33 results about "Detector geometry" patented technology

A coded localization system includes a plurality of optical channels arranged to cooperatively image at least one object onto a plurality of detectors. Each of the channels includes a localization code that is different from any other localization code in other channels, to modify electromagnetic energy passing therethrough. Output digital images from the detectors are processable to determine sub-pixel localization of the object onto the detectors, such that a location of the object is determined more accurately than by detector geometry alone. Another coded localization system includes a plurality of optical channels arranged to cooperatively image partially polarized data onto a plurality of pixels. Each of the channels includes a polarization code that is different from any other polarization code in other channels to uniquely polarize electromagnetic energy passing therethrough. Output digital images from the detectors are processable, to determine a polarization pattern for a user of the system.

A logging system for measuring parameters of earth formation penetrated by a well borehole. Measurements made with the system are not adversely affected by varying pressure encountered a borehole environment. This is accomplished by the use of a main compensation element and a detector compensation element render source and detector geometry invariant to varying pressure. The system is particularly suited for nuclear LWD systems such as back scatter gamma ray density systems. The basic concepts of the system are, however, applicable to other types of nuclear measurement systems that comprise one or more radiation sources, and one or more axially spaced radiation detectors, where system response is a function of source-detector spacing. The basic concepts of the system are also applicable to other types of logging systems, such as electromagnetic and acoustic, where source (transmitter) and sensor (receiver) elements require invariant geometry in order to maximize accuracy of measurements.

A computed tomography acquisition method, an imaging system, a computer readable medium provides laterally displacing a radiation detector (204) from a position with centered detector geometry with a centered transverse field of view to a first offset position (212); emitting first radiation by the radiation source (202), detecting the first radiation by the radiation detector (204) and acquiring projection data indicative of the first radiation; rotating the support around the rotational axis (214) by 180°; emitting second radiation by the radiation source (202), detecting the second radiation by the radiation detector (204) and acquiring projection data indicative of the second radiation; displacing the radiation detector (204) from the first offset position to a second offset position (226), with opposite direction and double length of the first displacement (a); emitting third radiation by the radiation source (202), detecting the third radiation by the radiation detector (204) and acquiring projection data indicative of the third radiation; rotating the support around the rotational axis (214) by 180°; and emitting fourth radiation by the radiation source (202), detecting the fourth radiation by the radiation detector (204) and acquiring projection data indicative of the fourth radiation.

The invention relates to a respiration correction technique in positron emission tomography, in particular to a technique for correcting the artifact of respiration tomography on the basis of the sensitivity characteristics of a three-dimensional positron emission detector, belonging to the field of nuclear medical tomography. The correction method provided by the invention can effectively compensate for the image artifact caused by respiration, thereby improving the diagnostic accuracy of doctors. The correction method comprises the following steps: frame segmentation is carried out on the acquired dynamic data by using the variation characteristics of the geometric sensitivity of a scanning detector in the three-dimensional PET, wherein the number of intra-frame photons can reflect the phase position of the organ motion, and the number of photons of each phase position has a linear relation with the motion displacement thereof; accordingly, each phase position is moved to certain reference phase position point for correcting; and the image reconstructed at last constitutes the image artifact caused by the respiration in the PET improved by correction. Compared with the prior art like the gating correction technique, the method of the invention dispenses with hardware equipment and extra preparation by patients or clinic before scanning, therefore, the method is easier, more effective and more reliable in actual application.

The invention discloses a device and a method for geometric correction of a detector of a cone-beam CT (computed tomography) system. The correction device comprises a correction board, an adjusting board, the detector, an X-ray source device and an X-ray source table, wherein the X-ray source table and the adjusting board are arranged at two ends of the correction device respectively, the X-ray source device is located on the X-ray source table, the bottom surface of the detector is placed on a horizontal table surface of the adjusting table, the correction board is arranged on the table surface of the adjusting table and positioned between the X-ray source device and the detector, a plurality of round through holes are formed in the correction board and form a through hole array, sizes of the through holes are the same, and the through holes are axially parallel. According to the device and the method for geometric correction of the detector of the cone-beam CT system, by means of the correction board with the through hole array, the detector of the cone-beam CT system can be subjected to convenient, fast, and effective geometric correction without calculation; by means of the correction board, the geometric position of the detector is firstly corrected, the position of a rotation table is subsequently corrected, and the operation is simple and fast.

An optimal design method of a self-powered neutron detector structure comprises the steps of 1, selecting shape and parameters of self-powered neutron detector geometry; 2, establishing a basic geometric characteristic layer in a program; 3, imparting a material to the basic geometric characteristic layer; 4, defining energy, position and incoming direction of primary incoming neutrons; 5, adding a required physical process; 6, simulating a process where the incoming neutrons physically react with the material, recording quantity of secondary electrons drifting from an emitter or an insulator to a collector and arrival time, and outputting based on class; 7, calculating a neutron sensitivity and transient current ratio of the self-powered neutron detector; 8, saving a data point, and judging whether returning to step 2 occurs; 9, acquiring a variation curve of detector performance with detector parameters; 10, determining the structure and size of the detector as required finally in order to improve the detector performance. The method of the invention can provide professional optimal design for neuron spectrums of any reactor.

The invention discloses a detector geometric correction phantom and correction method. The method includes the following steps: fixing the detector geometric correction phantom on a position directlyfacing a detector, and obtaining an exposed detector geometric correction phantom image; obtaining circle center coordinates of holes on the detector geometric correction phantom according to the detector geometric correction phantom image; correcting rotation angles of all detector chips according to the circle center coordinates of the holes, making all the detector chips kept at a relative level, and saving as a first correction template; calculating a gap between each adjacent detector chips according to the circle center coordinates of all the holes, and saving as a second correction template; calculating the vertical offset of each detector chip according to the circle center coordinates of all the holes, and saving as a third correction template; and completing geometric correctionof images according to all the correction templates during actual image acquisition. The correction method realizes the geometric correction of the images collected by all detector chips.

The invention provides a calibration method of the geometric position relationship of an X-ray machine and a detector. The calibration method includes: placing at least two small balls in an imaging zone and recording the distance d between the two small balls and the distance between the two small balls and the plane where the detector is located respectively; randomly selecting one from many digital X-ray projection drawings, and recording the projection positions C and D corresponding to the position information of the two small balls A and B; estimating the initial X coordinate Px and the initial Y coordinate Py of the X-ray machine, and calculating the Z coordinate Pz of the X-ray machine according to the geometric imaging relationship; calculating the X coordinates Ax and Bx and the Y coordinates Ay and By of the two small balls according to the geometric imaging relationship and the Z coordinate Pz of the X-ray machine; obtaining the positions of the X-ray machine in the digital X-ray projection drawing according to the geometric imaging relationship by aid of the three-dimensional coordinates and the projections C and D of the two small balls A and B.

The invention relates to an electromagnetic excitation response signal mutual inductance device, a detection device and a detection method. The electromagnetic excitation response signal mutual inductance device comprises a detector and a comparator arranged in a geometric position of the detector; the detector comprises a main excitation source and a main receiving probe; the comparator comprisesa standby excitation source and a standby receiving probe; the main excitation source and the standby excitation source are connected in parallel or in series; and the main receiving probe and the standby receiving probe are reversely connected in parallel or in series. Compared with the prior art, the electromagnetic excitation response signal mutual inductance device, the detection device and the detection method have the advantages that a signal comparator is used for following the detector in real time, a primary field signal caused by a signal magnetic field is reduced in an analog circuit, no matter what the excitation signal is, the primary field signal of the excitation signal can be completely inhibited, and the device is low in manufacturing cost.

The present application discloses a computed tomography system having non-rotating X-ray sources that are programmed to optimize the source firing pattern. In one embodiment, the CT system is a fast cone-beam CT scanner which uses a fixed ring of multiple sources and fixed rings of detectors in an offset geometry. It should be appreciated that the source firing pattern is effectuated by a controller, which implements methods to determine a source firing pattern that are adapted to geometries where the X-ray sources and detector geometry are offset.

The invention discloses a concentric divergent light source detection method. The method comprises the following steps that a detector unit faces the area likely to be hit by a concentric divergent light source; by means of online or offline calculation, a time-varying position sensitivity likelihood probability function of each unit is obtained; within a given time interval, by means of first-principle computation and Monte-Carlo simulation, a joint time-varying position sensitivity likelihood function of all detectors is built; by maximizing the joint time-varying position sensitivity likelihood function of all the detectors, the central position and diffusion amplitude of a point-shaped light source are estimated, and a point-shaped light source parameter meeting maximization of the joint time-varying position sensitivity likelihood function of all the detectors serves as an estimated value of the point-shaped light source attribute. A concentric divergent light source detection device comprises a detector geometric distribution module, a photon detection unit module, a detection unit joint probability density function setting module and a joint probability density function maximization module. The method and device are specially suitable for in-vivo small animal imaging and superficial clinical diagnosis.