A laser photopeak location system comprises a gamma-ray spectrometer and a processor. The processor computes a plurality of correlation coefficients based on a comparison of a pulse-height spectrum of the gamma-ray spectrometer with an array of values. The processor locates one or more photopeaks of the pulse-height spectrum based on at least one of the plurality of correlation coefficients. Additional apparatus, methods, and systems are disclosed.

The disclosure relates to a system and method for medical imaging. The method may include: move, by a motion controller, a phantom along an axis of a scanner to a plurality of phantom positions; acquire, by a scanner of the imaging device, a first set of PET data relating to the phantom at the plurality of phantom positions; and store the first set of PET data as an electrical file. The length of an axis of the phantom may be shorter than the length of an axis of the scanner, and at least one of the plurality of phantom positions may be inside a bore of the scanner.

Disclosed herein are variations of megavoltage (MV) detectors that may be used for acquiring high resolution dynamic images and dose measurements in patients. One variation of a MV detector comprises a scintillating optical fiber plate, a photodiode array configured to receive light data from the optical fibers, and readout electronics. In some variations, the scintillating optical fiber plate comprises one or more fibers that are focused to the radiation source. The diameters of the fibers may be smaller than the pixels of the photodiode array. In some variations, the fiber diameter is on the order of about 2 to about 100 times smaller than the width of a photodiode array pixel, e.g., about 20 times smaller. Also disclosed herein are methods of manufacturing a focused scintillating fiber optic plate.

A method for in-situ calibration of a fixed radiation dose rate instrument is provided, comprising: in a reference radiation field, calibrating a standard device, a first device to be calibrated to an n.sup.th device to be calibrated under a proposed database type, and obtaining a response signal of a first nonhomogeneous extended field generated by a first radiation source, and then establishing a database about type-relative position relationship-statistical data; generating a second nonhomogeneous extended field by a second radiation source with the same type as the first radiation source during in-situ calibration; and searching the type of a current device to be calibrated, and obtaining a final in-situ calibration factor of the current device to be calibrated according to a value in the database corresponding to the type.

A method for determining at least one artifact calibration coefficient is provided. The method may include obtaining preliminary projection values of a first object. The radiation rays may be detected by at least one radiation detector. The method may further include generating a preliminary image of the first object based on the preliminary projection values of the first object and generating calibrated projection values of the first object based on the preliminary image. The method may further include determining a relationship between the preliminary projection values and the calibrated projection values. The method may further include, for each of the at least one radiation detector, determining a location of the radiation detector and determining an artifact calibration coefficient corresponding to the radiation detector based on the relationship between the preliminary projection values and the calibrated projection values and the location of the radiation detector.

The present disclosure provides a multi-parameter calibration system for a spectrometer based on a nanosecond light source, including a main channel for outputting nuclear pulse signals, and a coincidence channel for outputting the nuclear pulse signals. Each channel uses current nuclear pulse signals to drive a light-emitting diode (LED) to emit nuclear pulse optical signals, and a simulated scintillator is irradiated to emit nanosecond nuclear pulse optical signals. The present disclosure can respectively test and calibrate multiple parameter performance indexes of the spectrometer throughput baseline restoration spectrometer. The stability of the spectrometer is tested and calibrated through output of certain regular nuclear pulse signals.

An x-ray based litho-density tool for measurement of formation surrounding a borehole is provided, the tool including at least an internal length comprising a sonde section, wherein said sonde section further comprises an x-ray source; at least one radiation measuring detector; at least one source monitoring detector; a plurality of sonde-dependent electronics; and a reference detector, wherein the reference detector is used to monitor the output of the x-ray source such that the reference detector's output effects corrections to the outputs of the detectors used to measure the density of the materials surrounding the borehole in order to correct for variations in the x-ray source output. Tool logic electronics, PSUs, and one or more detectors used to measure borehole standoff such that other detector responses maybe compensated for tool standoff are also provided. Shielding, through-wiring; wear-pads that improve the efficacy and tool functionality are also described and claimed.

A method and apparatus are provided for nonlinear energy correction of a gamma-ray detector using a calibration spectrum acquired from the background radiation of lutetium isotope 176 (Lu-176) present in scintillators in the gamma-ray detector. Further, by periodically acquiring Lu-176 spectra using the background radiation from the scintillators, the nonlinear energy correction can be monitored to detect when changes in the gamma-ray detector cause the detector to go out of calibration, and then use a newly acquired Lu-176 spectrum to update the calibration of the nonlinear energy correction as needed. The detector calibration is performed by comparing a reference histogram to a calibration histogram generated using the nonlinear energy correction, and adjusting the parameters of the nonlinear energy correction until the two histograms match. Alternatively, the detector calibration is performed by comparing reference and calibration values for specific spectral features, rather than for the whole Lu-176 spectrum.

A geometric calibration apparatus detects points from projection regions onto which markers disposed on a phantom are projected, and calculates an output vector representing a probability distribution that gives a probability with which each point is a projection of each marker, by inputting data corresponding to each point to a learning model. The geometric calibration apparatus extracts a predetermined number of samples based on the probability distribution, obtains a candidate projection matrix by transforming correspondences between markers determined based on the samples among the markers and points determined based on the samples among the points, calculates points into which the markers are transformed by the candidate projection matrix, calculates a difference between a set of the transformed points and a set of the detected points, and designates the candidate projection matrix as a projection matrix when the difference is less than or equal to a threshold.

A radiation imaging system comprises: an image obtaining unit including a radiation detecting unit in which pixels configured to output signals according to a dose of irradiated radiation are arranged in a two-dimensional area, and configured to obtain a radiation image based on the signals; a correction unit configured to correct the radiation image using an input/output characteristic of a pixel, which represents a relationship between the dose of radiation on the pixel and the signal output from the pixel and is obtained using gain data based on a plurality of gain images obtained under different doses; and an updating unit configured to update the gain data using an updating coefficient obtained based on the gain data and a gain image newly obtained by the image obtaining unit.