A dermal reflectance sensor method and system for calculating UV light and vitamin D absorption in a patient is provided. The present method and system allows for real-time accurate calculating of UV light absorbed and vitamin D produced during a UV light therapy session in the present light emitting device. The present method and system utilize at least five parameters for capturing and calculating data related to the specific UV light absorbed and vitamin D produced by a patient and then altering a light therapy machine to provide optimal UV light exposure. The parameters include: 1) measuring the light source output during a specific time; 2) calculating the specific wavelength of light reflected by the skin of the patient; 3) calculating the distance the patient is from the lamp and 4) measuring the temperature of a sensing module and applying a temperature compensation factor that adjusts a calculation used; and 5) providing a safety mechanism that limits dosage to a percentage increase within a specified range, which is based upon a calculation of historical exposures and typical dosage increases, and thereby minimizing the risk of accidental operator overdosing. Finally, the present light emitting device calculates the real-time absorption of UV light and production of vitamin D, which allows an operator to control the light emitting device accordingly in real-time to optimize the proper dosage, including even the ultimate vitamin D produced in the treatment.
The modern use of sunscreens and low levels of exposure to sunlight particularly in latitudes higher than Atlanta, have proven to cause extensive deficiencies in children and adults. According to Medical News Today, 24 Aug. 2009, 70% of children in the United States are Vitamin D insufficient or deficient as defined as less than 29 nanograms of Vitamin D per milliliter of blood. The inability to accurately measure the absorbed dosage of UV light has limited the ability of the light therapy industry from creating a in system to safely and accurately expose patients to UV light for proper UV light and vitamin D therapy. This invention creates an accurate measurement of continuous real-time absorbed dosage of UV at specific and selectable wavelengths and allows the therapist to accurately dispense UV illumination with measured joules of photon energy per square meter of skin. This accurate measurement and the ability of this invention to measure reflected energy provide the data required to control the light therapy procedure and to create a medically approvable level of photon energy defined as a Maximum Erythema Dosage (M.E.D.), (the smallest dosage of UV radiation to create erythema (reddening) of the skin 24 hours after exposure). Vitamin D production by UVB exposure is then calculated by published conversion tables.
It is long established that vitamin D is primarily created through skin exposure to UVB, ultraviolet light in the spectrum that extends from 280 to 320 nanometers in wavelength. Additionally, adequate vitamin D levels are essential to the proper functioning of the human body. “Medical News Today, 24 Aug. 2009” defined vitamin D as having significant impact in preserving the genes for healthy resistance to illnesses including cancer, autoimmune, cardiovascular, and infectious diseases. Human skin sensitivity to UVB varies significantly from individual to individual and changes with each exposure to UV radiation. In addition, the accurate measurement of absorbed dosage of UVB light energy in the light therapy procedure is essential for the physician to determine the proper dosage to treat various medical conditions.
Quantifiable absorbed UVB dosage data allows the physician to adjust exposure for optimum benefit and minimum risk in the light therapy process. Prior attempts to accurately determine dosage have been limited. One method is a subjective questionnaire, the “Fitzpatrick Skin Type Chart” and uses the combined score of this test as the basis for skin sensitivity in determining maximum UV light exposure time. In addition to the Fitzpatrick questionnaire, a photon energy level meter has been utilized by some devices but this method only records UV lamp/diode output. Combination of the Fitzpatrick subjective test with light output energy does not create the data required to accurately measure an individual's skin sensitivity to burning (erythema) and the actual UV light energy absorbed by the skin. Multiple UV light exposure testing is another method of determining an individuals' M.E.D. but this procedure is time consuming, results in erythema (sunburn) and does not account for the changes in skin sensitivity with each exposure.
The present method and system measures five parameters of the light therapy process allowing for the first time accurate absorbed dosage measurements and the calculation of Vitamin D production. The first parameter is light source output measurement with typical diminishing light output continuously compensated for in total exposure time calculations. Second, a band pass filter and photometer is incorporated to measure and quantify specific wavelength of light reflected by the skin. Third, the distance of patient to light source is measured for automatic compensation of light therapy exposure time. Fourth, temperature of the sensing module assembly of two photometers, band-pass filters, distance measuring ultrasonics, and compensating electronics is monitored for input to the controlling microprocessor. Fifth, providing a safety mechanism which limits dosage to a percentage increase within a specified range, which is based upon a calculation of historical exposures and typical dosage increases, and thereby minimizing the risk of accidental operator overdosing. Each of the five measured system parameters and their relative compensation calculations are used by the system microprocessor to create a real-time patient dosage value joules per square meter. System parameters and patient position are also continuously monitored and are used to automatically interrupt the procedure if safety or dosage prescription levels are exceeded.
Patient safety, UV light toxicity, and effectivity have all been limited by subjective answers to questionnaires and physician estimation of therapy time and dosage. The present method and system will eliminate over and under exposure of light therapy and the resultant danger to the patient of ineffective or potentially harmful treatment. Accurate absorbed dosage data and individualized skin sensitivity measurement provide the data required for physicians to optimize dosage and the light therapy medical procedure.
Attempts have been made to accurately calculate UV light exposure. For example, U.S. Pat. No. 9,068,887 to Bennouri discloses a UV dosimetry system having a wearable unit and a mobile computing device. The wearable unit measures the UV irradiance intensity and wirelessly communicates with the mobile computing device. The UV dosimetry system supports multi-user control and can link one mobile computing device with multiple wearable units. The UV dosimetry system processes the measured UV irradiance intensity to calculate the UV index (UVI) and the sensor site specific UV dose. It can also calculate the total absorbed UV dose and vitamin D production by taking into account user specific factors. The UVI data measured by a plurality of UV meters such as the disclosed UV dosimetry system are crowd sourced to a remote server together with the location and time data of the measurement. The remote server excludes invalid UVI measurement and generates UVI maps showing time-varying distribution of UVI data at different locations.
Further, U.S. Pat. No. 8,793,212 to McGuire discloses a system for managing a user's exposure to the ultraviolet radiation including a user input interface, display circuitry including a screen, control circuitry including at least one processor wherein the control circuitry is configured to communicate with the display circuitry and the user input interface, data storage means for storing program instructions that, when implemented by the control circuitry, are configured to determine UV index information corresponding to a user's location, communicate with the user input interface to retrieve information for at least one user parameter, calculate at least one recommended exposure time based on the UV index information and the user parameter information, and communicate with the display circuitry to display the recommended exposure time.
However, these patents fail to provide an accurate method and system for calculating the absorption of UV light absorbed by the skin in a person receiving light therapy and instead focus upon general UV exposure from the sun while outside. A need, therefore, exists for an improved method and system of calculating UV absorption and vitamin D production and wherein an operator may adjust the therapy device based on real-time information acquired by the calculations.
A dermal reflectance sensor method and system for calculating UV light and vitamin D absorption in a patient is provided. The present method and system allows for real-time accurate calculating of UV light absorbed and vitamin D produced during a UV light therapy session in the present light emitting device. The present method and system utilize at least five parameters for capturing and calculating data related to the specific vitamin D production of a patient. The parameters include: 1) measuring the light output during a specific time; 2) calculating the specific wavelength of light reflected by the skin of the patient; 3) calculating the distance the patient is from the light source and 4) measuring the temperature of a sensing module and applying a temperature compensation factor that adjusts the calculations used; and 5) providing a safety mechanism that limits dosage to a percentage increase within a specified range, which is based upon a calculation of historical exposures and typical dosage increases, and thereby minimizing the risk of accidental operator overdosing. Finally, the present light emitting device calculates the real-time production absorption of UV light and production of vitamin D, which allows an operator to control the fight emitting device accordingly in real-time to optimize the proper dosage.
Vitamin D is a steroid fat-soluble pro-hormone that is instrumental in the human absorption of calcium and phosphorus. Sufficient quantities of UVB tight provide adequate levels of Vitamin 02 (ergocalciferol) and 03 (cholecalciferol) the two types of Vitamin D found to be most important to the proper maintenance of the immune system. Vitamin D is created in the human body in the 3rd layer of skin by exposure to natural or artificial lighting in the UVB range of 280 to 320 nanometer (nm) wavelength. Vitamin D has been proven to boost the human immune system. The Institute of Physics, National Academy of Sciences of Ukraine, 252022 Kiev-22, Ukraine, New Method of UV Dosimetry have shown treatment with UVB light therapy is beneficial to the treatment of autoimmune diseases such as Parkinson's, cystic fibrosis, psoriasis, and cancer. These medical studies have been limited by a lack of ability to accurately measure the absorbed dosage of UVB light illumination by the test patients.
Human testing protocols are based on a subjective questionnaire called the “Fitzpatrick” test. This series of questions creates a numerical value on each of the test patient answers as to how easily they sun tan or the degree they sun burn with varying times of sun exposure and their opinion of their skin color. This subjective test is subsequently used to assign a skin type to each individual in a range from 1 to 6. The 1 through 6 number are utilized to determine the exposure time protocol for that patient's future treatment. The creation of Vitamin D by UVB radiation exposure to human skin and the varying amounts of Vitamin D produced by this exposure are different for each skin type. A problem with using the Fitzpatrick test is that it is a subjective opinion based on the patient's memory and understanding of the questions. Additionally no method exists to accurately measure the absorbed UV light energy by the patient's skin. Further complicating the task of creating a non-subjective testing protocol is each exposure to UVB light changes the patient's skin resulting in a new exposure time before sunburn occurs and the rate of absorption of UVB tight energy by skin. The present method and system addresses these issues by creating a device for use in establishing the patients initial skin type and in continually monitoring the absorbed dosage of UV light energy received by the patient during treatment. For the first time medical studies of UV light energy exposure can be accurately quantified. Treatment times and light energy output can be measured and affects of treatment can be determined to maximize beneficial medical affects. Risk of injury white testing and negative complications can be reduced and nearly eliminated by the present method and systems microprocessor (69),
A second measurement sensor measures a collimated beam of light energy reflected by the patient's skin. A microprocessor,
An advantage of the present dermal reflectance sensor and method is that the present method and system allows for providing a safe and accurate level of UV light absorbed and vitamin D produced by a patient.
For a more complete understanding of the above listed features and advantages of the dermal reflectance sensor method and system for calculating UV light absorbed and vitamin D produced, reference should be made to the following detailed description of the preferred embodiments and to the accompanying drawings. Further, additional features and advantages of the present method and system are described in, and will be apparent from, the detailed description of the preferred embodiments and from the drawings.
A method and system for calculating UV light and vitamin D absorption in a patient is provided. The present method and system allows for real-time accurate calculating of UV light absorption and vitamin D production during a UV light therapy session in the present light emitting device. The method utilizes at least five parameters for capturing and calculating data related to the specific vitamin D production of a patient. The parameters include: 1) measuring the lamp output during a specific time; 2) calculating the specific wavelength of light reflected by the skin of the patient; calculating the distance the patient is from the lamp; 4) measuring the temperature of a sensing module assembly of two photometers; and 5) providing a safety mechanism that limits dosage to a percentage increase within a specified range, which is based upon a calculation of historical exposures and typical dosage increases, and thereby minimizing the risk of accidental operator overdosing. Finally, the present light emitting device calculates the real-time UV light absorption and production of vitamin D and allows an operator to alter the tight emitting device accordingly in real-time to optimize the proper light therapy dosage.
Several embodiments of the present dermal reflectance sensor and light emitting device and method and system are set forth herein which relate to the monitoring of ultraviolet light energy and its absorption by human skin.
Electrical parameters of the dermal reflectance sensor are included with the physical construction of the 6, 4-lamp/diode panels and their construction for effective distribution of the light energy safely and effectively to humans. The preferred embodiment is shown but human skin varies significantly from person to person. Changes to the preferred embodiment will affect some people more or less effectively but will not alter the physics of this sensing and control system.
To ensure the difference in measurement, values are unaffected by manufacturing variables in sensing components for light energy at specific, selectable wavelengths. Microprocessor, (65),
Referring to
UV light therapy effectiveness and safety is dependent on accurate measurement of the joules of UV illumination absorbed by patient (38). Initial measurement of patient (38) skin type is necessary to assign a skin type index from 1 to 4 to patient (38). This index number from 1 to 4 determines the therapeutic exposure protocol to be appropriate to each patient (38). Each protocol from 1 to 4 sets the time of exposure limits to prevent patient (38) from being overexposed to UV illumination and burned or under-treated and obtaining no medical benefit. Sensor assembly (16) contains two identical UV sensors, reference UV tight energy silicone detector (105) and reflected UV light energy detector (108). Both silicone detectors (105) and (48) receive their UV light through band pass filter (106) and band pass filter (50) respectively. UV lamp/diode energy entering band pass titter (50) is restricted to only the UV light energy passing through collimator (47). The purpose of this collimation will be explained later in this section. To measure absorbed dosage of UV light energy by patient (38), the total exposure UV light energy received by patient (38) must be accurately measured on a continuous basis. UV light energy reflected from patient (38) skin is also required to be continuously measured.
The difference in these two measurements can then be determined by microprocessor (65). Absorbed dosage of UV light energy by patient (38) is equal to reference UV light energy value minus reflected UV light energy value. Patient absorbed UV light energy=reference UV light energy reflected UV light energy. The instantaneous UV light energy absorbed by patient can then be measured over time of exposure to result in the determination of total UV light energy absorbed by patient (38) and is reported as millijoules per square centimeter of patient (38) skin. Proper positioning by patient (38) as indicated by distance display (t9) is essential to accurately measuring the UV light energy level received by patient (38), too close illuminating LED (41) close, or too far illuminating LED (38) far will result in UV light energy over or under exposure by UV light (11), (12), (13), and (14) in panels (1), (3), (5), (7), (18), and (24) respectively to patient (38). Calculations by microprocessor, (65),
Linear motor (52) extends linear motor piston (55) 4″ in an upwardly or downwardly motion to enable sensor bracket (15) to move center most mounted sensor assembly (16) 4″ in an upwardly or downwardly motion with respect to mounting plate (52). This combination of vertical upwardly or downwardly motion of mounting plate (56) and linear motor (52) enables the light therapy operator or patient to adjust sensor assembly to meet the vertical positioning requirements of sensor assembly for varying heights of patients (38). The movement of the sensor assembly (16) therein provides for a more accurate reading of the reflected UV light from the patient (46) and therein allows for the increase or decrease of the amount of UV exposure to the patient to, for example, optimize vitamin D production.
Linear motor (54) is utilized to provide vertical most upwardly and downwardly movement for sensor (16) to measure patient (38) skin reflected light energy at two or more vertically most upwardly and downwardly scanning positions. Reflected light energy received by reflection light energy silicone detector (48) from two or more vertical most upwardly and downwardly spots on patient (38) provides verification of accuracy of the light energy reflected by patient (38). This multiple reading is analyzed by microprocessor (65) for acceptable deviation in reflected light energy value before microprocessor (65) assigns a skin type for patient (38). Microprocessor (65) outputs display information to touch screen (22) based on calculated values and inputs as noted above 110V AC power is provided by external source (72) to power input box (9) and switched on and off by power switch (10).
Mounted on outer most surface of power input box (9), solid-state relay (62) is maintained in a normally electrical current conducting mode to allow uninterrupted electrical power to microprocessor (65) for control of light source (11), (12), (13), and (14) in panels (1), (3), (5), (7); (18), and (24) respectively. Depression of emergency button (42) opens solid-state relay (62) and causes electrical power to be turned off to ballast (64) powering lamps/diodes (11), (12), (13), and (14) in panels (1), (3), (5), (7), (18), and (24) respectively. Secondary safety, activated after delay relay (63) is in series with electrical current input to ballast (64) and is set to 10 seconds or a similar delay time longer than the longest time previously selected as defined above therapy treatment protocol. If microprocessor (65) fails to function as programmed or an improper operator input to screen (85),
For all light and distance sensors, over-sampling and averaging are used to increase resolution and improve noise immunity.
Light sensor temperature compensation:
The outputs of the sensors vary depending upon their temperature. In order to get a consistent voltage output proportional to the light level, the output voltage must be compensated for this temperature effect. Temperature compensation is provided using a polynomial of the form:
V
tc=(Vs+Z0+(Z1*T)+(Z2*T2))*(1+(L1*(T−77)))
where
*Note that the above polynomial is a combination of two polynomials. The second half compensates for a change in the temperature affect between when the UV light is on and off.
The constants are empirically derived for each sensor. Following are an example of values derived for one of the sensors:
To improve accuracy, both sensors are embedded in the same metal block along with a temperature sensor. This helps keep all three components close to the same temperature. In addition, the part of the metal block that does not need to be visible to the light source is wrapped in insulation. The insulation reduces the rate of change in temperature caused by external sources such as the UV lights and room air handlers.
Distance compensation for body sensor.
For the body sensor, the temperature compensated value is also compensated for distance by applying a linear equation to the compensated value calculated above. This takes the form of:
V
dc
=V
tc*(1−D1*D14)
Where:
The linear coefficient has been derived empirically. An actual value derived for one of the sensors is:
Different skin types absorb UV light differently and the protocols used by the industry vary dependent on the skin type. A common term used in the industry is the Fitzpatrick number although other definitions are in use. Upon first use, the present system calculates a “Fitzpatrick” number and type using the following methodology:
Calculate the Body Ratio
B
R
=V
b
/V
ref
where
Calculate the Fitzpatrick number. This is accomplished using a linear equation that takes the form:
F
n
=F
0+(F1*BR)
where
The constants have been empirically derived. An example from one of the actual systems is:
Associate the Fitzpatrick number to a skin type using the following groupings:
Because the output of the sensor is a voltage while the exposure is tracked in Joules, a conversion factor is needed. This takes the form of:
E
r
=V
tc
*C
f
Where
This conversion factor is applied to every reading of the sensor which happens several times a second. Several factors affect the conversion factor. Therefore, it is set for each individual unit.
During patient exposure, the system maintains a running sum of the exposure. At the start of an exposure, the exposure sum is set to 0. Then every time the sensor is read, the sensor reading is multiplied by the elapsed time since the last reading to create an exposure for the current period.
E
c
=E
r
*T
e
where
This current exposure is added to the exposure sum to create a total exposure for the session.
Exp=Σ(Ec)
where
Reading of the sensor takes place several times a second to provide the accuracy and control required.
Although embodiments of the present invention are shown and described therein, it should be understood that various changes and modifications to the presently preferred embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages. It is, therefore, intended that such changes and modifications be covered by the appended claims.
The following application is based on U.S. provisional application Ser. No. 62/093,279 filed on Dec. 17, 2015 and Ser. No. 62/096,736 filed on Dec. 24, 2015 both currently co-pending, and claims the priority benefit of the '279 and the 736 U.S. applications; the entire contents of which are incorporated by reference.
Number | Date | Country | |
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62093279 | Dec 2014 | US | |
62096736 | Dec 2014 | US |