Patent ID: 11927652
Assignee: BEIJING UNIVERSITY OF AERONAUTICS AND ASTRONAUTICS
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A structure for multi-coil handheld magnetic particle imaging (MPI), comprising a processing device, a control device, and an imager, wherein the structure for multi-coil handheld MPI further comprises:
a gradient and scanning module, comprising a first circular coil pair and a second circular coil pair, wherein axes of two circular coils in each of the first circular coil pair and the second circular coil pair are parallel but not coaxial; the axes of the two circular coils in the first circular coil pair form a plane as a first plane; the axes of the two circular coils in the second circular coil pair form a plane as a second plane; the first plane is perpendicular to the second plane; the two circular coils in the first circular coil pair are arranged in parallel on a third plane and the two circular coils in the second circular coil pair are arranged in parallel on the third plane; and the third plane is perpendicular to the first plane and the second plane;
an excitation and correction module, comprising a circular excitation and correction coil; and
a detection module, comprising a circular detection coil;
wherein the circular excitation and correction coil and the circular detection coil are arranged in parallel at two sides of a plane where the two circular coils in the first circular coil pair are located;
the gradient and scanning module is configured to construct and adjust a gradient field in a space, wherein a field free point (FFP) is generated and driven to move and scan outside the detection module;
the excitation and correction module is configured to generate a biased high-frequency alternating field in a first direction, wherein the FFP is driven to move and scan in the first direction and an offset of the first direction during a movement process of the FFP outside the detection module is corrected through the biased high-frequency alternating field; and the first direction is perpendicular to the third plane;
the detection module is configured to detect a nonlinear magnetic induction signal of magnetic nanoparticles in an imaging region during a scanning process;
currents of a same direction are applied to the two circular coils in the first circular coil pair and the two circular coils in the second circular coil pair;
when the currents applied to the two circular coils in the first circular coil pair and the two circular coils in the second circular coil pair have equal magnitude, the constructed gradient field is symmetrical in a z-direction and the FFP is located in the z-direction; relative magnitude of the currents applied to the two circular coils in the first circular coil pair is adjusted to control the gradient field in a detection region, wherein the FFP is controlled to move and scan in an x-direction; and relative magnitude of the currents applied to the two circular coils in the second circular coil pair is adjusted to control the gradient field in the detection region, wherein the FFP is controlled to move and scan in a y-direction; and
a high-frequency sinusoidal current with a direct current bias is applied to the circular excitation and correction coil; a direct current component in the high-frequency sinusoidal current with the direct current bias is configured to correct movement trajectories of the FFP in the x-direction and they-direction; and a sinusoidal current component in the high-frequency sinusoidal current with the direct current bias is configured to generate the high-frequency alternating field in the z-direction, wherein the FFP in the z-direction is moved and superparamagnetic iron oxide (SPIO) nanoparticles in the FFP is excited to generate the nonlinear magnetic induction signal.