Patent Application
20080058782
The invention has other advantages and features which will be more readily apparent from the following detailed description of the invention and the appended claims, when taken in conjunction with the accompanying drawings, in which:
This invention describes an electromagnetic system with automatic adaptive control of fractional (photothermal and/or RF) treatment density, as well as a method of treating tissue in a fractional manner using an electromagnetic system with automatic adaptive control of treatment density. Treatment density is the number of treatment zones produced per unit surface area in a target region of skin or portion thereof. A nominal pattern and treatment density can be defined when the system begins treatment and this treatment density can be modified based on a measured position of the handpiece, an intrinsic characteristic of the tissue undergoing treatment and/or a change in an intrinsic characteristics of the tissue, a skin response to the treatment and/or a change in a skin response to the treatment. Sensors of various types can be used to determine the measured position parameter, skin characteristic and/or skin response. Algorithms that describe the positional parameter, skin characteristic and/or skin response to treatment are used to control the density of the fractional treatment.
As described herein, handpiece positional parameters include parameters relating to the position, velocity and/or acceleration of the handpiece used to deliver the fractional treatment. Skin characteristics include inherent characteristics, biological properties and/or features of the skin, such as, for example, skin tone, birefringence, temperature, water content, pH, elasticity, color, thickness, texture, mechanical damping properties, blood vessels, pigmented lesions, hairs, hair follicles, wrinkles, etc. Skin characteristics can include changes in these inherent characteristics, biological properties and/or features of the skin which are not brought about by or in response to the treatment. Skin responses include changes in inherent characteristics, biological properties and/or features of the skin which occur in response to the treatment, such as, for example, skin shrinkage, birefringence, temperature, water content, pH, elasticity, color, thickness, texture, mechanical damping properties, blood vessels, pigmented lesions, hairs, hair follicles, wrinkles, etc.
Which positional parameter measurements, skin characteristic measurements and/or skin response measurements are made can depend upon particular measurement results or treatment requirements. For example, if the handpiece is moving very rapidly across the skin and treatment power is proportional to relative handpiece speed, then bulk heating of the tissue can be a concern. In this case, the sensors can be instructed by the controller to measure skin parameters that are associated with blistering due to over treatment. If movement is slow, bulk heating and blistering can be less of a concern and more of the processing power of the controller can be used to make more accurate measurements of velocity with the sensors instead. Detailed examples of the invention are described below.
In some examples, a distinction can be made between micro-dosimetry and macro-dosimetry measurements. Micro-dosimetry measurements are substantially limited to one or more zones that are about to be treated or have been treated by a pulse, a set of sequential pulses, or a set of simultaneous pulses. For example, measurement of an approximately 1.2 mm diameter area that is co-centered with an approximately 1 mm diameter area that is about to be treated is micro-dosimetry because the measurement is substantially limited to the region that is about to be treated with a future pulse or a future set of essentially simultaneous pulses. In contrast, macro-dosimetry measurements are used to evaluate larger areas of skin to produce an average measurement of regions that include both areas that are about to be treated (or that have just been treated) and adjacent regions. In some examples, a sensor is used to produce micro-dosimetry or macro-dosimetry measurements in accordance with the feedback loops of this invention.
While the operator manually moves the handpiece 100 in direction 101 or after the operator has manually moved the handpiece 100, the positional sensor 180 measures one or more positional parameters of the handpiece 100 and the skin sensor 160 measures a skin response to the treatment and/or a skin characteristic. The positional sensor 180 and the skin sensor 160 communicate with the controller 115 and/or with the scanner control 125.
In another example, while the operator manually moves the handpiece 100 in direction 101 or after the operator has manually moved the handpiece 100, one or more skin response sensors measure one or more skin responses to the treatment within the range of the sensor. The skin response sensor(s) communicate with the controller 115, the handpiece 100 and/or with the scanner control 125 in order for the controller 115, handpiece 100 and/or scanner control 125 to adjust the treatment density in real-time based on the skin response feedback. In yet another example, while the operator manually moves the handpiece 100 in direction 101 or after the operator has manually moved the handpiece 100, one or more skin characteristic sensors measure one or more skin characteristics of the skin within the range of the sensor. The skin characteristic sensor(s) communicate with the controller 115, handpiece 100 and/or with the scanner control 125 in order for the controller 115, handpiece 100 and/or scanner control 125 to adjust the treatment density in real-time based on the skin characteristic feedback.
The controller 115, the handpiece 100 and/or the scanner control 125 materially alter the treatment in real-time in response to the positional parameter measurements, skin characteristic measurements and/or skin response measurements provided by the sensors by adjusting the treatment density. Alternatively, the controller 115, handpiece 100 and/or the scanner control 125 can materially alter the treatment in real-time by adjusting (i.e., increasing or decreasing) the number of treatment zones created, the spacing of the treatment zones created, and/or the size of the treatment zones created. This adjustment of treatment zone number, spacing or size can be made in response to a positional parameter, a skin response, and/or a skin characteristic. An adjustment of treatment zone number, spacing or size can be made alone or in conjunction with an adjustment in treatment zone density.
In some examples, the feedback loops comprising the controller 115 and/or the scanner control 125 in combination with one or more sensors (e.g., the positional sensor 180, the skin sensor 160, etc.) can be used to provide automated control of treatment density, as well as to provide automated control of other treatment variables which may or may not affect treatment density, such as, for example, treatment location, treatment zone overlap, treatment energy, treatment depth, treatment power, treatment zone size, treatment zone pattern, treatment cooling (including pre-cooling and post-cooling), etc. The treatment density and/or the other treatment variables (e.g., treatment location, treatment zone overlap, etc.) can be controlled through adjustment of device parameters, such as optical focus, spot size, treatment pattern, pulse width, pulse energy, pulse timing, pulse frequency, laser power, laser wavelength, spray cooling volume, spray cooling timing, etc.
Optionally, the controller 115 can be operably connected to the scanner control 125, which can be helpful for reducing the number of wiring connections from the sensors. The controller 115 can serve the function of both the controller 115 and the scanner control 125 as shown in the example of
Detailed examples of several components in
In general, an electromagnetic source 110 is a radio frequency (RF) source, an optical source, or a combination of the two. A RF source generates electromagnetic energy with a frequency in the range of about 0.1 MHz to about 20 MHz, or in the range of about 0.5 MHz to about 8 MHz. An optical source generates light, which is defined for this application as electromagnetic energy with a wavelength in the range of about 300 nm to about 12,000 nm. In some examples, use of optical energy permits the energy to be directed accurately and easily to the desired target regions of the skin so as to deliver a fractional treatment. RF energy can also be used, particularly for applications where deeper penetration or targeting of particular buried layers of skin is desired. The choice of RF or optical energy can also be made to reduce interference with a chosen type of position sensor, skin characteristic sensor, and/or skin response sensor.
In one example, the electromagnetic source 110 is a laser and the electromagnetic energy 130 is a laser beam. Examples of lasers are Nd:YAG lasers, diode lasers, erbium fiber lasers, CO2 lasers, Er:YAG lasers, Er:glass lasers, flashlamp-pumped lasers, free electron lasers, thulium fiber lasers, Raman shifted fiber lasers, dye lasers, gas lasers, Argon lasers, and ytterbium fiber lasers.
The skin characteristic and/or skin response can be measured by one or more skin sensors 160 employing one or more types of technology such as capacitive sensors, (hyper-) spectral imaging, terahertz imaging, optical coherence tomography, confocal microscopy, ultrasonic imaging, coherent detection, thermal detectors, thermal imaging, etc. In addition, one or more skin sensor(s) 160 can measure skin birefringence, skin water content, skin elasticity, skin mechanical damping parameters, skin color, skin features such as blood vessels and pigmented lesions, skin thickness, skin texture, wrinkles, etc. Other types of measurement technology and other dermatological features and tissue properties that can be measured will be apparent to those skilled in the art.
A mechanical mouse or roller wheel with an encoder can also be used as a positional sensor 180. Alternatively, a non-mechanical positional sensor which does not rely primarily on moving parts to measure positional parameters can be used. Non-mechanical positional sensors advantageously improve measurement reliability on slippery surfaces and reduce the chance of mechanical failure in comparison to mechanical positional sensors.
In one example of a non-mechanical positional sensor 180, coil sensors are used as described by Ben-Haim et al in U.S. Pat. No. 6,788,967, which is herein incorporated by reference. Three sensor coils that are mechanically coupled to the handpiece 100 in the appropriate orientations can be used to measure positional information, for example up to three dimensions and/or up to three angular orientations for the handpiece when the sensor coils are placed in the magnetic field generated by at least two radiators. Other geometries and numbers of radiators and sensor coils are possible for measurement of one-dimensional to six-dimensional positional parameters of the handpiece. Other non-mechanical positional sensors such as optical positional sensors are described below and can be detachable from the handpiece.
One example of the use of coil sensors is shown in more detail in
In one example, each of the magnetic field source elements 1285A-C and each of the magnetic field sensor elements 1284A-C comprise a loop antenna that is tuned to a desired frequency, for example a frequency of about 10 kHz. The loop antennas 1285A-C for the magnetic field source elements 1282 can each be driven with a current source, for example an op-amp current source. Alternately, a single current source 1288 can be electronically switched to power each of the loop antennas of the magnetic field source elements 1285A-C sequentially. The system can be operated in the near field of each of the magnetic field source elements 1285A-C and each of the magnetic field sensor elements 1284A-C, but operation in the far field is also possible. The source elements 1284A-C can be sequentially powered in order to time division multiplex the source signals. The controller 1215 comprises receiver electronics for measuring the response detected by the magnetic field sensors. The receiver electronics portion of the controller can be collocated with the magnetic field sensor elements 1284A-C or can be integrated with the other electronics of the controller 1215. The controller comprises appropriate electronics to de-multiplex the received signals to identify the measured magnetic field intensity due to each of the source elements. To synchronize the systems, particularly in the case of time division multiplexing, a common clock can be used for the source and receiver electronics. Other configurations of source, receiver, multiplexing/de-multiplexing, and electronic systems will be apparent. For example, additional examples and refinements of appropriate magnetic field systems can be found in U.S. Pat. Nos. 4,613,866, 4,737,794, 4,742,356, and 5,307,072, each of which is incorporated herein by reference.
In another example, the magnetic field source elements 1285A-C are located at one or more reference points outside the handpiece and the magnetic field sensor elements 1284A-C are attached to the handpiece. The location of and direction of the treatment beam(s) emitted from the handpiece relative to the reference coordinate system is then measured. For treatment on the face, the handpiece 1200 can include the magnetic source 1281, and a small earbud that is placed within the ear of the patient can contain the magnetic positional sensor 1280. To improve accuracy and to determine whether the earbud has fallen out or shifted, a second magnetic positional sensor (not pictured) can be used, for example in the opposite ear of the patient. If there is a discrepancy between the redundant sensors, the system can alert the physician, using, for example, an audible alarm.
The choice of which of the magnetic source 1281 and the magnetic positional sensor 1280 is located at the reference point(s) and which is located at the handpiece 1200 can be chosen based on the sources of electromagnetic interference and objects of electromagnetic field distortion, such as metal plates. For the example above, it is anticipated that there is a scanning motor element, such as for example used in
In one example of a magnetic field system as described in
In one example, one or more measured handpiece positional parameters include handpiece position or handpiece angle (angular orientation) or the time derivatives of these two parameters including handpiece velocity, handpiece acceleration, handpiece angular velocity, and handpiece angular acceleration. Handpiece positional parameters can be absolute or can be relative to the target region.
To enhance the serviceability of the apparatus and to allow handpieces to be interchanged and thus share expensive components, the handpiece can be detachable from one or more of the following: the electromagnetic source 110, the controller 115, and the scanner controller 125. To reduce the weight of the handpiece, these components can be located outside the handpiece. Alternatively, to enhance portability of the apparatus, these components can be included inside the handpiece.
The scanning delivery unit is configured to receive the electromagnetic energy 130 and deliver the electromagnetic energy 130 to the skin 150 regardless of where the other components are housed. For example, the electromagnetic source 110 can be a laser. The electromagnetic radiation can be coupled into an optical fiber, optical waveguide, or articulating arm for delivery to the handpiece. The handpiece can accept optical energy by using a fiber coupling or a fiber collimator. Similarly, it will be evident to those skilled in the art that the sensors 160 and 180 can be operably coupled to the controller 115, but do not need to be located inside the handpiece.
The controller 115 and scanner control 125 can be separate components as in
In the example of
In the example of
In
An example of a skin sensor 260 (i.e., a skin response sensor and/or a skin characteristic sensor) is a capacitive sensor as shown in
In an alternative example, the treatment pattern can be intentionally varied according to a predefined algorithm where treatment density is varied in real time in response to changes in the velocity or acceleration of the handpiece and where the treatment pattern is not predefined. For example, the treatment density can be controlled in real time by the user by appropriately adjusting the position, velocity, or acceleration of the handpiece. In some treatments, it is desirable to allow the operator to have control over the treatment density through the use of velocity. For example, if the user treats quickly, the system can be configured to allow a higher treatment density, which in turn can be measured by the skin sensor 260. If the user treats slowly, then the treatment density can be reduced. Thus, the user is able to control the treatment density simply by changing positional parameters of the handpiece. Thus, the treatment density, as well as treatment pattern, treatment intensity, and other treatment parameters are not predefined, but can be defined through an automated response to measured positional parameters, to measured skin response, to measured skin characteristics, or to combinations thereof. An electronic or computer interface (not pictured) can be provided to allow switching on or off different modes of user control.
In another example, a treatment status map is displayed on a monitor (not shown) for the user or the patient to observe. The positional sensor 280 can be used to measure the location within the target region of the tissue response that is measured by the skin sensor 260. In this way, a map can display which parts of the target region have been treated and how each part of the target region has responded to treatment. The user can take the information on this map to make treatment uniform over the entire target region or to have treatment vary in a desirable manner such as treating areas with deep wrinkles more densely than less wrinkled areas. Alternatively, the system can be configured to automatically reduce treatment density or disable treatment in the regions that have already been adequately treated as the user continues to move the handpiece over the target region. A picture or schematic representation of the target region, such as a line drawing of a face for treatment of wrinkles on the face, can be used as a background for a computer display of the map of the treatment response measurements.
The use of a positional sensor 280 and/or a skin sensor 260 (i.e., a skin response sensor and/or a skin characteristic sensor) to create a map can be used beneficially, particularly with small beam sizes less than 1 mm in their smallest dimension. Using such a map, treatment can be turned on or off, or the density of treatment increased or decreased, based on whether treatment has covered that area or not, based on the presence or absence of skin features such as wrinkles, blood vessels, pigmented lesions, etc., or based on the presence or absence of an exogenous pigment. The advantage of using a beam size of less than 1 mm is that the granularity of the beam size for treatments that are visually apparent after treatment will be less noticeable for such small beam sizes. Thus, the use of a positional sensor 280 and/or a skin sensor 260 is particularly suited to fractional treatment and/or treatments with a small beam size of less than 1 mm.
Controller 215, optical source 210, and other components can be external to the handpiece 200 instead of being included inside the handpiece as illustrated in
In one example, the electromagnetic source 210 is a single mode pulsed erbium doped fiber laser with a peak output power in the range of about 5 W to about 50 W and a wavelength in the range of 1.52-1.62 μm. This laser source can be focused to an optical spot size in the range of about 30 μm to about 600 μm or about 60 μm to about 300 μm on the surface of the skin. Pulse energies in the range of about 2 mJ to about 100 mJ or in the range of about 8 mJ to about 20 mJ can be used for these ranges of optical spot size, wavelength, and power. This example does not include surface skin cooling, but such cooling can be included if desired to reduce damage to the epidermis and dermal-epidermal junction.
The scanning delivery unit 220 used in this example is a scanner wheel rotating at least 360° around an axis 221 as described in detail in U.S. application Ser. No. 11/158,907, which is incorporated by reference herein. Other scanner types will be apparent to those skilled in the art. For example, galvanometer scanners, pseudo stationary deflection (PSD) scanners as described in co-pending and co-owned U.S. application Ser. No. 10/750,790, which is also incorporated by reference herein, polygonal scanners, light valves, liquid crystal display (LCD) screens, micro-electromechanical system (MEMS) based reflective scanners, and translation stages can be used for the scanning delivery unit for delivery of optical energy. Multiple scanning delivery units can be used in such systems to control multiple axes of deflection. For example, two galvanometer scanners can be used in series to scan the laser beam in two directions to cover an area on the surface of the skin 250. Alternatively, single scanning units can cause beam deflection in two directions as described in detail in U.S. application Ser. No. 11/158,907.
One algorithm that can be used to control operational parameters of the scanning delivery unit 220 is to adjust the rotational speed of a double or single wheel PSD scanner and the laser firing rate in proportion to the velocity of the handpiece. This allows microscopic treatment zones of fractional resurfacing to be placed in a predefined density on the skin.
Another algorithm for controlling treatment is to adjust the firing of the laser in approximate proportion to the relative velocity of the handpiece to create a predefined treatment density. A uniform density of treatment zones distributed across a target region by overlapping or abutting treatment zones can also be achieved. For example, if the scanner 220 shown in
In another example, the scanner wheel 220 can be run at a velocity that drags the optical beam 230 across the target region. This wheel velocity can even be in the opposite direction of the direction that would compensate for movement of the handpiece. This intentional dragging of the optical beam 230 across the surface of the skin 250 can be created with either variable-velocity or fixed-velocity scanner systems. With the fixed-velocity system, for example, the pulse duration of the laser beam can be adjusted according to the velocity of the handpiece 200 such that the optical beam is dragged across the skin by approximately the same distance with each pulse. By changing the angular velocity of the scanner wheel 220 or by changing the pulse duration for the optical beam 230, the distance over which the optical treatment occurs for each pulse can be changed. The controlled dragging of the optical beam can, for example, be used to increase the fill factor for a fractional resurfacing treatment by making each microscopic treatment zone larger by increasing the distance over which optical treatment occurs. Similarly, the controlled dragging of the optical beam can, for example, be used to increase the treatment density for a fractional treatment by increasing the number of treatment zones created in the target region of skin. As the velocity of the handpiece 200 is reduced, the increased pulse duration prescribed by this algorithm can cause a reduction in treatment density as measured by the skin sensor 260. Therefore, it can be desirable to increase the pulse energy to keep the tissue response the same.
The contact plate 239 beneficially reduces optical scattering from the skin surface for the treatment beam by creating a smooth surface that can be used to precisely and reproducibly position the skin relative to the focus depth of the optical beam 230. The contact plate 239 can also act as a thermal heat spreader or can conduct heat away from the surface to actively cool the skin when connected to a cooling source (not shown). The contact plate 239 and dichroic mirror 232 can comprise sapphire, fused silica, borosilicate glass, transparent plastic, or other transparent materials. The contact plate 239, dichroic mirror 232, and other optical components can have optical coatings applied on one or more sides to increase the efficiency of energy delivery into the skin or to enhance the reflectivity or transmission of the illumination 283 from the illumination source 282.
In some examples, the contact plate 239 can be undesirable and can be omitted. For example, in ablative laser treatments, it can be desirable to have the surface of the skin be mechanically free to enhance the ablation response of treatment.
To enhance the ability of the optical positional sensor 280 to read the positional parameters of the handpiece 200, a contrast enhancing agent 290 can be applied onto or into the skin 250. For example, uniform application of a dye to the surface of the skin 250 can preferentially decorate certain features, such as skin wrinkles or hair follicles, to create shapes that can be detected as objects by the positional sensor 280. The contrast enhancing agent 290 must be non-toxic when applied onto or into a patient's skin in amounts suitable for adequately enhancing measurements by the positional sensor 280. In one example, the contrast enhancing agent and the materials and geometry chosen for the handpiece 200 and contact window 239 allow the handpiece 200 to slide easily over the surface of the skin 250.
Examples of contrast enhancing agents 290 are carbon particles, India ink, and FD&C Blue #1. Many other dyes, inks, particulates, etc., can be used as contrast enhancing agents when applied to the skin and when used with the appropriate positional sensor 280. The wavelength illumination source 282 can be chosen to maximize the signal to noise ratio of the measurement of the positional parameters of the handpiece 200. For example, a red LED with a peak wavelength in the range of about 600 nm to about 640 nm can be used with FD&C Blue #1.
In many cases, the contrast enhancing agent can be chosen such that it has a low absorption of the treatment energy or of the treatment wavelength in the case of optical treatment energy. In this way, the contrast enhancing agent will not interfere with the deposition of the treatment energy in the target region. In some cases, the contrast enhancing agent is chosen such that a measurable or observable parameter changes in response to the treatment energy. A change in the contrast enhancing agent can be used to determine where treatment has occurred, which allows the treatment to be touched up in areas where it is not even or uniform.
It is desirable to choose a contrast enhancing agent 290 that can be removed without abrasive or harsh scrubbing. Alternatively, a removal facilitation substance (not shown) can be applied prior to application of the contrast enhancing agent 290 to allow the dye to be removed more easily. Dimethicone, urea, and arginine are examples of removal facilitation substances. These substances can be applied prior to the contrast enhancing agent 290 to facilitate subsequent removal of the contrast enhancing agent 290. These substances can be applied using common solvents such as water, alcohol, or oil. Concentrations of the removal facilitation substance can be used, for example, in the range of about 0.001M to about 0.1M.
It is desirable to choose a contrast enhancing agent 290 that is not clearly visible when illuminated with typical room light and/or sunlight. Contrast enhancing agents 290 are said to be “hypo-visible” if and only if the contrast enhancing agent is not readily visible on otherwise bare skin with the naked eye when illuminated with about 400 nm to about 650 nm light when the contrast enhancing agent 290 is applied such that the response of the detector 280 is beneficially and substantially enhanced when using an illumination wavelength from about 300 nm to about 400 nm or from about 700 nm to about 1100 nm. The use of hypo-visible contrast enhancing agents 290 is desirable because the contrast enhancing agent 290 will be less visible after treatment even if not all of the contrast enhancing agent 290 is removed from the target region.
Many fluorescent inks, lakes, dyes, and particulates are examples of hypo-visible contrast enhancing agents 290. Fluorescing agents are desirable because the wavelength of illumination can be filtered by the dichroic mirror 232 or by other optical components or coatings while the throughput of the fluorescent emission wavelength is maximized to improve the signal to noise ratio of the positional sensor 290. Polymer (PMMA) encapsulated fluorescent dyes are commercially manufactured by NewWest Technologies (Santa Rosa, Calif., USA). Other fluorescent materials include collagen, elastin, FD&C Orange No. 5, flavin adenine dinucleotide, flavin adenine mononucleotide, folic acid, niacin, nicotinamide, reduced nicotinamide adenine dinucleotide (NADH), porphyrins, pyranine (FD&C Green No. 7), pyridocine hydrochloride, quinine sulfate, riboflavin, riboflavin phosphate, tryptophan, uranine (fluorescein), or combinations thereof. The absorption and emission spectra for these substances are well published in the art. Other fluorescent materials that are well known in the art can also be used as the contrast enhancing agent 290, for example Carbazine, Coumarin, Stilbene 3, Kiton Red, etc.
As the intensity of fluorescent emission of pyranine varies with pH, pyranine can be used to evaluate changes in barrier function and alert the user or automatically stop treatment or reduce treatment intensity if a break in the stratum corneum or a rupture of the skin occurs during treatment. Thus, the contrast enhancing agent 290 can also be used to improve the signal to noise ratio of the skin sensor 260.
Indocyanine green (ICG) is an example of a contrast enhancing agent 290. Most contrast enhancing agents 165 can be diluted with water or other solvents to make them easier to apply or cheaper to use. The peak wavelength of ICG varies depending on the solvent and the concentration of ICG. For example, in water, ICG has an IR absorption peak at approximately 700 nm for high concentrations (e.g. about 129 μM to about 1290 μM) and at approximately 780 nm for low concentrations (e.g. about 6.5 μM to about 65 μM). For ICG in blood plasma, there is an absorption peak in the range of approximately 790 nm to approximately 810 nm across a broad range of concentrations (about 6.5 μM to about 1290 μM). In general, ICG typically has an absorption peak in the range of about 650 nm to about 850 nm for most solvents. ICG also has absorption peaks in the UV range. ICG does not have a strong absorption peak in the range of about 400 nm to about 650 nm, which makes it difficult to see with the naked eye. Thus, ICG is an example of a contrast enhancing agent that has low visibility to the human eye, but is easily discernable to a silicon based optical detector when illuminated appropriately. In non-fluorescing contrast enhancing agents, the wavelength (or wavelength range) of illumination can be chosen to be in a region where the peak absorption of the contrasting agent is at least about 3 times, or at least about 10 times, stronger or weaker than that of skin. It is also desirable to have the peak absorption of the contrasting agent in the chosen wavelength (or wavelength range) to be at least about 3 times, or at least about 10 times, stronger than the peak absorption within the wavelength range of about 400 nm to about 650 nm.
The contrast enhancing agent can also be applied in a pattern. The pattern can comprise a uniform grid of identical
Patterns of contrast enhancing agents can also be attached to the skin using adhesives as used in temporary tattoos. As in a temporary tattoo, a pattern can be created by printing a contrast enhancing agent on or embedding a contrast enhancing agent in an adhesive that attaches to the skin. The adhesive has the advantage of being easier to remove than many of the contrast enhancing agents that can be included in or on the adhesive. Lakes of Food and Drug Administration (FDA) approved colors such as FD&C Blue #1 (also packaged as Optiguide Blue by Reliant Technologies, Mountain View, Calif., USA) can be embedded in a polymer-based tattoo adhesive and painted onto the skin. Following treatment, these adhesive based patterns can be removed with alcohol and light scrubbing. The use of adhesive also allows the use of contrast enhancing agents in doses that would otherwise be toxic to the skin because the adhesive can be designed to provide a barrier between the skin and the contrast enhancing agent.
Alternatively, contrast enhancing agents can be suspended in sugar-based or gel based solutions without patterning. These solutions can desirably be made viscous so that they do not drip outside the target region.
Instead of applying a pattern of figures with a contrast enhancing agent, the laser treatment zones can form a pattern of figures that is used to enhance the response of the positional sensor 280. For example, a CO2 laser can ablate portions of the skin to create a pattern of ablated areas interspersed inside non-ablated areas. This pattern can be illuminated with a light emitting diode (LED) to provide visible features that enhance the signal to noise ratio of an optical mouse chip functioning as a positional sensor 280.
Other examples of positional sensor 280 are illustrated in
The positional sensors and skin sensors shown in
While the examples illustrated in
As shown in
Measurements of acceleration or angular acceleration can be integrated in time to produce measurements of velocity and position or angular velocity and angular position. In many configurations, an initial calibration and periodic recalibrations can be required to reset the reference velocity, angular velocity, position, and/or angular position.
Accelerometers measure absolute positional parameters of the handpiece 400 rather than relative positional parameters of the handpiece 400 with respect to the target region of the skin 450. If relative positional parameters are desired, accelerometers can be used when the target region is immobilized or when absolute movement of the target region is insignificant. Alternatively, the absolute movement of the target region of the skin 450 and the absolute movement of the handpiece 400 can both be measured and the relative motion between the handpiece 400 and the target region of the skin 450 can be calculated.
Relative measurements of angular position can be used to provide feedback to the system and disable the laser unless the relative angle of the handpiece is within a certain angular range relative to the surface normal from the surface of the target region. This can be useful, for example, to align properly a cooling spray and a treatment laser beam on a target region. Absolute measurements of angular position are useful if the handpiece 400 has components that are sensitive to gravity, such as fluid-filled cavities that leak if turned upside down. Relative measurements of position can be used to measure distance between locations for pulsing the electromagnetic source 410.
Absolute or relative measurements of velocity, acceleration, angular velocity, and angular acceleration are useful for evaluating whether the handpiece has been dropped or has suddenly slipped in an uncontrolled way, which might lead to undesired treatment outside the desired target region. A combination of relative positional parameter measurements and absolute positional parameter measurements can be used to measure movement of the patient. For example, if the patient suddenly moves, the difference between the relative acceleration and the absolute acceleration measurements can be significant. In any of the situations described in this paragraph, the controller 415 can temporarily disable the electromagnetic source 410 to prevent treatment in areas that are not desired by the user.
The number and location of transmitters and receivers determines the positional parameters that can be measured. For measuring the position of the handpiece in three dimensions, three transmitters and one receiver can be used. For measuring the position of the handpiece in up to three dimensions and also measuring the angular position for up to three independent angular directions, a second receiver can be used. For measuring all three dimensions and all three handpiece angles, three transmitters and three receivers can be used in order to have redundancy. A simple apparatus comprises two transmitters and one receiver. This apparatus can be used to measure the positional parameters of a handpiece in two dimensions along a predefined surface. In an alternate configuration, two receivers are used with one transmitter to produce the same measurement. The particular geometry and locations of transmitters and receivers can be generalized by one skilled in the art.
For simplicity in the examples described below, receivers are located on the handpiece and transmitters are located inside the target region 557 or are mechanically coupled to the target region 557 such that the measured positional parameters of the handpiece will be relative to the target region and not absolute measurements. Other configurations can be used if absolute measurements are desired. Light based or other electromagnetic communications systems can be used for these types of systems as well.
In one example, three radio frequency transmitters are attached to a cap, such as, for example, made of cloth or latex for ease of use and low cost. For example, transmitters can be attached to electroencephalograph (EEG) caps for this purpose. This type of cap is useful for locating the handpiece when treating wrinkles on the forehead or periorbital areas of the face, for example, because the transmitters can be mechanically coupled to the target region. This type of cap can also be used with the coil measurement system described in the text for
One advantage of the accelerometer, magnetic, gyroscope, and transmitter-receiver based measurement systems is that they can easily be used in noncontact treatment mode (i.e., where the handpiece does not come in direct contact with the skin), which reduces the chance of skin movement during treatment and allows the handpiece to be held at different distances from the skin in order to manually adjust the beam size that is incident on the skin surface.
Multiple positional sensors can also be used, for example, to allow lower quality signals from each of the positional sensors. For example, an optical mouse type sensor can be used with a magnetic radiator coil measurement system. The combination of multiple sensors can also be used to shut the system down if large discrepancies were noted between or among the sensors. If different types of sensors were used, discrepancies can be used to provide additional information, for example, about whether the skin is being stretched. This information can be used to detect situations when the handpiece is not sliding properly and can be used to provide feedback to the system and reduce localized over- and under-treatments.
The ultrasonic transmitter-receiver pairs shown in
During certain types of photothermal treatment, dermal collagen is coagulated, which causes a loss of optical birefringence for the collagen. This change in birefringence can be measured by the imaging sensor 850 and can be used, for example, as the endpoint of a treatment pulse to control the duration of a treatment pulse. Additionally, this change in birefringence can be measured by the imaging sensor 850 and can be used to evaluate a skin response or characteristic which can then be used by the controller to control treatment density as well as other treatment parameters.
The polarizer 867 can be adjustable (automatically or manually) to make alignment easier or more precise or to allow comparison of cross polarization and parallel polarization images.
The example shown in
In another implementation of the skin sensor illustrated in
Using a skin response sensor 961 before treatment and another skin response sensor 960 after treatment allows the controller 915 to calculate the treatment density applied, or how the skin response has changed after treatment for a particular treatment density setting. The controller 915 can then make adjustments as appropriate to adjust the treatment parameters of the electromagnetic source 910 in order to adjust the treatment density. This feedback loop allows real time adjustment of treatment density.
An example of a feedback loop uses a first capacitive sensor 961 and a second capacitive sensor 960. Each capacitive sensor measures the percentage of skin that has been treated with a nonablative fractional resurfacing treatment. The first and second capacitive sensors 961, 960 are positioned in front of and behind the treatment window such that the first capacitive sensor 961 measures the percentage of skin that had been treated prior to the current pass of the handpiece and the second capacitive sensor 960 measures the percentage of skin that has been treated after the current pass of the handpiece over the target region. The difference between the measurements for the two sensors 960, 961 describes the percentage of skin treated during the current pass of the handpiece over the treatment region. The calculation of the percentage of skin treated during the current pass can be used, for example, to avoid over-treatment caused by bulk heating of tissue by reducing the laser treatment density when unusually high percentages are calculated. Other examples of appropriate feedback sensors 960, 961 are described in U.S. application Ser. No. 10/868,134, which is incorporated by reference herein.
The characteristics of the generated stress wave vary based on mechanical and optical characteristics of the skin. The probe wavelength can be chosen such that there is a difference in absorption within the skin between untreated and treated skin. Alternatively, the pulse conditions are chosen such that the mechanical response is different for treated and untreated skin. Thus, the stress wave that is created can be measured to determine whether the probed skin is approaching, has reached, or has exceeded a desired density of treatment. Examples of mechanical characteristics of the skin that can be probed using a stress wave include elasticity, tension, and mechanical damping of the skin.
The signature of the stress wave that is generated can be measured using several different techniques. One technique is illustrated in
A second technique for measuring the stress wave is to observe the change in reflectance pattern from a beam incident on the surface of the skin as shown in
The components 1162, 1163, and 1164 are similar to their analogs in
The optional contact window 1165 can be comprised of a transparent material, such as fused silica or sapphire, through which the probe beam 1163 passes.
The probe beam 1163 is absorbed by the skin 1150 to create a stress wave in the skin 1150. As described above for
The coherent illumination source 1172 can be a coherent source, for example a HeNe laser. The angle of the coherent illumination beam 1173 relative to the surface of the skin 1150 and the angle of the imaging system relative to the surface of the skin 1150 and relative to the coherent illumination beam 1173 can be aligned to maximize the measurement signal. Once a signal has been measured, the decay constant and resonant frequency of the stress wave can be measured with of the apparatii described by
With the techniques described in
The examples presented here have all illustrated the use of these techniques on human skin. This invention is also applicable to treatment of other tissues of the body. For example, puncturing the surface of toenails for treatment of nail fungus, altering the soft palate for treatment of disorders such as sleep apnea and snoring, removing hair, delivering pharmaceuticals or nutriceuticals through the skin or mucosa, or treating heart tissue can all benefit from the use of this invention.
Although the detailed description contains many specifics, these should not be construed as limiting the scope of the invention but merely as illustrating different examples and aspects of the invention. It should be appreciated that the scope of the invention includes other embodiments not discussed in detail above. For example, in many of the examples above, lasers are used as the embodiment, but these can be generalized to RF, flashlamp, or other electromagnetic energy based treatments as well. Various other modifications, changes and variations which will be apparent to those skilled in the art may be made in the arrangement, operation and details of the method and apparatus of the present invention disclosed herein without departing from the spirit and scope of the invention as defined in the appended claims. Therefore, the scope of the invention should be determined by the appended claims and their legal equivalents. Furthermore, no element, component or method step is intended to be dedicated to the public regardless of whether the element, component or method step is explicitly recited in the claims.
All publications, patents and patent applications cited herein, whether supra or infra, are hereby incorporated by reference in their entirety.
In the specification and in the claims, reference to an element in the singular is not intended to mean “one and only one” unless explicitly stated, but rather is meant to mean “one or more.” In addition, it is not necessary for a device or method to address every problem that is solvable by different embodiments of the invention in order to be encompassed by the claims.
This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 11/468,275, “Method and Apparatus for Monitoring and Controlling Thermally Induced Tissue Treatment,” by Kin F. Chan, George Frangineas, Leonard C. DeBenedictis, and Robert Kehl Sink, Aug. 29, 2006, from which priority is claimed and which is incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11468275 | Aug 2006 | US |
| Child | 11737696 | US |
