Abstract: Methods, devices and computer-readable mediums for clock synchronization are provided. The methods include receiving a synchronizing clock in a unit clock cycle of a measuring clock, calibrating position information of a rising edge of the synchronizing clock in the unit clock cycle, determining a phase difference between the measuring clock and the synchronizing clock in the unit clock cycle based on the calibrated position information, and compensating a photon time in the unit clock cycle with the determined phase difference as a time compensation value.

Abstract: A PET image reconstruction method and device are provided. According to an example, a first diffusion expression representing a diffusion degree of projection data from a first incident point to a first crystal may be obtained with a first diffusion distribution, a second diffusion distribution, a point source position and position information of the first crystal in a projection direction. A second diffusion expression representing a diffusion degree of projection data from a second incident point to a second crystal may be obtained with the first diffusion distribution, the second diffusion distribution, the point source position and position information of the second crystal in the projection direction. A diffusion relationship representing a correspondence relationship between the point source position and projection data in the projection direction may be obtained with the first diffusion expression and the second diffusion expression.

Abstract: A method and apparatus for determining PET scanning time are provided. According to an example of the method, a CT image is divided into multiple single-bed CT images according to bed information of bed positions for a PET scan, wherein the CT image is obtained by performing a CT scan on a subject of the PET scan, and a one-to-one corresponding relation exists between the multiple single-bed CT images and all of the beds. A residual true coincidence count ratio is estimated for each of the beds based on corresponding single-bed CT image of the bed, and then a scanning time proportion for each of the beds may be determined based on each of the residual true coincidence count ratios for the beds.

Abstract: A method for reconstructing a Computer Tomography (CT) image is disclosed. The method may comprise: obtaining a X-ray projection data frame and a dynamic sensor information data frame, wherein the X-ray projection data frame may include a first timestamp indicating acquisition time of X-ray projection data and the dynamic sensor information data frame may include a second timestamp indicating acquisition time of dynamic sensor information data; extracting the first timestamp from the X-ray projection data frame and extracting the second timestamp from the dynamic sensor information data frame; searching X-ray projection data and dynamic sensor information data which may be acquired in same sampling period according to a first timestamp and a second timestamp; and reconstructing a CT image according to the searched X-ray projection data and dynamic sensor information data which may be acquired in the same sampling period.

Abstract: Methods and devices for calibrating a gain of a scintillator detector are disclosed, where a scintillation crystal of the scintillator detector includes two or more energy regions. In an example, the scintillation crystal of the scintillator detector is adopted as a radiation source for calibrating. Electric signals outputted from a rear end of the scintillator detector are collected, and actual counts of the electric signals from each of at least two energy regions of the scintillation crystal at a specified position are obtained, respectively. Then, a gain of the scintillator detector may be adjusted according to the obtained actual counts of the electric signals from the at least two energy regions.

Abstract: Methods and devices for controlling movement of a carriage of a multi-leaf collimator are provided. In one aspect, a method includes obtaining a desired position of each of a set of leaves on the carriage in each of a plurality of segments from a field, determining an allowable moving range set of the carriage according to the desired position, the allowable moving range set including a respective allowable moving range of the carriage in each of the segments, determining a respective position of the carriage in each of the segments according to the allowable moving range set, and controlling the movement of the carriage according to the determined positions of the carriage in the segments.

Abstract: A method and apparatus for selecting high and low energy scanning voltages for a dual energy CT scanner are provided. The method may comprise: setting a criterion of selection for selecting high and low energy scanning voltages; generating combinations of high and low energy scanning voltages according to all scanning voltages supported by a dual energy CT scanner, wherein each of the combinations may comprise a high energy scanning voltage and a low energy scanning voltage; and selecting a combination of high and low energy scanning voltages from the generated combinations of high and low energy scanning voltages based on the criterion of selection.

Abstract: A method for correcting a CT scan image is provided. A target image including a target region to be corrected is extracted from an original CT scan image. A target projection range corresponding to the target region is obtained by orthographically projecting the target image, and target projection data within the target projection range is corrected. Noise of the corrected target projection data is adjusted to generate noise-adjusted target projection data to improve noise consistency between target region and the rest of the CT scan image. A corrected CT scan image is reconstructed based on the noise-adjusted target projection data.

Abstract: A method for generating material hardening effect data is provided. Actual X-ray attenuation values of a universal phantom corresponding to different angles at each of channels may be obtained. Equivalent filtration thicknesses corresponding to each of the channels may be determined according to theoretical X-ray attenuation values and the actual X-ray attenuation values corresponding to different angles at each of the channels. Hardening effect data corresponding to a material may be generated according to a predetermined length of the material, a number of sampling points and the equivalent filtration thicknesses corresponding to each of the channels.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for processing a CT (Computed Tomography) image are provided. An example method includes accessing an original CT image that is reconstructed from a first set of raw data and includes windmill artifacts, generating a high-frequency image by processing the original CT image, generating a low-frequency image by processing a plurality of thick images reconstructed from a second set of raw data and combining the plurality of processed thick images, the second set of raw data including the first set of raw data and each of the plurality of thick images including substantially no windmill artifacts, generating an intermediate image by synthesizing the high-frequency image and the low-frequency image, and obtaining a target CT image based on the generated intermediate image.

Abstract: Methods, systems, and machine-readable storage mediums for determining response lines for reconstructing images are provided. An example imaging method includes: receiving single event signals in a detector module and associated with a single event, determining a crystal in the detector module and corresponding to a maximum single event signal of the single event signals, determining an actual energy weighting factor of the crystal, determining an actual depth position corresponding to the actual energy weighting factor of the crystal according to associations between depth positions of the crystal and respective reference energy weighting factors for the crystal, as an acting position in the detector module for the single event, determining a response line of a coincidence event according to respective acting positions in the detector module for two single events constituting the coincidence event, the two single events including the single event, and reconstructing an image according to the response line.

Abstract: A method for controlling an X-ray dose of a CT scan includes: setting an initial X-ray dose; performing a first CT scan with the initial X-ray dose to obtain an initial scan image; setting a region of interest (ROI) in the initial scan image; calculating a subsequent X-Ray dose with image values of the ROI in the initial scan image; perform an additional CT scan with the calculated subsequent X-Ray dose to obtain an average image; before receiving an end instruction, repeating the following operations: recalculating a subsequent X-Ray dose with image values of the ROI in the average image and performing an additional CT scan with the calculated subsequent X-Ray dose to obtain a new average image; and saving the average image when receiving the end instruction.

Abstract: A method for reconstructing a PET multi-bed image is provided, which may be applied to a PET scan having an axial overlapping region existed between every two adjacent beds. According to an example of the method, a combined set of PET projection data for at least two beds may be obtained by combining a set of PET projection data for at least two successive beds together in such a manner that two sets of PET projection data corresponding to an axial overlapping region between every two adjacent beds are added up. And then, a PET image for at least two beds may be reconstructed based on an image reconstruction iteration model and the combined set of PET projection data for the plurality of beds.

Abstract: A method for reconstructing a CT scan image, comprising: performing a first scan to acquire a first projection data, wherein the first scan is a scan that a subject is covered by a low dose X-ray beam in an axial plane; performing a second scan to acquire a second projection data, wherein the second scan is a scan that a target portion of the subject is covered by a high dose X-ray beam in the axial plane; determining a data filling point in the second projection data, wherein the data filling point is located in a truncated region; and filling the data filling point in the second projection data with a data from the first projection data which corresponds to the data filling point; and reconstructing a second scan image based on the filled second projection data.

Abstract: Methods, systems, and apparatus including computer programs encoded on a computer storage medium, for rendering an expanded lumen image are disclosed. The methods include extracting a center line of a lumen from a three-dimensional lumen image and obtaining a plurality of viewpoints by sampling the center line, establishing a spherical projection plane for each of the viewpoints, a point on the spherical projection plane corresponding to a point on an inner wall of the lumen, determining a relationship between a two-dimensional projection plane and the inner wall of the lumen according to a corresponding relationship between the spherical projection plane and the two-dimensional projection plane, and obtaining a two-dimensional expanded image of the three-dimensional lumen image by performing image rendering on the two-dimensional projection plane according to the determined relationship between the two-dimensional projection plane and the inner wall of the lumen.

Abstract: Methods and apparatus, including computer programs encoded on a computer storage medium, for image reconstruction are provided. The methods include: accessing a first set of projection data including a plurality of first projection data each corresponding to a respective projection angle of a plurality of projection angles, generating a first set of reconstructed data by image reconstruction with the first set of projection data, generating a second set of projection data comprising a plurality of second projection data each corresponding to a respective projection angle by projection calculation with the first set of reconstructed data, generating a third set of projection data by optimizing the first set of projection data based on a correlation between respective first projection data and respective second projection data corresponding to each projection angle, and generating a second set of reconstructed data by image reconstruction with the third set of projection data.

Abstract: A method of adjusting a gain of a detector is provided in the present disclosure. According to an example, whether a gain of a photomultiplier tube in the detector meets a gain determination condition may be determined, where the gain determination condition may indicate that an absolute of a difference between the gain of the photomultiplier tube and a target gain is within a predetermined numerical range. When the gain of the photomultiplier tube does not meet the gain determination condition, a voltage of the photomultiplier tube may be adjusted, such that the gain of the photomultiplier tube meets the gain determination condition.

Abstract: CT scanning techniques and systems thereof are disclosed. In various embodiments, a body surface measuring point of a subject on a scanning bed can be identified according to a frontal image captured by a first image capturing device. A measuring projection angle can be acquired using the body surface measuring point. A lateral image of the subject can be captured using a second image capturing device. Based on the lateral image, a vertical distance between the body surface measuring point and the scanning bed, a current height and the initial height of the scanning bed, a horizontal position of the body surface measuring point under the initial height can be acquired. A horizontal position of the body surface measuring point under the current height can be determined based on above acquired parameters.

Abstract: A method and system for CT image correction are provided. Contour data of a scanned subject can be obtained, and a shape image of the scanned subject can be reconstructed according to the contour data, wherein the contour data of the scanned subject can be obtained by scanning the scanned subject through a piece of visual equipment. Original CT projection data of the scanned subject can be obtained, and a CT image can be reconstructed according to the original CT projection data. For determining a supervision field image, image matching can be performed between the shape image and the CT image of the scanned subject. Supervision field projection data can be obtained, and the supervision field projection data can be used to correct the CT image.

Abstract: A method for controlling filament current of a computed tomography (CT) tube includes: detecting a present tube current of the CT tube and assigning the present tube current to a feedback value, calculating a difference between a set value of the tube current and the feedback value and assigning the difference to an error value, assigning a target upper bound value to a present filament current when the error value is greater than an first error threshold, and assigning a target lower bound value to the present filament current when the error value is less than a second error threshold, wherein the target upper bound value is greater than the target lower bound value, the first error threshold is greater than 0, and the second error threshold is less than 0.