Medical image processing methods and systems

A method, performed by a computing device including at least one processor and at least one storage device, wherein the method comprises:

• obtaining PET data of a target object within a field of view (FOV) of a positron emission computed tomography (PET) imaging device;
• obtaining corrected PET data by correcting the PET data based on a target normalization correction factor, wherein the target normalization correction factor is a normalization correction factor corresponding to a current state of the PET imaging device, and the target normalization correction factor is determined by:
• acquiring first background coincidence event data of a detector crystal of the PET imaging device at a predetermined time point;
• determining the target normalization correction factor based on the first background coincidence event data;
• and
• reconstructing a target PET image based on the corrected PET data.

A method, performed by a computing device including at least one processor and at least one storage device, wherein the method is implemented on a PET-CT system, the PET-CT system includes a computed tomography (CT) imaging device and a positron emission computed tomography (PET) imaging device, and the method comprises:

• obtaining a CT image of a phantom by placing the phantom in the FOV of the CT imaging device, the phantom not containing a radiation source;
• collecting background coincidence event data of the phantom by placing the phantom in the FOV of the PET imaging device;
• acquiring a first attenuation image in a coordinate system of the CT imaging device based on the CT image;
• and
• determining a target registration parameter based on target background coincidence event data, and the first attenuation image, wherein the target background coincidence event data is obtained based on the background coincidence event data of the phantom.