Week 5 Day 1: Ch 6/8 Dental xray characteristics and dental imaging

radiolucent

portion of the processed image that appears dark/black; structure that appears black on film lacks density; permits the passage of xray with little to no resistance

radiopaque

portion of processed image that appears white; structure that appears white on film is dense; absorbs or resists passage of the xray beam

density

overall darkness or blackness of a dental image; relative transparency depends on distribution of black silver particles in emulsion

contrast

difference in degrees of blackness between adjacent areas on a dental image; kilovoltage controls

short scale contrast

image with only two densities, black and white; occurs with machines functioning at low kVp

high contrast

what is short-scale contrast also known as?

long-scale contrast

image with many densities, many shades of gray; occurs with machines functioning at high kVp

low contrast

what is long-scale contrast also known as?

stepwedge

can demonstrate short-scale and long-scale contrast; consists of uniform layered thickness of an xray absorbing material; different densities appear on the dental image

sharpness

capability of the xray receptor to reproduce distinct outlines of an object

penumbra

lack of sharpness is present in every image

focal spot size; film composition; movement

what is sharpness in an image influenced by?

magnification

radiographic image that appears larger than the actual size of the object it represents; results from the divergent paths of the xray beam as they radiate from focal spot

target-receptor distance; object-receptor distance

what are 2 influencing factors of magnification?

distortion

variation in the true size and shape of object being radiographed; results from unequal magnification of different parts of the same object bc of improper receptor alignment/angulation of xray beam

object-receptor alignment; xray beam angulation

what are 2 influencing factors of distortion?

direct digital imaging

components include intraoral dental xray unit, sensor and computer imaging software

indirect digital imaging

components include intraoral dental xray unit, PSP plate, laser-scanning device and computer