Computed Tomography (CT) for Physiotherapy

Vocabulary-style flashcards covering the definitions, components, principles, and clinical applications of Computed Tomography (CT) for physiotherapy students.

Computed Tomography (CT)

An imaging technique that uses multiple X-ray images taken from different angles and a computer to create cross-sectional slices of the body.

Tomo

A Greek-derived term meaning slice or cut.

Graphy

A Greek-derived term meaning imaging or recording.

Sir Godfrey Hounsfield

An engineer who built the first practical CT scanner and produced the first brain CT image between 1971 and 1972.

Allan Cormack

A physicist who developed the mathematical principles used in CT reconstruction; co-recipient of the 1979 Nobel Prize.

Gantry

The circular ring that houses the scanner parts, including the X-ray tube and detector array.

Detector Array

The component of the imaging system that receives X-rays after they pass through the patient's body.

Data Acquisition System (DAS)

A system that collects detector signals and converts them into digital data.

Filtered Back Projection (FBP)

An algorithm used by the computer system for reconstructing raw data into images.

Multiplanar Reconstruction (MPR)

A post-processing technique that displays images in axial, coronal, and sagittal planes.

Maximum Intensity Projection (MIP)

A post-processing technique that highlights dense structures such as bones and blood vessels.

Minimum Intensity Projection (MinIP)

A post-processing technique that highlights low-density structures such as airways and lungs.

PACS

Picture Archiving and Communication System; the system used for storing CT images.

Axial (Transverse) Plane

The original CT slice orientation, representing 'top to bottom' slices of the body.

Coronal Plane

The imaging plane that divides the body into front and back sections.

Sagittal Plane

The side view imaging plane that divides the body into left and right sections.

RALP Rule

The CT image orientation rule where Right appears on the left side, Anterior is at the top, Left is on the right side, and Posterior is at the bottom.

Matrix

A grid of rows and columns making up a CT image (e.g., $512 \times 512$); larger versions provide better resolution.

Pixel

A small square on the image representing tissue information and assigned a specific Hounsfield Unit (HU).

Voxel

A volume element representing a small volume of tissue, calculated as $\text{Pixel} + \text{Thickness}$.

Slice Thickness

The thickness of tissue being imaged, usually ranging from $0.5$ to $5\text{ mm}$; thinner slices provide more detail.

Hounsfield Units (HU)

A measurement of tissue density; specifically, Air is $-1000$, Water is $0$, and Cortical bone is $>1000$.

Hypodense (Hypoattenuating)

Tissues with low HU and low X-ray absorption that appear dark on a scan, such as air or fat.

Hyperdense (Hyperattenuating)

Tissues with high HU that absorb more X-rays and appear bright on a scan, such as bone or metal.

Windowing

The process of adjusting brightness, contrast, and gray scale to make tissues easier to see, without changing actual HU values.

Artifact

A distortion or error in an image that does not represent the actual anatomy, such as motion blur or metal streaks.

Functional CT

A recent development in CT that provides information about organ function in addition to anatomical structure.