7/28/2023 0 Comments Plus imageNU: image x axis = near transducer axis, image y axis = unmarked transducer axis.FU: image x axis = far transducer axis, image y axis = unmarked transducer axis.NM: image x axis = near transducer axis, image y axis = marked transducer axis.FM: image x axis = far transducer axis, image y axis = marked transducer axis.There are four possible orientations for RF-mode images: UN: image x axis = unmarked transducer axis, image y axis = near transducer axis.UF: image x axis = unmarked transducer axis, image y axis = far transducer axis.MN: image x axis = marked transducer axis, image y axis = near transducer axis.MF: image x axis = marked transducer axis, image y axis = far transducer axis.There are four possible orientations for 2D B-mode images: The image orientation can be defined by specifying which transducer axis corresponds to the x and y image axes, respectively. In RF-mode images each scanline is stored in a 'row' (x = 0.n, y = constant). In B-mode images typically each scanline displayed approximately vertically (x = near constant, y = 0.n). y axis: points towards the y coordinate increase direction.x axis: points towards the x coordinate increase direction.The ultrasound image axes are defined as follows: Descending (D): elevational transducer axis, opposite to A direction, only for 3D probesĭirections for commonly used transducer types:ĭefinition of ultrasound image orientation.Ascending (A): elevational transducer axis, cross product of M and F axis (so that MFA forms a right-handed 3D coordinate system), only for 3D probes.Near (N): axial transducer axis (normal to the transducer surface), pointing towards the transducer.Far (F): axial transducer axis (normal to the transducer surface), pointing away from the transducer (towards increasing depth direction).Unmarked (U): lateral transducer axis, pointing towards the unmarked side of the transducer (from the center of the crystal array).Marked (M): lateral transducer axis, pointing towards the marked side of the transducer (from the center of the crystal array).The following transducer principal axes directions are defined: The third letter is only defined for three-dimensional probes and represents the +z direction in the image coordinate system. Plus defines the image orientation using a two or three letter acronym, the first and second letter specify the transducer principal axes directions corresponding to the +x and +y directions in the image coordinate system, respectively. When a transducer is calibrated (the image to probe transform is determined), the calibration is valid for one particular image orientation, therefore it is important to be able to exactly identify the current image orientation. The acquired ultrasound image orientation (which direction is left/right, which direction is towards the probe) depends on a number of factors, such as settings on the ultrasound device (horizontal, vertical flip), transducer type, and image acquisition hardware/software settings.
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