o. (Slovenia, EU). In the shown preferred embodiment a second laser source 4 and a second optical delivery system 6 with a second handpiece 7 is provided, wherein instead of the articulated arm a flexible elongated delivery fiber 19 for guiding the laser beam 5 is incorporated. Despite both laser sources 4, 4 and delivery systems 6, 6 being shown in combination, one of both in the alternative may be provided and used within the scope of the present invention. In this description, the expression medical laser system is sometimes used, meaning both, medical and dental laser systems. Moreover, the medical treatment laser system 1 may be configured with any appropriate components and/or elements configured to facilitate controlled application of laser energy, for example, in order to create vapor bubbles in a liquid 3 within an anatomical cavity 2 for cleaning, including fragmentation, debridement, material removal, irrigation, disinfection and decontamination of said anatomical cavity 2, as shown and described below. However, the invention including the here described inventive device and the inventive method are not limited to cleaning anatomical of body cavities 2. Within the scope of the invention any other cavity 2 like industrial or machinery cavities may be cleaned as well.

[0058] It is to be understood that in order to perform cleaning according to the invention, the treated cavity 2 (FIGS. 2, 3) must be filled with a liquid 3. In case of medical or dental applications the cavity 3 may be filled spontaneously with blood or other bodily fluids by the body itself. Alternatively, the cavity may be filled with water, or other liquids such as disinfecting solutions, by the operator. In yet another embodiment, the system may be designed to include a liquid delivery system 26 configured to fill the volume of the cavity with the liquid. Preferably, said liquid 3 is an OH-containing liquid, for example a liquid with its major portion being water. In other examples, the liquid 3 may include abrasive materials or medication, such as antibiotics, steroids, anesthetics, anti-inflammatory medication, antiseptics, disinfectants, adrenaline, epinephrine, astringents, vitamins, herbs, and minerals. Furthermore, the liquid 3 may contain an additive enhancing the absorption of introduced electromagnetic radiation.

[0059] The laser source 4 is a pulsed laser. The laser source 1 may be solid state, and configured with a pulse duration of less than 500 s. The laser pulse duration is defined as the time between the onset of the laser pulse, and the time when 50% of the total pulse energy has been delivered to the liquid. The pulse duration may be fixed; alternatively, the pulse duration may be variable and/or adjustable. The pulse energy may be fixed; alternatively, the pulse energy may vary during the treatment. The wavelength of the laser beam 5 is in a range from above 0.4 m to 11.0 m inclusive. As illustrated in FIGS. 9 to 11, the laser system 1 is adapted to be operated in pulsed operation with pulse sets containing at least two and maximally twenty individual pulses p of a temporally limited pulse duration t.sub.p, wherein a temporal separation T.sub.s between the pulse sets is 10 ms, and wherein the individual pulses p follow one another with a pulse repetition time T.sub.p within a range of 50 s, inclusive, to 1000 s, inclusive

[0060] The laser source 4, 4 may desirably be configured to generate coherent laser light having a wavelength such that the laser beam 5 is highly absorbed in the liquid 3, wherein the laser pulse duration is in the range of 1 s and <500 s, and preferably of 10 s and <100 s. Preferably, the laser source 4, 4 is one of an Er:YAG solid state laser source having a wavelength of 2940 nm, an Er:YSGG solid state laser source having a wavelength of 2790 nm., an Er,Cr:YSGG solid state laser source having a wavelength in a range of 2700 to 2800 nm, an Er:YA103 solid state laser having a wavelength of 2690 nm, a Ho:YAG solid state laser having a wavelength of 2100 nm, a CO.sub.2 or CO gas laser source having a wavelength of 9000 nm to 10600 nm, all of them providing a laser beam 5 highly absorbed in water and other OH-containing liquids. In particular, the laser source 4, 4 is an Er:YAG laser having a wavelength of 2940 nm, wherein the laser pulse energy is in a range from 1.0 mJ to 100.0 mJ, and preferably within a range from 5.0 mJ to 20.0 mJ.

[0061] Other examples of laser sources 4,4 with a laser wavelength highly absorbed in water and other liquids include quadrupled Nd:YAG laser which generates light having a wavelength of 266 nm; an ArF excimer laser which generates light having a wavelength of 193 nm, an XeCl excimer laser which generates light having a wavelength of 308 nm, and a KrF excimer laser which generates light having a wavelength of 248 nm.

[0062] In another embodiment, the laser source 4, 4 is one of a frequency doubled Nd:YAG laser source having a wavelength of 532 nm, a dye laser source having a wavelength of 585 nm, or a Krypron laser source having a wavelength of 568 nm, all of them providing a laser beam 5 highly absorbed in oxyhemoglobin within blood vessels. Alternatively, the laser source 4, 4 may desirably be configured to generate coherent laser light having a wavelength such that the laser beam 5 is weakly absorbed in the liquid 3, wherein the laser pulse duration is in the range of 1 fs and <100 ns, and preferably of 1 ns and <25 ns. Preferably, the laser source 4, 4 is one of a Q-switched Nd:YAG laser source having a wavelength of 1064 nm, a Q-switched ruby laser source having a wavelength of 690 nm, or an alexandrite laser source having a wavelength of 755 nm, including laser sources 4, 4 with frequency doubled wavelengths of these laser sources 4, 4, all of them providing a laser beam 5 weakly absorbed in water and other OH-containing liquids. For such weakly absorbed wavelength the pulse energy of one individual laser pulse p is in the range from 0.05 mJ to 1000 mJ, preferably in the range from 0.5 to 200 mJ, and in particular from 1 mJ to 20 mJ.

[0063] Moreover, any other suitable laser source 4, 4 may be utilized, as desired. In certain embodiments, the laser source 1 may be installed directly into the handpiece 7, 7, and no further laser light delivery system 6, 6 such as the articulated arm 14 or elongated delivery fiber 19 is required. Additionally, such handpiece may not be intended to be held in hand but may be built into a table-top or similar device as is the case with laser photo-disruptors for ocular surgery.

[0064] The handpiece 7, 7 includes an exit component 8, through which the laser beam 5 exits the delivery system 6, 6 for entering the liquid 3, as shown in FIGS. 2a, 2b, 3a and 3b. The handpiece 7, 7, and in particular its exit component 8 may be configured to deliver the laser light to the liquid 3 in a contact, and/or non-contact manner. Turning now to FIG. 2a, when the treatment handpiece 7 is configured for a contact delivery, the laser light is from the said contact handpiece 7 directed into a contact exit component 8 which is configured to be at least partially immersed into the liquid 3 within the treated anatomical cavity 2 in such a manner that the laser light exits the exit component 8 within the liquid 3, at a depth of at least 1 mm, and preferably of at least 3 mm, in order to generate vapor bubbles 18 within the liquid 3, and in order the laser generated vapor bubble(s) 18 to interact with the liquid-to-cavity surface. In various embodiments, the contact exit component 8 may consist of an optical fiber tip as shown in and described along with FIG. 2b and FIG. 3b or a larger diameter exit tip 24 as shown in and described along with FIGS. 4a and 4b. In certain embodiments (FIG. 2a), the treatment handpiece 7 together with a contact exit component 8 comprises H14 tipped laser handpiece model available from Fotona, d.d. (Slovenia, EU). And in certain embodiments, an ending of an elongated delivery fiber 19 of the laser light delivery system 6 may be immersed into the liquid 3, thus serving the function of a contact exit component 8 (FIG. 2b).

[0065] For the contact scenario as shown in FIGS. 2a and 2b one of the above described highly absorbed or weakly absorbed wavelengths including all other above described parameters is preferably used, thereby generating at least two vapor bubbles 8 within the liquid 3.

[0066] In one of the embodiments of our invention, the laser system comprises a feedback system 9 to determine a bubble oscillation dimension or amplitude of the prior vapor bubble 18 generated by the laser beam 3 within the liquid 5. The bubble oscillation intensity development and dynamics are described infra in connection with FIGS. 5 and 6. Furthermore, the laser system comprises adjusting means 10 for adjusting the pulse repetition time T.sub.p to achieve at least approximately that the subsequent bubble, i.e., the bubble generated by the subsequent laser pulse p.sub.b, starts to expand when the prior bubble p.sub.a has already contracted to a size in a range from about 0.7V.sub.max1 to about 0.1V.sub.max1, preferably in a range from about 0.5V.sub.max1 to about 0.1V.sub.max1, and expediently in a range from about 0.5V.sub.max1 to about 0.2V.sub.max1 (FIGS. 5 and 7). The feedback system 9 preferably comprises an acoustical, a pressure, or an optical measurement sensor for sensing the oscillating course of the bubble size V. As a result of the bubble oscillation sensing, the laser pulse repetition time T.sub.p might be manually adjusted by the user to be approximately equal to T.sub.p-opt. However, in a preferred embodiment, the feedback system 9 and the adjusting means 10 are connected to form a closed control loop for automatically delivering a second laser pulse at the moment when the feedback system has detected that the size of the prior bubble has contracted to a size in a range from about 0.7V.sub.max1 to about 0.1V.sub.max1, preferably in a range from about 0.5V.sub.max1 to about 0.1V.sub.max1, and expediently in a range from about 0.5V.sub.max1 to about 0.2V.sub.max1.

[0067] When the treatment handpiece 7, 7, and its exit component 8 are configured for a non-contact delivery (FIGS. 3a, 3b), the non-contact exit component 8 of the said non-contact handpiece 7 is configured to be positioned above the surface of the liquid 3 reservoir, with the laser energy being directed through air and possible other transparent materials (such as, for example an eye lens in case of ophthalmic applications) into the liquid 3 reservoir. In certain embodiments, a laser source 4 with a highly absorbed wavelength might be used as described above, and the exiting laser beam 5 is substantially focused onto the liquid 3 surface. In the shown non-contact scenario, however, preferably a laser source 4 with a weakly absorbed wavelength is used as described above, and the beam is substantially focused to a point located bellow the liquid surface by means of an appropriate focusing device, e.g. a lens system 20. The weak absorption allows the laser beam 5 to penetrate the liquid 3 until a certain penetration depth where the focal point is located. In the area of the focal point the laser energy concentration is high enough to generate the desired at least one vapor bubble 18, despite the weak absorption. In certain embodiments (FIG. 3a), non-contact treatment handpiece 7, together with a non-contact exit component 8 comprises H02 tip-less handpiece model available from Fotona, d.d. (Slovenia, EU). And in certain embodiments, an exit component 8 consists of an ending of an elongated laser light delivery fiber 19, which is positioned above the surface of a liquid 3 reservoir (FIG. 3b). Of course, a separate exit component 8 as described along with FIG. 2a might be used for the embodiments of FIGS. 2b, 3a and 3b as well. In yet other embodiments, the exit component 8 may represent a focusing optical system consisting of one or more lenses, such as is the case in ocular surgery photo-disruption procedures.

[0068] Moreover, treatment handpiece 7 may comprise any suitable components or elements configured for targeted and/or controllable delivery of laser energy to a liquid 3. Preferably, the laser system 1 comprises a scanner 15 as schematically indicated in FIGS. 2a, 3a, which allows scanning of the exit component 8 cross section with the laser beam 5, as shown in FIGS. 4a, 4b.

[0069] Turning now to FIGS. 4a and 4b, in various embodiments the exit component 8, preferably but not coercively configured for contact delivery, may consist of an exit tip 24 (FIGS. 4a, 4b) or any other optical element, which extends along a longitudinal axis and is made of a material which is transparent to the laser beam. The exit component 8 preferably has a generally circular cross section, which leads to a generally cylindrical shape. However, any other suitable cross section may be chosen. The exit tip 24 may be of a variety of different shapes (e.g., conical, angled, beveled, double-beveled), sizes, designs (e.g., side-firing, forward-firing) and materials (e.g. glass, sapphire, quartz, hollow waveguide, liquid core, quartz silica, germanium oxide). Further, the exit component 8 may comprise mirrors, lenses, and other optical components.

[0070] In one preferred embodiment the exit tip 24 of the exit component 8 has a flat output surface 11 (FIG. 4a). The exit tip 24 of the exit component 8 has a diameter D, while the laser beam 5 has a diameter d. The diameter D of the exit component 8 can be equal to the diameter of the elongated delivery fiber 19 and in particular equal to the diameter d of the laser beam 5. In the embodiment of FIG. 4a, where the exit component 8 is in the form of a larger diameter exit tip 24, the diameter D of the exit component 8 is substantially greater than the diameter d of the laser beam 5. In connection with the a.m. scanner 15 a certain scanning pattern on the flat output surface 11 can be achieved, thereby generating exiting beam portions 12 and as a result vapor bubbles 18 at corresponding locations within the liquid 3 (FIGS. 2a, 3a), as may be desired.

[0071] In another embodiment as shown in FIG. 4b, the exit component 8, again in the form of a larger diameter exit tip 24, has a conically shaped output surface 13 being disposed around the longitudinal axis and having an apex facing away from the incoming beam section, wherein the conically shaped output surface 13 has a half opening angle being adapted to provide partial or preferably total reflection of the incoming beam section into a reflected beam section within the exit component 8 and to provide refraction of the reflected beam section into an exiting beam portion 12 emerging from the exit component 8 through the conically shaped output surface 13 in approximately radial direction relative to the longitudinal axis. In various embodiments, the angle is expediently in the range 60120, and preferably about 90.

[0072] Typically, when fiber tips 23 are used, the laser beam 5 extends substantially across the whole cross section of the fiber tip 23. This will result in a circumferentially spread exiting beam portion 12. In certain embodiments, however, as shown in FIG. 4b, the exit component 8 may have a diameter D substantially larger than the diameter d of the laser beam 5, providing space for the laser beam to be scanned over the exit component's conical output surface 13. In such embodiments, the exit component 8 base is preferably of a cylindrical shape. However, any other suitable 3D shape, such as a cube, cuboid, hexagonal prism or a cone, can be used. Scanning the conical output surface 13 with the incoming laser beam 5 allows for generation of multiple exiting beam portions 12 and corresponding vapor bubbles located circumferentially around the exit component 8. Since more than one laser pulse p, i.e. a synchronized train of pulses p (FIGS. 8a to 11) needs to be delivered to the same spot, one could deliver one pulse p exiting beam portion 12 to a related vapor bubble 18 spot, then move to the next vapor bubble 18 spot on the circumference, and so on, and then return to the same initial vapor bubble 18 spot just in time for the next pulse p within the pulse train. This would enable faster procedures since the laser repetition rate would not be limited by the bubble oscillation period T.sub.B=(t.sub.min1t.sub.01) (FIG. 6) but by the maximum repetition rate of the laser system 1.

[0073] With reference now to FIGS. 4a, 4b, in accordance with various embodiments, when laser energy is delivered into a highly absorbing liquid 3 through an exit component 8 having a flat output surface 11 (FIG. 4a), that is immersed into the liquid 3, the above described vapor bubble 18 turns into a channel-like, extended or elongate vapor bubble 16, as schematically indicated in FIG. 5b. A channel-like bubble formation may be generated also when laser energy is delivered to a tubular cavity. On the other hand, when highly absorbed laser energy is delivered into a liquid 3 through an immersed conical output surface 13, or a flat output surface 11 of sufficient small diameter D compared to the beam diameter d, or when weakly absorbed laser energy is delivered in non-contact mode and focused within the liquid 3 as described above, a generally spherical vapor bubble 18 develops, as schematically indicated in FIG. 5a. It is to be appreciated, however, that in reservoirs with a small containment factor (), the bubble's shape will be influenced more by the reservoir's geometry, and less by the fiber tip's output surface.

[0074] It is also to be appreciated that with shock waves generated according to present invention, conically shaped tips may get more quickly damaged during the violent shock wave emission, and therefore it may be advantageous to use flat surface fiber tips with the present invention.

[0075] Moreover, it is to be appreciated, that when in certain embodiments a weakly absorbed laser beam is delivered to a liquid 3 in a non-contact manner, and the beam's focus is located within the liquid 3, and away from the liquid surface, no bubble gets formed at or near the liquid's surface. Instead, the beam gets transmitted deeper into the liquid, and providing that the pulse duration is sufficiently short (100 ns), and the power density at the focal point within the liquid is sufficiently high, a bubble 18 is generated only when the laser beam 5 reaches its focal point deeper within the liquid 3.

[0076] Turning now to FIG. 6, in various embodiments, the system utilizes an improved scientific understanding of the interaction of pulsed laser light with a highly absorbing liquid 3. When one pulse p of a pulsed laser beam 5 is delivered to such a liquid 3 at an onset time t.sub.01, a bubble oscillation sequence develops. In the 1st phase of the bubble oscillation sequence (from time t.sub.01 to time t.sub.max1), laser energy deposition into the liquid 3 via absorption causes superheating of the liquid 3, and boiling induces a vapor bubble 18. The vapor bubble 18 expands rapidly, and thereafter reaches its maximum size at t.sub.max1, when the internal pressure matches the pressure in the surrounding liquid 3.

[0077] In the 2.sup.nd phase (from time t.sub.max1 to time t.sub.min1), the internal pressure is lower than the pressure in the surrounding liquid 3, and this difference in pressures forces the vapor bubble 18 to collapse.

[0078] When the vapor bubble 18 collapse completes at time t.sub.min1, a rebound occurs thereafter, and the vapor bubble 18 starts to grow again up until time t.sub.max2. This 3.sup.rd phase (from time t.sub.min1 to time t.sub.max2) is followed again by a collapse in the 4.sup.th phase (from time t.sub.max2 to time t.sub.min2). This oscillation process of the vapor bubble 18 continues, decreasing in amplitude and temporal period each time as illustrated in FIG. 6.

[0079] In various embodiments, a temporal bubble oscillation period T.sub.B may be defined as the time between t.sub.01 and t.sub.min1. Temporal bubble oscillation period T.sub.B varies based at least in part on the thermo-mechanical properties of the liquid 3, the shape and volume of the liquid 3 reservoir, the laser beam 5 emission profile, pulse duration, pulse energy, and so forth. Specifically, when the liquid 3 medium is contained in a root canal, e.g. in a body cavity 2 as shown in FIGS. 2a, 2b 3a, 3b, and 5, the bubble's oscillation period T.sub.B is prolonged, the bubble's collapse is slowed down, and no shock wave is emitted.

[0080] The exemplary bubble dynamics shown in FIG. 6 represents a bubble dynamics as measured in a cylindrical model of a root canal. A LightWalker branded laser system available from Fotona, d.o.o., Slovenia was used in the measurement. The liquid 3 within the cavity 2 was water, and the laser source 4 was an Er:YAG laser with the wavelength of 2940 nm which is strongly absorbed in water. The laser pulse duration was about 100 sec and the laser pulse energy was about 20 mJ. The laser beam 5 was delivered from the laser source 4 through the Fotona Optoflex brand articulated arm 14 and the handpiece 7 (Fotona H14) to a water filled model of a root canal cavity 2 through a flat fiber tip 24 (Fotona Varian 400) with its flat surface ending 11 submersed in water to a depth of 3 mm. The fiber tip's diameter was 0.4 mm, and the lateral diameter of the cylindrical model of a root canal was d.sub.r=2 mm. A typical maximal bubble dimension in the lateral direction of the cylindrical root canal model was about d.sub.b=1.5 mm, resulting in an approximate containment factor of =d.sub.r/d.sub.b=1.33. It is to be appreciated that because of this small containment factor, no shock waves were observed when the bubble 18 imploded at t=t.sub.min1.

[0081] For comparison, FIG. 7 shows a measured bubble dynamics (full line) obtained in a large water reservoir, together with a measured bubble dynamics (dotted line) in a confined root canal model as already previously shown in FIG. 6. The same laser parameters and delivery system as described above were used for both liquid reservoir geometries. In the large reservoir, e.g. in a free liquid geometry, bubble oscillations can be accommodated by displacing the liquid at long distances, and therefore the oscillations were faster, with a bubble period T.sub.B being about two times shorter than in the root canal model. More importantly, in the free reservoir, shock wave emission was present during the bubble's collapse.

[0082] In the confined root canal model, a free expansion of the bubble laterally is not possible, and hence the water is pushed forward and backward in the root canal. Since the water obstructs the expansion of the vapor in the forward direction, the bubble grows backwards along the fiber, as can be seen from the insert in FIG. 6 at time t.sub.max1. The pressure inside the bubble remains high for a long time, since it has to fight against the resistance of the water which has to be displaced in the small canal. This process delays the dynamics of expansion and implosion compared to a free water situation. In the root canal, the lateral and forward bubble expansion is limited by the root canal wall, while the backward expansion is blocked by the fiber making the lumen of the canal even smaller. These differences with a free water situation result in a measured approximately two times longer bubble oscillation time T.sub.B in the root canal as compared to a large reservoir. Also, no shock wave emission was detected during single pulse experiments in the confined root canal geometry.

[0083] It is to be appreciated that the bubble implosion begins near the fiber tip where the expansion started, resulting in a separation of the bubble 18 from the fiber, as can be seen from the insert in FIG. 6 at time t.sub.sep. Referring now to FIG. 8a and FIG. 8b, according to present invention, at first a first laser pulse p.sub.a and then a second laser pulse p.sub.b with the same characteristics as the prior laser pulse p.sub.a is delivered into the root canal model at the respective onset times t.sub.0a and t.sub.0b with a pulse repetition time T.sub.p in between such that the second bubble 18 starts to expand at a time when the prior bubble 18 has already contracted to a certain size. This leads to a violent implosion of the prior bubble 18, and consequently to an emission of a shock wave 25 by the prior bubble 18 at the time of its collapse.

[0084] The foregoing oscillation dynamics of vapor bubbles 18 and 18 and associated relation to shock wave emission, facilitate the improved inventive system for and methods of treatment utilizing delivery of laser pulses p, for example treatment of root canals, drilled bone, and/or the like anatomical cavities 2 preferably with containment ratios <3, and even more preferably with containment factors <2. Moreover, and referring now to FIGS. 8a, 8b, in various embodiments, shock wave emission can be facilitated or enhanced in confined geometries preferably with containment ratios <3, and even more preferably with containment factors <2, and/or in highly viscous liquids by delivering a minimum of two laser pulses p.sub.a, p.sub.b in a sequence whereas the pulse repetition time T.sub.p between the two pulses p in a sequence is such that the subsequent bubble 18 resulting from a subsequent pulse p.sub.b starts substantially expanding at a time when the prior bubble 18 resulting from a preceding laser pulse p.sub.a has contracted during the 2.sup.nd phase (from time t.sub.max1 to time t.sub.min1) to a certain below defined size. It is to be appreciated that illustrations in FIGS. 8a, 8b are made only for the purposes of describing the invention, and do not necessarily depict amplitudes and shapes of laser pulses, bubble volumes or shock waves, as would be observed in actual embodiments of the invention.

[0085] It is to be appreciated that without the below described inventive double pulse set, no shock wave is emitted in confined liquid geometries, as shown in FIGS. 6 and 7. On the other hand, FIG. 8b shows the inventive laser pulse sequence with pulse durations t.sub.p and inventive pulse repetition time T.sub.p, and the resulting dynamics of the resulting vapor bubbles and shock wave emissions. Individual pulses p.sub.a and p.sub.b within one sequence follow each other by a pulse repetition time T.sub.p. The first pulse p.sub.a starts at an onset time t.sub.0a and generates, starting at the same onset time t.sub.0a, a first vapor bubble 18. The size or volume V of the vapor bubble 18 oscillates in an expansion phase from a minimal volume at the first t.sub.0a to a maximal volume V.sub.max-a at a maximum volume time t.sub.max1-a, and in a subsequent contraction phase from a maximal volume V.sub.max-a at the maximal volume time t.sub.max1-a to a minimal volume at a minimum volume time t.sub.min1-a. When within the inventive pulse sequence the pulse repetition time T.sub.P is adjusted to match T.sub.p-opt, in other words adjusted such that an onset time t.sub.0b of the subsequent laser pulse p.sub.b is delivered at about the time when the first vapor bubble 18 formed by the prior laser pulse p.sub.a has collapsed within ist first contraction phase to a size in a range from about 0.7V.sub.max-a to about 0.1V.sub.max-a, preferably in a range from about 0.5V.sub.max-a to about 0.1V.sub.max-a, expediently in a range from about 0.5V.sub.max-a to about 0.2V.sub.max-a, and according to FIG. 8b of 0.5V.sub.max-a as a preferred example, two effects happen in parallel: As a first effect the first bubble 18 has separated from the exit component 8 and moved away downwards (FIG. 8a), in consequence of whichalthough the exit component 8 has not movedthe second pulse p.sub.b is introduced at a location different to the location where the first vapor bubble 18 is now present at the time of introducing the second laser pulse p.sub.a, thereby generating the second vapor bubble 18 within the liquid 3. As a second effect the liquid pressure exerted on the collapsing prior bubble 18 by the expanding subsequent bubble 18, i.e., the bubble resulting from the subsequent laser pulse p.sub.b, forces the prior bubble 18 to collapse faster, thus enabling or enhancing the emission of a shock wave 25 by the prior bubble 18, as indicated in FIG. 8a. The inventive pulse repetition time T.sub.p ensures that when the subsequent bubble starts substantially expanding i) the prior bubble is already in the fast collapse phase, and is therefore sensitive to the sudden additional pressure caused by the expanding subsequent bubble; and ii) in embodiments with a contact delivery of the laser energy into a liquid, the prior bubble has already substantially separated and moved away from the exit component 8, and therefore the laser energy of the subsequent laser pulse does not get absorbed within the prior bubble. However, in any case where the created vapor bubbles 18, 18 have no sufficient tendency to separate from the exit component or to otherwise change their location, and also in embodiments with a non-contact delivery, the exit component 8 or laser focal point may be spatially moved in between the pulses, for example by a scanner, in order to avoid the laser energy of the subsequent laser pulse p.sub.b to be absorbed within the prior bubble 18.

[0086] It is to be appreciated that the invention is not limited to the emission of only two subsequent pulses within a pulse set. A third pulse following a second laser pulse, and fulfilling both conditions, may be delivered resulting in an emission of a shock wave by the previous (second) bubble. Similarly, an n.sup.th subsequent laser pulse will result in an emission of a shock wave by the (n1).sup.th bubble, and so on as further laser pulses are being added to the set of pulses. More laser pulses are delivered in one pulse set higher is the laser-to-shock wave energy conversion, with the energy conversion efficiency being proportional to the ratio (n1)/n where n is the total number of laser pulses delivered in one pulse set 21 (FIG. 10).

[0087] FIG. 9 shows in a schematic diagram the temporal course of the pulse sets 21 according to the invention. In this connection, the course of the amplitude of the pulse sets 21 is illustrated as a function of time. The pulse sets 21 follow one another along one single optical path within the laser system 1 with a temporal pulse set spacing T.sub.S being the temporal difference between the end of one pulse set 21 and the beginning of the next pulse set 21. The temporal pulse set spacing T.sub.S is expediently 10 msT.sub.S500 ms, advantageously 10 msT.sub.S100 ms, and is in the illustrated embodiment of the inventive method approximately 10 ms. The lower temporal limit for temporal set spacing T.sub.S of 10 ms is set in order to allow sufficient time for the laser active material, such as, for example, a flash-lamp pumped laser rod, to cool off during the time between subsequent pulse sets 21. The individual pulse sets 21 have a temporal set length t.sub.S of, for example, approximately 2 ms. Depending on the number of individual pulses p provided infra the value of the temporal set length t.sub.S can vary. The maximal number of pulse sets 21, and correspondingly the maximal number of individual pulses p, that may be delivered during a treatment is limited at least by the maximal delivered cumulative energy below which the temperature increase of the liquid 3 does not exceed an allowed limit.

[0088] FIG. 10 shows an enlarged detail illustration of the diagram according to FIG. 9 in the area of an individual pulse set 21. Each pulse set 21 has expediently at least two and maximally 20 individual pulses p, advantageously two to eight individual pulses p, and preferably two to four individual pulses p, and in the illustrated embodiment according to FIG. 10 there are six individual pulses p. Maintaining the aforementioned upper limit of the number of individual pulses p per pulse set 21 avoids overheating of the laser active material. The individual pulses p have a temporal pulse duration t.sub.p and follow one another along one single optical path within the laser system in a pulse repetition time T.sub.P, the pulse repetition time T.sub.P being the time period from the beginning of one single pulse p to the beginning of the next, subsequent pulse p.

[0089] The pulse duration t.sub.p is for weakly absorbed wavelengths in the range of 1 ns and <85 ns, and preferably 1 ns and 25 ns. The lower temporal limit of the pulse duration t.sub.p for weakly absorbed wavelengths ensures that there are no shock waves created in the liquid 3 during the vapor bubble 18 expansion. And the upper pulse duration t.sub.p limit for weakly absorbed wavelengths ensures that the laser pulse power is sufficiently high to generate optical breakdown in the liquid.

[0090] For highly absorbed wavelengths, the pulse duration t.sub.p is in the range of 1 s and <500 s, and preferably of 10 s and <100 s. The lower temporal limit for highly absorbed wavelengths ensures that there is sufficient pulse energy available from a free-running laser. And the upper pulse duration limit for highly absorbed wavelengths ensures that the generated heat does not spread via diffusion too far away from the vapor bubble, thus reducing the laser-to-bubble energy conversion efficiency. Even more importantly, the upper pulse duration limit ensures that laser pulses are shorter than the vapor bubble rise time, t.sub.max1-t.sub.01, in order not to interfere with the bubble temporal oscillation dynamics. In FIG. 10, the amplitude of the laser beam or of its individual pulses p is schematically plotted as a function of time wherein the temporal course of the individual pulses p, for ease of illustration, are shown as rectangular pulses. In practice, the pulse course deviates from the schematically shown rectangular shape of FIG. 10.

[0091] In order to facilitate improved adjustability and/or control, in various embodiments the laser system 1 is configured with a laser source 4 having a variable pulse rate, variable pulse set rate, and/or variable temporal pulse set length t.sub.S of the pulse set 21. In this manner, the shock wave emission may be optimized for a particular anatomical cavity 2 dimensions and shape, and also for a particular placement of the fiber tip or positioning of the laser focus in the different locations relative to the cavity. Namely, the placement of the fiber tip or positioning of the laser focus relative to the cavity may affect the properties of the bubble oscillations and shock wave emission. In one of the embodiments, a centering system may be used to center the fiber tip relative to the walls of the cavity, or to center the fiber tip near the entrance, or bottom of the cavity, or near an occlusion within the cavity.

[0092] The pulse repetition time T.sub.P is, according to the invention, in the range between approximately 75% T.sub.B and approximately 90% T.sub.B. The bubble oscillation period T.sub.B may vary from about 100 s to about 1000 s, based at least in part on the thermo-mechanical properties of the liquid 3, the shape and volume of the liquid reservoir, the laser wavelength, beam emission profile, configuration of the treatment head, and so forth. Accordingly, when the pulse repetition time T.sub.P will be adjusted to approximately match T.sub.p-opt, the pulse repetition rate F.sub.P, will be in the range from about 1.1 kHz to about 13.3 kHz.

[0093] The laser pulse energy E.sub.L, according to the invention, may be fixed for all pulses within a pulse set 21. In certain embodiments, however, the energy of the subsequent the pulse energy may be adjustable to automatically gradually decrease, for example linearly or exponentially, from pulse p to pulse p within each set 21. This approach may be especially advantageous for pulse sets with a pulse number of n=2, where the energy E.sub.L of the second pulse p.sub.b may be lower than that of the first pulse p.sub.a, since the function of the second bubble 18 is only to create an additional pressure on the collapsing bubble 18 during the initial expansion phase of the bubble 18.

[0094] Alternatively, the laser pulse energy E.sub.L may be adjustable to gradually increase from pulse to pulse p within a pulse set 21, in order to increase even further the pressure of the subsequent bubbles on the prior bubbles.

[0095] In one of the embodiments of our invention, the laser system comprises a feedback system 9 to determine a bubble oscillation dimension or amplitude of the prior vapor bubble generated within the liquid. Furthermore, the laser system comprises adjusting means for adjusting the pulse repetition time T.sub.p to achieve at least approximately that the subsequent bubble 18, i.e., the bubble 18 generated by the subsequent laser pulse p.sub.b, starts to expand when the volume of the prior bubble 18 has already contracted to the desired size as described above. The feedback system 9 preferably comprises an acoustical, a pressure, or an optical measurement sensor for sensing the bubble size V. As a result of the bubble oscillation sensing, the laser pulse repetition time T.sub.p might be manually adjusted by the user to be approximately equal to T.sub.p-opt. However, in a preferred embodiment, the feedback system and the adjusting means are connected to form a closed control loop for automatically delivering a subsequent laser pulse at the moment when the feedback system has detected that the size of the prior bubble has contracted to the required size, that is at an adjusted pulse repetition time T.sub.P=T.sub.p-opt (FIG. 8b). In either case of manual or closed loop control adjustment the number of pulses p within one sequence is not limited to one first and one second pulse p.sub.a, p.sub.b. It may also be advantageous, that multiple pulses p.sub.0 to p.sub.n, p.sub.n+1 of FIG. 10 within one pulse sequence 21 may follow one another at a certain adjusted pulse repetition time T.sub.P=T.sub.p-opt, as exemplarily shown in the left portion of FIG. 8b between two adjusted pulses p.sub.a, p.sub.b. In such case, every individual pulse p.sub.0 to p.sub.n serves as a first pulse p.sub.a of FIG. 8, while every individual pulse p.sub.1 to p.sub.n+1 serves as a second pulse p.sub.b of FIG. 8 for augmenting the shock wave generation with the first bubble 18 related to the preceding first pulse p.sub.a.

[0096] In yet another embodiment, and in order to facilitate automatic adjustability of the pulse repetition time T.sub.p to any geometric confinement conditions or liquid thermo-mechanical characteristics without the need for a feedback, the laser system 1 is configured with a laser source 4 having an automatically variable, sweeping pulse generation. In this manner, the shock wave emission may be automatically optimized for a particular anatomical cavity 2 dimensions and shape. The general idea of the inventive sweeping technique is to generate multiple pairs of first and second bubbles 18, 18 without the aid of feedback such, that the time difference between the onset time t.sub.0b of the second vapor bubble 18 and the onset time t.sub.0a of the first vapor bubble 18 (FIG. 8b) is repeatedly varied in a sweeping manner. By varying said time difference it is made sure, that at least one pair of bubbles 18, 18 matches the required timing, as with the first and second bubbles 18, 18 of FIG. 8b, and thus emitting at least one shock wave 25 (FIG. 8a) during each sweeping cycle. By repeatedly performing such sweeping cycles, the generation of shock waves 25 may be repeated to an extent until the desired irrigation goal is achieved.

[0097] Referring now to FIG. 10, a first inventive shock wave emission enhancing pulse (SWEEP) set 21 is proposed, wherein the pulse repetition time T.sub.P is varied or swept in discreet positive or negative steps , preferably across a range from 75 sec to 900 sec (or from 900 sec to 75 sec in the case of a negative ), even more preferably across a range from 300 sec to 600 sec (or from 600 sec to 300 sec in the case of a negative ), and expediently across a range from 350 sec to 550 sec (or from 550 sec to 350 sec in the case of a negative ). By using this inventive pulse repetition sweeping technique, it is ensured that at least one pair of pulses p within the number of multiple pulses p.sub.0 to p.sub.n, p.sub.n+1 of FIG. 10 matches the required pulse repetition rate, thereby resembling the first and second pulses p.sub.a, p.sub.b of FIG. 8b with the required adjusted and optimal pulse repetition time T.sub.P=T.sub.p-opt in between, and thus generating at least one fitting pair of bubbles 18, 18 (FIG. 8b) for emitting at least one shock wave during each sweeping cycle.

[0098] The pulse repetition time T.sub.P may be swept within each pulse set 21 as exemplarily shown in FIG. 10 where the pulse repetition time T.sub.p is discretely swept from pulse p.sub.0 to pulse p.sub.n+1 by changing the pulse repetition time T.sub.p from pulse to pulse by an additional discreet temporal step , while multiple pulse sets 21 of such or similar kind may follow one another. In the illustrated embodiment of the inventive method, pulse sets 21 consisting of six pulses p.sub.0 to p.sub.n+1 are shown, but pulse sets 21 with a larger or smaller number of pulses p may be used as well.

[0099] Alternatively, as a second preferred sweeping pattern, a number of m pulse sets 21 may be applied, wherein the pulse repetition time T.sub.P may be varied or swept from pulse set 21 to pulse set 21 as exemplarily shown in FIG. 11: The pulse repetition time T.sub.p is discretely swept from pulse set 21 to pulse set 21 by starting at an initial repetition time T.sub.p0, and then changing the pulse repetition time T.sub.p from pulse set 21 to pulse set 21, by a discreet temporal step to a final repetition time T.sub.pm. The sweeping cycle may be re-started each time the whole sweeping range has been covered. In the embodiment of the inventive method illustrated in FIG. 11, pulse sets consisting of two pulses p.sub.0, p.sub.1 are shown, but pulse sets with a larger number of pulses p may be used as well. In any case the same effect as with the sweeping pattern of FIG. 10 can be achieved: At least one pair of pulses p.sub.0, p.sub.1 within the number of m pulse sequences 21 of FIG. 11 matches the required pulse repetition rate, thereby resembling the first and second pulses p.sub.a, p.sub.b of FIG. 8b with the required adjusted and optimal pulse repetition time T.sub.P=T.sub.p-opt in between, and thus emitting at least one shock wave during each sweeping cycle.

[0100] A further preferred, third sweeping pattern is schematically depicted in FIG. 12: One pulse set 21 contains multiple pairs of two pulses p.sub.0, p.sub.1, wherein a subsequent pulse p.sub.2 of each pair follows a corresponding initial pulse p.sub.1, and wherein the pulse repetition times T.sub.p within all pairs is kept constant. However, from pair of pulses p.sub.0, p.sub.1 to pair of pulses p.sub.0, p.sub.1 the pulse energy of each second pulse p.sub.1 is varied in a sweeping manner. In the shown example the pulse energy is increased from pair to pair by a certain delta. On the other hand, an energy decrease may be applied as well. Such pulse energy sweeping is based on the finding, that the lower the second pulsed p.sub.1 energy is, the longer it will take the second bubble 18 (FIG. 8a, 8b) to develop appreciably to influence the first bubble's 18 collapse, and vice versa. This way it can again be achieved, that at least one pair of bubbles 18, 18 matches the required timing, as with the first and second bubbles 18, 18 of FIG. 8b, and thus emitting at least one shock wave 25 (FIG. 8a) during each sweeping cycle. Alternatively, the pulse energy of each second pulse p.sub.1 may be varied in a sweeping manner from one pulse set 21 to the next pulse set 21.

[0101] A combined SWEEP method may be used as well, where the pulse repetition time T.sub.P is swept within pulse sets 21 from one pulse p to another, and also from pulse set 21 to pulse set 21. Furthermore, the sweeping pulse energy of FIG. 12 may be combined with the sweeping pulse repetition times T.sub.P of FIG. 10 and/or of FIG. 11.

[0102] In yet another embodiment, either with a sweeping pulse repetition time T.sub.P or not, the electromagnetic radiation system may be adjusted to generate and deliver multiple pairs of two pulses p.sub.0, p.sub.1, and wherein from pair of pulses p.sub.0, p.sub.1 to pair of pulses p.sub.0, p.sub.1 the pulse energy of each second pulse p.sub.1 is reduced in comparison to the pulse energy of each first pulse p.sub.0, preferably to a pulse energy which is just sufficiently high to trigger an emission of a shock wave by the bubble generated by a first pulse p.sub.0, but not much higher. In this manner, the energy of a second pulse p.sub.1 remaining to be delivered by a second pulse p.sub.1 after a shock wave by a first pulse p.sub.0 has already been emitted, is not wasted for, for example, unnecessary heating of the cavity. The ratio of the pulse energy of the second pulse p.sub.1 to the pulse energy of the first pulse p.sub.0, may be in a range from 0.8 to 0.1, preferably in a range from 0.6 to 0.1, and expediently in a range from 0.5 to 0.2.

[0103] And in yet another embodiment, either with a sweeping pulse repetition time T.sub.P or not, the electromagnetic radiation system may be adjusted to generate and deliver multiple pairs of two pulses p.sub.0, p.sub.1, and wherein from pair of pulses p.sub.0, p.sub.1 to pair of pulses p.sub.0, p.sub.1 the pulse duration of each second pulse p.sub.1 is shorter in comparison to the pulse duration of each first pulse p.sub.0. For example, the pulse duration of each first pulse may be in a microseconds duration range, and the pulse duration of each second pulse may be in a nanoseconds duration range. In this manner, an emission of a shock wave by a bubble generated by a first pulse p.sub.1 shall occur faster and more readily. Alternatively, the pulse duration of each second pulse p.sub.1 may be longer in comparison to the pulse duration of each first pulse p.sub.0, in order to make the exact timing of the pulses (in terms of the pulse repetition time T.sub.p) less critical.

[0104] In summary and opposite to the prior art pulse sequence and vapor bubble formation, when the inventive synchronization is applied, the bubble's shock wave emission following each prior laser pulse is enhanced by the bubble's energy from the subsequent pulse. As a result, the cleaning efficacy of liquid filled cavities is substantially improved.

[0105] One of the methods that is claimed is a method for irrigation, including debriding, cleaning and decontamination, of a dental root canal (2) filled with liquid (3), such as water or another irrigant, comprising of the following steps: [0106] providing a laser system (1) comprising a laser source (4) for generating a laser beam (5), an optical delivery system (6), a treatment handpiece (7) including an exit component (8), and adjusting means (10), wherein the treatment handpiece (7) and its exit component (8) are configured to irrigate the anatomical cavity (2) in a contact manner, wherein a wavelength of the laser beam (5) is in a range from above 1.3 m to 11.0 m inclusive, wherein the laser system is adapted to be operated in pulsed operation with pulse sets (21) containing at least two and maximally twenty individual pulses (p) of a temporally limited pulse duration (t.sub.p), wherein the repetition time (t.sub.s) between the pulse sets is 10 ms, and wherein the individual pulses (p) follow one another with a fixed pulse repetition time (T.sub.p) within a range of 200 s, inclusive, to 450 s, inclusive; [0107] applying said pulsed laser beam (5) to the liquid (3) disposed within the anatomical cavity (2) to form at least one prior vapor bubble (18) and a at least one subsequent vapor bubble (18) in the liquid (3), in order to achieve at least one shock wave emitted by a prior vapor bubble (18). [0108] performing the treatment until desired cleaning, including debriding, irrigation and decontamination, is achieved.

[0109] In one of the embodiments, the treatment of an anatomical cavity may be performed until desired cleaning, including debriding, irrigation and decontamination, is achieved or until the average liquid's temperature rise within the anatomical cavity exceeds 3.5 degrees Celsius, whichever occurs first.

[0110] Alternatively, a SWEEP configuration may be used instead of a fixed pulse repetition time (T.sub.p).

[0111] Several irrigants for the endodontic treatment are available, and include sodium hypochlorite (NaOCl), chlorhexidine gluconate, alcohol, hydrogen peroxide and ethylenediaminetetraacetic acid (EDTA). However, in one of the preferred embodiments only water may be used instead of a potentially toxic irrigant since the generation of shock waves according to our invention reduces or eliminates the need for the use of chemicals.

[0112] Preferably, the laser source 4 is an Er:YAG laser source having a wavelength of 2940 nm, wherein laser pulse energy is in a range from 1 mJ to 40 mJ, wherein the exit component 8 is cylindrical, having a diameter D between 200 m and 1000 m, wherein the conical output surface 13 has a conical half angle being in the range from 16 to 38, preferably from 34 to 38, wherein the temporal separation T.sub.S between pulse sets 21 is <0.5 s, and wherein the cumulative delivered energy during a treatment is below 150 J.

[0113] Expediently, the laser system 1 is configured to generate coherent light having a wavelength highly absorbed in OH-containing liquids, by means of one of an Er:YAG laser source having a wavelength of 2940 nm, an Er:YSGG laser source having a wavelength of 2790 nm, an Er,Cr:YSGG laser source having a wavelength of 2780 nm or 2790 nm, and a CO.sub.2 laser source having a wavelength of about 9300 to about 10600 nm, and wherein laser pulse energy is in a range from 1 mJ to 1000 mJ, preferably in a range from 1 mJ to 100 mJ.

[0114] It will be appreciated that, while the foregoing example methods are directed to treatment of root canals and/or bone cavities, in accordance with principles of the present disclosure, similar methods and/or systems may be utilized to treat other body tissues, for example periodontal pockets, and/or the like. The method may be also used to irrigate, debride and clean selected small surfaces of electronic and precision mechanical components during manufacturing, maintenance and servicing, especially when it is not desirable or possible to expose the whole electronic or other component to a standard cleaning or irrigation procedure.

[0115] While the principles of this disclosure have been shown in various embodiments, many modifications of structure, arrangements, proportions, the elements, materials and components, used in practice, which are particularly adapted for a specific environment and operating requirements may be used without departing from the principles and scope of this disclosure. These and other changes or modifications are intended to be included within the scope of the present disclosure and may be expressed in the following claims.

[0116] The present disclosure has been described with reference to various embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present disclosure. Accordingly, the specification is to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present disclosure. Likewise, benefits, other advantages, and solutions to problems have been described above with regard to various embodiments. However, benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element of any or all the claims. Systems, methods and computer program products are provided. In the detailed description herein, references to various embodiments, one embodiment, an embodiment, an example embodiment, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.

[0117] As used herein, the terms comprises, comprising, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Also, as used herein, the terms coupled, coupling, or any other variation thereof, are intended to cover a physical connection, an electrical connection, a magnetic connection, an optical connection, a communicative connection, a functional connection, and/or any other connection. When language similar to at least one of A, B, or C is used in the claims, the phrase is intended to mean any of the following: (1) at least one of A; (2) at least one of B; (3) at least one of C; (4) at least one of A and at least one of B; (5) at least one of B and at least one of C; (6) at least one of A and at least one of C; or (7) at least one of A, at least one of B, and at least one of C.