Technique Chapter 6,7,12 Vocabulary

contrast

the difference between two adjacent densities

radiolucent

describes a substance that allows the passage of x-rays, appearing darker on radiographs

radiopaque

describes a substance that does not allow the passage of x-rays, appearing lighter on radiographs.

IR exposure

the amount of radiation reaching the image receptor, density

Spatial resolution

the sharpness or detail of the image

IR

image receptor

brightness

function of a display monitor, changes the image lightness/darkness

CR (central ray)

the middle of your field

CR (computed technology)

a two step process to take x-rays

What is the minimum amount to change the kVp by to see a difference in the image?

15%

What is the minimum amount to change the mAs by to see a difference in the image?

30%

mAs

milliamps per second, milliamps x seconds

ALARA

as low as reasonably achievable

attenuation

The reduction in intensity or energy of a radiation beam as it passes through a material due to absorption and scattering of photons or particles

scatter radiation

ionizing radiation that has been deflected in multiple directions after interacting with matter

What does radiation do when it interacts with matter?

attenuates, absorbs, scatters

distortion

The misrepresentation of the size or shape of an anatomical structure on a radiographic image

backup time circuit

protects patient and equipment, 150% of the anticipated manual technique (backup timer)

What does mAs control?

quantity

What does kVp control?

quality

AEC

Automatic exposure controls

What does the AEC do?

automatically terminates the x-ray exposure when a predetermined amount of radiation has reached the IR

Ionization Chambers

Measures the amount of radiation reaching the IR

SID

source to image distance, distance between source and IR

collimation

changing of the field size

APR

Anantomically programmed radiology

What does APR do?

Computerized exposure systems that use AEC capabilities

HVL

half value layer, reduces beam by half its value

exposure time

controls duration of exposure

More density in an image will result in ___

a darker image

Less density in an image will result in ___

a lighter image

X-rays are produced from a ____ in the x-ray tube.

point source

What are the 3 prime exposure factors?

kVp, mAs, SID

What do you do if you need a higher contrast in your image?

decrease kVp by 15%

DR

Digital radiography, an

EI#

Exposure Index #

What is EI#

tells us if we adequetly exposed the IR

OID

object to image distance

SOD

source to object distance

ESE

Entrance Skin Exposure, where the radiation hits first

Grid

absorbs bad radiation, is between Bucky and IR, cleans up the image

automatic rescaling

process by which images are produced with uniform brightness and contrast, regardless of the amount of exposure

contrast

the difference between two adjacent materials

contrast resolution

Ability to tell apart small differences in IR exposure from background noise in the image.

displayed image contrast

relative brightness difference between the adjacent pixels in a digital image as viewed on a monitor

distortion

misrepresentation of the true size or shape of an object

kVp

kilovoltage peak, the power of the beam

photon

quantum or particle of radiant energy

primary radiation

x-ray beam after it leaves the x-ray tube and before it reaches the object

remnant radiation

radiation resulting after the x-ray beam exits the object

scatter radiation

Radiation that is deflected from matter upon interaction

subject radiation

ranges of differences in the intensity of the x-ray beam after it has been attenuated by the subject

localization

determination of a precise area, typically through palpitating

the cardinal rules

time, distance, shielding/collimation

AEC controls the ____

mAs

APR controls the ____

kVp

what does the backup timer do?

protects patient from over exposure, protects the equipment

implied consent

consent given by actions or agreeing

written consent

signing a document

boning and pulmonary markings are examples of ___

spacial resolution