rads 2 - study guide portion Flashcards
(35 cards)
What is the heel effect
when the thickest part of the patient is placed toward the cathode side
how does mA affect the quantity of the x-ray beam
affects the contrast if to much mA is used, density / overall blackness
what does mA affect most when evaluating the radiograph
primarily affects the density, or the overall blackness of the radiograph - too little = overall grayness, too much = overall blackness
why do we want to decrease exposure times
to decrease patient motion blur
kVp is said to affect the quality of the x-ray beam. why is this true. what happens as kVp is increased / decreased
when decrease, there is little definition or detail. when increased there will be an increa in the radiographic density
how are we determining our kVp setting? what devise do we use, what do we do with this measurement
determined using the santes rule ( 2 x thickness in cm) + distance
what is the relationship between kVp and mA
higher kVp settings allow for lower mA’s. it is an inverse relationship, that also allows for a shorter exposure time
what is density
the darkness / blackness on the finished radiograph
what is the scale of density of objects
thick (bones, metal) –> thin (gas)
metal, bone, fluid, fat, gas
do denser objects appear lighter or darker
lighter
what is contrast
the difference between neighboring structures, when too high there will be a lot of black and white
what is a collimator, and why do we use this device
controls the size of the x-ray beam, to reduce scatter radiation
what is a grid? what is it composed of, and why do we use it
the grid allows only the primary beam to pass through. it is composed of lead strips interfaced with radiolucent spacers that can be made of plastic or aluminum. we use it to help absorb scatter radiation
what is a cassette
the film holder, it protects the screens and films from physical damage
what is an intensifying screen
covers the inside of the cassette, they emit light after being exposed to the xray beam
what do you include when labeling a radiograph
patient and owner name, date of image, name of practice, initials of radiographer
what must be included on a radiology log
owner / patient name, area of study, technique used, initials of the radiographer, and date
kept for 3-5 years
benefits of digital radiography
the machine automatically sets the mA and kVp settings, easily make adjustments, corrects films if too light / dark, faster radiographs
difference between a CR and DR unit
DR - an xray tube coupled to a specialized detector panel that changes xrays into electrical signals is used
CR - an xray detector similar to a cassette is used and must be processed in a special machine
what image format is used for radiographs
DICOM
manual flim processing
developing, rinse bath, fix, wash bath
requirements for a dark room
used only to process exposed radiographs, completely light proof, in use sign, using the safelight only in that room 4 ft away from the image / work area
technique chart and how put together
provides suggested exposure factors to use based on the part being radiographed, the thickness of the tissue, and the position of the pt
normally produced by the manufacturer
select pt, measure for you view for kVP settings, find the mA, time and mA settings
why is radiation safety important
so we are able to keep ourselves protected, and do not cause harm to the patient
