Advertisement Upgrade to remove ads

radiography general questions

umbra

true border of object as imaged radiographically

Source-to-image distance (SID)

distance between focal spot and image receptor (IR)

scatter

radiation produced from xray photon interactions with matter where resulting photons continue in a different direction

central ray

theoretical center of a beam of radiation

distortion

misrepresentation of true size or shape of an object

contrast

visible difference between adjacent densities; controlled by kVp primarily

fog

unwanted exposure or film densities

half-value layer

amount of filtration needed to reduce the intensity of the beam by half

image receptor (IR)

medium to capture radiographic image

inverse square law

relationship between intensity and source of radiation

kilovoltage peak (kVp)

potential difference; controls penetrating ability; quality of photons produced by xray tube

latent image

invisible image created after exposure but before processing

millampere seconds (mAs)

controls quantity of photons produced by xray tube

positive beam limitation (PBL)

automatic collimation system used on diagnostic xray units

primary radiation

beam after it leaves xray tube & before it reacts with the patient

attenuation

reduction in energy by passing through matter

recorded detail

representation of an object's true borders

remnant radiation

radiation resulting after the xray beam exits the object

resolution

measurement of recorded detail on a radiograph

inverse square law

the intensity of a beam of radiation is inversely proportional to the square of its distance from the source

scatter radiation

nondiagnostic radiation that travels in different direction after interacting with the patients body

absorbed radiation

radiation that is absorbed by the patient tissues

anode

method to stop electrons; target; positive electrode of xray tube

cathode

source of electrons; filament; negative electrode of xray tube

voltage

method to accelerate electrons rapidly

photographic qualities

density and contrast

geometric qualities

recorded detail and distortion

distortion

misrepresentation of an object's true size or shape

density

degree of darkening; overall blackening of film emulsion; controlled by mAs

mAs reciprocity

any combination of mA x time producing equal mAs values should produce equal exposures and densities

Becquerel (Bq)

unit of radioactivity; 1 disintegration per second (dps)

Compton Scatter

higher energy photon knocks outer shell electron from orbit

most occupational scatter exposure is from:

compton scatter

bone densitometry

the use of DEXA scanning to evaluate for osteoporosis

DEXA

dual energy xray absorptometry

classic coherent scatter

lower energy photon interacts with atom; same energy released in different direction; no energy transferred to patient

photoelectric effect

high energy photon knocks out inner shell electron; complete absorption of energy

biggest risk from scatter radiation is from:

photoelectric effect

pair production

high energy photon interacts with nucleus; produces two elextrons at 180 degrees from each other

Type of scatter produced by PET scan

pair production

Sievert (Sv)

measure of dose equivalence and biological damage; absorbed dose x quality factor; 1 sv = 100 rem

Gray (Gy)

measure of absorbed dose; 1 Gy = 100 rads

Detent

when xray tube is aligned with the grid in the table

Energy level for classic coherent scatter

below 10 KeV

energy level required for pair production

1.02 MeV

energy level required for photodisintregation

10 MeV

old unit for Gray (gy)

rad. Radiation Absorbed Dose

old unit for Seivert (sv)

rem. Radiation Equivalent Man

prodromal stage

nausea vomiting diarrhea;

latent period

body feels fine; cell changes are occurring

manifest stage

organism feels full effect of radiation

bone marrow syndrome

exposure between 2-10 Gy (200-1000 rad); infection, hemorrhage, anemia

gastrointestinal syndrome

10-50 Gy (1000-5000 rad); Massive diarrhea, nausea, vomiting, fever

CNS Syndrome

above 50 Gy; convulsions, coma, death from increased intracranial pressure

somatic effects of radiation exposure

cataract formation; carcinogenesis

genetic effects of radiation exposure

recessive mutations in DNA apparent in future generations

Core Values of Human Rights Law

autonomy, dignity, equality, solidarity

assimilation

abandoning original culture/language and melting into larger group

biculturalism

being able to negotiate two separate cultures individually

Over 85

fastest growing segment of american population

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set