Time-activity Curve
In medical imaging, a time-activity curve is a curve of radioactivity (in terms of concentration) plotted on the y-axis against the time plotted on the x-axis. It shows the concentration of a radiotracer within a region of interest in an image, measured over time from a dynamic scan. Generally, when a time-activity curve is obtained within a tissue, it is called as a tissue time-activity curve, which represents the concentration of tracer within a region of interest inside a tissue over time. Modern kinetic analysis is performed in various medical imaging techniques, which requires a tissue time-activity curve as one of the inputs to the mathematical model, for example, in dynamic positron emission tomography (PET) imaging, or perfusion CT, or dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) using a dynamic scan. A dynamic scan is a scan where two dimensional (2D) or three dimensional (3D) images are acquired again and again over a time-period forming a time-series of ...
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Screenshot From 2020-04-22 11-31-01
screenshot (also known as screen capture or screen grab) is a digital image that shows the contents of a computer display. A screenshot is created by the operating system or software running on the device powering the display. Additionally, screenshots can be captured by an external camera, using photography to capture contents on the screen. Screenshot techniques Digital techniques The first screenshots were created with the first interactive computers around 1960. Through the 1980s, computer operating systems did not universally have built-in functionality for capturing screenshots. Sometimes text-only screens could be dumped to a text file, but the result would only capture the content of the screen, not the appearance, nor were graphics screens preservable this way. Some systems had a BSAVE command that could be used to capture the area of memory where screen data was stored, but this required access to a BASIC prompt. Systems with composite video output could be conne ...
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