XRAY

radiography?

umbrella term for all types of studies involving the visualization of anatomy using x-ray techniques.

digital radiography vs computed radiography?

digital = new, most used now,

CR = old, involves imaging plates.

AP?

antero-posterior

PA?

posteroanterior

image receptor is at the back : receiving exit radiation

why are chest x-rays performed PA?

they are performed posteroanteriorly because the heart will be closer to the magnifier minimizing the hear size and maximizing lung visualization.

• when the heart is further (AP) the heart is magnified, and minimizes lung visualization.

radiolucent?

dark, air, little or no attenuation, signals go straight through tissues and into the detector.

radiopaque?

bright, bones (dense), more attenuation of the number of photons passing through.

x-ray, how?

basically ionizing radiation in the form of an x-ray beam is directed through the anatomical ROG, beam is then attenuated by internal structures and the remaining x-ray is transmitted to an image receptor = image!!

what is the x-ray beam called?

when being emitted from the focal spot = primary radiation

post attenuation and exiting patient = remnant or exit radiation

how do the beams get attenuated?

scattering or absorption, basically its the reduction of x-ray beams intensity

kVp?

• kilovoltage peak

• power and strength of the x-ray beam (quality)

• controls the penetrating strength of an x-ray beam

• also controls the contrast,

mAs?

• milli-ampere-second

• # x-ray photons produced by the x-ray tube at the setting selected (quantity of photons)

• no effect on strength (penetration), only quantity

• directly proportionate to the patient exposure rate (2x mAs = 2x radiation dose)

orthogonal projections?

images taken at 90 degress to eachother

optical density?

the degree of blackening, should remain within diagnsotic range, if not change technique. basically used to describe how much x-rays are absorbed by a material (film/detector) , its ability to absorb light.

exposure index?

over exposed = high optical density, high levels of x-ray photon transmission, hgih degree of film darkening,

underexposed = low optical density, low levels of x-ray photon transmission, low degree of film darkening (bright)

high vs low contrast?

low = many density levels

high = very few density levels

recorded detail?

distinctness of radiographic image margins

• ex: blurry = poor recorded detail

how are lateral radiographs taken

with the patients side against the image receptor, side closer to image receptor should be labelled on the image.

oblique images?

taken with a patients body slightly rotated

how to identify child vs adult?

• epiphyseal growth plates of long bones.

• usually close during puberty

• very common fractures for children

how do you protect yourself during an x-ray?

lead apron

bone densitometry

“ dual energy x-ray absorptiometry, DEXA DXA”

• uses small doses of ionizing radiation to produce pics of the inside of the body, spine hips, measures bone loss.

• used to diagnose osteoporosis, risk for it,

prep for boen densitometry?

• DO NOT TAKE CALCIUM SUPPLEMENT 24HRS BEFORE DEXA EXAM

• HAVE YOU RECENTLY HAD A BARIUM EXAM, RECEIVED CONTRAST FROM CT?

• POSSIBILITY OF PREGNANCY?

• DON’T WEAR JEWELRY OR CLOTHES WITH METAL BUTTONS/ZIPPERS

T-score?

the amount of bone you have compared with a young adult of the same gender with peak bone mass

• -1 and above is considered normal

• -1.1 and -2.4 = osteopenia (low bm)

• -2.5 and below = osteoporosis

z-score?

amount of bone you have compared with others in your own age group, size and gender.

• unusually high or low = no bueno