A pulsed laser ablation system

Abstract

The present invention discloses a pulse laser ablation system, comprising a first light source, a first light path homogenization system, an ablation catheter and an OCT imaging system, wherein the first light source is used to generate an initial light beam; the light path homogenization system is used to homogenize and shape the initial light beam into a light beam with uniform energy distribution; the beam combining and focusing system is used to combine the homogenized light beam of the light path homogenization system, and focus and couple it to the ablation catheter; the ablation catheter and the OCT imaging system cooperate to treat pathology; the femtosecond has the narrowest pulse width of all types of lasers, and its peak power is the highest under the same single pulse energy. The ultrashort pulse it generates has an extremely short action time with the material, and will not cause thermal effects on the surrounding materials, and has better processing effect and processing efficiency; an optical coherence tomography probe is added to monitor the laser ablation process in real time, and the real-time feedback signal of the lesion can also provide a basis for parameter setting for further treatment.

Description

Technical Field

[0001] The invention relates to a pulse laser ablation system and belongs to the field of photoelectric medical treatment. Background Art

[0002] With the aging of the population and the increasing number of unhealthy lifestyles such as obesity, hypertension / hyperlipidemia, smoking and drinking, and the diseases that affect health caused by them, the incidence and scope of intravascular diseases (PAD, CAD) are also increasing. Among them, intravascular calcification, CTO, ISR and other diseases are still difficult to treat. These lesions are relatively hard, and traditional balloon dilatation is limited, while mechanical atherectomy has the risk of vascular perforation or dissection. If these diseases cannot be treated in time or the treatment methods are inappropriate, it is easy to cause blood circulation problems, which will lead to life-threatening.

[0003] Ultraviolet laser ablation is based on intravascular laser plaque ablation technology. It uses a fiber bundle catheter to transmit ultraviolet high-energy laser to the lesion site in the vascular cavity, so that it acts on the stenosis / blockage and other affected areas. It uses photochemical, photothermal and photomechanical effects to pulverize the plaque into micron-sized particles, thereby achieving the effect of reducing volume and expanding the lumen.

[0004] For common ultraviolet lasers, the wavelength is short and the single photon energy is high. In industrial applications, it is often called cold laser, which means that the thermal effect of the reaction with the material is not obvious, and the thermal damage caused is also low. For 308nm excimer laser, it has a single photon energy of 4eV, which can directly radiate to break the molecular bonds of the patient's plaque and decompose it. This process is photochemical action, but the laser pulse width is generally in the order of hundreds of nanoseconds, and the thermal relaxation time is long, which increases the thermal effect;

[0005] 355nmND: YAG third harmonic solid laser, single photon energy is 3.5eV, its lower single photon energy is usually considered unsuitable as a band for plaque ablation, but the solid laser pulse width is narrower than that of the excimer laser, only on the order of 10ns, so the peak power is higher. Compared with the 308 excimer laser, the thermal effect is also not significant under the condition of one increasing while the other decreasing, but the kinetic energy of the bubbles that explode forward in the liquid is higher, that is, the proportion of photomechanical effect increases.

[0006] Intravascular OCT (optical coherence tomography) is a high-resolution intravascular or cavity imaging method with a resolution of about 10-20 microns and a penetration depth of about 1-2 mm. It can perform high-resolution real-time imaging of blood vessels or cavities. Summary of the invention

[0007] In view of the deficiencies in the prior art, the present invention provides a pulse laser ablation system with shorter pulse time, lower thermal impact, and higher treatment effect and efficiency.

[0008] The present invention is achieved through the following technical solutions: a pulsed laser ablation system, including a first light source, a first light path homogenization system, an ablation catheter and an OCT imaging system, wherein the first light source is used to generate an initial light beam; the light path homogenization system is used to homogenize and shape the initial light beam into a light beam with uniform energy distribution; the beam combining and focusing system is used to combine the homogenized light beam of the light path homogenization system and focus and couple it to the ablation catheter; the ablation catheter and the OCT imaging system cooperate to treat pathology.

[0009] Furthermore, the first light source is a femtosecond laser device, which has a wavelength of 1030nm, a single pulse energy of not less than 300μJ, a pulse width of <600fs, a repetition frequency of 100kHz (typical), a near-field spot of approximately 3mm, and a beam quality factor M² of not higher than 1.5.

[0010] Furthermore, it also includes a beam expansion system, which is arranged between the first light source and the light path homogenization system; the light path homogenization system includes a flat-top beam shaper, the diffraction efficiency of the flat-top beam shaper is greater than 90%, and an anti-reflection film is coated for 1030nm and nearby bands.

[0011] Furthermore, a 45° reflector is arranged between the first light source and the light path homogenization system, and the 45° reflector is made of ultraviolet fused quartz.

[0012] Furthermore, the beam expansion system includes a first lens and a second lens, the first lens is a convex lens or a concave lens, and the second lens is a convex lens.

[0013] Further, the beam combining and focusing system includes a first beam combining mirror, and the coating parameters are S1: T>99%@1030nm, 45°AOI; S2: T>99%@1030nm, R>99%@1310nm, 45°AOI;

[0014] Furthermore, it also includes a second light source, a second light path homogenization system, and a second beam combining mirror, and the light beam is transmitted to the first beam combining mirror via the second beam combining mirror.

[0015] Furthermore, the second light source is a 355nm ultraviolet laser, and the coating parameters of the second beam combiner are: S1: R>99%@355nm, 45°AOI; S2: R>99%@355nm, T>99%@1310nm, 45°AOI; the coating parameters of the first beam combiner are: S1: T>99%@1030nm, 45°AOI; S2: T>99%@1030nm, R>99%@1310nm&355nm, 45°AOI.

[0016] Furthermore, the ablation catheter includes a proximal incident end and a distal treatment end, and the distal end is sleeved with a developing ring; the ablation catheter includes an outer tube and an inner tube, and an optical fiber bundle cavity is arranged between the outer tube and the inner tube; the inner tube includes a suction cavity, a guide wire cavity, and an OCT probe cavity.

[0017] Furthermore, the OCT probe has two cavities, and the guide wire cavity and the suction cavity are respectively connected to the outside through Luer connectors.

[0018] The beneficial effects of the present invention are:

[0019] Ultrafast lasers (picosecond / femtosecond level) have a narrower pulse width than the above lasers, that is, picoseconds (ps) is 10 - 12 s, femtosecond (fs) is 10 -15 s, compared with these two, nanoseconds (ns) are only 10 -9 s, femtosecond has the narrowest pulse width among all types of lasers. Under the same single pulse energy, its peak power is the highest (single pulse energy = peak power * pulse width). The ultra-short pulse it generates has a very short interaction time with the material and will not cause thermal effects on the surrounding materials. In the field of industrial precision, ultrafast lasers have better processing effects and efficiency than traditional lasers.

[0020] The proposal of the solution of the present invention fills the gap in the application of femtosecond laser pulses in cardiovascular diseases;

[0021] The combination of these two types of lasers, the higher single-photon energy in the ultraviolet band and the higher peak power of ultrafast lasers, can achieve the optimal combination of photochemical and photomechanical effects, which is more conducive to ablation therapy; adding an optical coherence tomography (OCT) probe to monitor the laser ablation process in real time to avoid the laser hitting non-lesion locations. At the same time, the real-time feedback of the lesion signal can also provide a basis for parameter setting for further treatment;

[0022] The 355nm ND:YAG solid third harmonic laser solution in this technical solution is represented by the Auryon series of products under AngioDynamics. The pulse width is shorter than that of the excimer laser (10~25ns), so it has a higher peak power under the same pulse energy, which is more conducive to the ablation process; in addition, this technical solution has a lower cost, a smaller volume and a lighter weight. At the same time, the laser in this band does not show strong performance in contrast agents, which allows real-time visualization of the treatment process;

[0023] The two are used together, and the outgoing laser homogenizes / shapes the initial Gaussian light into homogenized light with uniform spatial intensity distribution through the homogenized coupling optical path. Compared with the initial laser, the homogenized light can allow higher energy to pass through the ablation catheter without damaging the fiber bundle end face of the catheter. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the structure of the pulsed laser ablation system according to Embodiment 1 of the present invention;

[0025] Figure 2 Schematic diagram of the structure of the laser beam combiner;

[0026] Figure 3 It is a schematic plan view of the ablation catheter of the present invention;

[0027] Figure 4 It is a schematic diagram of the cross-sectional structure of the distal end of the ablation catheter of the present invention;

[0028] Figure 5 It is a schematic diagram of the cross-section structure of the ablation catheter of the present invention in working state;

[0029] Figure 6 For the present invention Figure 3 Schematic diagram of the detailed structure of the ablation catheter;

[0030] Figure 7 It is a schematic diagram of the end surface structure of the optical fiber bundle in the ablation catheter of the present invention;

[0031] Figure 8 This is a schematic diagram of the structure of a pulsed laser ablation system according to Embodiment 2 of the present invention;

[0032] Fig. 9 It is a schematic diagram of the structure of the ultraviolet laser and femtosecond laser two-in-one ablation system of the present invention;

[0033] Fig.10 Schematic diagram of the principle and effect of light beam homogenization in Embodiment 1 of the present invention;

[0034] Among them: 1, femtosecond laser equipment; 2, beam expansion system; 3, first light path homogenization system; 4, first beam combiner; 5, first focusing lens; 6, ablation catheter; 7, OCT imaging system; 8, 45° reflector; 9, catheter connector; 10, Luer connector; 11, developing ring; 12, outer tube; 13, guide wire cavity; 14, suction cavity; 15, OCT probe cavity; 16, multi-cavity tube; 17, fiber bundle cavity; 18, 355nm laser equipment; 19, 45° reflector; 20, second light path homogenization system; 21, second beam combiner; 22, second focusing lens; 23, fixed base; 24, fiber bundle end face; 25, rectangular groove. DETAILED DESCRIPTION

[0035] In order to more clearly illustrate the technical solution of the present application, the technical solution of the present invention is further elaborated in detail through embodiments below.

[0036] The pulse laser ablation system of the present invention includes a light source, an optical path homogenization system, an ablation catheter, and an OCT imaging system; the light source can be a single light source or a two-in-one light beam formed by two different light sources. The following lists embodiments of different schemes for illustration.

[0037] Example 1

[0038] like Figure 1 As shown, the pulse laser ablation system in this embodiment includes a first light source, a beam expansion system 2, a first light path homogenization system 3, a first beam combiner 4, a first focusing lens 5, an ablation catheter 6, and an OCT imaging system 7; wherein the first light source is a femtosecond laser device 1, the parameters of which are a wavelength of 1030nm, a single pulse energy of not less than 300μJ, a repetition frequency of 100kHz (typical), a near-field spot of about 3mm, and a beam quality factor M² not higher than 1.5;

[0039] The double 45° reflector 8 is used for laser leveling output. It can be omitted if the coupling optical path is simplified. If this part is discarded, the position of the light spot at the light outlet and at least 1.5 meters away from the light outlet during the laser adjustment phase is required to be consistent. Furthermore, the 45° reflector is made of ultraviolet fused quartz. In order to reduce transmission loss, the lens should be coated with anti-reflection film on both sides: HR>99.5%@1030nm, 45°AOI;

[0040] Beam expansion system 2: Femtosecond laser has a small spot size and a high energy density. It needs to be expanded to increase the spot area and reduce its energy density to avoid damage to optical components due to excessive energy density. Beam expansion systems are divided into Keplerian and Galilean types. Figure 1 The figure shows a Kepler beam expansion system. Both lenses 1 and 2 are convex lenses and the focal length of lens 2 is greater than that of lens 1. If the Galilean type is used, lens 1 is a concave lens and lens 2 is a convex lens. Regardless of the scheme, the laser beam can be expanded. To increase the transmittance of the beam, the two lenses can be coated with an anti-reflection film for the band including 1030nm.

[0041] The first optical path homogenization system 3, in this example, is a flat-top beam shaper in a diffractive optical device (DOE), which is used to homogenize the Gaussian distributed spatial light into a rectangular light spot with a flat-top distribution. However, compared with the traditional microlens array, the flat-top beam shaper is more suitable for the single-mode laser type in this scenario. The diffraction efficiency of the device is required to be greater than 90%, and an anti-reflection film is applied for 1030nm and nearby bands to improve its transmission efficiency; Fig.10 As shown, a schematic diagram of the principle and effect of beam homogenization.

[0042] The first beam combiner, such as Figure 2As shown, the coating parameters are: S1: T>99%@1030nm, 45°AOI; S2: T>99%@1030nm, R>99%@1310nm, 45°AOI;

[0043] The first focusing lens is a plano-convex lens or an achromatic aspheric lens. To improve transmission efficiency, an anti-reflection film can be applied to the OCT light source bands including the 1030nm band and the 1310nm band.

[0044] Ablation catheter 6, such as Figure 3 As shown in the figure, the ablation catheter is divided into a proximal end (coupling end) and a distal end (treatment end). The proximal end is the incident end of the homogenized laser, and the distal end is the treatment end that enters the blood vessel for ablation. The arrangement of the optical fiber bundle at the incident end is determined according to the shape of the homogenized light spot, which is generally square. The optical fiber of the optical fiber bundle is a high-hydroxyl optical fiber with a core diameter of 100μm or less and a polyimide coating. The catheter as a whole and the proximal and distal ends are shown in the figure below. Figure 3 As shown, the developing ring 11 is forged and sleeved on the outer tube 12. The developing ring is made of platinum-iridium alloy or tantalum metal. The developing ring is made of X-ray-impermeable material and can display the position of the catheter tip in the human blood vessel in real time during the operation. The outer tube is a ring-shaped hollow thin-walled tube.

[0045] like Figure 4 As shown, the multi-lumen tube 16 is used as the inner tube, and the multi-lumen tube has four cavities, which are respectively a "suction cavity 14", a "guidewire cavity 13" and two "OCT probe cavities 15". The inner wall of each cavity of the multi-lumen tube can be coated with a fluorine coating to enhance the lubricity of the tube wall and enhance the passability of interventional instruments such as guidewires; an optical fiber bundle is filled in the annular area between the outer tube 12 and the multi-lumen tube 16, and a single optical fiber is a UV high-hydroxyl optical fiber with a core diameter of 100 μm or less, and is coated with a polyimide coating to enhance its tensile and bending resistance. The total number of optical fibers depends on the cavity area reserved for catheters of different specifications and is not specifically limited;

[0046] Figure 6 As shown, the fixed base 23 of the catheter connector 9 includes a rectangular groove 25, where the optical fiber bundle and the OCT probe optical fiber can be shaped into a rectangular end face. Figure 7 The black part in the middle is the optical fiber connected to the OCT probe. During installation, it should be placed as close to the center of the end face as possible. The optical fiber bundle needs to be pressed into the groove with glue or a physical spring plate to fix it.

[0047] Figure 5This is a schematic diagram of the structure of the ablation catheter in working state. As shown in the figure, there are two OCT probe cavities, which cooperate with each other to image the plaque outside the distal end. Only one of them is shown in the figure due to the cross-sectional projection relationship; the connecting optical fiber and optical fiber bundle of the OCT probe are fixed together at the catheter connector; there are two Luer connectors 10, and the guide wire cavity is connected to the outside through the first Luer connector. The first Luer connector can also be connected to a physiological saline injection device to facilitate real-time cooling during the ablation process; the suction cavity is centered and connected to the outside through the second Luer connector. An external peristaltic pump can be used to suck the lesion debris generated during the ablation process out of the body to prevent distal embolism caused by the fall of plaque particles;

[0048] The OCT imaging light source is a time domain OCT, frequency domain OCT or full-field OCT imaging light source. It emits infrared laser through a semi-transparent and semi-reflective mirror and a beam combiner into a fiber bundle catheter and is transmitted from the distal end to the lesion. Lesions such as thrombi outside the distal end reflect the light beam and are collected and transmitted via the OCT probe. After image processing, a real-time image of the lesion location can be displayed for medical staff to refer to and adjust the laser ablation parameters and the position of the distal end of the catheter accordingly, thereby achieving more accurate treatment and preventing medical accidents such as perforation and dissection caused by traditional treatments due to the inability to observe real-time images of the lesions.

[0049] Example 2

[0050] like Figure 8 The pulse laser ablation system in the embodiment shown includes a second light source, a second light path homogenization system 20, a second beam combining mirror 21, a second focusing lens 22, an ablation catheter 6 and an OCT imaging system 7;

[0051] The second light source is a 355nm laser device 18, which is also an independent light source. Specifically, the single pulse energy should be greater than 70mJ, the pulse width should be less than 10ns, and the repetition frequency should be ≥50Hz and continuously adjustable, because a higher laser repetition frequency is conducive to the ablation of calcified lesions, and the near-field spot is about 6mm. The laser beam quality factor M2 is not less than 10, and the higher the better within a certain range, the best is greater than 30 or even greater than 100;

[0052] The double 45° reflector 8 is used for laser leveling output. It is the same as in Example 1. It can be omitted if the coupling optical path is simplified. If this part is omitted, the position of the light spot at the light outlet and at least 1.5 meters away from the light outlet during the laser adjustment phase is required to be consistent. The reflector is made of ultraviolet fused quartz. To reduce transmission loss, the lens should be coated with anti-reflection film on both sides HR>99.5%@355nm, 45°AOI;

[0053] The second homogenization system 20 includes a homogenization device, which is a double microlens array. Since the spatial energy distribution of the original spot output by the laser is a Gaussian distribution, if it is focused on the ablation catheter without homogenization, it is easy to damage the incident end face of the catheter. The microlens array can homogenize the Gaussian distribution spot into a spot with uniform energy distribution. After homogenization, the spot is not easy to damage the incident surface of the catheter. The specifications of the double microlens array should be exactly the same. The material is ultraviolet fused quartz with a high damage threshold. The subunits are rectangular, hexagonal or other shapes, but squares are more commonly used. The spot after homogenization is also square. The subunit size should be between 300μm and 1mm. In order to reduce the transmission loss of the system, this microlens array is coated with a 355nm anti-reflection film on both sides. Fig.10 Schematic diagram shown;

[0054] The second beam combiner, the beam combiner coating parameters are: S1: T>99%@355nm, 45°AOI; S2: T>99%@355nm, R>99%@1310nm, 45°AOI;

[0055] The rest is the same as in Example 1.

[0056] Example 3

[0057] The first light source and the second light source are combined into a comprehensive light source, such as Figure 7 As shown, the 355nm laser device plus the femtosecond laser device two-in-one solution, specifically as follows Fig. 9 As shown, it includes a first light source, a beam expansion system 2, a first light path homogenization system 3, a first beam combining mirror 4, a first focusing lens 5, and an ablation catheter 6; and a second light source, a second light path homogenization system 20, a second beam combining mirror 21, an ablation catheter 6, and an OCT imaging system 7;

[0058] Femtosecond ultrafast laser 1, wavelength 1030nm, single pulse energy not less than 300μJ, pulse width <600fs, repetition rate 100kHz (typical), near-field spot size about 3mm, beam quality factor M² not higher than 1.5;

[0059] The coating parameters of the first beam combiner 4 are: S1: T>99%@1030nm, 45°AOI; S2: T>99%@1030nm, R>99%@1310nm&355nm, 45°AOI;

[0060] The coating parameters of the second beam combiner 21 are: S1: R>99%@355nm, 45°AOI; S2: R>99%@355nm, T>99%@1310nm, 45°AOI;

[0061] The first focusing lens is a plano-convex lens or an achromatic aspheric lens. To improve transmission efficiency, an anti-reflection film may be applied to three wavelength bands including 355 nm, 1030 nm and 1310 nm.

[0062] The second beam combiner transmits ultraviolet laser and reflects OCT laser (1310nm), thereby merging the two optical paths into one to the S2 surface of the femtosecond beam combiner. The S1 and S2 surfaces of the laser beam combiner are coated with 355nm anti-reflection film on both sides, and the S2 surface is coated with a 45° high-reflection film for the OCT light source band. As shown in the figure, the two lasers have independent homogenized and shaped external optical paths. After homogenization, the light spot has a more uniform spatial distribution. Compared with the initial unprocessed Gaussian distribution light spot, in the subsequent spatial light coupling process, higher energy incidence can be allowed and the fiber bundle end face of the catheter is less likely to be damaged.

[0063] Example 3 can be regarded as an integration of Example 1 and Example 2, combining the photochemical effect of the ultraviolet laser and the photomechanical effect of the femtosecond ultrafast laser in the two schemes to better perform ablation treatment. This scheme combines the optical paths of the 355nm ultraviolet laser and the femtosecond ultrafast laser through a beam combiner, and then couples them into the treatment catheter, thereby using the two lasers for ablation treatment at the same time.

[0064] The specific working process and principle of the present invention are as follows: the homogenized light of a single light source or two homogenized light beams of dual light sources are combined and focused by a focusing lens to couple to the proximal end of the front of the ablation catheter. The catheter treatment end is inserted into the vascular lesion through a guide wire (the specific position of the intervention in the blood vessel is confirmed by a developing ring). At this time, laser is emitted for treatment, and the plaque is eroded into 10μm-level particles that can be absorbed by the human body. However, there will still be larger damaged plaques that cannot be discharged normally. The catheter treatment head is closely attached to the plaque during the treatment process, and the suction cavity can pump the larger plaque out of the body. The suction cavity is connected to a peristaltic pump to perform negative pressure suction on the ablation plaque.

[0065] During the treatment, the OCT imaging light source emits near-infrared laser, which enters the optical fiber bundle inside the catheter through the laser beam combiner and is transmitted to the plaque. The plaque will reflect the imaging beam and be collected by the ablation catheter and transmitted back to the system, interfering with the reference light inside the system to form an image. Real-time ablation effect evaluation can be achieved, which is beneficial for doctors to control the advancement speed and adjust the advancement direction, and complete the laser ablation surgery with high quality. Since OCT can penetrate 1~2mm plaques for imaging and can effectively identify the vascular media, it can also warn of the risk of vascular perforation in advance, reminding doctors to adjust the direction of the ablation catheter to avoid vascular perforation.

Claims

1. A pulsed laser ablation system, characterized in that: It includes a first light source, a first light path homogenization system, a beam combining and focusing system, an ablation catheter and an OCT imaging system. The first light source is used to generate an initial light beam; The first light path homogenization system is used to homogenize and shape the initial light beam into a light beam with uniform energy distribution; The beam combining and focusing system is used to combine the homogenized light beams of the light path homogenization system, and focus and couple them to the ablation catheter; The ablation catheter and the OCT imaging system cooperate to treat the pathology; The first light source is a femtosecond laser device, which has a wavelength of 1030nm, a single pulse energy of not less than 300μJ, a pulse width of <600fs, a repetition frequency of 100kHz, a near-field spot of about 3mm, and a beam quality factor M² of not more than 1.5; The beam combining and focusing system includes a first beam combining mirror, and the coating parameters of the first beam combining mirror are S1: T>99%@1030nm, 45°AOI; S2: T>99%@1030nm, R>99%@1310nm, 45°AOI; The pulsed laser ablation system also includes a second light source, a second optical path homogenization system, and a second beam combiner, and the light beam is transmitted to the first beam combiner via the second beam combiner; the second light source is a 355nm ultraviolet laser, and the coating parameters of the second beam combiner are: S1: R>99%@355nm, 45°AOI; S2: R>99%@355nm, T>99%@1310nm, 45°AOI.

2. The pulse laser ablation system according to claim 1, characterized in that: It also includes a beam expansion system, which is arranged between the first light source and the light path homogenization system; the light path homogenization system includes a flat-top beam shaper, the diffraction efficiency of the flat-top beam shaper is greater than 90%, and an anti-reflection film is plated for 1030nm and nearby bands.

3. The pulse laser ablation system according to claim 2, characterized in that: A 45° reflector is arranged between the first light source and the light path homogenization system, and the 45° reflector is made of ultraviolet fused quartz.

4. The pulse laser ablation system according to claim 3, characterized in that: The beam expansion system comprises a first lens and a second lens, wherein the first lens is a convex lens or a concave lens, and the second lens is a convex lens.

5. The pulse laser ablation system according to claim 1, characterized in that: The ablation catheter comprises a proximal incident end and a distal treatment end, the distal end is sleeved with a developing ring; the ablation catheter comprises an outer tube and an inner tube, an optical fiber bundle cavity is arranged between the outer tube and the inner tube; the inner tube comprises a suction cavity, a guide wire cavity, and an OCT probe cavity.

6. The pulse laser ablation system according to claim 5, characterized in that: The OCT probe has two cavities, and the guide wire cavity and the suction cavity are respectively connected to the outside through Luer connectors.

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