US9226722 (B2) - Medical Imaging System and Method with Separate Primary and Scattered Components

In an aspect, a computed tomography (CT) or ultra sound imaging system is provided including: a radiation or ultrasound source including a collimating or a blocking device configured to generate both a narrow beam and a wide beam; a detector configured to detect radiation or ultrasound wave from the radiation or ultrasound wave from the radiation or ultrasound source; and at least one processing circuit configured to: determine a scatter-to-primary ratio (SPR) of the wide beam based on the narrow beam; determine a primary component of the wide beam based on the SPR to thereby separate the primary component from a scattered component of the wide beam; and construct an image of an object inside a patient using the primary component to thereby improve a contrast of the object.

In some implementations, the object comprises a foreign object, and the foreign object comprises at least one of: a needle, a catheter, a dye, a drug, a therapeutic agent, or a diagnostic agent.

In some implementations, the detector is configured to move along a path of the narrow beam to thereby measure a radiation level at a plurality of positions along the direction to facilitate the determining of the SPR.

In some implementations, the detector comprises a plurality of detection elements disposed at a plurality of positions along a path of the narrow beam to facilitate the determining of the SPR.

In some implementations, the imaging system further includes at least one of: a needle, a catheter, a dye, a drug, a therapeutic agent, or a diagnostic agent for insertion and/or injection into the patient.

In some implementations, the at least one processing circuit is configured to use an analytical pencil beam model, and predict the primary component of the wide beam using the narrow beam based on the analytical pencil beam model.

In some implementations, the at least one processing circuit is configured to use a Monte Carlo algorithm, and predict the primary component of the wide beam.

In some implementations, the at least one processing circuit is configured to perform an iteration of an output image, wherein the output image is used as an input density map to the Monte Carlo algorithm, to generate a more accurate density map image.

In some implementations, the imaging system further includes a timing device configured to turn on a detecting element for a short period such that the detecting element detects only the primary component.

In some implementations, the detector is configured to selectively read an output from a selected detecting element to thereby separate the primary and scattered components.

In some implementations, the at least one processing circuit is configured to generate an image of the object based on the scattered component.

In another aspect, an image reconstruction method is provided for Computed Tomography (CT) or ultrasound imaging, the method including: determining a scatter-to-primary ratio (SPR) of a wide beam based on a narrow beam; determining a primary component of the wide beam based on the SPR to thereby separate the primary component from a scattered component of the wide beam; and constructing an image of an object inside a patient using the primary component.

In some implementations, the method further includes: using a first set of CT or ultrasound images without separating the primary and scattered components as input density maps to a computer model; constructing a second set of CT or ultrasound images based on the primary component using the computer model; and iterating the above operations to obtain CT or ultrasound images with improved contrast of the object.

In some implementations, the computer model comprises at least one of an analytical equation of an SPR as a function of a position and attenuation properties of a material along a beam path, or a Monte Carlo algorithm.

In some implementations, the method further includes coordinating an emitting time from a radiation or ultrasound source and a detecting time of a detecting element, to facilitate separation of the primary component and the scattered component of the wide beam.

In some implementations, the method further includes turning on a detecting element for a short period such that the detecting element detects substantially only the primary component.

In some implementations, the object comprises a foreign object, wherein the foreign object comprises at least one of: a needle, a catheter, a dye, a drug, a therapeutic agent, or a diagnostic agent, wherein the improved contrast of the object is a contrast against a background, wherein the background comprises at least one of tissue, blood, blood vessels, bones, or body fluid, and the method further comprises: based on the reconstructed image, at least one of: guiding tracheal intubation to thereby enhance anesthesia safety; guiding epidural puncture; guiding selective dorsal root ganglion radiofrequency treatment of postherpetic neuralgia; treating trigeminal neuralgia with CT-guided and/or ultrasound-guided percutaneous foramen ovale blocking; observing changes of atelectasis after general anesthesia; or positioning an obstetrics or surgical tool.

In another aspect, a non-transitory computer-readable medium is provided having instructions stored thereon, the instructions including: transmitting a narrow beam of radiation or ultrasound wave through an object onto a detector array; transmitting a wide beam of radiation through the object onto the detector array; recording signal strengths at a plurality of positions along a path of the narrow beam using the detector array; calculating a scatter-to-primary ratio (SPR), using a computer model, as a function of position; separating primary and scattered components of the wide beam based on the calculated SPR; constructing a first set of images using the primary component; constructing a second set of images using the scattered component; and determining a position of the object based on the first and second set of images.

In some implementations, the computer model comprises an analytically-derived formula describing the SPR as a function of positions and attenuation properties of material along a path of the narrow beam.

In some implementations, the computer model comprises a Monte-Carlo-derived numerical relationship describing the SPR as a function of positions and attenuation properties of material along the path of the narrow beam, and wherein the computer model further comprises predetermined scattering characteristics of the object.