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20 sie 2019 · X-Y, or azimuthal, tube current modulation (aTCM) allows a further degree of fine-tuning of the radiation output to match the projection attenuation.
11 sty 2024 · Computed tomography (CT), also known as, especially in the older literature and textbooks, computerized axial tomography (CAT), is an imaging modality that uses x-rays to build cross-sectional images ("slices") of the body.
The x and y axes (in-plane) refer to the left to right and front to back imaging planes. The z axis (through-plane) refers to the head to toe axis and is also used to define the sFOV and the scan time.
21 lip 2020 · For CT of the hand, a field of view (FoV) of 60mm is used for diagnostic imaging of the scaphoid, or 80mm for the entire carpus. From these geometric scan parameters in the x-y plane, a theoretical in-plane resolution of 0.12×0.12 or 0.16/×0.16 (edge length of the voxel) can be calculated.
Cartesian coordinates define on a physical cubic corner (CC) with the corner tip as the origin and three corresponding line angles as (x, y, z)-axes.
Conceptually, the CT numbers of three materials of known composition and density are plotted on a graph, where the y-axis is the CT number at low energy (eg, 80 kV) and the x-axis is the CT number at the high energy (eg, 140 kV) . Ideally, the three basis materials should be sufficiently different as to create a broad triangle in this plot.
Angular (x, y) modulation changes the mAs as the x-ray tube rotates 360° around the patient to account for different attenuations in different projections of the x-ray beam [1]. Combined x, y, and z modulation adjusts the mAs in all 3 axes on the basis of the patient's attenuation [8].
