Abstract: Disclosed herein is a method comprising: aligning a collimator and a plurality of radiation detectors of an image sensor by: moving the radiation detectors along a first direction; moving the collimator along a second direction perpendicular to the first direction; rotating the collimator about an axis perpendicular to the first direction and the second direction; wherein the plurality of radiation detectors are configured to capture images of portions of a scene at different image capturing positions, respectively, and to form an image of the scene by stitching the images of the portions.

Abstract: A scintillation block detector employs an array of optically air coupled scintillation pixels, the array being wrapped in reflector material and optically coupled to an array of silicon photomultiplier light sensors with common-cathode signal timing pickoff and individual anode signal position and energy determination. The design features afford an optimized combination of photopeak energy event sensitivity and timing, while reducing electronic circuit complexity and power requirements, and easing necessary fabrication methods. Four of these small blocks, or “miniblocks,” can be combined as optically and electrically separated quadrants of a larger single detector in order to recover detection efficiency that would otherwise be lost due to scattering between them.

Abstract: A method of fabricating a semiconductor detector device to exhibit a target sensitivity to incident radiation in a predetermined energy range is described, the method comprising: providing a semiconductor detector; defining on a detector surface of the semiconductor detector a large plurality of pixels; wherein the detector is geometry is controlled with reference to the size of the said pixels such that a single interaction event in the predetermined energy range will produce a detectable signal in each of a plurality of adjacent pixels making up a cluster of at least three pixels. A detector fabricated by such a method and a method of obtaining spectral information about incident radiation using such a detector are also described.

Abstract: A radiation detection device (300) is used in a nuclear medicine diagnosis apparatus, and includes a plurality of scintillators (44), a semiconductor light-receiving device (SiPM), a position detection circuit (214), and a timing detection circuit (216). Each of the scintillators converts a gamma ray emitted from a subject (15) into fluorescence. The semiconductor light-receiving device is provided corresponding to each of the scintillators and converts the fluorescence converted by a corresponding one of the scintillators into an electrical signal. The position detection circuit specifies a gamma ray detection position in the scintillators based on the electrical signal from the semiconductor light-receiving device. The timing detection circuit is connected to an anode of the semiconductor light-receiving device, and specifies time information corresponding to a time of occurrence of an event in which the gamma ray is detected.

Abstract: An apparatus suitable for detecting X-ray is disclosed. In one example, the apparatus comprises an X-ray absorption layer comprising a first pixel and a second pixel, and a controller. The controller is configured for determining that carriers generated by a single X-ray photon are collected by the first pixel and the second pixel. The controller is also configured for determining energy of the single X-ray photon based on a first voltage detected from the first pixel and a second voltage detected from the second pixel. The first voltage and the second voltage are caused by the single X-ray photon.

Abstract: An apparatus suitable for detecting X-ray is disclosed. In one example, the apparatus comprises an X-ray absorption layer comprising a first pixel and a second pixel, and a controller. The controller is configured for determining that carriers generated by a single X-ray photon are collected by the first pixel and the second pixel. The controller is also configured for determining energy of the single X-ray photon based on a first voltage detected from the first pixel and a second voltage detected from the second pixel. The first voltage and the second voltage are caused by the single X-ray photon.

Abstract: A one-dimensional multi-element photo detector includes a photodiode array with a first upper row of photodiode pixels and a second lower row of photodiode pixels. The photodiode array is part of the photo detector. A scintillator array includes a first upper row and a second lower row of scintillator pixels. The first upper and second lower rows of scintillator pixels are respectively optically coupled to the first upper and second lower rows of photodiode pixels. The photo detector also includes readout electronics, which are also part of the photo detector. Electrical traces interconnect the photodiode pixels and the readout electronics.

Abstract: A compact spectrometer system comprising an improved detector is provided herein. The spectrometer system herein disclosed can comprises a filter, a Fourier transform optical element, and a detector. The detector can comprise a custom detector having a shape that corresponds to the pattern of light incident on the detector. The custom detector may comprise a plurality of separate detection areas, each area configured to detect a portion of the light pattern incident on the detector. The custom detector may comprise a material capable of detecting wavelengths in the short-wavelength infrared (SWIR) range. The custom detector may be configured to require a relatively low number of electrical connections such that it may be implemented using standard, low-cost electronic packaging techniques. An improved, custom detector as described herein can provide the functionality of a two-dimensional pixel array detector while being relatively simple and inexpensive to manufacture.

Abstract: A method for correcting PET data includes acquiring first PET data at a time interval. The method also includes acquiring a first normalization coefficient corresponding to the first PET data. The method also includes determining a scale factor based at least partially on the first normalization coefficient. The method also includes determining second PET data based on the first PET data, the scale factor, and the second normalization coefficient. The method also includes determining a first dead time correction coefficient corresponding to the second PET data. The method also includes determining third PET data based on the second PET data and the first dead time correction coefficient. The method further includes reconstructing a first image based on the third PET data.

Abstract: A nuclear medicine diagnostic apparatus according to an embodiment includes a scintillator configured to be formed of a single crystal and convert a gamma ray into light; a plurality of photodetectors configured to be arranged on different faces or tangents of the scintillator and each of which is configured to output an electric signal in response to incidence of the light resulting from the converting by the scintillator; storage circuitry configured to store, in advance, correspondence information in which each position in the scintillator is associated with a first intensity distribution indicating intensities of the electric signals that are output by the respective photodetectors; and specifying circuitry configured to specify a conversion position in which the gamma ray that is emitted from the subject is converted into the light in the scintillator by using the correspondence information and a second intensity distribution indicating the intensities of the electric signals.

Abstract: An information processing apparatus includes a sonic wave output unit that outputs a sonic wave. A horn restricts an output direction of the sonic wave output from the sonic wave output unit. A cover member is provided on the sonic wave output unit, wherein a region on the cover member corresponding to an opening of the horn is provided with a horizontally arranged slit having a width equal to or larger than a horizontal width of the opening.

Abstract: A lateral-effect position-sensing detector includes a second lateral-current collector layer, an electron barrier layer on the second lateral-current collector layer, an absorber layer on the electron barrier layer, a first lateral-current collector layer on the absorber layer, and a first elongate electrical contact and a second elongate electrical contact on each of the lateral-current collector layers. Incident light radiates a transparent first lateral-current collector layer to be absorbed by the undepleted absorber layer where electron and holes are generated. The depleted electron barrier layer prevents a flow of electrons from the absorber layer to the second lateral-current collector layer but allows electrons to flow to the second lateral-current collector layer. The lateral-effect position-sensing detector is sensitive to a lateral position between the first elongate electrical contact and the second elongate electrical contact of incident light on each of the lateral-current collector layer.

Abstract: A system (10) and a method (100) compensate for one or more dead pixels in positron emission tomography (PET) imaging. A pixel compensation processor receives PET data describing a target volume of a subject. The PET data is missing data for one or more dead pixels. The pixel compensation estimates PET data for the dead pixels from the received PET data.

Abstract: A system for detecting high-energy photons includes a pixelated image detector exposed to visible light and high-energy photons, and the pixelated image detector generates one or more images from the exposure to the visible light and high-energy photons. The system further includes one or more processors operably connected to the pixelated image detector and configured to perform operations on the one or more images to discriminate between visible light and high-energy photons. A method for detecting high-energy photons includes exposing a pixelated image detector to visible light and high-energy photons and discriminating between the visible light that interacts with the pixelated image detector and the high-energy photons that interact with the pixelated image detector.

Abstract: A CT system includes a gantry having an opening for receiving an object to be scanned, an x-ray tube attached to the gantry, and a detector assembly. The detector assembly is positioned to receive x-rays that pass through the object and includes a light-sealed enclosure formed by at least first and second rails, a back support, and a light seal structure, and a plurality of liquid-cooled modules positioned in the enclosure. Each module includes a digital cable that passes from inside the enclosure, and each module is configured to convert the x-rays to a digital signal and output the signal via a digital cable.

Abstract: Measurements of electric charges obtained by the impact of ionizing radiation on a semiconductor detector are grouped in a histogram. Calibrations and data otherwise obtained are used to obtain acceptance probabilities of measurements, which are used to construct a histogram of events by weighting the measurements so as to exclude the influence of some factors (such as diffused radiation) or on the contrary to enhance this influence.

Abstract: The present invention relates to a pixel detector (10), comprising a semiconductor sensor layer (12), in which charges can be generated upon interaction with particles to be detected. The semiconductor layer defines an X-Y-plane and has a thickness extending in Z-direction. The detector further comprises a read-out electronics layer (14) connected to said semiconductor layer (12), said read-out electronics layer (14) comprising an array of read-out circuits (20) for detecting signals indicative of charges generated in a corresponding volume of said semiconductor sensor layer (12). The neighboring read-out circuits (20) are connected by a relative timing circuit configured to determine time difference information between signals detected at said neighboring read-out circuits (20).

Abstract: A method for determining parameters of a beam. As a part of the disclosed method, a beam is received at an image detection array where charges are generated and collected, at a plurality of pixels. Values associated with at least one of a plurality of parameters of the beam are determined by integrating information supplied from each of the pixels. Feedback is generated that presents the values.

Abstract: Apparatuses and methods are provided that minimize the effects of dark-current pulses. For example, in one embodiment of the invention, a method is provided where a first pixel is struck (i.e., a primary pixel). Pixels struck within a fixed time frame after the primary pixel is struck are referred to as secondary pixels. After a short fixed time frame has expired, the number of primary and secondary pixels is added. If the count exceeds a threshold, the primary pixel was activated by the first (or early) photon from a true gamma event. If the threshold is not met then it is likely the primary pixel generated a dark pulse that should be ignored.

Abstract: A High Purity Germanium (HPGe) radiation detector has been specially machined to be this invented series multi-chamber coaxial configuration. So extra-large volume HPGe detectors can be easily produced with current available HPGe crystal, and the entire detector body structure can be uniquely optimized in accordance with the exact semiconductor crystal ingot situation so the overall detector can be easier depleted and the photo-induced carriers can be better collected as the signal output. This invention makes extra-large efficiency HPGe gamma ray detectors of 100% to 200%, and maybe even higher efficiency, possible and easier to be produced based on current HPGe crystal supply capability. The invention improves the detector performance for very high energy gamma ray detection especially. The invention could also be applied to any other kind of semiconductor materials if any of them could be purified enough for this application in future.

Abstract: A particle beam sensor comprising: scattering means providing a surface for intercepting obliquely a path of a particle beam thereby to permit a scattering of particles from the particle beam by the scattering means; sensor means responsive to receipt of one or more said scattered particles to generate a sensor signal; aperture mask means arranged between the scattering means and the sensor means to present to the scattering means a screen opaque to said scattered particles and having at least one aperture through which an unobstructed view of the scattering means is provided to the sensor means, the aperture (s) thereby permitting selection of all of those particles scattered by the scattering means which may be used to form at the sensor means an image representative of at least a part of a foot print cast by the particle beam upon the scattering means. By scattering particles from a sectional area of a particle beam, scattered beam particles can be used more efficiently compared to existing techniques.

Abstract: A radioactive ray detecting apparatus provides for reduction of the dead area or region where radioactive rays cannot be detected, even if disposing the radioactive ray detectors to be dense or crowded. The radioactive ray detecting apparatus satisfies the following relationships, when assuming that distance between semiconductor elements is “XG1”, while the distance from the semiconductor element of one of the radioactive ray detectors up to the semiconductor element of other radioactive ray detectors is “XG2”, and distance between the semiconductor elements alighted in a Y-direction is “YG1”, and a horizontal pitch of a predetermined pixel pitch to be used as the radioactive ray detector is “a” and a vertical pitch thereof is “b”, width of a surface of each of plural numbers of semiconductor elements is “c” and length thereof is “d”, respectively: c=a?(XG1+XG2)/2 d=b?YG1=2e+(n?2)f.

Abstract: Two and three dimensional position sensing systems and sensors for use in such systems are disclosed. The sensors incorporate linear array sensors and an aperture plate to block light or other radiation from reaching most elements of the sensors. A direction of a radiation source relative is determined based on illuminated sensor elements in each sensor. The sensors are combined in systems to allow the position of a radiation source to be estimated.

Abstract: A method for detecting radiation during the examination of a sample (1) comprises the steps of generating the radiation, more particularly X-ray radiation or proton radiation, by means of a source device (10), passing the radiation through the sample (1), and detecting the radiation by means of at least one photoelectric solid-state detector (20) containing a photoconduction section having a predetermined response threshold and a potential well section for taking up free charge carriers. The solid-state detector (20) is a GaN- or GaAs-based semiconductor detector and the potential well section contains a two-dimensional electron gas (2DEG). A setting of the radiation is provided in such a way that the solid-state detector (20) is operated separately from the response threshold of the photoconduction section and in a sensitivity range of the potential well section.

Abstract: A system and method for determining a probability of the location of an illicit radiation source within an environment based on directional detectors. An embodiment includes a plurality of directional radiation detectors distributed about the environment and integrated with a processing unit adapted to determine the probability of the source location based on the radiation count data received from the plurality of detectors. The processing unit is further adapted to output information indicative of the location of the radiation source within the environment.

Abstract: Disclosed is a radiation imaging device configuring a radiation imaging system. Specifically disclosed is a radiation imaging device wherein external force action mechanisms are capable of applying external force to the peripheral sections of a radiation conversion panel, or applying the external force while being laminated on the radiation conversion panel, or pressing the radiation conversion panel against the inner wall of a panel containing unit, which contains the radiation conversion panel, at least in imaging when radiation is applied.

Abstract: A high-energy radiation detector apparatus, comprising a high-energy radiation detector substrate and a plurality of charge collection electrodes operatively coupled to first and second opposing sides of the detector substrate is disclosed. Charge collection circuitry is associated with the plurality of charge collection electrodes for collecting charge induced on the charge collection electrodes by a high energy radiation photon interaction event caused by high-energy radiation incident on the detector substrate.

Abstract: A photon-counting Geiger-mode avalanche photodiode intensity imaging array includes an array of pixels (200), each having an avalanche photodiode (250). A pixel senses an avalanche event and stores, in response to the sensed avalanche event, a single bit digital value therein. An array of accumulators (320) are provided such that each accumulator is associated with a pixel. A row decoder circuit (310) addresses a pixel row within the array of pixels. A bit sensing circuit (300) converts a precharged capacitance into a digital value during read operations.

Abstract: Detection of ionizing radiation with modulation doped field effect transistors (MODFETs) is provided. There are two effects which can occur, separately or together. The first effect is a direct effect of ionizing radiation on the mobility of electrons in the 2-D electron gas (2DEG) of the MODFET. An ionizing radiation absorption event in or near the MODFET channel can perturb the 2DEG mobility to cause a measurable effect on the device conductance. The second effect is accumulation of charge generated by ionizing radiation on a buried gate of a MODFET. The conductance of the MODFET can be made sensitive to this accumulated charge, thereby providing detection of ionizing radiation. 1-D or 2-D arrays of MODFET detectors can be employed to provide greater detection area and/or spatial resolution of absorption events. Such detectors or detector pixels can be integrated with electronics, such as front-end amplification circuitry.

Abstract: A semiconductor detector device, such as a PIN diode or silicon drift detector, including a substrate with an entrance window. The entrance window comprises a conductive layer, and an insulating layer disposed between the conductive layer and the substrate. The insulating layer and conductive layer cover a center portion of the surface of the substrate.

Abstract: A sensor assembly for electric field sensing is provided. The sensor assembly may include an array of Micro-Electro-Mechanical System (MEMS)-based resonant tunneling devices. A resonant tunneling device may be configured to generate a resonant tunneling signal in response to the electric field. The resonant tunneling device may include at least one electron state definer responsive to changes in at least one respective controllable characteristic of the electron state definer. The changes in the controllable characteristic are configured to affect the tunneling signal. An excitation device may be coupled to the resonant tunneling device to effect at least one of the changes in the controllable characteristic affecting the tunneling signal. A controller may be coupled to the resonant tunneling device and the excitation device to control the changes of the controllable characteristic in accordance with an automated control strategy configured to reduce an effect of noise on a measurement of the electric field.

Abstract: Embodiments of radiographic imaging systems; radiography detectors and methods for using the same can include radiographic imaging array that can include a plurality of pixels that each include a photoelectric thin-film conversion element coupled to a conversion thin-film switching element. In certain exemplary embodiments, a radiographic imaging array can include a bias control circuit to provide a bias voltage to the photosensors for a portion of the imaging array, an address control circuit to control scan lines, where each of the scan lines is coupled to a plurality of pixels in the portion of the imaging array; and a signal sensing circuit connected to data lines, where each of the data lines is coupled to at least two pixels in the portion of the imaging array, where power of the bias control circuit, the address control circuit, and the signal sensing circuit is not removed simultaneously.

Abstract: In an optical position detecting device, a position detecting section detects the position of a target object on the basis of a result obtained by receiving detection light, which is emitted from a light source section and reflected by the target object, using a light detection section. As seen from an emitting direction of the detection light, the light detection section is located inside a region surrounded by a closed circuit passing through a plurality of the light source sections or inside a region pinched by the plurality of light source sections. The plurality of light source sections has a first light-emitting element, and a second light-emitting element located closer to the light detection section side than the first light-emitting element. The light source driving section alternately turns on the first light-emitting element and the second light-emitting element.

Abstract: A radiation imaging apparatus has a pixel region arranged on a substrate. Arranged in a matrix pattern in the pixel region are pixels, each pixel including a conversion element which converts radiation to electrical charges, and a switching element which is connected to the conversion element therein. The radiation imaging apparatus has, in a region outside the pixel region of the substrate, an intersection at which a signal line connected to the switching element and a bias line connected to the conversion element intersects. At the intersection, a semiconductor layer is arranged between the signal line and the bias line, and a carrier blocking portion is arranged between the semiconductor layer and the signal line.

Abstract: The present invention provides a radiation detector for detecting both the intensity and direction of one or more sources of radiation comprising a radiation sensor, an inverse collimator that shields the sensor from at least a portion of the incident radiation originating from the direction in which the inverse collimator is pointed and a means for pointing the inverse collimator in different directions.

Abstract: An imaging apparatus includes an image sensor in which a plurality of area sensors arranged adjacent to each other to form an image sensor. A control circuit controls timing for reading out image data from each of the plurality of the area sensors based on area sensor arrangement information concerning the arrangement of each of the plurality of the area sensors.

Abstract: A PET scanner (8) includes a ring of detector modules (10) encircling an imaging region (12). Each of the detector modules includes at least one detector pixel (24,34). Each detector pixel includes a scintillator (20, 30) optically coupled to one or more sensor APDs (54) that are biased in a breakdown region in a Geiger mode. The sensor APDs output a pulse in response to the light from the scintillator corresponding to a single incident radiation photon. A reference APD (26, 36) also biased in a break-down down region in a Geiger mode is optically shielded from light and outputs a temperature dependent signal. At least one temperature compensation circuit (40) adjusts a bias voltage applied to the sensor APDs based on the temperature dependent signal.

Abstract: An apparatus and method to increase the sensitivity at the edge of radiation detector blocks is disclosed herein. Reduced sensitivity can result from photons entering a first detector block, escaping, and scattering into an adjacent detector, thereby depositing energy into two detectors blocks. Energy lost into adjacent detector blocks can be compensated with energy detected in the adjacent detector block. This can be done, for example, by processing channels from multiple detector blocks with one Field Programmable Gated Array (FPGA) on one Event Process Module (EPM) board. This can enable summing energy of one detector block with energy from an adjacent detector block when the initial interaction occurs at the edge of the first detector block. This can result in a better estimate of the amount of energy associated with the initial photon being detected.

Abstract: The scintillator plate has a reflective layer, a resinous anti-corrosion layer and a scintillator layer provided sequentially in that order on a heat resistant resin substrate. The scintillator plate is employed as a component for a flat panel radiation detector. The scintillator plate has a protective film between the scintillator layer and the flat light receiving element which makes up the flat panel radiation detector. There is point contact between the surface of the scintillator layer and the protective film and there is point contact between the flat light receiving element and the protective film.

Abstract: Systems that increase the position resolution and granularity of double sided segmented semiconductor detectors are provided. These systems increase the imaging resolution capability of such detectors, either used as Compton cameras, or as position sensitive radiation detectors in imagers such as SPECT, PET, coded apertures, multi-pinhole imagers, or other spatial or temporal modulated imagers.

Abstract: A radiation detector of this invention includes a pulse width modulation circuit for binarizing an analog electrical pulse outputted from a detector cell with a predetermined threshold, and modulating it into a digital electrical pulse, and a data superposer for outputting an incident position pulse train by superposing incident position pulses and concerning the position of the detector cell on which the radiation has fallen, and the digital electrical pulse detected by the radiation. Thus, position information which has conventionally been added after output of digital electrical pulse can be added into the digital electrical pulse. Therefore, compared with the conventional technique of adding position information after digital electrical pulse and transmitting the position information, the position of the radiation incident on the detector cell can be detected in a short time.

Abstract: The apparatus has an energy calculation section 32 that calculates energy deposit values of interactions based on signals obtained from segmented electrodes 11, 12 provided on two opposite surfaces of a semiconductor crystal, a reference waveform storing section 33 that stores beforehand waveforms that will be obtained from the segmented electrodes when a single interaction occurs for multiple positions in the crystal, a waveform synthesis section 34 that synthesizes reference waveforms corresponding to arbitrary two points in the crystal as candidate points of interaction at a ratio equal to a ratio of their energy deposit values, and a comparison section 35 that compares a measured waveform and the synthesized waveforms. The candidate points from which the synthesized waveform most similar to the measured waveform is obtained is determined to be the positions of interactions. Thus, even in cases where multiple interactions occur, the positions of the interactions can be detected.

Abstract: Systems that increase the position resolution and granularity of double sided segmented semiconductor detectors are provided. These systems increase the imaging resolution capability of such detectors, either used as Compton cameras, or as position sensitive radiation detectors in imagers such as SPECT, PET, coded apertures, multi-pinhole imagers, or other spatial or temporal modulated imagers.

Abstract: A system in one embodiment includes an array of radiation detectors; and an array of imagers positioned behind the array of detectors relative to an expected trajectory of incoming radiation. A method in another embodiment includes detecting incoming radiation with an array of radiation detectors; detecting the incoming radiation with an array of imagers positioned behind the array of detectors relative to a trajectory of the incoming radiation; and performing at least one of Compton imaging using at least the imagers and coded aperture imaging using at least the imagers. A method in yet another embodiment includes detecting incoming radiation with an array of imagers positioned behind an array of detectors relative to a trajectory of the incoming radiation; and performing Compton imaging using at least the imagers.

Abstract: Methods are presented that increase the position resolution and granularity of double sided segmented semiconductor detectors. These methods increase the imaging resolution capability of such detectors, either used as Compton cameras, or as position sensitive radiation detectors in imagers such as SPECT, PET, coded apertures, multi-pinhole imagers, or other spatial or temporal modulated imagers.

Abstract: A direct conversion radiation detector includes a detector body made from a direct conversion material, a plurality of segmented electrode members operatively coupled to a radiation-receiving side of the detector body and at least one electrode operatively coupled to a second side of the detector body. The radiation detector is configured such that received radiation is incident on the segmented electrode members. The radiation detector provides reduced polarization effects for a variety of high flux radiation detection applications.

Abstract: A semiconductor 2D position detector for two-dimensionally detecting positions of radiation is a Schottky diode comprising: a semiconductor substrate 2; a first to an nth (n is an integer of 2 or higher) stripe electrodes 3 arranged on the surface 2A of the semiconductor substrate 2 at given intervals in the X direction and in parallel to the Y direction; and an electrode 15 formed on the rear surface 2B of the semiconductor substrate 2. The top and the bottom ends of each of the stripe electrodes 3 are sequentially connected via a resistor 4, 5, and signals V1 to V4 output from the radiation 16 applied to the semiconductor substrate 2 are obtained from each of the both ends of the first and the nth stripe electrodes placed far left and right.

Abstract: An imaging system comprises a first charge-coupled device (CCD), a second CCD, and a processor. The first CCD is configured to receive one or more light flashes, record a first set of data based on the light flashes, shift the first set of data in a first direction, read out the first set of data, and read out continuously. The second CCD is configured to receive the one or more light flashes, record a second set of data based on the light flashes, shift the second set of data in a second direction opposite to the first direction, read out the second set of data, and read out continuously. The processor, coupled to the first CCD and second CCD, is configured to determine a time and a location of the one or more light flashes based on the first set of data and the second set of data.

Abstract: A sensor device of the type for sensing incident radiation by charge generation, has a substrate within which charge may be generated by incident radiation. A plurality of electrodes are arranged to cover an image area of the substrate and are selectively connectable to supplied DC voltages such that an electric field is created across the image area to sweep charge across multiple electrodes from the image area to an output. The voltage applied to one of the electrodes may be a voltage of a level so as to present a barrier to charge within the image area. The sensor thus has a variable sample area defined by the barrier voltage level.

Abstract: A system and method for determining a probability of the location of an illicit radiation source within an environment based on directional detectors. An embodiment includes a plurality of directional radiation detectors distributed about the environment and integrated with a processing unit adapted to determine the probability of the source location based on the radiation count data received from the plurality of detectors. The processing unit is further adapted to output information indicative of the location of the radiation source within the environment.