Patent Description:
Many personal care activities and skin measurement and monitoring activities involve a person viewing or inspecting their own skin or the skin of another person. For example, a person may view their reflection in a mirror, or a representation of their face or body on the screen of a computing device (e.g. a tablet computer) or an imaging device (e.g. a camera while performing a personal care activity, such as applying make-up. Similarly, a medical professional may inspect the skin of another person when assessing the person for an injury or illness, such as bruising or inflammation of part of the body.

Prior art light sources are disclosed in documents <CIT>, <CIT> and <CIT>.

Under broadband light (e.g. white light), it can be difficult for the human eye to distinguish clearly between inflamed tissue and uninflamed tissue. The reason for the inability of the naked human eye to clearly identify the boundary between inflamed and uninflamed regions of tissue is due to the fact that the spectral signatures of these different regions of tissue are averaged and smoothed out by broadband light. This, in combination with the wide-spectral properties of the L-, M- and S- cones of the human retina, results in poor contrast between inflamed and uninflamed regions of tissue when broadband light is used.

There is, therefore, a need for a system which enables the human eye to more clearly distinguish between inflamed and uninflamed regions of tissue.

It would be advantageous to be able to better distinguish between regions of tissue that are inflamed and regions of tissue that are not inflamed. This would allow better visibility of bruises, spots, and other lesions and inflammations of skin or tissue. It has been recognized by the inventors that such regions can be more readily distinguished from one another using a combination of light having particular characteristics. For example, it has been recognized that blood-rich regions of tissue (e.g. lips, inflamed spots or pimples, and regions of skin irritation) appear redder when illuminated with a combination of green and red light. Using a combination of radiation in particular wavebands, or broadband radiation filtered leave a combination of radiation in the particular wavebands, can further improve the distinction between the inflamed and uninflamed regions.

According to a first aspect, the present invention provides a tissue illumination system comprising at least one radiation source configured to generate: first radiation in a first wavelength band at a first intensity, the first radiation having a peak wavelength, λ<NUM>; and second radiation in a second wavelength band at a second intensity, the second radiation having a peak wavelength, λ<NUM>; and a radiation delivery unit configured to deliver the first radiation and the second radiation towards tissue of a subject; wherein an intensity ratio of the first intensity relative to the second intensity is between <NUM> and <NUM>; and wherein the peak wavelength λ<NUM> of the first wavelength band and the peak wavelength λ<NUM> of the second wavelength band are selected such that they satisfy the following relationships: <MAT>.

If the generated radiation (e.g. the first radiation and the second radiation) is used to illuminate inflamed and uninflamed regions of tissue of the subject, then the contrast between these tissue regions becomes more enhanced, such that a viewer of the subject is able to more clearly see the distinction between the different regions. Under white light/broadband radiation, inflamed tissue regions may be harder to distinguish from uninflamed tissue regions to a human viewer.

The first radiation and the second radiation each have a spectral full-width-at-half-maximum of between <NUM> and <NUM>.

The tissue illumination system may, in some embodiments, further comprise a polarizer to linearly polarize the radiation after it is emitted from the at least one radiation source or after the radiation has been reflected from the tissue of the subject. In some embodiments, the tissue illumination system may comprise a first polarizer to linearly polarize the radiation after it is emitted from the at least one radiation source and a second polarizer to linearly polarize, in a direction perpendicular relative to the polarization direction of the first polarizer, radiation reflected from the tissue of the subject.

In some embodiments, the tissue illumination system may further comprise one or more sensors configured to measure a light intensity and/or a color temperature of ambient light at or in the vicinity of the tissue of the subject. The tissue illumination system may further comprise a processor operatively coupled to the at least one radiation source. The processor may be configured to adjust, based on an output of the one or more sensors, one or more of: an intensity of radiation generated by the at least one radiation source; and an intensity ratio of the first intensity relative to the second intensity.

The tissue illumination system may further comprise an image capture device configured to receive radiation reflected from the tissue of the subject.

According to a second aspect, the present invention provides an optical filter system comprising at least one bandpass filter configured to enable transmission of: first radiation in a first wavelength band at a first intensity, the first radiation having a peak wavelength, λ<NUM>; and second radiation in a second wavelength band at a second intensity, the second radiation having a peak wavelength, λ<NUM>; wherein the at least one bandpass filter is configured to enable transmission of the first radiation and the second radiation such that an intensity ratio of the first intensity relative to the second intensity is between <NUM> and <NUM>; and wherein the peak wavelength λ<NUM> of the first wavelength band and the peak wavelength λ<NUM> of the second wavelength band are selected such that they satisfy the following relationships: <MAT>.

The at least one bandpass filter is configured to enable transmission of the first radiation and the second radiation such that the first radiation and the second radiation each have a spectral full-width-at-half-maximum of between <NUM> and <NUM>.

According to a third aspect, the present invention provides a device comprising a tissue illumination system having at least one broadband radiation source. The at least one radiation source of this device being configured to generate broadband radiation including a first radiation having a wavelength, λ<NUM>; and a second radiation having a peak wavelength, λ<NUM>. The device further comprising a radiation delivery unit configured to deliver the broadband radiation to the tissue of the subject, and an optical filter system as discussed above.

The optical filter system might be positioned to filter the broadband radiation after the broadband radiation is emitted from the at least one radiation source and before it is reflected from the tissue of the subject, or to filter the broadband radiation after the radiation has been reflected from the tissue of the subject.

The device may comprise a medical instrument, a mirror, a headset or a mask.

According to a fourth aspect, the present invention provides a tissue illumination method comprising generating first radiation in a first wavelength band at a first intensity, the first radiation having a peak wavelength, λ<NUM>; generating second radiation in a second wavelength band at a second intensity, the second radiation having a peak wavelength, λ<NUM>; and delivering the radiation in the first radiation and the second radiation towards tissue of a subject; wherein an intensity ratio of the second intensity relative to the first intensity is between <NUM> and <NUM>; and wherein the peak wavelength λ<NUM> of the first wavelength band and the peak wavelength λ<NUM> of the second wavelength band are selected such that they satisfy the following relationships: <MAT>.

In some embodiments, the tissue illumination method may further comprise measuring one or more of a light intensity and a color temperature of ambient light at or in the vicinity of the tissue of the subject; and adjusting, based on the measured light intensity and/or on the measured color temperature, one or more of an intensity of the first radiation and/or the second radiation, and an intensity ratio of the first intensity relative to the second intensity.

According to a fifth aspect, the present invention provides a computer program product comprising a non-transitory computer-readable medium, the computer-readable medium having computer-readable code embodied therein, the computer-readable code being configured such that, on execution by a suitable computer or processor, the computer or processor is caused to: operate at least one light source to generate first radiation in a first wavelength band at a first intensity to be delivered to tissue of a subject, the first radiation having a peak wavelength, λ<NUM>; and operate the at least one light source to generate second radiation in a second wavelength band at a second intensity to be delivered to the tissue of a subject, the second radiation having a peak wavelength, λ<NUM>; wherein an intensity ratio of the first intensity relative to the second intensity is between <NUM> and <NUM>; and wherein the peak wavelength λ<NUM> of the first wavelength band and the peak wavelength λ<NUM> of the second wavelength band are selected such that they satisfy the following relationships: <MAT>.

The first radiation and the second radiation each has a spectral full-width-at-half-maximum of between <NUM> and <NUM>.

The computer-readable code may be further configured such that, on execution by a suitable computer or processor, the computer or processor is caused to: receive sensor data indicative of a light intensity and/or a color temperature of ambient light at or in the vicinity of the tissue of the subject; and adjust, based on the received sensor data, one or more of: an intensity of radiation generated by the at least one radiation source; and an intensity ratio of the first intensity relative to the second intensity.

Embodiments disclosed herein provide a mechanism by which inflamed tissue may be distinguished more readily from uninflamed or less inflamed tissue by a human viewer. Under white or broadband light, such a distinction may be more difficult, due to the way such light is reflected from the tissue and received by photoreceptors in the eye of a human. However, by applying the systems and methods disclosed herein, it is possible to clearly distinguish between these types of tissue. As used herein, the term "tissue" is intended to refer to any part of the human or animal body tissue, such as skin.

The inventors of the present disclosure have recognized that combinations of radiation in certain wavebands can be particularly helpful to a person hoping to be able to distinguish between regions of inflamed tissue (e.g. blood-rich tissue) and regions of uninflamed tissue. Through a number of simulations, the inventors were able to determine the particular wavebands of radiation which, when combined, improve the contrast between the inflamed and uninflamed regions of tissue. Graphs showing the outputs of the various simulations are shown in <FIG>.

<FIG> is a series of graphs showing the visual contrast of inflamed and uninflamed tissue regions when illuminated using white light (e.g. broadband light) and dual-color radiation. <FIG> is a graph <NUM> showing the relative intensities of the white light <NUM> and the dual color radiation <NUM> used during the simulations. While the white light <NUM> has a constant relative intensity for all visible wavelengths, the intensity of the dual-color radiation peaks at the wavelengths of red light and green light. Specifically, the dual-color radiation included radiation having a first peak wavelength of <NUM> nanometers (nm), with a full-width-at-half maximum (FWHM) of <NUM>, and a second peak wavelength of <NUM>, with an FWHM of <NUM>. The dual-color radiation used in the simulation had an intensity ratio of <NUM>:<NUM> (i.e. the radiation having the peak wavelength at <NUM> was provided at double the intensity of the radiation having the peak wavelength at <NUM>). The two types of radiation were used in the simulation to illuminate two regions of tissue: a region of regular, uninflamed tissue, and a region of inflamed tissue.

<FIG> is a graph <NUM> showing observations of two different tissue regions, described numerically using color-matching functions as defined in the International Commission on Illumination (CIE). The CIE color-matching functions, x(λ), y(λ) and z(λ), represent a numerical description of the chromatic response of the observer. The functions may be considered to be the spectral sensitivity curves of the three linear light detectors, yielding the CIE tristimulus values X, Y and Z. In <FIG>, value X is represented by the line <NUM>, value Y is represented by the line <NUM> and value Z is represented by the line <NUM>. The CIE color-matching functions are, collectively, referred to as the CIE standard observer.

<FIG> show, respectively, graphs <NUM> and <NUM> of reflectance spectra for white light (<FIG>) and dual-color radiation (<FIG>) for inflamed and uninflamed tissue regions. In the graph <NUM>, line <NUM> represents the reflectance from the uninflamed tissue region, and line <NUM> represents the reflectance from the inflamed tissue region. In the graph <NUM>, line <NUM> represents the reflectance from the uninflamed tissue region, and line <NUM> represents the reflectance from the inflamed tissue region. <FIG> show, respectively, graphs <NUM> and <NUM> of corresponding tristimulus values for white light (<FIG>) dual-color radiation (<FIG>). In the graph <NUM>, the data bars <NUM> represent the tristimulus value in respect of the uninflamed tissue region, and the data bars <NUM> represent tristimulus value in respect of the inflamed tissue region. In the graph <NUM>, the data bars <NUM> represent the tristimulus value in respect of the uninflamed tissue region, and the data bars <NUM> represent tristimulus value in respect of the inflamed tissue region. From the tristimulus values shown in the graphs <NUM> and <NUM>, it can be observed that the difference in relative ratios of X, Y and Z values between reflections from inflamed and uninflamed tissue regions are larger when dual-color radiation is used than when white light is used. This difference in relative ratios can be quantified by calculating the resulting color difference or distance metric between the inflamed and uninflamed tissue regions.

<FIG> is a series of contour plots showing perceived color difference and perceived contrast between inflamed and uninflamed tissue regions, for different peak-wavelength combinations of two light sources with equal intensities and equal spectral widths (FWHM) of <NUM>. <FIG> shows a contour plot <NUM> of the calculated perceived contrast in terms of lightness, L, <FIG> shows a contour plot <NUM> of the calculated perceived contrast in terms of hue, H, <FIG> shows a contour plot <NUM> of the calculated perceived contrast in terms of chroma, C, and a <FIG> shows a contour plot <NUM> of the calculated perceived total contrast (denoted delta E, or dE94, in accordance with the standard CIE <NUM>). In <FIG>, "Emission band A" corresponds to wavelengths in a first emission band (wavelengths in the red part of the visible spectrum), and "Emission band B" corresponds to wavelengths in a second emission band (wavelengths in the green part of the visible spectrum). The dotted line shown in the plots of <FIG> represent iso-lines corresponding to the contrast between inflamed and uninflamed tissue regions when illuminated by white radiation. It is evident from the plot <NUM> in <FIG> that the total perceived contrast between the inflamed and uninflamed tissue regions is larger, relative to white radiation, when dual-color radiation is used which has peak wavelengths at <NUM> and <NUM>.

<FIG> is a series of plots showing how the relative contrast varies as a function of the spectral width (i.e. FWHM). <FIG> shows a plot <NUM> of the relative contrast improvement as a function of FWHM for various intensity ratios. <FIG> shows a plot <NUM> of wavelengths in the first emission band (i.e. "Emission band A" - wavelengths in the red part of the visible spectrum) as a function of FWHM for various intensity ratios, and <FIG> shows a plot <NUM> of wavelengths in the asecond emission band (i.e. "Emission band B" - wavelengths in the green part of the visible spectrum) as a function of FWHM for various intensity ratios. From the plot <NUM> in <FIG>, it is evident that the relative contrast improvement peaks when the spectral bandwidth is at approximately <NUM>. The plot <NUM> also indicates that the optimum intensity ratio is <NUM>, and that strong contrast improvements can also be seen when intensity ratios of <NUM> and <NUM> are used. The relative contrast improvement reduces when the intensity ratio is reduced <NUM> or lower, or increased to <NUM> or more. Thus, the optimum contrast improvement is seen with intensity ratios of between <NUM> and <NUM>.

Based on the outputs of the various simulations, it is possible to determine ranges of peak wavelengths, ranges of spectral widths, and optimal intensity ratios that give rise to an improvement in the contrast between inflamed and uninflamed tissue regions. Table <NUM> below summarizes optimal parameter ranges for two emission bands that give rise to an improvement in the contrast of greater than <NUM>%.

<FIG> is a chart <NUM> showing data from <FIG> replotted for different ratio values, r. The data are the fitted with a rational function, <MAT> where fitted values are: a = <NUM> ± <NUM> and b = -<NUM> ± <NUM>, and the values for A are ratio-dependent. Table <NUM> below shows how A varies for different ratios, r.

Substitution of the variable y for λ<NUM> and of the variable x for λ<NUM> gives: <MAT>.

<FIG> is a chart <NUM> showing the values of A from Table <NUM> above plotted as a function of their respective ratio values, r. The curve fitted to the data in the chart <NUM> fits the function: <MAT> where fitted values are: c = <NUM> ± <NUM> and t = <NUM> ± <NUM>. Combining Equations <NUM> and <NUM>, gives: <MAT> <MAT> where B = <NUM>/c = <NUM>, and <MAT>.

Equation <NUM> relates a peak wavelength λ<NUM> within a first wavelength band (e.g. <NUM> to <NUM>), a peak wavelength λ<NUM> within the second wavelength band (e.g. <NUM> to <NUM>) and r the relative intensity ratio between λ<NUM> and λ<NUM>. Thus, Equation <NUM> can be used to determine an intensity ratio r, given peak wavelengths λ<NUM> and λ<NUM> in the first and second wavelength bands respectively. If the relative intensity ratio r is within the range <NUM> to <NUM>, then the combination of λ<NUM>, λ<NUM> and r is considered to provide good contrast between inflamed and uninflamed tissue regions.

<FIG> shows the chart <NUM> of <FIG>, with an additional region <NUM> indicated by a dashed line. Data points falling within the region <NUM> have parameters of λ<NUM> falling within the intended waveband of <NUM> to <NUM>, λ<NUM> falling within the intended waveband of <NUM> to <NUM> and r falling within the intended range of intensity ratios <NUM> to <NUM>. Thus, points falling within the region <NUM> correspond to radiation that would illuminate tissue regions in such a way that the human eye would see a good contrast between inflamed and uninflamed regions of tissue.

The intended ranges of the first wavelength band and the second wavelength band can be expressed independently of the intensity ratio. From Table <NUM> above, for r = <NUM>, A = <NUM> and, for r = <NUM>, A = <NUM>. This can be expressed as: <MAT> and <MAT> and substituting in Equation <NUM> gives: <MAT>.

Combining all inequalities, the operational range of the first and second wavelength bands may be described as: <MAT>.

The last two relationships define the wavelength range of the first peak wavelength λ<NUM> as a function of the second peak wavelength λ<NUM>.

Thus, various embodiments disclosed herein may use radiation having parameters including a first peak wavelength in a range from <NUM> to <NUM>, a second peak wavelength in a range from <NUM> to <NUM>, and an intensity ratio of the radiation at the second peak wavelength relative to the radiation at the first peak wavelength in a range from <NUM> to <NUM>. Within these bounds, the first peak wavelength falls within a range given by: <MAT> and <MAT>.

The radiation preferably has a spectral width (e.g. FWHM) in a range from <NUM> to <NUM>. In other embodiments, outside the scope of the invention, the radiation may have a spectral width (e.g. FWHM) outside of this range, and may still provide a good contrast between inflamed and uninflamed tissue.

Radiation having the above-identified parameters may be delivered towards skin or tissue of a subject using a tissue illumination system as disclosed herein. Alternatively, white or broadband radiation may be delivered towards the skin or tissue of the subject, and one or more filters may be used to filter the radiation incident on or reflected from the skin or tissue such that the radiation viewed by a viewer has one or more of the above-identified parameters. Examples of various systems that may be used to view tissue of a subject that has been illuminated using radiation having the above-identified parameters are discussed below.

<FIG> is a schematic illustration of an example of a tissue illumination system <NUM>, and <FIG> is a schematic illustration of a further example of a tissue illumination system <NUM>. The tissue illumination systems <NUM>, <NUM> comprises at least one radiation source <NUM> and a radiation delivery unit <NUM>. In the embodiment shown in <FIG>, the tissue illumination system <NUM> comprises a single radiation source <NUM> while, in the embodiment shown in <FIG>, the tissue illumination system <NUM> comprises two radiation sources 702a and 702b. In other examples, more radiation sources may be provided.

In the tissue illumination system <NUM>, the radiation source <NUM> is configured to generate first radiation in a first wavelength band at a first intensity, the first radiation having a peak wavelength, λ<NUM>. The peak wavelength of the first radiation is between <NUM> and <NUM>, and the first radiation has a spectral full-width-at-half-maximum of between <NUM> and <NUM>. The at least one radiation source <NUM> is also configured to generate second radiation in a second wavelength band at a second intensity, the second radiation having a peak wavelength, λ<NUM>. The peak wavelength of the second radiation is between <NUM> and <NUM>, and the second radiation has a spectral full-width-at-half-maximum of between <NUM> and <NUM>. The peak wavelength λ<NUM> of the first wavelength band and the peak wavelength λ<NUM> of the second wavelength band are selected such that they satisfy the following relationships: <MAT> <MAT>.

In some examples, the radiation source <NUM> may generate multi-band broadband radiation including the first radiation and the second radiation while, in other examples, the radiation source <NUM> may generate radiation in two distinct wavebands, having the above-mentioned parameters.

In the tissue illumination system <NUM>, the multiple radiation sources 702a, 702b may each be configured to generate radiation in a different waveband. For example, the radiation source 702a may be configured to generate the first radiation in the first wavelength band at the first intensity (e.g. having the corresponding parameters mentioned above) and the radiation source 702b may be configured to generate the second radiation in the second wavelength band at the second intensity (e.g. having the corresponding parameters mentioned above).

The radiation delivery unit <NUM> is configured to deliver the first radiation and the second radiation towards tissue of a subject. The subject may, for example, comprise a person (i.e. a human) who is being examined as part of a medical examination or as part of a personal care or hygiene activity, or who is viewing a representation or a reflection of their own head or body while performing a self-examination for medical reasons or as part of a personal care activity. In other examples, the subject may comprise an animal. As discussed above, when tissue of a subject is viewed under radiation having the above-identified parameters (i.e. under a combination of the first radiation and the second radiation), it is possible to distinguish more clearly between inflamed tissue regions and uninflamed tissue regions.

The radiation delivery unit <NUM> may be in optical communication with the at least one radiation source <NUM>, such that radiation generated by the radiation source(s) can be delivered towards tissue of the subject. To achieve this, the radiation delivery unit <NUM> may comprise one or more optical elements.

<FIG> is a schematic illustration of an example of the tissue illumination system <NUM> in use. Radiation (i.e. the first radiation and second radiation) is generated by the at least radiation source <NUM>, and directed via the radiation delivery unit <NUM> towards tissue <NUM> of a user. In this example, the tissue <NUM> includes an uninflamed region <NUM> and an inflamed region <NUM>. The inflamed region <NUM> may comprise tissue having a relatively larger amount of blood therein, for example a lip, a bruise or a spot. Radiation may reflect from the tissue <NUM> towards an eye of a viewer <NUM>. It will be appreciated that the viewer <NUM> may be the subject whose tissue <NUM> is being viewed, for example if the viewer is looking at a reflection of their own head or body in a mirror, or looking at a representation of their own head or body in a computing device, such as a tablet computer or smartphone. Alternatively, the viewer <NUM> may be a person who is not the subject whose tissue <NUM> is being viewed.

In some embodiments, the first radiation and the second radiation may be generated and/or emitted/delivered towards the tissue of the subject with equal intensities. Thus, the intensity ratio of the second intensity relative to the first intensity may be <NUM>. However, in other embodiments, the second intensity may be less than the first intensity, such that the second radiation is generated, emitted or delivered having intensity is less than that of the first radiation. Thus, the intensity ratio of the first intensity relative to the second intensity may be between <NUM> and <NUM>. In other examples, the intensity ratio of the first intensity relative to the second intensity may be between <NUM> and <NUM>. More specifically, particular intensity ratios of <NUM>, <NUM> or <NUM> may be applied in some examples. As will become apparent below, the intensity ratio may be varied based on parameters of ambient light, such as ambient light intensity.

According to some embodiments, the tissue illumination system <NUM>, <NUM> may comprise one or more other components, such as optical components, to enhance the contrast between the inflamed and uninflamed tissue regions. For example, the tissue illumination system <NUM>, <NUM> may comprise a diffuser configured to diffuse radiation (e.g. light) emitted from the radiation source(s) <NUM>. In other examples, the tissue illumination system <NUM>, <NUM> may comprise one or more polarizers configured to polarize radiation (e.g. light) emitted by the radiation source(s) <NUM>. <FIG> is a schematic illustration of an example of the tissue illumination system <NUM> in use with various optional components. As noted above, the tissue illumination system <NUM> may, in some embodiments, comprise a polarizer <NUM> to linearly polarize the radiation after it is emitted from the at least one radiation source <NUM> or after the radiation has been reflected from the tissue of the subject thus, the polarizer <NUM> may be positioned in one of a number of locations with respect to the radiation source <NUM> and the viewer <NUM>. As shown in <FIG>, the polarizer <NUM> may be provided a first position such that the radiation emitted by the radiation delivery unit <NUM> passes through the polarizer before reaching the tissue of the subject, or in a second position such that the radiation passes through the polarizer after reflecting from the tissue of the subject. In some examples, multiple polarizers may be provided (e.g. two polarizers) configured to polarize light in directions orthogonal to one another, in order to reduce specular reflections from the tissue. For example, the tissue illumination system <NUM>, <NUM> may comprise a first polarizer to linearly polarize the radiation after it is emitted from the at least one radiation source and a second polarizer to linearly polarize, in a direction perpendicular relative to the polarization direction of the first polarizer, radiation reflected from the tissue of the subject. In other words, the first polarizer may linearly polarize the radiation in a first direction after it is emitted from the at least one radiation source and the second polarizer may polarize the radiation in a second direction which is orthogonal to the first direction.

The tissue illumination system <NUM> may, in some embodiments, further comprise a processor <NUM> and/or one or more sensors <NUM>. The one or more sensors <NUM> may be configured to measure a light intensity and/or a color temperature of ambient light at or in the vicinity of the tissue of the subject. The one or more sensors <NUM> may, for example, comprise a photometer. The processor <NUM> may be operatively coupled to the at least one radiation source <NUM>. The processor <NUM> may be configured to adjust, based on an output of the one or more sensors <NUM>, a parameter of the radiation source or of radiation emitted by the radiation source. For example, the processor <NUM> may be configured to adjust, based on an output of the one or more sensors <NUM>, one or more of an intensity of radiation generated by the at least one radiation source; and an intensity ratio of the first intensity relative to the second intensity. In other embodiments, the processor <NUM> may be configured to adjust one or more other parameters in addition to those mentioned above. By adjusting parameters based on measurements recorded using the one or more sensors <NUM>, it is possible to adjust the radiation delivered towards the tissue of the subject to further enhance the contrast between the inflamed and uninflamed tissue regions, depending on ambient conditions. For example, in bright sunlight, the one or more sensors <NUM> may detect that a high ambient brightness and, therefore, the intensity of radiation generated by the radiation source <NUM>, may be increased accordingly. In some examples, one or more sensors may be configured to measure the intensity of radiation in each waveband (e.g. the red and green waveband) separately, and a processor <NUM> may be configured to adjust the intensity of radiation generated in one or more of the waveband separately.

The tissue illumination system <NUM> may, in some embodiments, further comprise an image capture device <NUM> configured to receive radiation reflected from the tissue of the subject. The image capture device <NUM> may, for example, comprise a charge-coupled device (CCD) or a camera capable of capturing single images or a series of images (e.g. video footage). In this way, an image or images of the tissue of the subject may be recorded and reviewed at a later time. Since the tissue is illuminated using the radiation in two different wavebands, the contrast between any inflamed and uninflamed regions of tissue are distinguishable in the captured image.

The tissue illumination system <NUM>, <NUM> may comprise a single apparatus or device, with the various components discussed herein forming part of a single integrated unit. In other embodiments, however, the various components may form part of a distributed system, as shown in <FIG>. One or more of the components of the tissue illumination system <NUM> discussed herein may form part of a mirror or smart mirror that a user may use to view their face or body. For example, such a mirror may include the radiation source(s) <NUM>, the radiation delivery unit <NUM>, the polarizer <NUM>, the processor <NUM>, one or more sensors <NUM> and/or the image capture device <NUM>.

As discussed above, the contrast between inflamed and uninflamed tissue regions may be enhanced by illuminating the tissue with radiation having the particular range of characteristics discussed herein. Specifically, the combination of radiation falling within the red waveband and the green waveband have been found to provide a particularly strong contrast between inflamed and uninflamed tissue regions. As also noted above, the visual contrast may be enhanced by using a filter system to filter broadband radiation (e.g. white light) to significantly filter out any radiation falling outside of the red and green wavebands, or to filter out any radiation that does not have the particular characteristics discussed herein. Thus, in some embodiments, the at least one radiation source comprises a broadband radiation source configured to generate broadband radiation including the first radiation and the second radiation. In other words, the broadband radiation source generates white light which includes the light within the particular wavebands discussed herein. In such embodiments, the radiation delivery unit <NUM> is configured to deliver the broadband radiation to the tissue of the subject. The tissue illumination system <NUM> may further comprise at least one filter configured to filter the broadband radiation to filter out radiation having a wavelength falling outside the first wavelength band and radiation having a wavelength falling outside the second wavelength band. Specifically, the at least one filter may be configured to filter the broadband radiation to transmit the first radiation in the first wavelength band at the first intensity, the first radiation having a peak wavelength of between <NUM> and <NUM>, and to transmit the second radiation in the second wavelength band at the second intensity, the second radiation having a peak wavelength of between <NUM> to <NUM>. The first and second radiation preferably have a spectral full-width-at-half-maximum of between <NUM> and <NUM>. In some examples, a single filter may be used while, in other examples, two or more filters may be used to provide appropriate filtering of the broadband radiation. Thus, the at least one filter may comprise at least one bandpass filter.

Such an optical filter may, for example, be characterized by its spectral transmission band (i.e. the transmitted wavelength range) and its spectral transmittance (i.e. the amount (e.g. percentage) of radiation transmitted). Therefore, the broadband radiation source may be filtered by an optical filter that is configured to transmit radiation at two spectral bands (e.g. using a dual-band pass filter). Each spectral band may at a different transmittance value, such that the transmitted radiation from the first spectral band of the optical filter at a first optical transmittance is at a first intensity and the transmitted radiation from the second spectral band of the optical filter at a second optical transmittance is at a second intensity.

According to a further aspect, the present invention provides an optical filter system. <FIG> is a schematic illustration of an example of an optical filter system <NUM> that may be used to improve the contrast between uninflamed and inflamed tissue regions of a subject. The optical filter system <NUM> comprises at least one bandpass filter <NUM>. The at least one bandpass filter <NUM> is configured to enable transmission of first radiation in a first wavelength band at a first intensity, the first radiation having a peak wavelength, λ<NUM>, and to enable transmission of second radiation in a second wavelength band at a second intensity, the second radiation having a peak wavelength, λ<NUM>,. The at least one bandpass filter (<NUM>) is configured to enable transmission of the first radiation and the second radiation such that an intensity ratio of the first intensity relative to the second intensity is between <NUM> and <NUM>. The peak wavelength λ<NUM> of the first wavelength band and the peak wavelength λ<NUM> of the second wavelength band are selected such that they satisfy the following relationships: <MAT>.

According to the invention, the at least one bandpass filter (<NUM>) is configured to enable transmission of the first radiation and the second radiation such that the first radiation and the second radiation each have a spectral full-width-at-half-maximum of between <NUM> and <NUM>. In some examples, multiple bandpass filters may be provided, for example a first bandpass filter to enable transmission of the first radiation and a second bandpass filter to enable transmission of the second radiation. In use, the tissue of a subject may be illuminated using broadband radiation (e.g. white light) and the optical filter system <NUM> may restrict the radiation that it transmits such that a viewer of the tissue, when using the optical filter system, is able to view the inflamed and uninflamed regions of tissue with enhanced contrast.

The optical filter system <NUM> may, in some embodiments, comprise a radiation source, such as a broadband radiation source, or a white light source, to direct radiation towards the tissue. Radiation reflected from the tissue may pass through the optical filter system <NUM>, such that the filtered radiation reaches the viewers eyes. The optical filter system <NUM> may be configured and/or positioned to cause spectral filtering of radiation after it is emitted from the radiation source, or to cause spectral filtering of radiation reflected from the tissue of the subject.

In some embodiments, the at least one bandpass filter <NUM> is configured to enable transmission of the first radiation and the second radiation such that an intensity ratio of the second intensity relative to the first intensity is between <NUM> and <NUM>.

The optical filter system <NUM> may comprise, or form part of, a device or apparatus used by the subject or by a viewer of the subject. Thus, according to a further aspect, the present invention provides a device comprising a tissue illumination system <NUM>, <NUM> as disclosed herein or an optical filter system <NUM> as disclosed herein. The device may, in some embodiments, comprise a medical instrument, a mirror (e.g. a smart mirror), a headset (e.g. smart glasses) or a mask. Such devices may be worn by a viewer of the subject or by the subject itself. In one example, the device may comprise a magnifying device or an optical relay device, incorporated into as a scope for viewing tissue in orifices of the subject, such as the nostril, the mouth or the ear canal. Such a device may incorporate a tissue illumination system <NUM>, <NUM> or an optical filter system <NUM> as disclosed herein, to enable a user of the device to identify inflamed tissue.

According to a further aspect, the present invention provides a tissue illumination method. <FIG> is a flowchart of an example of a method <NUM>, such as a tissue illumination method. The method <NUM> may, for example, be performed using the tissue illumination system <NUM>, <NUM> disclosed herein. The method <NUM> comprises, at step <NUM>, generating first radiation in a first wavelength band at a first intensity, the first radiation having a peak wavelength, λ<NUM>. At step <NUM>, the method <NUM> comprises generating second radiation in a second wavelength band at a second intensity, the second radiation having a peak wavelength, λ<NUM>. An intensity ratio of the first intensity relative to the second intensity is between <NUM> and <NUM>, and the peak wavelength λ<NUM> of the first wavelength band and the peak wavelength λ<NUM> of the second wavelength band are selected such that they satisfy the following relationships: <MAT>.

The method <NUM> comprises, at step <NUM>, delivering the radiation in the first radiation and the second radiation towards tissue of a subject. The delivered radiation may then be viewed by a viewer, and the combination of the first and second radiation may enhance the contrast between any inflamed and uninflamed regions of tissue, enabling the viewer to better distinguish between such regions.

The method <NUM> may, in some embodiments, further comprise measuring one or more of a light intensity and a color temperature of ambient light at or in the vicinity of the tissue of the subject. The method <NUM> may further comprise adjusting, based on the measured light intensity and/or on the measured color temperature, one or more of an intensity of the first radiation and/or the second radiation, and an intensity ratio of the first intensity relative to the second intensity. In this way, the regions of tissue of the subject and, in particular, the contrast between such regions, maybe even more clearly distinguishable to a viewer.

In some embodiments, the method <NUM> may further comprise capturing an image of the tissue of the subject after the radiation has been reflected from the tissue. In this way, the image of the tissue of the user may be viewed later time by a viewer, and the improved contrast between the inflamed and uninflamed regions of tissue may be captured.

The at least one radiation source may, in some embodiments, comprise a broadband radiation source configured to generate broadband radiation including radiation in the first wavelength band and radiation in the second wavelength band. In such embodiments, delivering the radiation may comprise delivering the broadband radiation towards tissue of a subject. The method may further comprise filtering the broadband radiation to filter out radiation having a wavelength falling outside the first wavelength band and radiation having a wavelength falling outside the second wavelength band. More specifically, the method may further comprise filtering the broadband radiation to allow transmission of first radiation in a first wavelength band at a first intensity, the first radiation having a peak wavelength of between <NUM> and <NUM>, and second radiation in a second wavelength band at a second intensity, the second radiation having a peak wavelength of between <NUM> to <NUM>. The method may, in some embodiments, comprise filtering the broadband radiation to allow transmission of first radiation and second radiation having a spectral full-width-at-half-maximum of between <NUM> and <NUM>.

According to a further aspect, the present invention provides a computer program product. <FIG> is a schematic illustration of an example of a processor <NUM> communication with a computer-readable medium <NUM>. In various embodiments, a computer program product comprises a non-transitory computer-readable medium <NUM>, the computer-readable medium having computer-readable code embodied therein, the computer-readable code being configured such that, on execution by a suitable computer or processor <NUM>, the computer or processor is caused to operate at least one light source to generate first radiation in a first wavelength band at a first intensity to be delivered to tissue of a subject, the first radiation having a peak wavelength, λ<NUM>,; and operate the at least one light source to generate second radiation in a second wavelength band at a second intensity to be delivered to the tissue of a subject, the second radiation having a peak wavelength, λ<NUM>. An intensity ratio of the first intensity relative to the second intensity is between <NUM> and <NUM>. The peak wavelength λ<NUM> of the first wavelength band and the peak wavelength λ<NUM> of the second wavelength band are selected such that they satisfy the following relationships: <MAT>.

The first radiation and the second radiation each have a spectral full-width-at-half-maximum of between <NUM> and <NUM>. More generally, the computer-readable code may be configured such that, on execution by the processor <NUM>, the processor is configured to perform one or more steps of the method <NUM> disclosed herein. The processor <NUM> may comprise the processor <NUM> discussed above.

In some embodiments, the computer-readable code may be further configured such that, on execution by a suitable computer or processor <NUM>, the computer or processor is caused to receive sensor data indicative of a light intensity and/or a color temperature of ambient light at or in the vicinity of the tissue of the subject; and adjust, based on the received sensor data, one or more of: an intensity of radiation generated by the at least one radiation source; and an intensity ratio of the second intensity relative to the first intensity. The sensor data may, for example, comprise data acquired and/or received from the one or more sensors <NUM> discussed above.

The processor <NUM>, <NUM> can comprise one or more processors, processing units, multicore processors or modules that are configured or programmed to control components of the systems <NUM>, <NUM>, <NUM> in the manner described herein. In particular implementations, the processor <NUM>, <NUM> can comprise a plurality of software and/or hardware modules that are each configured to perform, or are for performing, individual or multiple steps of the method described herein.

The term "module", as used herein is intended to include a hardware component, such as a processor or a component of a processor configured to perform a particular function, or a software component, such as a set of instruction data that has a particular function when executed by a processor.

It will be appreciated that the embodiments of the invention also apply to computer programs, particularly computer programs on or in a carrier, adapted to put the invention into practice. The program may be in the form of a source code, an object code, a code intermediate source and an object code such as in a partially compiled form, or in any other form suitable for use in the implementation of the method according to embodiments of the invention. For example, a program code implementing the functionality of the method or system according to the invention may be sub-divided into one or more sub-routines. An embodiment relating to a computer program product comprises computer-executable instructions corresponding to each processing stage of at least one of the methods set forth herein. These instructions may be sub-divided into sub-routines and/or stored in one or more files that may be linked statically or dynamically. Another embodiment relating to a computer program product comprises computer-executable instructions corresponding to each means of at least one of the systems and/or products set forth herein. These instructions may be sub-divided into sub-routines and/or stored in one or more files that may be linked statically or dynamically.

Claim 1:
A tissue illumination system (<NUM>, <NUM>) comprising:
at least one radiation source (<NUM>) configured to generate dual-colored radiation with:
first radiation in a first wavelength band at a first intensity, the first radiation having a peak wavelength, λ<NUM>; and
second radiation in a second wavelength band at a second intensity, the second radiation having a peak wavelength, λ<NUM>; and
a radiation delivery unit (<NUM>) configured to deliver the first radiation and the second radiation towards tissue of a subject;
wherein an intensity ratio of the first intensity relative to the second intensity is between <NUM> and <NUM>; and
wherein the peak wavelength λ<NUM> of the first wavelength band and the peak wavelength λ<NUM> of the second wavelength band are selected such that they satisfy the following relationships: <MAT> and
wherein the first radiation and the second radiation each has a spectral full-width-at-half-maximum of between <NUM> and <NUM>.