Radiology Flashcards
Function of Aluminum filter
blocks low-energy photons to decrease dose to patient
function of tungsten filament
creates e- cloud
function of molybdenum focusing cup
focuses e- from the tungsten filament to tungsten focal spot
tungsten focal spot
smaller focal spot = sharper image
hit with e- to create X-ray beam
function of copper stem
dissipates heat
step up transformer
high voltage
increases potential
step down transformer
filament
decreases voltage
Bremsstrahlung
primary source of X-ray production
What determines quality of X-ray beam
energy of photons
what determines quantity of beam
number of photons
what does kilovoltage determine
increasing kVp increases quality and quantity
what does miliamperage determine
increase the quantity of photons
what does time determine
increase the quantity of photons
what does the inverse square law say
the intensity of x–ray beam is inversely proportional to the square of the distance from the source
What are deterministic effects of radiation biology
effects that occur once threshold is reached, and after threshold is reached the severity is proportional to dose
oral mucositis
what are stochastic effects of radiation biology
effects may occur independent of dose (no threshold)
probability not severity is proportional to dose
radiation induced cancer
What cells are most sensitive to radiation
nucleus and DNA are most sensitive parts of the cell
mitotically active and cells with long mitotic futures are most sensitive cells (bone marrow, gonads)
Parts and function of parts in X-ray film
emulsion = silver halide grains (sensitive to x-ray) base = supports emulsion
function of intensifying screen
phosphor layer used as screen converts x-ray into light
more light than x-ray = less radiation needed, but decreased resolution
How to improve image sharpness
small focal spot
increase distance between focal spot and object
decrease distance between object and receptor
what causes forshortening
film is at right angle to xray, but object isn’t
what causes elongation
object is at right angle to xray, but film is not
steps of x-ray developping
- developper, converts silver halide into metallic grains
- rinse, stops developper
- fixer, dissolves and removes undevelopped silver halide crystals
- washing, prevents staining from left over fixer
charge coupled device, or complementary metal oxdie semiconductors
as Digital imaging detectors
CCD and CMOS = silicon captures x-ray energy as voltage and sends it to computer
photostimulable phosphor plates
barium fluorohalide with europium
capture and store x-ray energy, laser used releases fluoresence
what is contrast resolution of radiographs
the ability to distinguish shades of gray
what is spatial resolution of radiographs
the ability to detect edges or close points
film is better than CCD/CMOS
what makes up the Y line of Ennis
superimposition of the floor of the nasal cavity and the border of maxillary sinus
what does the Y line of Ennis mark
maxillary canine
