Hounsfieldin

Hounsfieldin is not a widely recognized term in radiology or medical imaging. It may be a misspelling or language-specific form referring to Hounsfield units, the standard quantitative measure used in computed tomography (CT) imaging. If encountered, it is generally best interpreted as an indirect reference to the Hounsfield unit.

The Hounsfield unit (HU) is a dimensionless scale that quantifies radiodensity in CT images. It is named after Sir Godfrey Hounsfield, a co-inventor of the CT scanner. The scale defines the radiodensity of distilled water at standard pressure as 0 HU and air as -1000 HU. Tissue densities are expressed as CT numbers relative to water, allowing comparison across scans and patients. The value is derived from the linear attenuation coefficient of the tissue and a calibration reference, and it can be influenced by scanner settings and reconstruction parameters.

Typical HU ranges include: air around -1000, fat roughly -100 to -50, water 0, soft tissues about 20 to 60, blood and some soft tissues in the low tens, and dense cortical bone from around +700 up to +3000 HU or higher depending on bone mineral density and scanning conditions. These numbers facilitate tissue differentiation, lesion characterization, and measurements such as bone mineral density or contrast-enhanced studies.

Limitations and variability exist: HU values can vary with scanner model, tube voltage, reconstruction kernel, and patient factors. Artifacts, partial volume effects, and beam hardening can affect accuracy. Despite these caveats, HU is a foundational concept in CT interpretation and quantitative imaging. See also: Godfrey Hounsfield, computed tomography, CT imaging.