Leukocyte scintigraphy is a medical imaging test which displays the distribution of radiolabeled (for example labeled with 111In indium) leukocytes in the body to detect infection / inflammation. Whole-body scintigrams, and/or images of specific anatomic regions are recorded. Additionally, single photon emission computed tomography can be obtained.

See also Granulocyte Scintigraphy and Abscess Scintigraphy.

Linearity is a property of a system, characterized by output that is directly proportional to the input.
In computed tomography (CT), linearity describes the amount to which the CT number of a material is exactly proportional to the density of this material (in Hounsfield units). This accuracy between the linear attenuation coefficient and the CT number is also utilized to describe the performance of a CT scanner.
The linearity of a gamma camera is a measure of the geometrical correctness of the images.

(LCR) The low contrast resolution describes the ability to discriminate between tissues with slightly differences in attenuation properties. The LCR depends on the stochastic noise.
The low contrast resolution is usually expressed as the minimum detectable size of an image structure, for a fixed percentage difference in contrast relative to the adjacent background.
A strength of computed tomography (CT) is its ability to visualize structures of low contrast in an object, a task that is limited by noise and is closely associated with the radiation dose. For example, a reduction of the dose at constant spatial resolution affects the visibility of structures with low contrast (e.g. vessels in the liver), due to increased noise. The visibility of these low contrast structures can partly be improved by decreasing the spatial resolution, while keeping the dose constant.

See also CT Number, Image Quality and Low Contrast Detectability.

On October 19, 2001, Philips Medical Systems completed an acquisition strategy through its purchase of Marconi Medical Systems.
The History of Marconi Medical Systems
2001 Royal Philips Electronics and Marconi plc announced that Philips has agreed to acquire Marconi Medical Systems for $1.1 billion.
2000 Marconi introduces Infinite Detector Technology for Mx8000 multislice CT scanner, which acquires an unprecedented 16 simultaneous slices with sub-millimeter isotropic accuracy.
1999 At RSNA, Picker International unveils the new Marconi Medical Systems name and corporate vision.
1998 Picker International acquires the Computed Tomography Division of Elscint Ltd, immediately positioning Picker at the forefront of major global CT suppliers.
1986 Picker produces the industry's first 1.0T MR imager.
1981 Picker is sold to General Electric Co. Ltd. of England (GEC). Picker merged with Cambridge Instruments, GEC Medical, and American Optical to form Picker International.
1967 The name changed from Picker x-ray to Picker Corporation. Picker acquired Dunlee.
1946 The Dunlee Corporation started in Chicago by Dunmore Dunk and Zed. J. Atlee to meet demand for quality x-ray tubes and special purpose tubes.
1915 James Picker Company formed in New York City offering sales and service of x-ray equipment, film and accessories.

A matrix is an array of numbers in rows and columns. The horizontal lines in matrices are called rows and the vertical lines are called columns. A matrix with m rows and n columns is called an m-by-n matrix (or mxn matrix) and m and n are called its dimensions. The matrix used in computed tomography determines the scan resolution.
Matrices are useful to record data that depend on two categories, and to keep track of the coefficients of systems of linear equations and linear transformations.

See also Image Resolution and Zooming.