Scan

Scan refers to the systematic examination of a subject, area, or volume by moving a sensor or detector across it or through it and recording data about its properties. The term is used across many fields, with variations such as document scanning, medical imaging, and security screening. Scanning emphasizes collecting data over a defined region rather than capturing a single snapshot.

Medical imaging scans include X-ray computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, and positron emission tomography (PET); each modality uses different physical principles to visualize internal structures. In document handling, scanning converts physical documents into digital images using optical sensors, enabling storage, search, and optical character recognition.

Security and customs use body scanners and luggage scanners to detect concealed items. In manufacturing, non-destructive testing scanners map the interior of objects to detect defects or measure geometry. Astronomy employs scanning techniques to map portions of the sky with telescopes or radio arrays, producing wide-area images and data sets.

The scanning process generally involves data acquisition, signal processing, image reconstruction or data interpretation, and quality control. Key factors include resolution, sampling rate, noise, artifacts, and calibration. Different applications balance accuracy, speed, and safety considerations, such as radiation exposure in medical or security contexts and privacy concerns in screening environments.

Related concepts include scanning in biology (e.g., DNA microarray scanning), barcode scanning, and network scanning in information technology.