Determining absolute and relative tissue oxygen saturation

Cross-reference to description-related applications This application claims the interests of US Patent Applications 62 / 326,630, 62 / 326,644 and 62 / 326,673 filed April 22, 2016. These applications are hereby incorporated by reference, along with all other references cited in these applications.

Background of the Invention The present invention generally relates to an optical system for monitoring oxygen levels in a tissue. More specifically, the present invention includes an oximeter that includes a source and a detector on the sensor head of an optical probe and uses a locally stored simulated reflectance curve to determine tissue oxygen saturation, etc. Regarding the optical probe of.

An oximeter is a medical device used to measure the oxygen saturation of tissues in humans and living organisms for a variety of purposes. For example, the oximeter is for medical and diagnostic purposes in hospitals and other medical facilities (eg, ambulance or other mobility monitoring such as surgery, patient monitoring, or hypoxia); sports and exercise purposes in sports arenas. (Eg, monitoring of professional athletes); Individual monitoring by individuals or at home (eg, monitoring of general health, or training of people for marathons); and veterinary medical purposes (eg, animal monitoring). Used in.

Pulse oximeters and tissue oximeters are two types of oximeters that operate on different principles. A pulse oximeter requires a pulse to function. A pulse oximeter typically measures the absorbance of light from pulsating arterial blood. In contrast, a tissue oximeter does not require a pulse to function and can be used to make an oxygen saturation measurement of a tissue valve disconnected from the blood source.

As an example, human tissue contains various light absorbing molecules. Such chromophores include oxygenated hemoglobin, deoxygenated hemoglobin, melanin, water, lipids, and cytochromes. Oxygenated hemoglobin, deoxygenated hemoglobin and melanin are the most dominant chromophores in tissues for most of the visible and near-infrared spectral range. The absorption of light is significantly different for oxygenated hemoglobin and deoxygenated hemoglobin for light of a particular wavelength. The tissue oximeter can measure the oxygen level in human tissue by utilizing these light absorption differences.

<p>Despite the success of existing oximeteres, for example, improving measurement accuracy, reducing measurement time, lowering costs, reducing size, weight, or shape factors, reducing power consumption. , And for other reasons, and by any combination of these measurements, it is continuously desired to improve the oximeter.</p><p>In particular, assessing a patient's oxygenation status at both regional and local levels is important as it is an indicator of the patient's local tissue health. Therefore, oximeters are often used in clinical settings such as during surgery and recovery where the oxygenation of the patient's tissue may be suspected to be unstable. For example, during surgery, the oximeter must be able to quickly perform accurate oxygen saturation measurements under a variety of non-ideal conditions. Existing oximeters were sufficient for postoperative tissue monitoring where absolute accuracy was not important and only trend data was sufficient, but to determine if the tissue was viable or needed to be removed. Accuracy is required during surgery where spot testing can be used.</p><p>Therefore, there is a need for improved tissue oximeter probes and methods for making measurements using these probes.</p>

<p>Summary of the Invention The oximeter probe utilizes a relatively large number of simulated reflectance curves to quickly determine the optical properties of the tissue under examination. The optical properties of the tissue make it possible to further determine the oxygenated hemoglobin concentration and the deoxidized hemoglobin concentration of the tissue along with the oxygen saturation of the tissue.</p><p>In one embodiment, the oximeter probe can measure oxygen saturation without the need for a pulse or heart rate. The oximeter probe of the present invention is applicable to many medical fields including molding and surgical fields. The oximeter probe can measure oxygen saturation in pulsating tissue. Such tissue may be isolated from the body (eg, a piece of tissue) and will be transplanted elsewhere in the body. Aspects of the present invention are also applicable to pulse oximeters. In contrast to oximeter probes, pulse oximeters require pulsation to function. A pulse oximeter typically measures the absorption of light by pulsating arterial blood.</p><p>In one embodiment, relative values of oxygenation measurements, such as oxygen saturation measurements, are determined and displayed, and the use of an oximeter probe affects oxygen saturation over time, such as epinephrine or other drugs. The efficacy of the administered drug can be determined.</p><p>In one embodiment, one method is to bring the probe tip into contact with the patient's target tissue, to transmit the first light from the source structure of the oximeter probe to the target tissue in the first time, and from the target tissue. The first reflected light reflected is detected by a plurality of detector structures of the oximeter probe, and the first reflectance data of the first reflected light detected by the detector structure is generated by the detector structure. One of the simulated reflectance curves from the fact that the reflectance data is adapted to multiple simulated reflectance curves and that the first reflectance data is adapted to multiple simulated reflectance curves. Each simulated reflectance curve is associated with the value of the absorption coefficient, and the method further comprises the above, with respect to the first reflectance data of the simulated reflectance curve. To determine at least the first absorption coefficient for one or more curves that best fit, and to determine the first value of the first oxygen saturation based on the first absorption coefficient. It is provided with storing the first value of the oxygen saturation of 1 in the memory.</p><p>In this method, the second light is transmitted from the source structure of the oximeter probe to the target tissue at the second time, and the second reflected light reflected from the target tissue is transmitted to the target tissue by a plurality of detector structures of the oximeter probe. To detect by the detector structure, to generate the second reflectance data for the second reflected light detected by the detector structure by the detector structure, and to convert the second reflectance data into multiple simulated reflectance curves. Determining the best fit curve of one or more of the simulated reflectance curves from the fit and the fit of the second reflectance data to multiple simulated reflectance curves, and the simulated reflectance. Determining at least the second absorption coefficient for one or more of the curves that best fits the second reflectance data, and the second oxygen saturation based on the second absorption coefficient. Be prepared to determine the second value of.</p><p>The method is to retrieve the first value from memory, determine the percentage difference between the first and second values, and display the percentage difference on the display of the oximeter probe. And.</p><p>In certain embodiments, the system comprises an oximeter device, the oximeter device comprising a probe tip comprising a source structure and a detector structure on the distal end of the oximeter device, and a display in close proximity to the probe tip. , The oximeter device calculates the first oxygen saturation value, the second oxygen saturation value, and the relative oxygen saturation value between the first oxygen saturation value and the second oxygen saturation value. , Displaying the relative oxygen saturation value between the first oxygen saturation value and the second oxygen saturation value, the oximeter device is measured from the light source of the oximeter probe, especially during the first period. Light is transmitted to the first tissue to be to be, and the light reflected by the first tissue in response to the transmitted light in the first period is received by the detector of the oximeter probe, and in the second period, the light is received. The light source of the oximeter probe is configured to transmit light to the second tissue to be measured, the second period is after the first period, and the oximeter device is further to the transmitted light in the second period. In response, the light reflected by the second tissue is received by the detector of the oximeter probe to determine the first oxygen saturation value for the first tissue and the second oxygen saturation for the second tissue. It is configured to determine the value, calculate the relative oxygen saturation value between the first oxygen saturation value and the second oxygen saturation value, and display the relative oxygen saturation value on the display.</p><p>A system comprising an oximeter probe, the oximeter probe is housed in a handheld housing, a processor housed in the handheld housing, and housed in the handheld housing, electronically coupled to the processor to control the processor. A memory that stores the first code for, a display that is accessible from outside the handheld housing and is electronically coupled to the processor, and a display that is housed inside the handheld housing and coupled to the processor, memory, and display. Includes a processor, memory, and a battery that powers the display.</p><p>This code contains instructions that can be executed by the processor, which control the source structure of the oximeter probe during the first time to illuminate the patient's target tissue with the first light and from the target tissue. Controlling the detection of the reflected first reflected light by the multiple detector structures of the oximeter probe, and the first reflected light detected by the detector structure produced by the detector structure. From receiving reflectance data from the detector structure, adapting the reflectance data to multiple simulated reflectance curves, and adapting the first reflectance data to multiple simulated reflectance curves. It is for determining the best fit curve of one or more of the simulated reflectance curves, each simulated reflectance curve is associated with the value of the absorption coefficient, and the instructions are further simulated reflections. Determining at least the first absorption coefficient for one or more of the rate curves that best fits the first reflectance data, and the first oxygen saturation based on the first absorption coefficient. It is for determining the first value of degree and storing the first value of the first oxygen saturation in memory.</p><p>This code contains instructions that can be executed by the processor, which are reflected from the target tissue to control the source structure of the oximeter probe to illuminate the target tissue with a second light during the second time. The second reflected light is detected by multiple detector structures of the oximeter probe, and the second reflectance data is generated by the detector structure for the second reflected light detected by the detector structure. , One of the simulated reflectance curves from the adaptation of the second reflectance data to multiple simulated reflectance curves and the adaptation of the second reflectance data to multiple simulated reflectance curves. Determining one or more best fit curves and determining at least the second absorption coefficient for one or more of the simulated reflectance curves that best fits the second reflectance data. And for determining the second value of the second oxygen saturation based on the second absorption coefficient.</p><p>This code contains an instruction that can be executed by the processor, which retrieves the first value from memory and determines the percentage difference between the first and second values. It is for controlling the display of percentage differences on the display of the oximeter probe.</p><p>In one embodiment, one method is to bring the probe tip into contact with the patient's target tissue, to transmit the first light from the source structure of the oximeter probe to the target tissue in the first time, and from the target tissue. The first reflected light reflected is detected by a plurality of detector structures of the oximeter probe, and the first reflectance data of the first reflected light detected by the detector structure is generated by the detector structure. One of the simulated reflectance curves from the fact that the reflectance data is adapted to multiple simulated reflectance curves and that the first reflectance data is adapted to multiple simulated reflectance curves. Each simulated reflectance curve is associated with the value of the absorption coefficient, and the method further comprises for determining the first reflectance data of the simulated reflectance curves. Determining at least the first absorption coefficient for one or more curves that best fit, and determining the first value of the first micrometric value based on the first absorption coefficient, and microstructural measurement. It comprises storing the first value of the value in memory.</p><p>In this method, the second light is transmitted from the source structure of the oximeter probe to the target tissue at the second time, and the second reflected light reflected from the target tissue is transmitted to the target tissue by a plurality of detector structures of the oximeter probe. To detect by the detector structure, to generate the second reflectance data for the second reflected light detected by the detector structure by the detector structure, and to convert the second reflectance data into multiple simulated reflectance curves. Determining the best fit curve of one or more of the simulated reflectance curves from the fit and the fit of the second reflectance data to multiple simulated reflectance curves, and the simulated reflectance. Determine at least the second absorption coefficient for one or more of the curves that best fits the second reflectance data, and the second tissue measurement based on the second absorption coefficient. Be prepared to determine the second value of.</p><p>The method retrieves the first value from memory, determines the percentage difference between the first and second tissue measurements, and the first on the display of the oximeter probe. It comprises displaying the percentage difference between the tissue measurement of the first and the second tissue measurement.</p><p>Other objects, features and advantages of the invention will become apparent by taking into account the following detailed description and accompanying drawings. In drawings, similar reference symbols represent similar features throughout the drawing.</p>

<figref num="1">An embodiment of an oximeter probe is shown.</figref><figref num="2">The end view of the probe tip in an embodiment is shown.</figref><figref num="3">It is a block diagram of an oximeter probe in an embodiment.</figref><figref num="4A">Shown is a top view of an oximeter probe in an embodiment in which a display is adapted to display oxygen saturation values and total hemoglobin values.</figref><figref num="4B">Shown is a top view of an oximeter probe in an embodiment in which a display is adapted to display oxygen saturation and blood volume values.</figref><figref num="4C">FIG. 6 shows a top view of the oximeter probe 101 in an embodiment in which the display is adapted to display relative oxygen saturation values between two time points.</figref><figref num="4D">FIG. 6 shows a top view of the oximeter probe 101 in an embodiment in which the display is adapted to display relative oxygen saturation values between two time points.</figref><figref num="4E">The display shows a top view of the oximeter probe 101 showing the absolute oxygen saturation value and the relative oxygen saturation value.</figref><figref num="4F">The flow chart of the method of determining the value of the relative oxygen saturation of a tissue and displaying the value on a display is shown.</figref><figref num="4G">The flow chart of the method of determining the value of the relative oxygen saturation of a tissue and displaying the value on a display is shown.</figref><figref num="4H">The display shows the value of the relative oxygen saturation, and further shows the top view of the oximeter probe 101 which displays the arrow indicating the increase / decrease of the relative oxygen saturation.</figref><figref num="4I">The display shows the value of the relative oxygen saturation, and further shows the top view of the oximeter probe 101 which displays the arrow indicating the increase / decrease of the relative oxygen saturation.</figref><figref num="4J">A flow diagram of a method for determining the relative oxygen saturation value of a tissue, where the user inputs or selects a first value for oxygen saturation and the probe determines the latter second value for oxygen saturation. show.</figref><figref num="4K">A flow chart of a method for determining the optical properties of a tissue (eg, an actual tissue) by an oximeter probe in one embodiment is shown.</figref><figref num="5">FIG. 5 is a flow chart of a method for determining the optical properties of a tissue by an oximeter in an embodiment.</figref><figref num="6">FIG. 5 is a flow chart of a method for determining the optical properties of a tissue by an oximeter in an embodiment.</figref><figref num="7">Shown is an exemplary graph of a reflectance curve that may relate to a particular configuration of the source and detector structures, such as the configuration of the source and detector structures at the probe tip.</figref><figref num="8">Absorption coefficient μ of any unit for oxygenated hemoglobin, deoxidized hemoglobin, melanin, and water in tissues_aThe graph of the wavelength of the light is shown.</figref><figref num="9">Shown is a table of a database of tissue homogeneity models of simulated reflectance curves stored in memory of an oximeter probe in embodiments.</figref><figref num="10">Shown is a table of a database of layered models of texture of simulated reflectance curves stored in memory of an oximeter probe in embodiments.</figref><figref num="11A">Each row of the database is for a layered model of tissue, with four simulated reflectance curves for four wavelengths of light emitted from the simulated source structure and detected by the simulated detector structure. The table of the database for is shown.</figref><figref num="11B">Each row of the database is for a layered model of tissue, with four simulated reflectance curves for four wavelengths of light emitted from the simulated source structure and detected by the simulated detector structure. The table of the database for is shown.</figref><figref num="12A">FIG. 3 is a flow diagram of a method for determining the optical properties of a tissue (eg, actual tissue) with an oximeter probe, where the oximeter probe uses reflectance data and a simulated reflectance curve to determine the optical properties. ..</figref><figref num="12B">FIG. 3 is a flow diagram of a method for determining the optical properties of a tissue (eg, actual tissue) with an oximeter probe, where the oximeter probe uses reflectance data and a simulated reflectance curve to determine the optical properties. ..</figref><figref num="13">The flow chart of another method of determining the optical property of a tissue by an oximeter probe is shown.</figref><figref num="14">The flow chart of the method of weighting the reflectance data generated by a selective detector structure is shown.</figref>

Detailed Description of the Invention FIG. 1 shows an oximeter probe 101 in an embodiment. The oximeter probe 101 is configured to perform intraoperative and postoperative tissue oximetry measurements. The oximeter probe 101 may be a handheld device that includes a probe unit 105 and a probe tip 110 (also referred to as a sensor head) that may be located at the end of the sensing arm 111. The oximeter probe 101 is configured to measure the oxygen saturation of a tissue by irradiating the tissue with light such as near-infrared light from the probe tip 110 and collecting the light reflected from the tissue at the probe tip. ..

The oximeter probe 101 includes a display 115 or other notification device that notifies the user of the oxygen saturation measurement made by the oximeter probe. The probe tip 110 is described as being configured for use with the oximeter probe 101, which is a handheld device, but the probe tip 110 is a module with the probe tip at the end of a cable device that couples to the base unit. It can also be used with other oximeter probes such as the type oximeter probe. The cable device may be a disposable device configured for use with a single patient, and the base unit may be a device configured for repeated use. Such modular oximeter probes are well understood by those of skill in the art and will not be described further.

FIG. 2 shows an end view of the probe tip 110 in the implementation example. The probe tip 110 is configured to be in contact with the tissue from which the tissue oxygen concentration measurement should be made (eg, the patient's skin). The probe tip 110 has first and second source structures 120a and 120b (generally source structure 120) and first, second, third, fourth, fifth, sixth, seventh and eighth detectors. Includes structures 125a-125h (generally detector structure 125). In an alternative implementation, the oximeter probe contains more or less source structure, more or less detector structure, or both.

Each source structure 120 comprises one or more light sources, such as four light sources adapted to emit light (eg, infrared light) and producing the emitted light. Each light source can emit light of one or more wavelengths. Each light source can include light emitting diodes (LEDs), laser diodes, organic light emitting diodes (OLEDs), quantum dot LEDs (QMLEDs), or other types of light sources.

Each source structure can include one or more optical fibers that optically couple the light source to the surface 127 at the tip of the probe. In one implementation, each source structure contains four LEDs, including a single optical fiber that optically couples the four LEDs to the surface of the probe tip. In an alternative implementation, each source structure comprises two or more optical fibers (eg, four optical fibers) that optically couple the LED to the surface of the probe tip.

Each detector structure contains one or more detectors. In one embodiment, each detector structure comprises a single detector adapted to detect the light emitted from the source structure and reflected from the tissue. The detector can be a photodetector, a photoresistor, or another type of detector. The detector structure is arranged relative to the source structure so that two or more (eg, eight) unique source-detector distances are formed.

In one implementation, the shortest source-detector distances are approximately equal. For example, the shortest source-detector distance (S1-D4) between the source structure 120a and the detector structure 125d and the shortest source-detector distance (S2-S2-) between the source structure 120b and the detector structure 125a. It is almost equal to D8). The next longest source-detector distance between the source structure 120a and the detector structure 125e (eg longer than each of S1-D4 and S2-D8) (S1-D5), and the source structure 120b and the detector structure 125a. The next longest source-detector distance (S2-D1) between is approximately equal. The next longest source-detector distance between the source structure 120a and the detector structure 125c (eg longer than each of S1-D5 and S2-D1) (S1-D3), and the source structure 120b and the detector structure 125g. The next longest source-detector distance (S2-D7) between is approximately equal. The next longest source-detector distance between the source structure 120a and the detector structure 125f (eg longer than each of S1-D3 and S2-D7) (S1-D6), and the source structure 120b and the detector structure 125b. The next longest source-detector distance (S2-D2) between is approximately equal. The next longest source-detector distance between the source structure 120a and the detector structure 125c (eg longer than each of S1-D6 and S2-D2) (S1-D2), and the source structure 120b and the detector structure 125f. The next longest source-detector distance (S2-D6) between is approximately equal. The next longest source-detector distance between the source structure 120a and the detector structure 125g (eg longer than each of S1-D2 and S2-D6) (S1-D7), and the source structure 120b and the detector structure 125c. The next longest source-detector distance (S2-D3) between is approximately equal. The next longest source-detector distance between the source structure 120a and the detector structure 125a (eg longer than each of S1-D7 and S2-D3) (S1-D1), and the source structure 120b and the detector structure 125e. The next longest source-detector distance (S2-D5) between is approximately equal. Next longest source-detector distance between source structure 120a and detector structure 125hc (eg longest source-detector distance, S1-D1 and S2-D Longer than each of 5) (S1-D8) and the next longest source-detector distance (S2-D4) between source structure 120b and detector structure 125d are approximately equal. In other embodiments, the source-detector distances can all be unique or have nearly equal less than eight distances.

Table 1 below shows eight unique source-detector distances for an implementation. The increase between the nearest source-detector distance is about 0.4 mm.

<tables><img file="JP6992003B2_D0001.tif" /></tables>

In embodiments, two, three, each wavelength of light configured to be emitted by the oximeter probe, such as red light, infrared light, or both visible and infrared light in the visible spectrum. For every 4 or more wavelengths of light), the oximeter probe is at least less than about 1.5 mm, less than about 1.6 mm, less than about 1.7 mm, less than about 1.8 mm, less than about 1.9 mm, or less than about 2.0 mm. There are two sources-detector distance, and greater than about 2.5 mm, less than about 4 mm, less than about 4.1 mm, less than about 4.2 mm, less than about 4.3 mm, less than about 4.4 mm, less than about 4.5 mm, about 4.6 mm. Includes two source-detector distances that are less than, less than about 4.7 mm, less than about 4.8 mm, less than about 4.95 mm, or less than about 5 mm.

In one embodiment, the detector structures 125a and 125e are arranged symmetrically around a point on a straight line connecting the sources 120a and 120b. The detector structures 125b and 125f are arranged symmetrically around that point. The detector structures 125c and 125g are arranged symmetrically around that point. The detector structures 125d and 125h are arranged symmetrically around that point. This point can be centered on the connecting line between the source structures 120a and 120b.

The reflectance plot detected by the source-detector distance vs. detector structure 125 can provide a reflectance curve with the data points sufficiently spaced along the x-axis. These spacings in the distance between the source structures 120a and 120b and the detector structure 125 can reduce data redundancy and lead to the generation of relatively accurate reflectance curves.

In one embodiment, the source and detector structures can be placed at various locations on the probe surface to provide the desired distance (as shown above). For example, two sources form a line, and there are an equal number of detectors above and below this line. The position of the detector (above the line) is point symmetric with another detector (below the line) for the selected point on the line of the two sources. As an example, the selected point may, but does not necessarily have, be between the two sources. In other implementations, this positioning can be based on shapes such as circles, ellipses, oval, random, triangles, rectangles, rectangles, or other shapes.

The following patent applications describe various oximeter devices and oxygen measurement operations, and the discussions in the following patent applications can be combined with aspects of the invention described herein in any combination. The following patent applications, namely Patent Application Nos. 14 / 944,139 filed on November 17, 2015, Nos. 13 / 887,130 filed on May 3, 2013, and filed on May 24, 2016. No. 15 / 163,565, No. 13 / 887,220 filed on May 3, 2013, No. 15 / 214,355 filed on July 19, 2016, No. 13 / filed on May 3, 2013. 887,213, 14 / 977,578 filed December 21, 2015, 13 / 887,178 filed June 7, 2013, 15 / 220,354 filed July 26, 2016 , No. 13 / 965,156 filed on August 12, 2013, No. 15 / 359,570 filed on November 22, 2016, No. 13 / 887,152 filed on May 3, 2013, 2016 No. 29/561,749 filed on April 16, 2012, Nos. 61 / 642,389, 61 / 642,393, 61 / 642,395, 61 / 642,399, filed May 3, 2012, 2012 No. 61 / 682,146 filed on August 10, 2017, Nos. 15 / 493,132, 15 / 493,111, 15 / 493,121, filed on April 20, 2017, April 21, 2017. Filing 15 / 494,444, filing April 24, 2017, fifteen / 495,194, 15 / 495,205, and fifteen / 495,212 are all references cited in these applications. Also incorporated here by citation.

FIG. 3 shows a block diagram of the oximeter probe 101 in the implementation example. The oximeter probe 101 is a display 115, a processor 116, a memory 117, a speaker 118, one or more user-selected devices 119 (eg, one or more buttons, switches, touch input devices associated with the display 115), a source structure. Includes set 120, set 125 of detector structure, and power supply (eg, battery) 127. The components listed above may be connected together via bus 128, which may be the system bus architecture of the oximeter probe 101. This figure shows one bus connecting to each component, but this bus connection is any interconnection that helps connect these components or the other components contained in the oximeter probe 101. This is an example of the method. For example, the speaker 118 may be connected to a subsystem through a port or may have an internal direct connection to the processor 116. In addition, the components described are housed in a movable housing (see FIG. 1) of the oximeter probe 101 in the embodiment.

Processor 116 can include microprocessors, microcontrollers, multi-core processors, or other processor types. The memory 117 can include various memories such as volatile memory 117a (eg RAM), non-volatile memory 117b (eg disk or flash). Different embodiments of the oximeter probe 101 can include any number of enumerated components in any combination or configuration, including other components not shown.

The power supply 127 can be a battery such as a disposable battery. Disposable batteries are discarded after the stored charge is consumed. Some disposable battery chemistry techniques include alkali, zinc carbon, or silver oxide. The battery has sufficient stored charge to allow the use of the handheld device for several hours. In one embodiment, the oximeter probe can be discarded.

In another embodiment, the battery is rechargeable and the battery can be charged multiple times after the stored charge has been consumed. Some rechargeable battery chemistry technologies include nickel cadmium (NiCd), nickel metal hydride (NiMH), lithium ion (Li ion) and zinc air. For example, the battery can be charged via an AC adapter with a cord that connects to a handheld unit. The circuit system within the handheld unit can include a recharge circuit (not shown). The rechargeable battery chemical battery may be used as a disposable battery, and the battery is discarded after use without being recharged.

4A and 4B show a top view of the oximeter probe 101 in the embodiment. The top view shows that the display 115 is placed on the probe unit 105 at the top of the oximeter probe. The display is adapted to show one or more of the information about the oximeter probe and the measurements made by the probe.

In one embodiment, the display is adapted to display a tissue oxygen saturation 200 value ("oxygen saturation value") as measured by the oximeter probe. The display can display oxygen saturation as a percentage value, a bar graph with a number of bars in one or more colors (eg, if the display is a color display), or other displayable information.

The display can also be configured to display, for example, a value of 205 during which the oximeter probe has been operating since reset. The reset of the oximeter probe is from the first power increase of the previously unused battery (new battery) set to the power increase from the hard power down to the soft power down when the battery in the probe is changed. It can occur from a power rise from (eg hibernation mode) or in another reset event.

The display can display a total hemoglobin value of 225 by blood volume (FIG. 4A) or a blood volume value (eg, percentage of blood per volume of probed tissue, FIG. 4B). .. Measurements of total hemoglobin and blood volume with an oximeter probe are described below. In certain embodiments, the melanin display value is a value representing the hemoglobin concentration (eg, an index value), the hemoglobin concentration in the tissue volume is sampled, and the value may be a unitless value.

FIG. 4C shows a top view of the oximeter probe 101 in an embodiment in which the display is adapted to display the relative oxygen saturation value of the tissue. The relative oxygen saturation value is a percentage of the first value of oxygen saturation determined in the first time and the second value of oxygen saturation determined in the second time after the first time. It can be displayed as a difference.

In one embodiment, the oximeter probe can display other combinations of information such as absolute St02 and relative St02 values, total hemoglobin and relative St02 values, blood volume and relative hemoglobin values. FIG. 4E shows a top view of the oximeter probe 101 where the display displays absolute and relative oxygen saturation values.

FIGS. 4F to 4G show a flow chart of a method of determining a value of relative oxygen saturation of a tissue and displaying the value on a display. This flow chart represents one embodiment. Steps can be added, deleted, or combined with respect to the flow diagram without departing from the scope of the embodiment.

At 400, the input device (eg, a button such as button 119 or a second button on the oximeter probe, a rocker switch on the oximeter probe, or other input device) is activated. The input device can be activated by the user. Upon activation of the input device, the oximeter probe is put into a "relative" mode of operation and the oximeter probe can determine the value of tissue relative oxygen saturation. The oximeter probe may be set to relative mode by activating the button by pressing it twice relatively quickly (eg, "double-clicking"). A second activation of the input device (eg, subsequent double-clicking of a button) or activation of another input device (eg, third button) puts the oximeter device in "absolute" mode and the oximeter probe , The value of the absolute oxygen saturation of the tissue can be determined.

At 405, the oximeter probe 101 irradiates the tissue with light (eg, near-infrared light) from one of the source structures in the first period. After the irradiated light is reflected from the tissue, the detector structure 125 detects the light (step 410) and produces tissue reflectance data (step 415). Steps 405, 410, and 415 may be repeated for light of multiple wavelengths and for one or more other source structures such as source structure 120b.

At 420, the oximeter probe fits the reflectance data to the simulated reflectance curve 315 to determine the simulated reflectance curve with the best fit of the reflectance data. The database stored in memory and fitted to the reflectance data may be database 900, database 1000, or database 1100 described below. Then, in step 425, the oximeter probe is based on the optical properties of the simulated reflectance curve that best fits the reflectance data (eg μ in the case of Database 900 or Database 1000)._aAnd μ'_s, Or in the case of Database 1100, determine the melanin content, the first value of oxygen saturation, blood volume and scattering). For example, the oximeter probe is μ from database 900 or 1000_aAnd μ'_sWhen determining, the oximeter probe then has an absorption coefficient (μ)._a) Can be used to determine the first value of oxygen saturation. μ μ_aJudgment of the oxygen saturation value from is described below.

At step 430, the input device of the oximeter probe (eg, any or other input device described) is activated. When the input device is activated, the oxygen saturation value is stored in the memory of the oximeter probe (eg, memory 117, processor buffer memory, or other memory). The time stamp of the first value can also be stored.

At 435, the oximeter probe 101, in the second period after the first period, differs from patient to tissue (eg, two breasts or contralateral breast tissue of one breast, etc.) from one of the source structures. Irradiate light (eg, near-infrared light) into (possibly dislocated tissue). After the irradiated light is reflected from the tissue, the detector structure 125 detects the light (step 440) and produces reflectance data for the tissue (step 445). Steps 435, 440, and 445 may be repeated for light of multiple wavelengths and for one or more other source structures such as source structure 120b.

At 450, the oximeter probe fits the reflectance data to the simulated reflectance curve 315 to determine the simulated reflectance curve with the best fit of the reflectance data. The database stored in memory and fitted to the reflectance data may be database 900, database 1000, or database 1100 described below. Then, in step 455, the oximeter probe is based on the optical properties of the simulated reflectance curve that best fits the reflectance data (eg μ in the case of Database 900 or Database 1000)._aAnd μ'_s, Or in the case of database 1100, the second value of melanin content, the second value of oxygen saturation, the second value of blood volume and the second value of scattering). For example, the oximeter probe is μ from database 900 or 1000_aAnd μ'_sWhen determining, the oximeter probe then has an absorption coefficient (μ)._a) Can be used to determine the second value of oxygen saturation.

In step 460, the processor calculates the difference (eg, percentage difference) (eg, relative oxygen saturation) between the first and second values of oxygen saturation. At step 465, the difference in oxygen saturation or the difference in percentage is shown on the display. The relative oxygen saturation value is not available for display until after the second period and after the determination of the second oxygen saturation value. In one embodiment, the relative oxygen saturation value is symbolically displayed on the display and the second oxygen saturation value is above the first oxygen saturation value (eg, an up arrow is shown), the first. Indicates that it is below or equal to the oxygen saturation value of (eg, a down arrow) or equal to the first oxygen saturation value (eg, a dash or other symbol). When the symbol indicator is displayed, the oxygen saturation value may not be displayed. A symbol indicator may be displayed when the oxygen saturation value is displayed.

Steps 435-465 can be repeated in a continuous manner to calculate subsequent values of oxygen saturation (third, fourth, fifth and higher). Thereby, the oximeter probe determines and displays a continuous change in oxygen saturation at a later time with respect to the value of oxygen saturation at the first time. Entering and exiting relative mode can reset the first value of oxygen saturation.

The steps of the method shown in FIGS. 4F-4G are the first tissue measurement at the first time, the second tissue measurement at the second time (after the first period), and the second tissue measurement (after the second period). Can be repeated for multiple tissue measurements, such as a third tissue measurement at a third time, or more tissue measurements at a later time. The calculated and displayed relative oxygen saturation values are the first and second tissue measurements (eg, first relative oxygen saturation), the second and third tissue measurements (eg, second relative oxygen). It can be for saturation values), or for first and third tissue measurements (eg, third relative oxygen saturation). The first, second and third tissue measurements can be for two identical tissue locations, two different tissue locations, or three different tissue locations. The display of the first, second or third relative oxygen saturation values (eg, first, second and third operating modes) is user-input by the user (eg, button 119, touch screen, or other). Can be selected through the operation of (things).

Two or more of the three modes of operation can be operated simultaneously, with the first and second relative oxygen saturation values displayed simultaneously (eg, the third relative oxygen saturation value not displayed) and the second. And the third relative oxygen saturation are displayed at the same time (eg, the first relative oxygen saturation value is not displayed), and the first and third relative oxygen saturation values are displayed at the same time (eg, the second). Relative oxygen saturation values are not displayed).

In one embodiment, the percentage difference in oxygen saturation value (eg, relative oxygen saturation value) is greater than or less than the threshold amount, or the absolute value of oxygen saturation is greater than or less than the threshold amount. , May be adapted to provide notifications. The threshold amount can be an amount selected from the display amount displayed on the display, or input to the oximeter probe by wire or wirelessly, and input to the oximeter probe by the user. This amount can be the value entered in step 470 of FIG. 4J. If the percentage difference is above or below the threshold, the oxygen saturation values displayed are up arrow, down arrow, blinking display, colored display value (eg red or green), lit red LED, lit green. It may be displayed with one or more additional displays such as LEDs, a set of illuminated red pixels on the display (eg, red or green), or other displays. The oximeter probe may emit one or more sounds (eg, tones or clicks) or provide tactile feedback (eg, vibration) when the oxygen saturation percentage is above or below the threshold. You may. In some embodiments, one of these additional notifications is when the percentage difference is below the threshold (eg, oxygen saturation decreases) but does not exceed the threshold (eg, oxygen saturation does not increase). One or more is displayed.

Oxymeter probes are used when the percentage difference in oxygen saturation (eg, relative oxygen saturation) is greater than or less than the threshold, or the absolute value of oxygen saturation is above or below the threshold (eg, absolute). , Threshold + offset value, and threshold-offset value) can be adapted to display the percentage difference in oxygen saturation value. Offsets above and below the threshold are Threshold + 2% of Threshold and Threshold-2% of Threshold, Threshold + 5% of Threshold and Threshold-5% of Threshold, Threshold + 1% of Threshold and Threshold-5% of Threshold, Threshold. + Threshold 5% and threshold-2% of threshold, or other values, may be equal or unequal. Absolute percentages above and below the threshold may be selected by the user from the amount displayed on the display and input to the oximeter probe, or may be input to the oximeter probe by wire or wirelessly. If the percentage difference is above or below the threshold + or-absolute value offset, the oxygen saturation values displayed are up arrow, down arrow, blinking display, colored display value (eg red or green), It may be displayed with one or more additional displays such as a lit red LED, a lit green LED, a set of lit red pixels on the display (eg, red or green), or another display. The oximeter probe may emit one or more sounds (eg, tones or clicks) or provide tactile feedback (eg, vibration) when the oxygen saturation percentage is above or below the threshold. You may. In some embodiments, one of these additional notifications is when the percentage difference is below the threshold (eg, oxygen saturation decreases) but does not exceed the threshold (eg, oxygen saturation does not increase). One or more is displayed. In some embodiments, one of these additional notifications is when the percentage difference is below the threshold (eg, oxygen saturation decreases) but does not exceed the threshold (eg, oxygen saturation does not increase). One or more is displayed.

In one embodiment, the difference between the first and second values of oxygen saturation is displayed instead of the percentage difference between the first and second values of oxygen saturation. Be adapted. The oximeter probe can display percentage differences or calculated differences at one or more of the various indicators that indicate an increase or decrease in relative oxygen saturation. For example, the reduced relative oxygen saturation value is a down arrow (Figure 4H) with a colored indicator (eg, a red dot on the display or a lit red lighting element such as a red LED on the probe 105). Can be displayed with. For example, the increased relative oxygen saturation value is an upward arrow (Figure 4I), a colored indicator (eg, a green dot on the display or a lit green lighting element such as a green LED on the probe 105). ) Can be displayed. The relative oxygen saturation value may be displayed in the first color (eg red) as the value decreases and in the second color (eg green) as the value increases. The oximeter probe can display the value as, for example, blinking, when the value of the percentage difference or the value of the calculated difference decreases. The oximeter probe can be adapted to emit one or more noises, for example, when these values are reduced. The oximeter probe can be adapted to provide tactile feedback (eg, vibration) when these values decrease. If relative oxygen saturation decreases below the lower threshold, increases above the upper threshold, or both, these additional indicators (eg, arrow, illumination, flashing display, color, sound, etc.) It can emit tactile feedback, or the value displayed by other indicators).

Relative modes of operation are numerous, with knowledge of relative changes in oxygen saturation (relative oxygen saturation) values helping to determine whether a medical procedure should be started, advanced, or stopped. May be useful for medical procedures. For example, to reduce blood flow in the tissue, epinephrine infusion or other drug may be administered to the patient (eg, locally administered to the tissue) to reduce blood flow in the tissue. Before administering epinephrine or in a relatively short time after administration of other drugs to the patient, the hemoglobin content or baseline value of blood volume in the tissue can be determined (eg, in steps 405-425, hemoglobin content. The first value of volume or blood volume is determined, for example, using the database 1100 described below).

Then, based on the ongoing display of the updated relative hemoglobin or blood flow values (eg, in steps 435-425, eg, using database 1100, a second value for hemoglobin content or blood flow). The practitioner decides whether epinephrine administration has been successful in reducing blood flow and whether more epinephrine needs to be given to the patient to further reduce blood flow in the tissue. , Or whether the procedure should be stopped. That is, the oximeter probe displays updated relative hemoglobin or blood volume values so that the practitioner can "observe" the medication acting on the tissue.

FIG. 4J shows a flow chart of a method of determining a value of relative oxygen saturation of a tissue and displaying the value on a display. This flow chart represents one embodiment. Steps can be added, deleted, or combined with respect to the flow diagram without departing from the scope of the embodiment.

At the 470, the oximeter receives a first value of oxygen saturation via an input such as a user input or an input from another device. User input may be input via one or more button presses or other input devices such as a touch screen. A first value of oxygen saturation may be input to the oximeter probe via a wired or wireless connection to the oximeter probe. In some embodiments, the oximeter probe can display a range of first values of oxygen saturation that can be selected by the user, for example by pressing a button or other input.

At 471, the oximeter probe 101 irradiates the tissue with light (eg, near-infrared light) from one of the light source structures. After the irradiated light is reflected from the tissue, the detector structure 125 detects the light (step 472) and produces reflectance data for the tissue (step 473). Steps 471, 472, and 473 may be repeated for light of multiple wavelengths and for one or more other source structures such as source structure 120b.

At 474, the oximeter probe fits the reflectance data to the simulated reflectance curve 315 and finds the simulated reflectance curve with the best fit of the reflectance data. The database stored in memory and fitted to the reflectance data may be database 900, database 1000, or database 1100 described below. Then, in step 475, the oximeter probe is based on the optical properties of the simulated reflectance curve that best fits the reflectance data (eg μ in the case of Database 900 or Database 1000)._aAnd μ'_s, Or in the case of database 1100, the second value of melanin content, the second value of oxygen saturation, the second value of blood volume and the second value of scattering). For example, the oximeter probe is μ from database 900 or 1000_aAnd μ'_sWhen determining, the oximeter probe then has an absorption coefficient (μ)._a) Can be used to determine the second value of oxygen saturation.

In step 460, the processor calculates the difference (eg, percentage difference) between the first and second values of oxygen saturation. At step 477, the percentage difference in oxygen saturation values is shown on the display.

Steps 471-477 can be repeated in a continuous manner to calculate subsequent values of oxygen saturation (third, fourth, fifth and higher). Thereby, the oximeter probe determines and displays a continuous change in oxygen saturation at a later time with respect to the value of oxygen saturation at the first time. Entering and exiting relative mode can reset the first value of oxygen saturation.

Tissue Analysis Figure 4K is a flow diagram of a method for determining the optical properties of a tissue (eg, actual tissue) with an oximeter probe 101 in one embodiment. The oximeter probe uses the melanin content determined for the tissue to correct the various tissue parameters measured by the oximeter probe. This flow chart represents one embodiment. Steps can be added, deleted, or combined with respect to the flow diagram without departing from the scope of the embodiment.

At 480, the melanin reader optically binds (eg, contacts) the tissue. The melanin reader is an optoelectronic device adapted to irradiate the tissue with light in step 482 and detect the light in step 484 after the light has passed through or reflected from the tissue. In step 486, the light detected by the melanin reader is converted into an electrical signal and used by the device in step 488 to determine the melanin content of the tissue. The melanin reading unit can output the value of the melanin content on the display of the reading unit or via a wired or wireless output in step 490.

In an embodiment, at 492, information about the melanin content (eg, numerical value) is input to the oximeter probe 101. Information can be input to the oximeter probe via a user (eg, a human user) or via wired or wireless communication between the melanin reader and the oximeter probe.

In a first embodiment, at 494, the oximeter probe uses information about the melanin content to adjust one or more measurements produced by the probe. In one embodiment, the oximeter probe determines the value of oxygen saturation in the tissue. The oximeter probe then adjusts the oxygen saturation value with information about the melanin content. Oxymeter probes can adjust oxygen saturation values via one or more arithmetic operations, mathematical functions, or both. For example, information about melanin content can be used as an offset (eg, additive offset), scale factor, or both for adjusting oxygen saturation values.

In an alternative embodiment, at 494, the oximeter probe has an absorption coefficient μ for tissue for several wavelengths of light emitted and detected by the oximeter probe (eg, four wavelengths of light)._a, Reduced scattering factor μ_s'Or judge both of them. The oximeter probe then uses the information about the melanin content to determine the absorption (μ) for each wavelength of light._a) Adjust the value. The oximeter probe has an absorption coefficient (μ) via one or more arithmetic operations, mathematical functions, or both._a) The value can be adjusted. For example, information about melanin content can be absorbed (μ)._a) Can be used as an offset to adjust the value (eg, an additive offset), a scale factor, or both. The oximeter probe is then absorbed (μ)_a) Values are used to determine the oxygen saturation value of the tissue. Absorption (μ_a) And reduced scattering (μ)_sThe judgment of') is described below.

In another embodiment, in 494, the oximeter probe applies one or more melanin correction functions to the reflectance data generated by the detector structure. The melanin correction function is based on information about melanin content. The reflectance data can be analog reflectance data or digitized reflectance data that is then digitized by one or more electronic components of the oximeter probe generated by the detector structure. The melanin correction function can be applied to analog reflectance data or digitized reflectance data. The melanin correction function contains one or more mathematical operations applied to the reflectance data. The scale factor is determined by the oximeter probe based on the information about the melanin content input to the oximeter probe. The reflectance data can be adjusted for the melanin content for each wavelength of light emitted by the oximeter probe.

In certain embodiments, the melanin correction function can be a coupling function (eg, having a scale factor) combined with one or more calibration functions (eg, having a scale factor). The calibration function may include scale factors to correct the detector response based on various factors such as differences resulting from manufacturing, differences resulting from temperature drift of the detector structure, or other considerations. can. After the reflectance data is adjusted by the oximeter probe, the probe can determine the oxygen saturation of the blood in the tissue to be measured.

FIG. 5 shows a flow chart of a method for determining the optical properties of a tissue by the oximeter probe 101 in the embodiment. The oximeter probe uses information about the melanin content of the tissue to correct the various tissue parameters measured by the oximeter probe. This flow chart represents one embodiment. Steps can be added, deleted, or combined with respect to the flow diagram without departing from the scope of the embodiment.

At 500, the tissue color is compared to two or more color samples from several color samples (sometimes called color swatches) to determine if one color in the color sample closely matches the tissue color. .. Each color sample used for color comparison is associated with a melanin content value. Information that identifies the melanin content of the color sample (eg, numerical value) can be located on the color sample.

Comparison of tissue color to color sample color can be done with color comparison tools such as one or more of the X-Rite, Incorporated color comparison tools in Grand Rapids, Michigan. In embodiments, the comparison can be performed visually by a human such as a patient or healthcare provider. In one embodiment, the oximeter probe is adapted to determine the value of tissue melanin content, which can be displayed on the probe's display. One embodiment of the oximeter probe is adapted to illuminate one or more wavelengths of light, such as visible light or IR, to determine the melanin content of the tissue.

At 505, following the comparison, the value of the melanin content of the tissue is determined based on the comparison.

In an alternative embodiment, the melanin content value is determined from a content estimate based on a finite range of melanin content values. The number of values within the range of melanin content can include more than one value. For example, the number of values within the range of melanin content is 2 (eg 1 for light tissue, 2 for dark tissue) and 3 (eg 1 for light color, neutral color). Can contain 2, dark colors 3), 4, 5, 6, 7, 8, 9, 10 or more. Estimates of melanin content values may be provided by the patient or healthcare provider.

At 510, information about the melanin content can be input to the oximeter probe. Step 510 can be skipped by the way the oximeter probe determines the value of melanin content. Button 119 can be activated a predetermined number of times to set the oximeter probe in a data entry mode in which information about the melanin content can be entered. The melanin content information is then given by further activation of the button, through wired communication with the probe, wireless communication with the probe, and through the display if the display is a touch interface display, a voice interface (eg, a microphone in the probe). And voice recognition software), or other input technology can be input to the probe.

At 515, the oximeter probe is adapted to use information about the melanin content to coordinate one or more measurements or calculations performed by the oximeter probe. For example, an oximeter probe uses this information to regulate tissue oxygen saturation and absorb (μ)._a) To reduce scattering (μ)_s') Can be adjusted, the value produced by the detector can be adjusted, or one or more of these adjustment combinations can be adjusted. Each of these adjustments is described further above with respect to step 435.

FIG. 6 is a flow chart of a method for determining the optical properties of a tissue by an oximeter probe 101 in an embodiment. The oximeter probe uses the melanin content determined for the tissue to correct the various tissue parameters measured by the probe. This flow chart represents one embodiment. Steps can be added, deleted, or combined with respect to the flow diagram without departing from the scope of the embodiment.

At 600, one or more contralateral measurements of tissue are made with an oximeter probe. The contralateral measurement is a portion of healthy tissue (eg, healthy breast tissue) before measuring with an oximeter probe on the target tissue to be measured (eg, breast tissue for which tissue health should be determined). This is done above using an oximeter probe. Contralateral measurements of tissue can be made for each wavelength of light emitted by the oximeter probe.

At 605, the reflectance data generated by the detector structure is digitized by the electronic elements of the oximeter probe and stored in memory. Reflectance data provide the basis for comparison for subsequent tissue measurements. For example, the contralateral measurement provides a baseline measurement of the melanin content of the contralateral tissue, and the baseline measurement can be used by the processor to correct various measurements of the oximeter probe.

At 610, an oximetry of the target tissue to be measured is performed by an oximeter probe.

In an embodiment, at 615, the processor uses an oximetry measurement to generate an oxygen saturation value for the target tissue. The processor then retrieves the stored reflectance data stored at 605 for the contralateral tissue and adjusts the oxygen saturation value using the retrieved values. That is, the processor uses baseline measurements of healthy contralateral tissue melanin content to adjust the oxygen saturation value of the target tissue.

In another embodiment, at 615, the processor absorbs μ from an oximetry measurement of the target tissue._a, Reduced scattering factor μ_s'Or both. The processor then retrieves the reflectance data stored in 605 for the contralateral tissue and uses the retrieved values to μ._a, Μ_s, Or both. Next, the processor is tuned μ_aThe values are used to calculate oxygenated hemoglobin, deoxygenated hemoglobin, or other values for the target tissue. That is, the processor uses baseline measurements of melanin content in healthy contralateral tissue to μ the target tissue._aTo adjust.

In 615, in another alternative embodiment, the processor retrieves the stored reflectance data stored in 605 for the contralateral tissue and uses the retrieved values by the detector structure for the target tissue. Adjust the generated reflectance data. The adjustments applied by the processor to the reflectance data are simple offsets (eg, additive offsets), scale factors (eg, multiplying offsets), functional corrections, other corrections, or any combination of these adjustments. Can be. That is, the processor adjusts the reflectance data of the target tissue by adjusting the value produced by the detector structure using the baseline measurement of the melanin content of the healthy tissue.

A memorized simulated reflectance curve. According to one embodiment, the memory 117 stores some Monte Carlo simulated reflectance curves 315 ("simulated reflectance curves") that may be generated by a computer for later storage in memory. Each of the simulated reflectivity curves 315 is irradiated from one or more simulated source structures into the simulated tissue, from the simulated tissue to one or more simulated detector structures. Represents a simulation of reflected light (eg near infrared). The simulated reflectivity curve 315 is a simulated source, such as the configuration of the source structure 120a-120b and the detector structure 125a-125h of the probe tip 110 with the source-detector distance, as described above with respect to FIG. For a particular configuration of the structure and the simulated detector structure.

Therefore, the simulated reflectance curve 315 models the light emitted from the source structure of the oximeter probe 101 and collected by the detector structure of the oximeter probe 101. In addition, each of the simulated reflectance curves 315 represents a unique actual tissue state such as a particular tissue absorption value and a tissue scatter value for a particular concentration of tissue chromophores and a particular density of tissue scatterers. For example, simulated reflectivity curves include different melanin content, different oxygenated hemoglobin concentrations, different deoxygenated hemoglobin concentrations, different water concentrations, static values of water concentration, different concentrations of fat, etc. Static values of fat concentration, or various absorptions (μ)_a) Value and reduced scattering (μ)_s') Used for values.

The number of simulated reflectance curves stored in memory 117 may be relatively large and may not be all of the optical and tissue properties that may be present in the actual tissue analyzed for viability by the oximeter probe 101. But it can represent almost any practical combination. Although memory 117 is described herein as storing a Monte Carlo simulated reflectance curve, memory 117 captures simulated reflectance curves generated by methods other than the Monte Carlo method, such as using a diffusion approximation. You may remember.

FIG. 7 shows an exemplary graph of a reflectance curve that may be for a particular configuration of source structure 120 and detector structure 125, such as the configuration of the source structure and detector structure of probe tip 110. .. The horizontal axis of the graph represents the distance between the source structure 120 and the detector structure 125 (ie, the source-detector distance). If the distance between the source structure 120 and the detector structure 125 is properly selected and the simulated reflectivity curve is a simulation for the source structure 120 and the detector structure 125, then between the data points in the simulated reflectivity curve. The lateral spacing is relatively uniform. Such uniform spacing can be seen in the simulated reflectance curve of FIG. The vertical axis of the graph represents the simulated reflectance of the light reflected from the tissue and detected by the detector structure 125. As shown by the simulated reflectivity curve, the reflected light that reaches the detector structure 125 varies with the distance between the source structure and the detector structure and is detected at a smaller source-detector distance. Is greater than the reflected light detected at the larger source-detector distance.

FIG. 8 shows the absorption coefficient μ for some important tissue chromophores, namely blood containing oxygenated hemoglobin, blood containing deoxygenated hemoglobin, melanin, and water._aThe graph of the wavelength of the light is shown. In one embodiment, the Monte Carlo simulation used to generate the simulated reflectance curve is a function of one or more selective chromophores that may be present in the tissue. The chromophore can include melanin, oxygenated hemoglobin, deoxygenated hemoglobin, water, lipids, cytochromes or other chromophores in any combination. Oxygenated hemoglobin, deoxygenated hemoglobin and melanin are the most dominant chromophores in tissues for most of the visible and near-infrared spectral range.

According to one embodiment, the memory 117 stores a selected number of data points for each of the simulated reflectance curves 315 and may not store the entire simulated reflectance curve. The number of data points stored for each of the simulated reflectance curves 315 may match the number of source-detector pairs. For example, if the probe tip 110 contains two source structures 120a and 120b and eight detector structures 125a-125h, the oximeter probe 101 contains 16 source-detector pairs and the memory 117 is therefore the source. 16 selected data points can be stored for each simulated reflectance curve of each wavelength of light emitted by the structure 120a or 120b. In embodiments, the stored data points are for a particular source-detector distance of probe tip 110, such as those shown in Table 1.

Therefore, the size of the simulated reflectance curve database stored in memory 117 can be 16 × 5850, with 16 points for each curve generated and illuminated by each source structure 120 and measured by each detector structure 125. It can be remembered and there are a total of 5850 curves over the optical characteristic range. Alternatively, the size of the simulated reflectance curve database stored in memory 117 can be 16x4x5850, with 16 points per curve for each of the four different wavelengths produced and emitted by each source structure. It is memorized and has a total of 5850 curves over the optical characteristic range. The 5850 curves have, for example, 39 scattering coefficients μ._s'Values and 150 absorption coefficients μ_aDerived from a matrix of values. In other embodiments, more or fewer simulated reflectance curves are stored in memory. For example, the number of simulated reflectance curves stored in memory can range from about 100 curves to about 250,000 curves, about 400,000 curves, or more.

Reduced scattering coefficient μ_s'The range of values may be from 5: 5: 24 per centimeter. μ μ_aThe range of values may be from 0.01: 0.01: 1.5 per centimeter. The above range is an example, and the number of source-detector pairs, the number of wavelengths produced by each source structure, and the number of simulated reflectance curves may be smaller or larger. Will be understood.

FIG. 9 shows a database 900 of simulated reflectance curves 315 stored in memory of an oximeter probe in an embodiment. This database is for a homogeneous model of tissue. Each row in the database is irradiated to the simulated tissue from two simulated source structures (eg, source structures 120a-120b) and eight simulated detectors after reflection from the simulated tissue. Shown is a simulated reflectance curve generated from a Monte Carlo simulation for simulated light detected by a structure (eg, detector structures 125a-125h). The Monte Carlo simulation used to generate the simulated reflectance curve for the database is for a homogeneous tissue model. The simulated tissue for the homogeneous tissue model has homogeneous optical properties from the tissue surface through the epidermis, dermis and subcutaneous tissue. That is, the optical properties of the epidermis, dermis and subcutaneous are the same in the Monte Carlo simulation. In the database, each of the simulated reflectance curves is absorbed (μ)._a) Value and reduced scattering (μ)_s') Associated with the value. Each of the simulated reflectance curves in the database can be associated with the values of other chromophores.

A database of simulated reflectance curves can contain actual values of simulated reflectance (eg, floating point values), or indexed values against actual values of simulated reflectance (eg, floating point values). For example, a binary value) can be included. As shown in Figure 9, the database contains indexed values (eg, binary values) relative to the actual value of the simulated reflectance. The database can contain binary words of various lengths, depending on the accuracy of the entry, for example. Binary words can be 2 bits long, 4 bits long, 8 bits long, 16 bits long, 32 bits long, or any other length.

In one embodiment, one or more mathematical transformations are applied to the simulated reflectance curve before entering the values of the simulated reflectance curve into the database. Mathematical transformations can improve the fit of the reflectance data generated by the detector structure to the simulated reflectance curve. For example, a logarithmic function can be applied to the simulated reflectance curve to improve the fit of the measured data generated by the detector structure to the simulated reflectance curve.

When the oximetry measurement is made, the reflectance data for each wavelength of the emitted light is detected by the detector structure and individually fitted to the simulated reflectance curve of Database 900. The oximeter probe absorbs μ for the reflectance data of each wavelength of the irradiation light conforming to the simulated reflectance curve._a, Reduced scattering μ_s'Or determine both of these values. For example, the first set of reflectance data for light of the first wavelength is fitted to the simulated reflectance curve to absorb μ._aAnd reduced scattering μ_sDetermine one or more of'(eg, the first set of organizational parameters). Fitting the reflectance data to the simulated reflectance curve is described further below.

The second set of reflectance data for light of the second wavelength is then fitted to the simulated reflectance curve of Database 900 and absorbed μ for the second wavelength._aAnd reduced scattering μ_sDetermine one or more of'(eg, the second set of organizational parameters). The third set of reflectance data for light of the third wavelength is then fitted to the simulated reflectance curve of Database 900 to absorb μ._aAnd reduced scattering μ_sDetermine one or more of'(eg, the third set of organizational parameters). Then, the set of the fourth reflectance data for the light of the fourth wavelength is adapted to the simulated reflectance curve of the database 900, and the absorption μ is applied for the fourth wavelength._aAnd reduced scattering μ_sDetermine one or more of'(eg, the fourth set of organizational parameters).

Four sets of tissue parameters can be used together by an oximeter probe to determine various values of tissue, such as oxygenated hemoglobin concentration, deoxygenated hemoglobin concentration, melanin content, or other parameters.

FIG. 10 shows a database 1000 of simulated reflectance curves stored in the memory of an oximeter probe in an embodiment. The database is for a layered model of tissue (eg, layered skin). The Monte Carlo simulation that generated the simulated reflectance curve uses a layered texture model for the simulation. The layered structure can include two or more layers. In one embodiment, the layered tissue comprises two tissue layers. The two panniculi have different absorption μ_a, Reduced scattering μ_s'Or have different optical properties, such as both of these properties.

In one embodiment, the first simulated panniculus is for the epidermis and the second simulated panniculus is for the dermis. The thickness of the epidermis used in the Monte Carlo simulation can range from about 40 microns to about 140 microns. For example, the thickness of the epidermis can be 40 microns, 50 microns, 60 microns, 70 microns, 80 microns, 90 microns, 100 microns, 110 microns, 120 microns, 130 microns, 140 microns or other thicknesses. The thickness of the dermis used in the Monte Carlo simulation can range from less than 1 millimeter to virtually infinite thickness, eg 12 millimeters or more.

When a simulated reflectance curve is generated for the dermis, one or more optical properties of the epidermis can fluctuate. For example, when a simulated reflectance curve is generated for the dermis, the melanin content can vary for the epidermis. Alternatively, when a simulated reflectance curve is generated for the dermis, μ_aCan vary with respect to the epidermis.

In one embodiment, the database 1000 includes a simulated reflectance curve for the light reflected by the combination of epidermis and dermis.

For the actual tissue measured by the oximeter probe, the reflectance data for each wavelength of light emitted by the source structure and detected by the detector structure is fitted to the simulated reflectance curve one at a time by the processor. To. Based on the fit of one or more simulated reflectance curves in the database, the oximeter probe absorbs μ for one or both layers of real tissue._aAnd reduced scattering μ_s'Judge one or both. Absorption determined for one layer (μ_a) Value, the oximeter probe determines the oxygenated and deoxygenated hemoglobin concentrations of the tissue.

11A-11B show a database 1110 of simulated reflectance curves stored in the memory of the oximeter probe in embodiments. The database is for a layered model of the organization. Each row of the database contains a simulated reflectance curve for each of the four wavelengths of light emitted from the simulated source structure and detected by the simulated detector structure. Each row of the four simulated reflectance curves contains 16 values for each simulated reflectance curve. More specifically, each row contains 16 values for the 16 source-detector distances of source structures 120a-120b and detector structures 125a-125h. In total, each row is illuminated from two simulated source structures and has 64 values for four simulated reflectance curves for four wavelengths of light detected by eight simulated detector structures. include.

If more or less wavelengths are emitted from the source structure, the layered model of the texture of Database 1110 can include more or less simulated reflectance curves per row. Database 1110 may include, for example, one or more source structures in the probe tip, more or less detector structures in the probe tip, or both. For each of the rate curves, it can contain more or less than 16.

Each of the four simulated reflectance curves for each row in Database 1110 is associated with four tissue parameters including melanin content, blood volume, scatter, and oxygen saturation (ratio of oxygenated hemoglobin to total tissue hemoglobin). Be done. Database 1110 can contain more or fewer organizational parameters.

When the set of detector values produced by the detector structure 125a-125h for the tissue to be measured by the oximeter probe is fitted to one or more of the rows by the processor, the oximeter probe thereby contains melanin. One or more of the tissue parameters such as volume, blood volume, scattering, and oxygen saturation are determined in any combination. In one embodiment, the oximeter probe is adapted to determine the oxygen saturation of the tissue and display the oxygen saturation value on the display.

As briefly described above, database 1110 includes a simulated reflectance curve 315 for a layered tissue model. The simulated layer of tissue can include the epidermis, dermis, subcutaneous tissue, or any combination of one or more of these layers. These layers can include higher resolution of skin morphology such as reticular dermis and superficial plexus. A Monte Carlo simulation that produces a simulated reflectance curve can simulate the texture of various chromophores contained in the panniculus. For example, Monte Carlo simulations can use tissue models for epidermis with different melanin contents, but may not use tissue models for epidermis containing blood. Monte Carlo simulations can use tissue models for the dermis layer with different blood volumes and different oxygen saturations. In certain embodiments, the Monte Carlo simulation does not use a tissue model for the dermis containing melanin. Similarly, Monte Carlo simulations can use tissue models of adipose tissue with different blood volumes and different oxygen saturations. In certain embodiments, the Monte Carlo simulation does not use a tissue model for adipose tissue with melanin. The tissue model of the panniculus can include concentrations for other tissue chromophores, such as water and fat, where the concentration of other tissue chromophores is a relatively typical physiological value.

In one embodiment, the various chromophore concentrations used by the Monte Carlo simulation to generate the simulated reflectance curve are relatively large and relatively accurate ranges of the actual physiological values present in the actual tissue. Over. The number of values within the range of actual physiological values can be varied to balance the various parameters of the tissue oximeter measurement. For example, the number of values used for the range of chromophore concentrations in the simulated tissue can be relatively high or low and can affect the accuracy of the measurements made by the oximeter probe. In one embodiment, a value of 355 is used in the Monte Carlo simulation for the range of melanin content for light absorption in the simulated epidermal tissue. In one embodiment, a value of 86 is used in the Monte Carlo simulation for the range of melanin content for light absorption in the simulated dermal tissue. For scattering in both simulated epidermal and simulated dermal tissue, a value of 65 is used in the Monte Carlo simulation. In other embodiments, the number of these values varies.

Tissue Analysis FIGS. 12A-12B determine the optical properties of tissue (eg, skin) by the oximeter probe, where the oximeter probe 101 uses reflectance data and a simulated reflectance curve 315 to determine the optical properties. It is a flow chart of the method for. The optical characteristics are the absorption coefficient μ of the structure._aAnd reduced scattering factor μ_s'Can include. Tissue absorption coefficient μ_aFurther methods for converting tissue to oxygen saturation values are described in more detail below. This flow chart represents one embodiment. Steps can be added, deleted, or combined with respect to the flow diagram without departing from the scope of the embodiment.

At 1200, the oximeter probe 101 emits light (eg, near-infrared light) into the tissue from one of the source structures 120, such as the source structure 120a. The oximeter probe is generally in contact with the tissue when it is emitting light from the source structure. After the irradiation light is reflected from the tissue, the detector structure 125 detects a portion of this light in step 1205 and generates a reflectance data point for the tissue in step 1210. Steps 1200, 1205, and 1210 can be repeated for multiple wavelengths of light (eg, red light, near-infrared light, or both), and for one or more other source structures, such as source structure 120b. A reflectance data point at one wavelength may contain 16 reflectance data points, for example if the tissue oximetry probe 115 has 16 source-detector distances. The reflectance data point is sometimes referred to as the N vector of the reflectance data point.

At 1215, the reflectance data points (eg, raw reflectance data points) are corrected for the gain of the source-detector pair. During the calibration of the source-detector pair, a gain correction is generated for the source-detector pair and stored in memory 117. The generation of gain correction will be described in more detail below.

At 1220, processor 116 fits the reflectance data points to the simulated reflectance curve 315 (eg, via residual squared sum calculation) and best fits the reflectance data points (ie, has the lowest fit error). Find a specific reflectance data curve. The database stored in memory and fitted to the reflectance data can be database 900, database 1000, or database 1100. In one particular embodiment, a relatively small set of simulated reflectance curves, which is a "coarse" grid in the database of simulated reflectance curves, is selected and utilized in fitting step 1220. For example, 39 scattering coefficients μ_s'Values and 150 absorption coefficients μ_aFor the database 900 given values, the coarse grid of simulated reflectance curves has a scattering coefficient of μ every 5 for a total of 40 simulated reflectance curves in the coarse grid by processor 116._s'Value and absorption coefficient μ every 8_aMay be sought by taking. It will be appreciated that the specific values above are for embodiments of the example and that coarse grids of other sizes may also be utilized by processor 116. The result of adapting the reflectance data points to the coarse grid is the coordinates (μ) in the coarse grid of the simulated reflectance curve that best fits._a, μ_s’)_coarseIs. For Database 1000, the coarse grid covers the absorption of each layer and the reduced scattering. Each of the following steps on the method for Database 1000 is μ for each layer_a, And μ_s'Adjusted about. For Database 1100, the coarse grid covers melanin content, oxygen saturation, blood volume, and scattering. Each of the following steps of the method for database 1100 is μ_a, And μ_s'Instead of being adjusted for melanin content, oxygen saturation, blood volume, and scattering.

In 1225, a specific simulated reflectance curve from a coarse grid with the lowest fit error is utilized by processor 116 to define a "fine" grid of simulated reflectance curves, simulated reflections within the fine grid. The rate curve is around the simulated reflectance curve from the coarse grid with the lowest fit error.

That is, the fine grid has a defined size, and the lowest error simulated reflectance curve from the coarse grid defines the center of the fine grid. The fine grid may have as many simulated reflectance curves as the coarse grid, or may have more or less simulated reflectance curves. The fine grid has an absorption coefficient μ in the vicinity of the fine grid in step 1230._aValue and scattering coefficient μ_s'Provide enough points to determine the peak surface array of values. Specifically, the threshold can be set by the processor 116 using a particular offset in addition to the lowest error value from the coarse grid. Scattering coefficient μ on a fine grid with an error below the threshold_s'And absorption coefficient μ_aAll positions have a scattering factor μ for reflectance data_s'And absorption coefficient μ_aCan be identified for use in determining the peak surface array to further determine. Specifically, error matching is made for the peak, and the absorption coefficient μ at the peak._aAnd scattering coefficient μ_s'The value is calculated. At step 1240, the peak absorption coefficient μ_aAnd scattering coefficient μ_s'Weighted averages of values (eg centroid calculations) are utilized by the oximeter probe and the absorption coefficient μ for the reflectance data points of the tissue._aAnd scattering coefficient μ_s'The value can be calculated.

Absorption coefficient μ for weighted average_aAnd scattering coefficient μ_s'The weight of the value can be determined by the processor 116 as the threshold minus the fine grid error. Points on the fine grid are selected with an error below the threshold, which gives them a positive weight. The expected scattering factor μ for the reflectance data points of the tissue by a weighted calculation of the weighted average (eg centroid calculation)._s'And absorption coefficient μ_a(That is, (μ)_a, μ_s’)_{fine fine}) Is provided. Absorption coefficient μ fitted using one or more of various nonlinear least squares methods_aOther methods may be utilized by the oximeter probe, such as finding the true minimum error peak of.

According to one embodiment, the processor 116 calculates the logarithms of the reflectance data points and the simulated reflectance curve, and divides each logarithm by the square root of the source-detector distance (eg, expressed in centimeters). The logarithm divided by the square root of the source-detector distance is utilized and simulated by the processor 116 for reflectance data points and simulated reflectance curves in the above steps (eg steps 1215, 1220, 1225, and 1230). The fit of reflectance data points to the reflectance curve can be improved.

According to another reification, the offset is set to virtually zero, which effectively gives the offset of the difference between the coarse grid minimum and the fine grid minimum. The true minimum error on the fine grid is typically lower because the method described above for FIG. 12A relies on the minimum fit error from the coarse grid. Ideally, the threshold is derived from the lowest error on the fine grid, which typically requires further computation by the processor.

The following is a more detailed description for finding a particular simulated reflectance curve that best fits the reflectance data points in the fine grid for one reification. FIG. 12B is a flow diagram of a method of finding a specific simulated reflectance curve that best fits a reflectance data point in a fine grid, according to one embodiment. This flow chart represents one embodiment. Steps can be added, deleted, or combined with respect to the flow diagram without departing from the scope of the embodiment.

Specific simulated reflectance curve (μ) from the coarse grid that best fits the reflectance data points in step 1225_a, μ_s’)_coarseAfter finding, in step 1250, the processor 116 is a fully simulated reflectance curve database of simulated reflectance curves (ie 16 × 5850 (μ))._a, μ_s') Database) (μ)_a, μ_s’)_coarseCompute the error surface in the area around. The error surface is err (μ)_a, μ_s') Is shown. Then, in step 1255, processor 116 err_minIs called err (μ)_a, μ_sFind the minimum error value in'). Processor 116 then in step 1260, pksurf (μ) if the peak surface is greater than zero._a, μ'_s) = k + err_min-err (μ_a, μ'_s), Or if the peak surface is less than or equal to zero, pksurf (μ)_a, μ'_s) = k + err_min-err (μ_a, μ'_s) = 0 err (μ_a, μ_sGenerate a peak surface array from'). In this equation, k has a width greater than zero of about 10 elements err (μ)._a, μ'_s) Is selected from the peak at the minimum point. In step 1265, pksurf (μ)_a, μ'_s) Peak mass center (ie centroid calculation) uses the height of the point as a weight. The position of the center of mass is the absorption coefficient μ of the reflectance data point of the tissue._aAnd scattering coefficient μ_sIt is the interpolation result of'.

Absorption coefficient μ of tissue reflectance data points_aAnd scattering coefficient μ_sThe method described above with respect to FIGS. 12A and 12B for determining'can be repeated for each of the wavelengths produced by each of the source structures 120 (eg, 3 or 4 wavelengths).

Oxygen saturation judgment. According to the first reification, processor 116 has an absorption coefficient μ (as described above) obtained for three or four wavelengths of light produced by each source structure 120._a(For example, 3 or 4 absorption coefficients μ_a) To determine the oxygen saturation of the tissue probed by the oximeter probe 101. According to the first reification, the absorption coefficient μ for oxygen saturation_aA look-up table of oxygen saturation values is generated to find the best fit for. The look-up table assumes a range of possible total hemoglobin, melanin, and oxygen saturation values, μ for each of these scenarios._aCan be generated by calculating. Then, by dividing by the norm of the unit vector, reducing the system error and relying only on the relative shape of the curve, the absorption coefficient μ_aPoints are converted to unit vectors. The unit vector is then compared to the look-up table to find the best fit, which gives the oxygen saturation.

According to the second embodiment, the processor 116 determines the oxygen saturation of the tissue by calculating the deoxidized hemoglobin and the net excipient signal (NAS) of the oxygenated hemoglobin. NAS is defined as the part of the spectrum that is orthogonal to the other spectral components in the system. For example, the NAS of deoxygenated hemoglobin in a system that also contains oxygenated hemoglobin and deoxygenated hemoglobin is part of the spectrum orthogonal to the oxygenated hemoglobin spectrum and the melanin spectrum. Then, the vector can calculate the concentration of deoxygenated and oxygenated hemoglobin by multiplying each NAS by a predetermined absorption coefficient at each wavelength. Oxygen saturation is then easily calculated as the concentration of oxygenated hemoglobin divided by the sum of oxygenated hemoglobin and deoxygenated hemoglobin. Lorber's Anal. Chem. 58: 1167-1172 (1986) is incorporated herein by reference to provide a framework for a more detailed understanding of the second embodiment for determining tissue oxygen saturation. do.

According to the embodiment of the oximeter probe 101, the reflectance data is generated by the detector structure 125 at 30 hertz and the oxygen saturation value is calculated at about 3 hertz. A moving average of the determined oxygen saturation values (eg, at least three oxygen saturation values) can be shown on the display 115, which may have an update rate of 1 hertz.

optical properties. As briefly described above, each simulated reflectance curve 315 stored in memory 117 represents the unique optical properties of the tissue. More specifically, the unique shape of the simulated reflectance curve for a given wavelength is a unique value of the optical properties of the tissue, i.e. the scattering coefficient (μ)._s), Absorption coefficient (μ_a), Anisotropy of the structure (g), and the refractive index of the structure, from which the characteristics of the structure may be determined.

Relatively small source-Reflectance detected by detector structure 125 for detector distance has a reduced scattering factor μ_s'Mainly depends on. The reduced scattering coefficient is the scattering coefficient μ._sAnd a "lumped" characteristic that incorporates the anisotropy g of the structure, μ_s'= μ_s(1-g), 1 / μ_sUsed to describe the diffusion of photons in a random walk of many steps of size', each step involves isotropic scattering. Such a description has many small steps 1 / μ_sEquivalent to the description of photon transfer using, each of these steps is when there are many scattering events prior to the absorption event, ie μ._a&lt;&lt; μ_sIf it is', only a partial deflection angle is included.

In contrast, the reflectance detected by the detector structure 125 for a relatively large source-detector distance has an effective absorption coefficient μ._effMainly depends on, this is

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Defined as μ_aAnd μ_s'Both functions.

Therefore, reflectance at relatively small source-detector distances (eg S1-D4 and S2-D8 in Figure 2) and relatively large source-detector distances (eg S1-D8 and S2-D4 in Figure 2). By measuring μ_aAnd μ_sBoth of'can be obtained independently of each other. The optical properties of the tissue may then provide sufficient information for the calculation of oxygenated and deoxidized hemoglobin concentrations, and thus the oxygen saturation of the tissue.

Iterative adaptation for data acquisition optimization. FIG. 13 shows a flow chart of another method of determining the optical properties of a tissue with the oximeter probe 101. This flow chart represents one embodiment. Steps can be added, deleted, or combined with respect to the flow diagram without departing from the scope of the embodiment.

At 1300, the oximeter probe 101 emits light (eg, near-infrared light) into the tissue from one of the source structures 120, such as the source structure 120a. After the irradiated light is reflected from the tissue, the detector structure 125 detects the light (step 1305) and produces reflectance data for the tissue (step 1310). Steps 1300, 1305, and 1310 may be repeated for light of multiple wavelengths and for one or more other source structures, such as source structure 120b. At 1315, the oximeter probe 101 fits the reflectance data to the simulated reflectance curve 315 to determine the simulated reflectance curve with the best fit of the reflectance data. The database stored in memory and fitted to the reflectance data can be database 900, database 1000, or database 1100. Then, in step 1320, the oximeter probe 101 is based on the optical properties of the simulated reflectance curve that best fits the reflectance data (eg, μ in the case of Database 900 or Database 1000)._aAnd μ_s'Or, in the case of Database 1100, determine melanin content, oxygen saturation, blood volume and scattering).

At 1325, the oximeter probe 101 has the optical properties determined in step 1320 (eg mfp = 1 / (μ)._a+ μ'_s)) Find the mean free path of light in the tissue. Specifically, the average free process is for all source-detector pairs (eg, pair 1: source structure 120a and detector structure 125a, pair 2: source structure 120a and detector structure 125b, pair 3: source structure). 120a and detector structure 125c, vs 4: source structure 120a and detector structure 125d, vs 5: source structure 120a and detector structure 125e, vs 6: source structure 120a and detector structure 125f, vs 7: source structure 120a and Reflectivity data for detector structure 125g, vs. 8: source structure 120a and detector structure 125h, vs. 9: source structure 120b and detector structure 125a, vs. 10: source structure 120b and detector structure 125b, etc.) It can be obtained from the optical characteristics obtained from the cumulative reflectivity curve including.

At 1330, the oximeter probe 101 has the mean free path calculated for a given region of tissue longer than twice the shortest source-detector distance (eg S1-D4 and S2-D8 in Figure 2). To judge. If the average free process is longer than twice the shortest source-detector distance, use the reflectance data collected from the detector structure of the shortest source-detector pair of sources-detector. Instead, the collected reflectance data is refitted (ie, reanalyzed) to the simulated reflectance curve. For example, in steps 1315 to 1330, the source structure 120a is acting as the source of the detector structure 125d, the reflectance data from the detector structure 125e is not used, and the source structure 120b is the detector structure 125h. It is repeated without using the reflectance data from the detector structure 125h while acting as a source of. The process of calculating the average free process and discarding the reflectance data for one or more source-detector pairs is the calculated average free process of the source-detector pairs that contributes to the reflectance data for the fit. Can be repeated until there are no more pairs with a source-detector distance shorter than half of. Then, in step 1335, the oxygen saturation is determined from the best-matched simulated reflectance curve and reported by the oximeter probe 101, for example on the display 115.

Light emitted from one of the source structures 120 into the tissue and traveling less than half of the average free process is non-diffuse or nearly non-diffuse (eg, it can have a diffuse element). .. The re-emission distance of this light largely depends on the tissue phase function and the local tissue composition. Therefore, the use of this light reflectance data tends to reduce the accuracy of determining optical and texture properties as compared to light reflectance data that has experienced multiple scattering events.

Data weighted detector structure. The detector structure 125, located at an increased distance from the source structure 120, receives a diminishing amount of reflection from the tissue. Therefore, the reflectance data generated by the detector structure 125 with a relatively short source-detector distance (eg, S1-D4 and S2-D8 in FIG. 2) is a relatively long source-detector distance (eg, S1-D4 and S2-D8). For example, it tends to show a higher signal by nature compared to the reflectance data generated by the detector structure with S1-D8 and S2-D4) in FIG. Therefore, the matching algorithm makes the simulated reflectivity curve denser than the reflectivity data produced by the detector structure with a relatively long source-detector distance (eg, a source-detector distance greater than the average distance). For reflectivity data generated by the detector structure 125 with a relatively short source-detector distance (eg, a source-detector distance below the average distance between the source structure and the detector structure). , May be preferentially adapted. This distance-proportional skew may not be desirable in order to obtain the optical properties relatively accurately from the reflectance data and can be corrected by weighting the reflectance data as described immediately below.

FIG. 14 shows a flow diagram of a method of weighting the reflectance data generated by the selective detector structure 125. This flow chart represents one embodiment. Steps can be added, deleted, or combined with respect to the flow diagram without departing from the scope of the embodiment.

At 1400, the oximeter probe 101 irradiates tissue into tissue from one of the source structures, such as source structure 120a. After the irradiated light is reflected from the tissue, the detector structure 125 detects the light (step 1405) and produces reflectance data for the tissue (step 1410). Steps 1400, 1405, and 1410 may be repeated for light of multiple wavelengths and for one or more other source structures, such as source structure 120b. At 1415, the oximeter probe 101 fits the first portion of the reflectance data to the simulated reflectance curve 315. The database stored in memory and fitted to the reflectance data can be database 900, database 1000, or database 1100. The first part of the reflectance data is generated by the first part of the detector structure that is less than the threshold distance from the source structure. The threshold distance may be the average distance between the source structure and the detector structure (eg, approximately midrange distance). At 1420, the reflectance data for the second portion of the reflectance data is fitted to the simulated reflectance curve. The second part of the reflectance data is generated by the first part of the detector structure and another detector structure at the next largest source-detector distance from the source compared to the threshold distance. For example, if the first part of the detector structure contains the detector structures 125c, 125d, 125e and 125f, the detector structure at the next largest source-detector distance is the detector structure 125g (see Table 1). ..

At 1425, the fit generated in step 1415 is compared to the fit generated in step 1420 to determine if the fit generated in step 1420 is better than the fit generated in 1415. As will be appreciated by those skilled in the art, the "closeness" of the data to the curve can be quantified based on various parameters, and the closeness of the fit is the data having a closer fit to the curve. Can be compared directly to determine. As will be further understood, closer fits are also referred to as better fits or tighter fits. If the fit generated in step 1420 is better than the fit generated in step 1415, then an additional detector structure placed at the next increased source-detector distance from the source (source, according to the example considered). Steps 1420 and 1425 are repeated with the reflectivity data generated by the detector structure including structure 125c). Alternatively, if the fit generated in step 1420 is not better than the fit generated in step 1415, the reflectance data for the detector structure 125 located at the source-detector distance greater than the threshold distance will be , Not used for conformance. The oximeter probe 101 then uses the fit generated in step 1415 or (if better than the fit determined in step 1415) step 1420 to determine the optical properties and oxygen saturation of the tissue (step). 1430). The oxygen saturation is then reported in step 1435 by the oximeter probe 101, such as on the display 115.

According to an alternative embodiment, if the fit generated in step 1420 is not better than the fit generated in step 1415, the reflectance data will be for the detector structure with a source-detector distance greater than the threshold distance. , Weighted by a weighting factor so that the effect of this weighted reflectance data on fit is reduced. Reflectance data not used for adaptation can be considered to have a weight of zero and can be associated with reflectance from the tissue below the tissue layer of interest. The reflectance from the tissue below the tissue layer of interest is said to indicate a characteristic strain (kink) in the reflectance curve indicating this particular reflectance.

It should be noted that the curve matching algorithm that fits the reflectance data to the simulated reflectance curve can take into account the amount of uncertainty in the reflectance data and the absolute position of the reflectance data. The uncertainty of the reflectance data corresponds to the amount of noise from the generation of the reflectance data by one of the detector structures, and this amount of noise can be scaled as the square root of the magnitude of the reflectance data.

According to a further embodiment, the oximeter probe 101 iteratively weights the reflectance data based on the amount of noise associated with the measurement of the reflectance data. Specifically, the reflectivity data produced by a detector structure with a relatively large source-detector distance is generally the reflectivity produced by a detector structure with a relatively short source-detector distance. It has a lower signal-to-noise ratio compared to the data. By weighting the reflectance data produced by the detector structure with the relatively large source-detector distance, it is possible that this data contributes to the fit equally or approximately equally with other reflectance data.

The method described to match the reflectance data to a large number of Monte Carlo simulated reflectance curves allows for a relatively quick and accurate determination of the optical properties of the actual tissue probed by the oximeter probe. The speed at which tissue optical properties are determined is an important consideration in the design of intraoperative probes compared to postoperative probes. In addition, the Monte Carlo method described allows for a robust calibration method, which in turn allows the generation of absolute optical properties compared to relative optical properties. Reporting absolute optical properties as opposed to relative optical properties is relatively important for intraoperative oximeter probes compared to postoperative oximeter probes.

This description of the invention is presented for purposes of illustration and illustration. It is not intended to be exhaustive or to limit the invention to the exact form described, and many modifications and variations are possible in view of the above teachings. Embodiments have been selected and described to best illustrate the principles of the invention and its practical uses. This description will allow one of ordinary skill in the art to best utilize and practice the invention in various embodiments with various modifications to suit a particular use. The scope of the invention is defined by the following claims.