Chapter 17 – The Patient as a Beam Emitter Principles of Radiographic Imaging

A comprehensive set of vocabulary flashcards covering key concepts, definitions, and essential information from the lecture on radiological imaging principles.

Attenuation

Reduction in the number of x-ray photons remaining in the beam after it passes through a material.

Photoelectric absorption

An interaction process in the diagnostic range that produces useful image information.

Compton scatter

An interaction process that does not contribute useful image information; mainly adds radiation to personnel and fog to the image.

Factors that increase attenuation

Increased part thickness, increased tissue density, and higher effective atomic number (Z#).

Exponential process

Attenuation is characterized as an exponential process where a constant fraction of the beam is removed per unit thickness.

Subject density

Describes how changes in the amount or type of tissue being irradiated affect image receptor exposure.

Subject contrast

Degree of differential absorption of x-ray photons in the body due to differences in tissue composition, density, and thickness.

Subject detail

Refers to how well the anatomic structures are recorded on the image, influenced by anatomical location and distance to the image receptor.

Subject distortion

Misrepresentation of the size or shape of anatomy on the image due to its position relative to the x-ray beam and the IR.

Additive conditions

Conditions that increase tissue thickness, Z#, and/or tissue density, causing increased attenuation of the x-ray beam.

Destructive conditions

Conditions that decrease tissue thickness, Z#, and/or tissue density, resulting in decreased attenuation of the x-ray beam.

Inversely related

Relationship of additive conditions to IR exposure; more additive pathology results in less IR exposure.

Systemic destructive conditions

Conditions such as anorexia nervosa, atrophy, and emaciation that decrease attenuation.

Examples of additive conditions

Includes ailments such as atelectasis, congestive heart failure, and pneumonia.

Examples of destructive conditions

Includes ailments such as emphysema, bowel obstruction, and osteoporosis.