摘要:
In addition to the traditionally calculated photodetector sum signal or energy value, and X, Y position values, the second order moment of the photodetector signals is calculated from photodetector signals to obtain a value proportional to light spread out in the scintillation camera giving an indication of the depth of interaction "DOI". A position correction vector is selected according to the initially calculated position values and the second order moment value and is added to the initial position values to obtain more accurate scintillation event position values. The correction values can be calculated by interpolation using empirically determined or simulation determined values contained in a table. The method of correction using the second order value proportional to DOI can also be used to correct the first order moment value or energy value.
摘要:
A PET/CT imaging system is provided. The imaging system includes a PET detection system having a plurality of detector rings and an axial gap between at least two adjacent detector rings within the plurality of detector rings. The imaging system includes a CT system having an x-ray generator and a CT detection system positioned within the axial gap between the at least two detector rings. The system is configured to collect PET data and CT data on the same volume of interest substantially simultaneously.
摘要:
A method and apparatus for determining a coincidence window for imaging a region of interest of an object using a Positron Emission Tomography (PET) scanner. The method includes determining a diameter of a transverse field of view (FOV) for imaging the region of interest of the object; and calculating the coincidence window based on the determined diameter, a ring diameter of the PET scanner, an axial length of the PET scanner, and a time-of-flight resolution of the PET scanner.
摘要:
A PET imaging system includes a measurement subsystem, a data acquisition subsystem, and a reconstruction subsystem. The measurement subsystem detects deflection in a patient pallet, and generates deflection information based on the detected deflection. The data acquisition subsystem receives the deflection information from the measurement subsystem and PET measurement data corresponding to a plurality of coincidence events from a PET scanner, and communicates the received deflection information and PET measurement data to the reconstruction subsystem. The reconstruction subsystem includes a processor that reconstructs a PET scan image using the deflection information and the PET measurement data communicated by the data acquisition subsystem.
摘要:
A gamma ray detector module that includes at least one crystal element arranged in a plane, a plurality of light sensors arranged to cover the at least one crystal element and to receive light emitted from the at least one crystal element, and a light guide arranged between the at least one crystal element and the light sensors, the light guide being optically connected to the at least one crystal element. Further, the light guide includes a narrow portion that positions at least one light sensor of the plurality of light sensors closer to the at least one crystal element than other light sensors of the plurality of light sensors. In addition, the light guide may include an angled recessed portion that positions another light sensor at an oblique tilt angle with respect to the plane of the at least one crystal element.
摘要:
An apparatus and associated method for gamma ray detection that improves the timing resolution is provided. A crystal of interaction in a scintillation crystal array emits scintillation light in response to interaction with a gamma ray. The scintillation light is detected by one or more photomultiplier tubes. Each photomultiplier tube that detects the scintillation light detects the light at a different time. The apparatus determines the location of the gamma ray interaction and uses the location of the interaction to generate correction times for each waveform generated by the photomultiplier tubes. The waveforms are corrected with the correction timings and combined to extract a time of arrival estimate for the gamma ray. Noise thresholding is also used to select waveforms having low noise for combination to extract the time of arrival estimate.
摘要:
A method and system for use in positron emission tomography, wherein a first processor element (234) is configured to reconstruct a plurality of positron annihilation events detected during a positron emission tomography scan using a list-based reconstruction technique to generate first volumetric data. A second reconstructor (226) is configured to reconstruct the plurality of events using a second reconstruction technique to generate second volumetric data for determining an error correction (228), the error correction applied to the first volumetric data to generate corrected volumetric data for generating a human-readable image (234). In one embodiment a multiplicative error correction is performed on the plurality of events, the first processor element (234) reconstructing the corrected plurality of events; and the second volumetric data error correction comprises an additive error correction.
摘要:
When correcting attenuation in a nuclear image (e.g., PET or SPECT), an MR-based attenuation correction (AC) map (16) is generated using MR image data (14) of a subject (60). The subject (60) is then placed in a nuclear imaging device with a radioactive point or line source (18, 18′) from which transmission data is measured as the patient is imaged. In order to resolve ambiguity between air voxels and bone voxels in the MR-based AC map (16), estimated transmission data (24) is generated from the AC map and compared to the measured trans-mission data (22) from the point or line source. An error is iteratively calculated for the estimated and measured transmission data, and attenuation values of the AC map (16) are refined to minimize the error. The refined AC map (32) is used to correct attenuation in collected nuclear data (41) which is reconstructed into an attenuation corrected image (99) of the patient.
摘要:
A diagnostic imaging device includes detector elements (16) for detecting y-rays indicative of nuclear decay events. Pairs of concurrently detected γ-rays define lines of response (LORs) which are collected, time stamped, and compiled in list-mode. In tissue perfusion studies, it is beneficial to use the data that concurrently maximizes contrast and signal-to-noise ratio in the reconstructed images. Using the list-mode data, events in an adjustable temporal window (33) are reconstructed and the reconstructed images are analyzed to determine a figure of merit based on contrast and signal-to-noise properties of the image. By iteratively adjusting the temporal window, extending its start point (36) backwards in time, and repeating the reconstructing, analyzing, and adjusting steps, an image with an optimal figure of merit is obtained.
摘要:
When compensating for truncated patient scan data acquired by a multi-modal PET/CT or PET/MR imaging system (14, 16), such as occurs when a patient is larger than a field of view for an anatomical imaging device, a segmented contour of a non-attenuation-corrected (NAC) PET image is used to identify a contour of the truncated region. An appropriate tissue type is used to fill in truncated regions of a truncated CT or MR image for the attenuation map. The corrected attenuation map is then used to generate an attenuation-corrected PET image of the patient or a region of interest. Alternatively, the system can be employed in PET/CT or PET/MR imaging scenarios where two modalities are performed sequentially (e.g., not simultaneously), and thus the contour derived from the PET scan can be compared to the CT or MR image to infer potential subject motion between the PET and CT or MR scans. Additionally, the system can be employed in PET imaging scenarios where the contour derived from the NAC PET image is used as emission boundary for scatter correction using single-scatter simulation, in which a tail-fitting procedure utilizes an emission boundary to define pure-scatter tails (e.g., in the absence of true coincidence events).