Abstract: A method and system for MRI may be provided. A plurality of signals of a subject generated using an MRI device may be acquired. Each signal may correspond to a set of values in a plurality of signal dimensions of signal acquisition. A primary signal dimension associated with a signal representation of the subject among the plurality of signal dimensions may be determined. A first value and a second value relating to the signal representation may be determined based on the plurality of signals. The first value may represent the signal representation along a first direction of the primary signal dimension, the second value may represent the signal representation along a second direction of the primary signal dimension, and the first direction may be opposite to the second direction. A value of a quantitative parameter of the subject may be determined based on the first value and the second value.

Abstract: An MRI method and system may be provided. A plurality of sets of k-space data of a region of interest (ROI) of a subject may be obtained. Each of the plurality of sets of k-space data may be collected during one of a plurality of acquisition periods after an MR sequence is applied on the subject. Then, for each of the plurality of sets of k-space data, position information of a reference region during the corresponding acquisition period may be determined based on the set of k-space data. The set of k-space data may be corrected based on the position information of the reference region. Further, a dynamic MR image sequence may be generated based on the plurality sets of corrected k-space data.

Abstract: The present disclosure relates to systems and methods for pulse parameter modulation. The systems may perform the methods to obtain information related to a treatment plan; determine a backward window based on the information related to the treatment plan, within which one or more radiation pulses have been transmitted; determine backward information associated with the backward window based on the information related to the treatment plan and the backward window; determine a forward window based on the information related to the treatment plan, within which one or more radiation pulses are to be transmitted; determine forward information associated with the forward window based on the information related to the treatment plan, the backward information, and the forward window; and determine one or more pulse parameters of the forward window based on the forward information.

Abstract: A detector module for single SPECT may be provided. The detector module may include a semi-monolithic crystal and a plurality of SiPM photodetectors forming a photodetector array. The semi-monolithic crystal may include a plurality of monolithic crystal plates configured to receive gamma rays. The plurality of monolithic crystal plates may be arranged side by side along a thickness direction of the plurality of monolithic crystal plates. The photodetector array may include a plurality of columns arranged side by side along the thickness direction of the plurality of monolithic crystal plates. Each monolithic crystal plate may be in optical communication with one or more columns of SiPM photodetectors in the photodetector array, and the one or more columns of SiPM photodetectors may be configured to detect scintillation light produced by gamma ray interactions in the monolithic crystal plate.

Abstract: A system and method for generating augmented segmented image set obtain are provided. The method may include: obtaining a first image including a first anatomical structure of a first object; determining first feature data of the first anatomical structure; determining one or more first transformations related to the first anatomical structure, wherein a first transformation includes a transformation type and one or more transformation parameters related to the transformation type; applying the one or more first transformations to the first feature data of the first anatomical structure to generate second feature data of the first anatomical structure; and generating a second image based on the second feature data of the first anatomical structure.

Abstract: The present disclosure relates to systems and methods for pulse parameter modulation. The systems may perform the methods to obtain information related to a treatment plan; determine a backward window based on the information related to the treatment plan, within which one or more radiation pulses have been transmitted; determine backward information associated with the backward window based on the information related to the treatment plan and the backward window; determine a forward window based on the information related to the treatment plan, within which one or more radiation pulses are to be transmitted; determine forward information associated with the forward window based on the information related to the treatment plan, the backward information, and the forward window; and determine one or more pulse parameters of the forward window based on the forward information.

Abstract: The present disclosure is related to systems and methods for image reconstruction. The method may include obtaining at least one positron emission tomography (PET) image of a subject. The at least one PET image may be generated based on PET data acquired during an examination period. In the examination period, the subject may be injected with a tracer. The method may also include determining, based on the at least one PET image, an input function that reflects a concentration change of the tracer in the subject during the examination period. The method may further include generating a parametric image based on the input function and the at least one PET image according to a non-linear parametric estimation algorithm. The parametric image may reflect a kinetic parameter of the tracer in the subject.

Abstract: A device may include a collimator positioned between a radiation source of a scanner and a bore of the scanner. The bore may include a detecting region configured to accommodate a subject. The collimator may be configured to prevent at least one portion of radiation rays emitted from the radiation source from being incident on the subject. The device may further include a first filter and a second filter. The first filter may be positioned between the radiation source and the collimator. The second filter may be positioned between the collimator and the bore. The first filter and the second filter may be configured to adjust a distribution of radiation impinging upon the subject.

Abstract: The present disclosure is related to systems and methods for motion signal recalibration. The method includes obtaining a motion signal of a subject based on positron emission tomography (PET) data of the subject. The motion signal may represent a plurality of motion cycles. The method includes determining a distribution of the motion cycles. The distribution of the motion cycles may indicate a probability that each motion cycle of the plurality of motion cycles corresponds to an actual motion cycle. The method includes correcting the motion cycles of the motion signal based on the distribution of the motion cycles to obtain corrected motion cycles. The method includes reconstructing a PET image by gating the PET data based on the corrected motion cycles.

Abstract: Methods and systems for detecting a three-dimensional position of a scintillation event converting a radiation into a light. For example, a system includes a crystal array including a plurality of crystal elements, a light sensor array including a plurality of light sensors, a first crystal pair of the plurality of crystal pairs corresponds to a first light sensor pair of the plurality of light sensor pairs; a second crystal pair of the plurality of crystal pairs corresponds to a second light sensor pair of the plurality of light sensor pairs; and a third crystal pair of the plurality of crystal pairs corresponds to the first light sensor pair and the second light sensor pair such that a scintillation event in the third crystal pair is detected by both the first light sensor pair and the second light sensor pair.

Abstract: The present disclosure provides a system and method for medical imaging. The method may include obtaining a treatment plan, a planning image, and one or more treatment images of the subject, wherein the one or more treatment images are generated by performing at least a portion of the treatment plan including delivering at least a radiation beam towards the subject using a radiation device. The method also includes determining primary images of the subject based on the one or more treatment images, and determining inversely-attenuated primary images of the subject by inversely attenuating the primary images to a plane located between the subject and a collimator assembly of the radiation device. The method may further include estimating machine parameters of the radiation device corresponding to the inversely-attenuated primary images.

Abstract: An imaging method may include obtaining original imaging data of an object in a raw-data domain including original time of flight (TOF) information. The method may also include gating the original imaging data into a plurality of data sets in the raw-data domain. The method may also include determining a plurality of motion vector fields based on the plurality of data sets. The method may also include generating corrected imaging data in the raw-data domain by performing motion correction on at least one of the plurality of data sets based on the original TOF information and at least one corresponding MVF of the plurality of MVFs. The method may also include generating one or more target images of the object by performing, based on the corrected imaging data, image reconstruction.

Abstract: A method for medical imaging may include obtaining a plurality of successive images of a region of interest (ROI) including at least a portion of an object's heart. The plurality of successive images may be based on imaging data acquired from the ROI by a scanner without electrocardiography (ECG) gating. The plurality of successive images may be related to one or more cardiac cycles of the object's heart. The method may also include automatically determining, in the plurality of successive images, target images that correspond to at least one of the one or more cardiac cycles of the object's heart.

Abstract: The present disclosure provides a system for MRI. The system may obtain a plurality of echo signals relating to a subject that are excited by an MRI pulse sequence applied to the subject. The system may perform a quantitative measurement on the subject based on the plurality of echo signals. The MRI pulse sequence may include a CEST module configured to selectively excite exchangeable protons or exchangeable molecules in the subject, an RF excitation pulse applied after the CEST module configured to excite a plurality of gradient echoes, and one or more refocusing pulses applied after the RF excitation pulse. In some embodiments, the quantitative measurement may include determining various quantitative parameters including a T1, a T2, a T2*, an R2 value, an R2* value, an R2?, a B0 field, a pH value, an MWF, and an APT simultaneously.

Abstract: A target assembly for generating radiation may comprise a target, a substrate and a window. The target may be capable of generating first radiation when impinged by a beam. The window may be at least partially permeable to the beam. The window and the substrate may form at least part of a hermetically sealed chamber and the target may be positioned in the chamber. The chamber may be filled with air having a normal or reduced content of oxygen.

Abstract: Systems and methods for image reconstruction are provided. The methods may include obtaining a first image sequence of a subject and obtaining an initial input function that relates to a concentration of an agent in blood vessels of the subject with respect to time. The first image sequence may include one or more first images generated based on a first portion of scan data of the subject. The methods may further include, for each of a plurality of pixels in the one or more first images, determining at least one correction parameter associated with the pixel and determining, based on the initial input function and the at least one correction parameter, a target input function The methods may further include generating one or more target image sequences related to one or more dynamic parameters based at least in part on a plurality of target input functions.

Abstract: The present disclosure directs to a system and method for CT imaging. The method may include acquiring computed tomography (CT) data, wherein the CT data is generated by scanning a subject using a CT scanner, the CT scanner including a focal spot and a detector, and the detector including a plurality of detector units. The method may also include obtaining a forward projection model and a back projection model, wherein the forward projection model and the back projection model are associated with sizes of the detector units and a size of the focal spot of the CT scanner. The method may further include reconstructing a CT image of the subject iteratively based on the CT data, the forward projection model, and the back projection model.

Abstract: A method may include acquiring MR signals by an MR scanner and generating image data in a k-space according to the MR signals. The method may also include classifying the image data into a plurality of phases. Each of the plurality of phases may have a first count of spokes. A spoke may be defined by a trajectory for filling the k-space. The method may also include classifying the plurality of phases of the image data into a plurality of groups and determining reference images based on the plurality of groups. Each of the reference images may correspond to the at least one of the phases of the image data. The method may further include reconstructing an image sequence based on the reference images and the plurality of phases of the image data.

Abstract: The present disclosure is related to systems and methods for isocenter calibration. The method includes providing a phantom including a first member and a second member with a fixed position relationship. The method includes acquiring, using a first device, at least one first image of the first member of the phantom. The method includes determining, based on the at least one first image, a first position relationship between a first isocenter of the first device and the first member. The method includes acquiring, using a second device, at least one second image of the second member of the phantom. The method includes determining, based on the at least one second image and the fixed position relationship, a second position relationship between a second isocenter of the second device and the first member. The method includes determining, based on the first position relationship and the second position relationship, a third position relationship between the first isocenter and the second isocenter.

Abstract: A system for limited view imaging is provided. The system may obtain a reference image of an object. The system may identify, from the reference image, one or more critical boundaries between a target organ of the object and one or more adjacent organs of the target organ. The system may determine an imaging angle range of the object based on the one or more critical boundaries. The system may further cause an imaging device to scan the object based on the imaging angle range, the object being in a breath-hold state during the scan.