invented x-ray grid in 1913

working ability of a grid is described, ratio of height

Grid Ratio used for Greater than 90 kVp - for 20-40 kVp (mammography)- for 70-90 kVp -

ratio of incident radiation

no actual grid, latest innovation for scatter radiation

strips are slightly angled, used at specified focal distance

used for short or long distance

eliminates fine grid lines

Layers of Intensifying Screen BRLP

What phosphor layer emits blue light? CT & LO

What phosphor layer emits green light? G.0

Rare Earth Elements GLY

* film sensitive to UV, Blue, Green Light * film sensitive to UV & Blue Light

2 Processing Errors that affect density

processing that requires rigorous quality control

controls density of radiograph

What Scatter is Decreased, Contrast is what?

magnifying the anatomical structure, usually caused by increased OID

can be controlled by proper exposure factor

misinterpretation of shape, controlled by alignment of beam, referred as true distortion

Influencing factors of shape distortion include: CB

central portion of the beam

number used to change one set of units

alters intensity of beam

- compromise visibility of detail - degree of overall blackening

describe concept of density displayed on soft copy monitor, amount of luminescence

describe the digital processing that produce change

5 Factors affecting density KFABA

effect that alters intensity

great deal of influence on IR and film density

affects recorded detail, fails enough time for image to form

* patient based artifact that occur with voluntary and involuntary movement * under the direct control of patient * not under the control of patient

technique used to track movement of objects with xrays ex. cartilage

instrument that provides a read of amount of blackening or density

unwanted absorption of x-rays via an x-ray grid

to minimize distortion

Use only the SID distances of?

What do with mAs when distance increases? when distance decreases?

Restricting beam does what? RN, RA, RO

Scatter rad is produced when? HL

can alter absorption characteristics of anatomic part

- conditions that increase absorption characteristics, making it difficult to penetrate - conditions that decrease the absorption characteristics, making part easier to penetrate

BEST METHODS IN REDUCING MOTION IN ORDER

major controller of image resolution and penumbra

- what focal spot reduces bluriness or penumbra effect and is used where spatial resolution is important (mammography) - what focal spot results in more unsharpness and reduced recorded detail, used when shorter exposure time is prio

The ________ between source or focal spot, object, part and image receptor are critical in establishing sufficient recorded detail

when OID is decreased, resolution is ________ when SID is increased, resolution and recorded detail is ________

distance between focal spot and radiographic film

- lower x-ray beam intensity - need higher mAs to prevent underexposure

commonly classified by speed

Slow Film Screen Combination equals to better or worse resolution?

helps control geometric distortion and grid cut off

degree to which radiation is attenuated, depends on cell component, relative atomic no, thickness, cell density

- anything that changes the nature of radiation beam - purpose is scatter control

- filtration from components of x-ray tube - filtration from interchangeable metal sheets

filtration used in mammography

Diagnostic X-ray Beams are _________ (meaning spectrum of many diff energies)

substance that attenuates the beam to a different degree than surrounding tissue