WO2014013438A1

WO2014013438A1 - System for laser application

Info

Publication number: WO2014013438A1
Application number: PCT/IB2013/055850
Authority: WO
Inventors: Gidon GOREN-GRATZYANI; Kfir Azoulay; Pazit Pianka; Barak Eliezer AZMON
Original assignee: Lumenis Ltd.
Priority date: 2012-07-16
Filing date: 2013-07-16
Publication date: 2014-01-23

Abstract

The present invention provides a system comprising: an illumination device configured to illuminate a treatment area; a microscope configured to enable a user to view the treatment area illuminated by the illumination device; a projector configured to project images; an imaging device configured to capture digital images of the treatment area illuminated by the illumination device; and a processing unit configured to identify a transformation between each digital image from the imaging device and a corresponding reference image; the processing unit further configured to transform one or more graphics from the corresponding reference image based on the respective identified transformation and to provide the respective one or more transformed graphics to the projector; wherein the projector is configured to project the respective one or more transformed graphics to the microscope such that the respective one or more transformed graphics are overlaid on the view of the treatment area in the microscope.

Description

SYSTEM FOR LASER APPLICATION

BACKGROUND

The development of the first working LASER (Light Amplification by Stimulated Emission of Radiation) by Theodore H. Maiman in 1960 - based on theoretical concepts set forth by Albert Einstein in 1916; and the work of Townes and Schawlow on the MASER in the 1950's - heralded a new era in Ophthalmology.

Laser photocoagulation surgery is used to treat various eye diseases and has become widely used in recent decades.

Retinal photocoagulation has been performed for more than 30 years for various diseases of the eye and the beneficial effects have been well established. Initially, sunlight and later xenon light was used for photocoagulation. Since the discovery of the laser for ophthalmology, nearly all retinal photocoagulation procedures are performed using laser energy.

The mechanism of action of conventional retinal photocoagulation is purely thermal. The main absorbing layer of the laser energy in the retina, is the retinal pigment, epithelium. The heat conduction out of the energy absorbing retinal pigment, epithelium, leads to irreversible thermal denaturation of the retina and to destruction of retinal and choroidal tissue.

Retinal photocoagulation is used in many retinal diseases, such as, diabetic macular edema, proliferative diabetic retinopathy, proliferative retinopathies of other origin, macular edema of other etiologies such as vein occlusion, retinal tears and detachment, choroidal neovascularization (CNV) in age related macular degeneration and other causes of CNV, and central serous chorioretinopathy.

Laser treatment is typically performed under local anesthetic as an outpatient procedure. In a typical procedure, the patient's pupil is dilated and the laser treatment is delivered using a slit lamp. To visualize the exact location for treatment on the retina, a contact lens is placed on the patient's cornea. During treatment, laser power is usually adjusted so that a grey or white lesion appears on the retina. The size of the laser spot and number of laser spots applied are dependent on the pathology treated.

Multi-spot pattern scanning laser was introduced in 2006 and since then has gained acceptance due to its rapid delivery of laser burns in a predetermined semi- automated sequential manner. Unlike standard Laser photocoagulation, scanning Lasers feature shorter pulse durations in the range of 10 ms to 30 ms. And in light of the fact that heat diffusion with shorter exposures is decreased, the applied laser lesions tend to be lighter and smaller than conventional ones.

A further advance towards a truly minimally invasive retina treatment was the development of Selective Retina Therapy (SRT) and the introduction of micropulse mode. Both technologies offer even shorter pulse duration and the result in non- visible retinal burns.

Laser photocoagulation has also been proven as a beneficial treatment for the anterior segment disease namely open angle glaucoma. Since the introduction of argon laser trabeculoplasty (ALT) by Wise and Witter, several studies such as the the Glaucoma Laser Trial (GLT), has shown that laser trabeculoplasty was at least as effective in maintaining IOP reduction in comparison with a single medication.

The introduction of selective laser trabeculoplasty (SLT) in 2000 opened the era of sub-threshold laser treatment. Rather than blanket destruction of the trabecular meshwork, SLT preferentially destroys the pigmented trabecular meshwork cells because they adsorb more energy during the short laser burst and sustain thermal damage before other cells adsorb damaging amounts of energy. To date ALT and SLT have been shown to produce equivalent pressure reductions and compared with ALT, SLT was associated with less per operative discomfort and adverse events.

The current methodology of laser delivery to ocular structures and/or tissues has changed very little during the past 40 years. The introduction of new laser media for the retina laser treatments (such as diode, DPSS and OPSL) have reduced product costs significantly and also positively impacted on product reliability and field-serviceability. However, these developments have had limited impact on the methodology of laser procedures, predictability of clinical outcomes, enhanced accuracy, improved treatment protocol, safety and overall clinical workflow.

Furthermore, the gradual shift towards minimally thermal, sub-threshold and potentially selective laser applications, where laser applications are invisible, further complicate the means to achieve a successful, reliable and predictable clinical outcomes over large populations.

It is an object of the present invention to address these deficiencies.

SUMMARY

The present invention provides a system comprising: an illumination device configured to illuminate a treatment area; a microscope configured to enable a user to view the treatment area illuminated by the illumination device; a projector configured to project images; an imaging device configured to capture digital images of the treatment area illuminated by the illumination device; and a processing unit configured to identify a transformation between each digital image from the imaging device and a corresponding reference image; the processing unit further configured to transform one or more graphics from the corresponding reference image based on the respective identified transformation and to provide the respective one or more transformed graphics to the projector; wherein the projector is configured to project at least part of the respective one or more transformed graphics to the microscope such that at least part of the respective one or more transformed graphics are overlaid on the view of the treatment area in the microscope.

The present invention also provides program product comprising a processor- readable medium on which program instructions are embodied, wherein the program instructions are configured, when executed by at least one programmable processor, to cause the at least one programmable processor to: register each of a plurality of received digital images of a treatment area to the other digital images of the plurality of received digital images, each of the digital images having a different resolution and orientation from the other digital images, wherein registering each of the plurality of received digital images includes transforming each of the digital images to the same coordinate system; provide control signals to a display device to cause the display device to superimpose the plurality of registered digital images over one another; process user input data to provide control signals to the display device to cause the display device to display graphics on the superimposed images for use in planning treatment of the treatment area; and save the superimposed images and graphics.

DRAWINGS

Understanding that the drawings depict only exemplary embodiments and are not therefore to be considered limiting in scope, the exemplary embodiments will be described with additional specificity and detail through the use of the accompanying drawings, in which:

Figure 1 is a block diagram of one embodiment of a system according to the present invention.

Figure 2 is a flow chart depicting a feedback loop of the system in Figure 1.

In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize specific features relevant to the exemplary embodiments.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific illustrative embodiments. However, it is to be understood that other embodiments may be utilized and that logical, mechanical, and electrical changes may be made.

Furthermore, the method presented in the drawing figures and the specification is not to be construed as limiting the order in which the individual steps may be performed. The following detailed description is, therefore, not to be taken in a limiting sense.

The embodiments described below provide a system and method for planning, execution, recording, and documentation of laser treatments, such as retinal laser treatment. In particular, the embodiments described below provide software instructions and supporting hardware to enable fast and robust multimodality registration, tracking and real time visual feedback for ophthalmic diagnostic and laser treatment through a computer guided slit lamp based ophthalmic laser device.

For example, in the exemplary embodiment shown in Figure 1 , the system 100 comprises software instructions 106, computer module 102, optical module 104 and power supply 108. The software instructions 106 are executed by the processing unit 110 and control hardware components of the computer module 102 and the optical module 104 for execution and recording of the treatment, as well as for treatment planning. Indeed, the software instructions can be executed by a processing unit in another system as a stand-alone application for treatment planning and documentation.

The software instructions 106 are stored on memory 112 in this example.

Memory 112 can be implemented as any appropriate computer readable medium used for storage of computer readable instructions or data structures. The computer readable medium can be implemented as any available media that can be accessed by a general purpose or special purpose computer or processor, or any programmable logic device. Suitable processor-readable media may include storage or memory media such as magnetic or optical media. For example, storage or memory media may include conventional hard disks, Compact Disk-Read Only Memory (CD-ROM), volatile or nonvolatile media such as Random Access Memory (RAM) (including, but not limited to, Synchronous Dynamic Random Access Memory (SDRAM), Double Data Rate (DDR) RAM, RAMBUS Dynamic RAM (RDRAM), Static RAM (SRAM), etc.), Read Only Memory (ROM), Electrically Erasable Programmable ROM (EEPROM), and flash memory, etc. Suitable processor-readable media may also include transmission media such as electrical, electromagnetic, or digital signals, conveyed via a communication medium such as a network and/or a wireless link.

For planning a retinal eye treatment, a physician can import one or more images of the eye to be treated via an input device 114. The input device 114 can be

implemented as any appropriate device for importing an image to be processed. For example, the input device 114 can be implemented as a CD-ROM drive, universal serial bus (USB) port, image scanner, etc. The images can come from different sources (different modalities), e.g. fundus camera color image, red-free image, Fluorescent Angiography and Optical coherence tomography (OCT). The images give the physician orientation where to treat and identify pathologies and treatment areas.

The processing unit 110 executes the software instructions 106 to process the imported images. In particular, a registration analysis is performed to automatically register the images to one another. The images are displayed for the physician or other user via the user interface device 116. The user interface device 116 includes a display element for providing information to a user. The display element can be implemented as any suitable display element capable of rendering a visual display, such as, but not limited to, a cathode ray tube (CRT) display, an active matrix liquid crystal display (LCD), or a passive matrix LCD, Organic LED (OLED) . The user interface device 116 also includes a user input element to enable a user to interact with the provided information. For example, the user interface device 116 can be implemented as a touch screen for display and input of user data. Alternatively, the user interface device 116 can be implemented with a display element and a separate user interface element, such as, but not limited to, a keyboard, electronic mouse, joystick, touchscreen, etc.

The user can overlay one image over the other using the user interface device 11 , and display the different image modalities on the same coordinate system. In addition, the user can draw markers on the reference image or images. These markers may define the treatment areas, the treatment parameters and areas not to be treated (non-firing zones), or any annotation marker. These markers will follow through to the treatment execution as described below.

In particular, the optical module 104 and the computer module 102 function together to aid the physician in performing the treatment. The optical module 104 includes a beam-splitter 118, imaging device 120, and micro-projector 122. The optical module 104 also includes a microscope 124, illumination device 126 and laser system 128. The microscope 124 and illumination device 126 are commonly referred to together as a slit lamp. The laser unit 128 is integrated into or added onto the slit lamp. For example, the laser unit 128 can be connected to the slit lamp with optic fiber and a beam splitter. Thus, the physician is observing and aiming the laser using the slit lamp microscope oculars. Aiming can be performed with a visual low power aiming beam projected on the treated retina.

The illumination device 126 illuminates the eye such that an image of the eye can be viewed with the microscope 124. The beam-splitter 118 splits the image of the retina such that the image is seen in the microscope 124 and another copy of the image of the retina is captured by the imaging device 120. The imaging device can be implemented with any suitable image capturing technology such as, but not limited to, a charge coupled device (CCD), CMOS. The images are captured with the imaging device 120 at a predetermined video frame rate. The video frames are transferred to the processing unit 110.

The processing unit 110 executes the software instructions 106 to identify the transformation between the images coming from the slit lamp and the reference image processed during treatment planning. The processing unit 110 then transforms the planning graphics based on the determined transformation and provides the transformed planning graphics, such as the markers discussed above, to the micro-projector - (the micro-projector can be LCD, OLED, DLP or other technology) , 122. The micro- projector 122 may project at least part of the transformed planning graphics via the beamsplitter 118 to the microscope 124 such that the planning graphics are overlaid and displayed on the ocular image viewed by the physician in real time. Thus, without removing his eyes from the oculars, the physician can see the treatment planning on an image of the actual retina. The physician may control the amount of data displayed through the input interface. The laser parameters can also be projected onto the treatment area such that the physician can see these too without the requirement to remove his eyes from the treatment area.

During retinal eye treatment, the physician operates the laser system 128 to shoot laser spots on the retina. The imaging device 120 captures the shooting which is processed by the processing unit 110 and saved in memory 112. In addition, the processing unit 110 provides graphics displaying the location of the laser burns to the micro-projector 122 which are projected via the beam-splitter 118 to the microscope 124. The imaging device 120 and processing unit 110 may also capture and register the exact location of each laser shot even if the treatment laser is invisible, for example infra-red, or even if there is no visible burning on the tissue. This may be done in a number of ways, for example, by tracing the aiming beam or by using a thermal imager or sensor. Hence, the physician is able see where he has already treated the retina and can control the treatment better than without the additional aid of the post-burn marks projected by the micro-projector 122. In a sub-threshold treatment domain, where there is little or even no visible burn or any other visualized damage or mark on the tissue, the system of the invention may provide online and offline tracking and monitoring of the treatment and to compare actual treatment to the planned treatment. The graphics and/or post-burn marks are processed and provided to the physician in approximate real time to aid in performing the treatment. Additionally, in some embodiments, the processing unit 110 can provide control signals to the laser system 128 to aid and/or automate positioning of the laser during treatment.

After the execution of the treatment ends, the processing unit 110 executes the software instructions 106 to produce a report with the reference image or images, laser burns or laser treatment spots where the treatment spots are not visible, position and laser settings of each shot, treatment statistic information, such as shot count, power range, etc.

Figure 2 is a diagram depicting a feedback loop during treatment with system 100. As shown in the example of Figure 2, an image of the retina as seen with the slit lamp is split with the beam-splitter 218. Thus, one copy of the image is provided to a camera 220. The video images from the camera 220 are processed in the processing unit 210. The processing unit outputs video frames containing graphics to the projector 222 which projects the video graphics to the microscope via the beam splitter 218. Thus, a user is able to view the graphics overlaid directly on the actual image from the slit lamp. Thus, during treatment the laser unit 128 provides feedback to the processing unit 110 regarding the laser settings of each shot. In addition, the projector can be used to project further additional or complementary data relating to the treatment plan or registered reference images taken from other modalities. In fact, the projector may project any information which may prove useful to the physician during the actual treatment period. Thus, the embodiments described herein provide various benefits and advantages over conventional treatment systems and methods of treatment especially when multiple sub-threshold treatment spots are involved. Such benefits, among other things, include multimodality registration and overlay of images. The multimodality registration includes registration of different images from different imaging technologies and devices; registration of images with different resolution, orientation, light wavelength, imaging technologies, and distortion to certain level; transformation of images to the same coordinate system; and display of images overlaid and superimposed on one another.

A further benefit of the present invention is the ability to plan the treatment, project that onto the treatment area, but also real time images may be taken during the treatment itself, these can be compared with the actual treatment plan and any changes projected onto the treatment area, to assist the physician in the actual treatment itself.

Another benefit of the embodiments described herein is real time slit lamp video tracking, registration, monitoring and presenting of visualized or un-visualized treatment spots. That is, the system described above enables real time tracking of slit lamp video and registration between slit lamp video frames and reference image, such as from a Fundus camera and the aiming beam and the treatment laser beam. The registration algorithm is robust to narrow field of view, fast eye movements, changes in lighting, reflection, blurring, low signal to noise, and sudden image magnification changes.

Additionally, the imaging system and laser system are connected and synchronized which enables identifying the laser aiming beam position on the retina by image processing in real time. A further feature is the ability to track the aiming beam itself, such that the actual treatment can be compared with the planned treatment and any differences there between may be highlighted to the physician.

The feedback mechanism discussed above provides a "heads up" display feedback for the slit lamp to project graphical feedback to the doctor's eye during the treatment. Thus, the system described above enables a safer, more accurate, and more efficient treatment through displaying treatment planning overlaid on the treated eye during treatment in real time; recording and displaying post burns on the treated eye; and superimposing different imaging modalities overlaid on the treated eye in real time. Furthermore, the treatment planning is improved over conventional systems through the display of registered and overlaid images from different imaging devices sources and through the ability to mark treatment and non-firing zones on a multi-layer and multi-modality reference image. The reference image and markings are then saved for use during the treatment. Marking non firing zones represents another aspect of the present invention. Since the system monitors online the exact location of the treatment beam e.g. by tracking the aiming beam, the system may provide the physician a graphical or audial indication if the laser targets a tissue in a non-firing zone. Moreover, the system may block the laser from getting shooting instructions from the physician when the laser targets a non-firing zone.

In addition, post-treatment activities are improved by the ability to issue treatment reports, as discussed above. In particular, the system records and displays laser shots on the reference image in the report. The report also includes laser parameters and treatment statistics that are automatically recorded. The report and treatment video can be stored in the patient record and used for analysis of the doctor's performance of the treatment.

Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiments shown. For example, although the system is described above with respect to retinal eye treatment, it is to be understood that other laser treatments can be implemented in other embodiments. Such other treatments include, but are not limited to, Selective Laser Trabeculoplasty (SLT) for glaucoma. Furthermore, such treatments are not limited to not ophthalmic treatments, but also include surgical and aesthetic laser treatments.

Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.

Claims

CLAIMS What is claimed is:

1. A system comprising:

an illumination device configured to illuminate a treatment area;

a microscope configured to enable a user to view the treatment area illuminated by the illumination device;

a projector configured to project images;

an imaging device configured to capture digital images of the treatment area illuminated by the illumination device; and

a processing unit configured to identify a transformation between each digital image from the imaging device and a corresponding reference image; the processing unit further configured to transform one or more graphics from the corresponding reference image based on the respective identified transformation and to provide the respective one or more transformed graphics to the projector;

wherein the projector is configured to project at least part of the respective one or more transformed graphics to the microscope such that at least part of the respective one or more transformed graphics are overlaid on the view of the treatment area in the microscope.

2. The system of claim 1, further comprising a laser unit configured to direct a laser beam toward the treatment area.

3. The system of claim 1 further comprising:

a user interface device configured to display data from the processing unit and to provide data from a user to the processing unit; and

an input device configured to provide a plurality of digital images of a treatment area, the plurality of digital images obtained from respective different imaging technologies and having different resolution and orientation from the other digital images; wherein the processing unit is configured to register each of the plurality of digital images to each other and to direct the user interface device to display the plurality of registered images overlaid on each other.

4. The system of any preceding claim, wherein the processing unit is further configured to register images of areas of treatment and images areas of non-treatment and to direct the user interface to display the images.

5. The system of any preceding claim, wherein the processing unit is further configured to provide a report of the treatment plan, the laser parameters and the images of the treatment and non-treatment areas to the user interface device.

6. The system of any preceding claim, wherein the processing unit is configured to direct the projector to project the laser parameters to be overlaid on the view of the treatment area in the microscope.

7. The system of claims 2 to 6, further comprising a device to emit a warning signal, should the laser beam be directed towards a non-treatment area.

8. The system of claim 7, wherein the warning signal is one of: an audible signal, a visual signal or said warning device prevents the laser unit from directing the laser beam toward the non-treatment area.

9. The system of any preceding claim, further comprising a beam splitter configured to split the image received from the projector and direct it to the imaging device and the microscope.

10. A program product comprising a processor-readable medium on which program instructions are embodied, wherein the program instructions are configured, when executed by at least one programmable processor, to cause the at least one programmable processor to:

register each of a plurality of received digital images of a treatment area to the other digital images of the plurality of received digital images, each of the digital images having a different resolution and orientation from the other digital images, wherein registering each of the plurality of received digital images includes transforming each of the digital images to the same coordinate system; provide control signals to a display device to cause the display device to superimpose at least two digital images of the plurality of registered digital images over one another;

process user input data to provide control signals to the display device to cause the display device to display graphics on the superimposed images for use in planning treatment of the treatment area; and

save the superimposed images and graphics.

11. A method of treatment by laser, the method comprising:

illuminating a treatment area;

viewing the illuminated treatment area in a microscope;

projecting images on a projector;

capturing digital images of the illuminated treatment area on an imaging device; identifying a transformation between each digital image from the imaging device and a corresponding reference image; transforming one or more graphics from the corresponding reference image based on the respective identified transformation and providing the respective one or more transformed graphics to the projector; and

projecting at least part of the respective one or more transformed graphics to the microscope such that at least part of the respective one or more transformed graphics are overlaid on the view of the treatment area in the microscope.

12. The method of claim 11, further comprising:

displaying data from a processing unit and providing data from a user to the processing unit; and

providing a plurality of digital images of a treatment area, the plurality of digital images obtained from respective different imaging technologies and having different resolution and orientation from the other digital images; and registering each of the plurality of digital images to each other and directing the user interface device to display the plurality of registered images overlaid on each other, wherein the image registration is either off-line or in real-time.

13. The method of claim 11 or 12, further comprising registering images of areas of treatment and images areas of non-treatment and displaying the images on the user interface to display.

14. The method of any of claims 11 to 13, further comprising: providing a report of the treatment plan, the laser parameters and the images of the treatment and non- treatment areas to the user interface device, from the processing unit.

15 The method of any of claims 1 to 14, wherein the laser parameters are projected onto the treatment area.

16. The method of claims 11 to 15, further comprising: emitting a warning signal, should the laser beam be directed towards a non-treatment area.

17. The method of claim 16, wherein the warning signal is one of: an audible signal, a visual signal or preventing the laser unit from directing the laser beam toward the non- treatment area.

18. The method of any of claims 11 to 17, further comprising: using a beam splitter to split the image received from the projector and directing it to the imaging device and the microscope.