Abstract:
A radiation detector system includes a photosensor configured to detect a radiation level, a processor configured to process the radiation level, and a wireless interface configured to transmit the processed radiation level to a network. A method of determining a radiation value using the radiation detector includes receiving a new radiation event data, maintaining a record of the new radiation event data among a record of previously received radiation events data, calculating a user-configured average value radiation level based on the record of the radiation events data, calculating a radiation level on the basis of the record of the received new radiation event data and the record of previously received radiation events data, and outputting the radiation value and the user-configured average value radiation level.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 61/582,772, entitled “Radiation Sensor System,” filed on Jan. 3, 2012, which is expressly incorporated by reference herein in its entirety. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    The present disclosure relates to radiation detection devices. More particularly, the disclosure relates to electromagnetic and/or particle radiation detection devices. 
         [0004]    2. Background 
         [0005]    There are a variety of radiation sensors available today, including solid state sensors. These are semiconductors, which directly convert the incident radiation into electrical current, much as a proportional counter tube does, except that rather than gas, a material such as silicon is used. Other common materials are germanium, cadmium zinc telluride, etc. 
         [0006]    Semiconductor radiation sensors consist of a p-n junction across which a pulse of current develops when a particle of ionizing radiation traverses it. In a different device, the absorption of ionizing radiation generates pairs of charge carriers (electrons and electron-deficient sites called holes) in a block of semiconducting material; the migration of these carriers under the influence of a voltage maintained between the opposite faces of the block constitutes a pulse of current. The pulses created in this way are amplified, recorded, and analyzed to determine the energy, number, or identity of the incident-charged particles. The sensitivity of these detectors is increased by operating them at low temperatures—commonly that of liquid nitrogen, −164° C. (−263° F.)—which suppresses the random formation of charge carriers by thermal vibration. 
         [0007]    Applications may include flow monitoring in radiochemical synthesis (such as for diagnostic techniques in nuclear medicine using radioactive tracers with short-lived isotopes), monitoring of stack effluents, security monitoring and detection of illegal transportation and location of nuclear medicines, radiological dirty bombs, and weapons grade nuclear materials. 
         [0008]    A major advantage of such sensors is their extremely high energy resolution. That is, they are very good at determining accurately what the energy of the incident radiation is. For many applications involving the detection of beta radiation (electrons), x-rays and gamma radiation (photons), performance may be superior to the conventional Geiger-Mueller tube with respect to signal output and noise. A disadvantage is cost, as the detectors themselves are quite expensive, as are the associated electronics required. There is a need in the art for a low cost radiation sensor. Operation at ambient temperature, and low power consumption is also preferable. 
       SUMMARY 
       [0009]    In an aspect of the disclosure, a radiation detector includes a photosensor configured to detect a radiation level, a processor configured to process the radiation level, wherein the processing includes one or more of a Kalman filter and a running average filter, and a wireless interface configured to transmit the processed radiation level to a network. 
         [0010]    In an aspect of the disclosure, a radiation detector includes a photosensor configured to detect radiation, the photosensor comprising a voltage input having a rated voltage, and a power source configured to apply a voltage to the voltage input of the photosensor, wherein the applied voltage exceeds the rated voltage. 
         [0011]    In an aspect of the disclosure, a radiation detector includes a photosensor configured to detect radiation, the photosensor having a voltage input, a housing supporting the photosensor, the housing further comprising an AC power plug configured to be removably connectable to an AC wall socket, and a converter configured to apply a voltage to the voltage input of the photosensor when the AC power plug is connected to the AC wall socket. 
         [0012]    In an aspect of the disclosure, a method of determining a radiation value includes receiving a new radiation event data, maintaining a record of the new radiation event data among a record of previously received radiation events data, calculating a user-configured average value radiation level based on the record of the radiation events data, calculating a radiation level on the basis of the record of the received new radiation event data and the record of previously received radiation events data, and outputting the radiation value and the user-configured average value radiation level. 
         [0013]    In an aspect of the disclosure, a radiation detector apparatus includes a means for detecting a radiation level, a means for processing the radiation level, wherein the processing means includes one or more of a Kalman filter and a running average filter, and a means for wirelessly transmitting the processed radiation level to a network. 
         [0014]    In an aspect of the disclosure, a radiation detector apparatus includes a means for detecting a radiation level, a processing means comprising a filter, the processor being configured to process the detected radiation level using the filter, wherein the filter includes one or more of a Kalman filter and a running average filter. 
         [0015]    In an aspect of the disclosure, a computer readable media including program instructions which when executed by a processor cause the processor to perform the method of receiving from a photosensor a signal descriptive of a level of radiation, processing the signal to calculate a radiation level, and transmitting the processed radiation level to a network via a wireless interface coupled to the processor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  illustrates an exemplary radiation detector system, according to an embodiment. 
           [0017]      FIG. 2  illustrates an exemplary processor with inputs and outputs used in an embodiment of a radiation detector system of  FIG. 1 . 
           [0018]      FIG. 3  illustrates an exemplary housing supporting the radiation detector system, according to an embodiment. 
           [0019]      FIG. 4  is a flowchart of a method of output selection process in an embodiment. 
           [0020]      FIG. 5  illustrates exemplary user interfaces configured for use with embodiments of a radiation detector system, according to an embodiment. 
           [0021]      FIG. 6  illustrates a local area map with radiation readings, according to an embodiment. 
           [0022]      FIG. 7  illustrates a global area map with radiation readings, according to an embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Various concepts will now be presented with reference to a radiation detector, such as a Geiger counter, a particle detector, and a photosensor. However, as those skilled in the art will readily appreciate, these concepts may be extended to other devices that detect particles or energy, regardless of the source and nature of the particles and energy. By way of example, various concepts presented throughout this disclosure may be extended to cameras, radar detectors, artificial eyes, medical devices (CT scanners), or any other suitable system having a requirement to detect particles and/or energy. Accordingly, any reference to a specific radiation detector is intended only to illustrate various aspects of the present disclosure, with the understanding that these concepts have a wide range of applications. 
         [0024]      FIG. 1  illustrates an exemplary radiation detector system  100 . In the embodiment shown in  FIG. 1 , a radiation detector system may include a photosensor  105 , a power converter module  110 , a power source  120 , an amplifier  130 , and a processor  140 . The photosensor  105  may vary in accordance with the various embodiments of the disclosure. By way of illustration, the photosensor  105  may include analog or digital circuitry; the photosensor  105  may include a solid-state photosensor. The photosensor may include an array of solid-state radiation detecting sensors. The array may be arranged in a uniform grid. The system may be powered by a portable battery or from a fixed power source such as an A/C wall socket. The photosensor  105  may be calibrated to a radioactive isotope such as, for example, to Cesium-137 (Cs137), or Iodine-125 (I-125), or Cobalt-60 (Co60), or other isotopes. Such isotopes have a known half-life of decay rate with known decay products, and may be used as standards for calibration. Calibration is usually performed by a qualified radiation safety officer or an agency certified to perform calibration correctly. The process includes exposing the sensor to a radiation source of known activity at precisely measured distances. The reading is compared to the dose that is actually being given off by the source at each of the distances. The response must be within a known percentage (e.g., 10%) of the dose actually given off by the source at that distance in order to be considered calibrated. In some embodiments, the sensor may not be calibrated due to location or configuration of the sensor, in which case the detection is qualitative, not quantitative. 
         [0025]    The sensitivity of the sensor may be measured at a radiation level, such as counts per minute (CPM), or at a dose rate, such as rads per hour (Rad/hr) or millirads per hour (mRad/hr). The photosensor  105  may detect any combination of energy or particles. For example, the sensor may be configured to detect electromagnetic radiation including high energy (short wavelength) photons, e.g., gamma radiation and x-rays. The photosensor  105  may detect particles including high energy particles such as alpha particles and beta particles. The photosensor  105  may be used to detect both electromagnetic radiation and particles. In addition, the photosensor  105  may be used to detect radiation in water and food. The photosensor  105  may be used to detect radiation at high elevation (such as on an airplane), medium elevation, low elevation, and underground. The photosensor  105  may also be used as detectors in a medical imaging procedure such as an X-ray or computed tomography (CT) scanning imaging. The photosensor  105  may be contained in a metallic enclosure that may serve as a radiation shield. For example, the shielding may protect electronic circuitry from radiation damage. The metallic enclosure may be fabricated from aluminum, tin or other similar materials. The photosensor  105  may output a wavelength, count, intensity, or similar measurement, and may also identify the type of radiation or particles. In an embodiment, the amplifier  130  increases the power of the signal from the photosensor  105 . Processor  140  receives the amplified signal. In other embodiments, the amplifier  130  may be included with the photosensor  105  or the processor  140  to increase a signal-to-noise (S/N) ratio. The photosensor  105  may also output directly to the processor  140  without amplification. The radiation detector system  100  may also include an analog to digital converter (not shown). For example, the processor  140  may receive an analog signal and convert the signal to a digital signal in order that additional signal processing may be performed digitally, or to prepare the signal for digital transmission. 
         [0026]    The radiation detector system  100  may include a power source  120  and power converter module  110  for applying a voltage to the photosensor  105 . In an aspect, the photosensor  105  may include a voltage input having a rated voltage. The rated voltage may be a maximum rated voltage. The power source  120  and power converter module  110  may be configured to apply a voltage to the voltage input that exceeds the rated voltage. A portion of the input voltage is applied across the photosensor, which acts as a capacitor that charges up in response to the voltage. Ionizing radiation causes current to flow in an amount corresponding to the energy of the incident radiation. 
         [0027]    Increasing the applied voltage, such as when the input voltage is raised above the rated voltage, reduces the capacitance of the photosensor  105 . This capacitance reduction reduces noise in the photosensor  105 , which increases the signal-to-noise ratio (SNR) of the photosensor  105 . With a lower SNR, the photosensor  105 , whether used in conjunction with the amplifier  130  or not, may detect pulses of ionizing radiation of lower energy, thus increasing its sensitivity. For example, the photosensor  105  may include a rated voltage of 50-60 volts, and the power source may apply a voltage of 70-90 volts. For example, the rated voltage may be lower or higher than the 50-60 volt range. In addition, the power source  120  and power converter module  110  may be configured to apply a voltage lower or higher than the 70-90 volt range. In other embodiments, the power converter module  110  may be included in the power source  120 , or the power source  120  may be configured to apply a voltage to the photosensor  105  without the power converter module  110 . 
         [0028]    Reducing the capacitance of the photosensor  105  by increasing the applied voltage also increases the speed of the sensor. This has the effect of improving time resolution, i.e., the detection of individual radiation events. 
         [0029]      FIG. 2  illustrates an exemplary processor  140  used in the exemplary radiation sensor system of  FIG. 1 . The exemplary processor  140  configuration may include the processor  140 , a power switch  200 , a sound indicator  210 , a visual indicator  220 , and a data interface  230 . The power switch  200  enables or disables the processor  140 . A user of the system may use the power switch  200  to activate or deactivate the radiation detector system  100 . The power switch  200  may also be coupled to other elements of the system (e.g., power source  120 ) to enable or disable the other elements of the system. The processor  140  activates either or both the sound indicator  210  and visual indicator  220  based on a count of the radiation. For example, the processor  140  may activate the sound indicator  210  or visual indicator  220  when the level of the radiation exceeds a threshold. The processor  140  may activate the sound indicator  210  or visual indicator  220  to reflect the radiation level. Thus, an output level from the sound indicator  210  or visual indicator  220  may correspond to the radiation level. In such an embodiment, the radiation detector system  100  may act as a dosimeter where the audible signal assists and alerts the user, who may be required to focus visual attention on the environment being inspected. 
         [0030]    In an embodiment, the radiation detector system  100  may also send data to an external device, such as a remote data collection receiver. The collection receiver may receive the data from a plurality of radiation detector systems  100  in separate locations to construct a map of radiation levels. 
         [0031]    In other embodiments, the visual indicator  220  may be an on/off light to indicate when the processor  140  is active. The sound indicator  210  may be, for example, an alarm, a buzzer, or a speaker. The visual indicator  220  may be, for example, a light such as a light emitting diode (LED), a dial, or a digital display. 
         [0032]    The processor  140  may be coupled to a data interface  230 . For data output, the processor  140  may output raw or processed data. Raw or processed data may be sent to displays included in the device, such as the visual indicator  220 . The displays may display or otherwise represent the raw or processed data (see  FIG. 5 ). The processor  140  may also receive input through the data interface  230 , such as user configuration data. This configuration data may be used to configure various aspects of the processor, such as the output and control of the sound indicator  210  and visual indicator  220 , or other outputs. The radiation sensor system  100  may be configured to operate with a separate user device, or as a stand alone device. 
         [0033]    The data interface  230  may be coupled to a wireless data interface (not shown). In addition, the data interface  230  may include a wireless data interface. In an embodiment, the radiation detector system  100  may send data through the wireless data interface based on a level of the radiation. For example, the radiation detector system  100  may be configured to send a message, such as an email or a user datagram, to a network device such as a server or database based on the radiation level. The email or user datagram message may warn the user that the radiation level exceeds a threshold or is increasing. The radiation detector system  100  may be configured to send a message at predetermined intervals, such as once a day or multiple times a day. The radiation level data may include a location, such as provided by a global position system (GPS), such that the radiation level data may be associated with the location. When data is sent to the network device, the data may be stored or used in real time. A local, regional, or global map of radiation level and other photosensor data may be generated based on data from a plurality of radiation detector systems  100  using any combination of real time data and historical data. In a further embodiment, the radiation detector system  100  may be configured to send data continuously to the network device and receive data from other devices. The wireless data interface may be, for example, a Wi-Fi interface including the IEEE 802.11 interface, although other wireless interfaces may be used. 
         [0034]      FIG. 3  illustrates an exemplary housing  300  supporting the radiation detector system  100  of  FIG. 1 . The housing  300  may be coupled to the radiation detector system  100  using any combination of fasteners or other suitable mounting elements. The housing  300  may include an AC power plug  310  to be inserted into an AC wall socket. The AC power plug  310  may also be removed from the AC wall socket, for example, when not in use or to disable the radiation detector system  100 . In a further embodiment, the AC power plug may be coupled to the power source  120  which may be external to the detector system, and may couple the power source  120  to the power switch  200 . When the AC power plug  310  is connected to the AC wall socket, and the power switch  200  is in an operative mode, a voltage is applied to the radiation detector system  100 . 
         [0035]      FIG. 4  is a flowchart of a method of output selection  400 , used with the exemplary radiation detector system  100  of  FIG. 1 . The process begins by receiving radiation data (block  405 ). The radiation data may be derived from the output of the photosensor  105  or data processed by the processor  140  on the basis of the output from the photosensor  105 . Next, at block  410 , the process maintains a record of radiation level data in a memory that may be included in the processor. Next, at  420 , a user-configured average value radiation level is calculated. The user-configured average value may be a running-average over a user-defined time window, and may adjust the time window to meet the needs of a particular application. A user may configure the process to calculate an average for a 10 second window or a 1 minute window. Other time windows may be user-defined to calculate an average. The process may also calculate the user-configured average value of the radiation level based on the user-defined time window. Next, at  430 , the process calculates a radiation level using a Kalman filter and also calculates a running-average value. The Kalman filter is an algorithm which operates recursively on streams of noisy input data to produce a statistically optimal estimate of the radiation level. Next, at  440 , the process determines whether the running-average value is outside of a threshold range. The threshold range may be configured by the user or may be a default range based on a calibration of the radiation detector system  100 . As an example, the threshold range may output the running-average when the Kalman filter value is likely to be unreliable. If the running-average value is outside the threshold range, the process selects the Kalman filter value (block  450 ); otherwise, the process selects the running-average value (block  460 ). The process then outputs the selected value of the Kalman filter or the running-average, and may also output the user-configured average value. One skilled in the art will recognize that the Kalman filter may vary with the various embodiments of the disclosure. For example, the Kalman filter may produce estimates of the true values of the radiation measurements and their associated calculated values by predicting a value, estimating the uncertainty of the predicted value, and computing a weighted average of the predicted value and the measured value. The most weight is given to the value with the least uncertainty. Other calculated values of the radiation count may be determined using any suitable method. The process may be configured to calculate and output an instantaneous value of the radiation count. 
         [0036]      FIG. 5  illustrates exemplary user interfaces for the radiation detector system  100 . The processor  140  of  FIG. 1  may be configured to send data to a user device with user interfaces  500 ,  510 ,  520  for displaying the radiation data. Exemplary user interfaces  500 ,  510 ,  520  include graphical user interface elements for displaying the radiation count and data. A first user interface  500  includes a display gauge  502  and an on/off toggle switch  504 . The display gauge  502  may show the radiation count in a dial layout with three discrete zones of radiation counts. A second user interface  510  includes a digital gauge  512 , a scope gauge  514 , and an on/off switch  516 . The on/off switch  516  (e.g., a knob) enables or disables the digital gauge  512  and scope gauge  514 . The digital gauge  512  shows the radiation count in a digital format for ease of use, along with a scope gauge  514  to show a running radiation count and trends. A third user interface  520  includes a first dial gauge  522  and a second dial gauge  524 . The on/off switch  526  enables or disables the first dial gauge  522  and second dial gauge  524 . The first dial gauge  522  may show the radiation count in, for example, microSievers/hr (uSv/hr) while the second dial gauge  524  may show the radiation count in counts per second (CPS). The user interfaces may vary with the various embodiments of the disclosure. 
         [0037]      FIG. 6  illustrates a local area map with radiation readings. The number markers  610 ,  620 ,  630 ,  640 ,  650  may indicate radiation count levels. The number markers  610 ,  620 ,  630 ,  640 ,  650  may alternatively indicate absolute average radiation counts or a scaled value. In an embodiment, the number markers  620 ,  630 ,  640 ,  650  may correspond to historical readings at different locations, while number marker  610  may be a current location reading. Number markers  620 ,  630 ,  640 ,  650  may also correspond to current readings of other users at different locations, while number marker  610  may be a current location reading. The number markers may be any combination of historical or current radiation readings. Those skilled in the art will also recognize that the local area map is for illustration purposes only, and the embodiments are not so limited. 
         [0038]      FIG. 7  illustrates a global area map with radiation readings according to an embodiment. Markers  710 ,  720  may indicate radiation count levels at indicated locations. The number markers  710 ,  720  may indicate absolute average radiation counts or a scaled value. In an aspect, the number marker  720  may correspond to historical readings at a different location, while number marker  710  is a current location reading. In another aspect, the number marker  720  may correspond to a current reading of other users at a different location, while number marker  710  is a current location reading. The number markers may be any combination of historical or current radiation readings. Those skilled in the art will also recognize that the local area map is for illustration purposes only, and the embodiments are not so limited. 
         [0039]    In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements may be implemented with a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside on a computer-readable medium. The computer-readable medium may be a non-transitory computer-readable medium. A non-transitory computer-readable medium includes, by way of example, a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., compact disk (CD), digital versatile disk (DVD)), a smart card, a flash memory device (e.g., card, stick, key drive), random access memory (RAM), read only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), a register, a removable disk, and any other suitable medium for storing software and/or instructions that may be accessed and read by a computer. The computer-readable medium may also include, by way of example, a carrier wave, a transmission line, and any other suitable medium for transmitting software and/or instructions that may be accessed and read by a computer. The computer-readable medium may be resident in the processing system, external to the processing system, or distributed across multiple entities including the processing system. The computer-readable medium may be embodied in a computer-program product. By way of example, a computer-program product may include a computer-readable medium in packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system. 
         [0040]    It is to be understood that the specific order or hierarchy of steps in the methods and processes disclosed is an illustration of exemplary processes. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the methods may be rearranged. 
         [0041]    The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”