Exam Review Flashcards
what setting is controlled by mA?
quantity of the beam
what kind of crystal is in a dosimeter?
lithium crystal
when a radiograph is developed for too long, what happens to the image?
it appears too dark
what part of cells is most negatively affected by radiation?
DNA
true or false; does changing the SID change the density of the radiograph?
true
how thick is the layer of lead in our gloves, gowns, etc?
0.5mm
as the energy of an x-ray photon increase, does the wavelength increase or decrease?
decrease
true or false; when electrons collide with the target anode 1% is heat and 99% is photons
false; collisions result in only 1% photons (x-rays) and 99% result in only heat
how long are clinics required to keep their log books on record?
5 years
if you are preparing to take radiographs and the SID is set at 65 inches, is this a problem? why?
yes; SID should always be maintained at 40 inches otherwise the radiograph will be too intense
what is the relationship between mA and electrons? kVp?
mA is directly related to the AMOUNT of electrons, kVp is directly related to the SPEED of electrons
what is the purpose of the developer?
converts exposed silver halide crystals to black metallic silver; makes the latent image visible
what is the purpose of the fixer?
clear the unexposed silver halide crystals; hardens the emulsion
where would you measure for a lateral abdomen radiograph? peripheral borders?
measure: caudal of the thirteenth rib to T7 (thoracolumbar junction)
peripheral borders: caudal of 13th rib, femoral head
what three things will increase scatter?
larger field of view, higher kVp, higher mAs
how are x-rays produced? explain the process of excitation.
- electrons released from negatively charged cathode
- electrons accelerated via kVp toward positively charged metal anode
- electrons collide with particles (electrons) from the anode
- they react; process of excitation begins
- as electron gains energy, it is able to move up in orbit
- when it gains even more energy, it is able to “fall” back to original orbit
- during “fall” an electromagnetic photon (x-ray) is released by loss of energy
why would you not perform a VD abdominal radiograph? give at least 3 reasons
bloated patient, obese animal, pregnancy, trauma, spinal injury, etc
how would you alter settings for a repeat radiograph if your bones appear too grey?
contrast was too low; lower kVp by 10-15% to achieve higher contrast
what MUST be included on every label ? list at least 3
patient name, RAD log number, date, etc
landmarks that indicate the left side of the animal on a VD abdomen radiograph?
left kidney appears LOWER than the right right kidney
majority of stomach rests on left side
spleen
what views should be taken if the vet suspects elbow dysplasia?
lateral with extension, lateral with flexation 9of elbow), cranial caudal
how do radiographs get black crescent shaped artifacts? what are those black crescents? when are they acquired ?
crescents are scratches from handler’s nails, occurs after exposure but before development (i.e. when removing film from cassette)
define: penumbra; how does this occur?
penumbra: an unclear image caused by movement (of animal)
should thoracic radiographs be taken on inspiration or expiration? 3 differences you can appreciate between inspiration and expiration?
should be taken on inspiration; no contact between heart and diaphragm, less sternal contact, heart looks smaller on inspiration
what types of crystals are in intensifying screens?
fluroescent phosphor crystals
lanthanide crystals (rare earth)
calcium tungstate crystals
what factors affect the speed of intensifying screens?
type of phosphor crystals
thickness of crystal layer
size of crystals
efficiency of the reflective layer
you’ve taken an abdominal radiograph and can only kind of make out the organs/soft tissue but not perfectly; how would you alter the settings?
double mAs
how often are dosimeters replaced?
every 3 months
what factors determine whether or not an x-ray will be absorbed or will penetrate through materials?
density of material
strength of the beam
what material is made up of
true or false; when radiographing a young, squirmy animal, you would choose 100mA and 60ms over 200mA and 30ms for better results
false; in patients that are young/prone to moving during the x-ray process, it is advisable to
what happens in the tube head when you press and hold the “ready” button?
the cathode is heated
true or false; for a thoracic radiograph you want high density and low contrast settings
true; high density will allow you to distinguish between soft tissues, low contrast allows you to see past the ribs
what 4 views could you take of a paw?
metacarpal-phalanges lateral
m-p dorsoplantar
m-p obliques
m-p ventropalmar
what is different about a metacarpal-phalanges lateral radiograph and a m-p obliques radiograph?
m-p lateral is like any other lateral radiograph where as m-p obliques separates each toe to be viewed
what is the optimal/most correct view for a thoracic radiograph?
DV
what causes foreshortening on a limb radiograph?
limbs not parallel, tilted beam
