Week 2.1 Imaging Fundamentals Flashcards
what is the most common modality for bone and joint
conventional radiography
what are the benefits of conventional radiography
first order diagnostic study
little risk
time effective
cost effective
how are images produced in standard radiographs
on a sensitive plate or film,
- x-rays
- gamma rays
- similar radiation
radiation passes through a patient where it is ____, and then what
attenuated (blocked by bones depending on the density)
then the remnant radiation is incepted by the receptor and creates a visual image
what are the 4 key points when talking about ionizing radiation
- neural atoms gain or lose an electron
- disrupts composition of matter
- disrupts life processes
- protection against excessive exposure
expand on the phrase “protection against excessive exposure”
do no harm, and is the information gained from this study more important then the risk you are putting the patient in, and the harm it does to them
Air Kerma
absorbed in the absence of scatter, the radiant radiation absorbed by the air
Dose area product
integral of air Kerma, for an entire x-ray beam
Absorbed dose/CT dose
dose from the primary beam plus scatter from surrounding slices.
Equivalent dose
absorbed dose adjusted by weighting factor of type of radiation (CT and X-ray weighting factor of 1)
effective dose
adjustment to of equivalent dose based on the tissue susceptibility to ionizing radiation (type of tissue, abdomen vs ankle… very different)
absorbed dose is the dose
of energy that is deposited in the patient
equivalent dose is the
absorbed dose that is adjusted for harmful effects
effective dose is
equivalent dose that is adjusted for harm that it causes to different tissues
what is the cut off for tolerable levels of exposure
20mSv
how many mSv do you get from the sun every year
2mSv
what does tolerable levels of radiation mean
no symptoms, and no detectable increased risk for cancer.
what is the cut off for moderate risk, and what does it mean
no immediate symptoms, and an increased risk of serious illness later in life. Cut off is 1000 mSv
what are the components of a typical conventional radiograph
you have an emitting device that has a plate of some kind to absorb the remaining radiation
what is radio density
the physical qualities of an object that determine how much radiation is absorbed
what affects radio density
the composition of the tissue (anatomic number and the volume density)
thickness
the greater the atomic number, volume density and or thickness, the ___ the radio density
greater
what is the difference between radiolucent and radiopaque
radiolucent is black, and radiopaque is going to be white
a single radiograph provides __ dimensions
2, length and width
what adds a third dimension to a conventional radiographs
90 degree angle, another radiograph
always need ___ images
2, if you have 1 you have none
in conventional radiographs, the projection describes…
the path of the beam
- anterior to posterior (above to below)
- posterior to anterior (prone)
what are the 4 image quality factors for a conventional radiograph
- density (blackening of image)
- contrast (difference between adjacent densities)
- detail (geometric sharpens or accuracy)
- distortion (difference between actual object and its recorded image- size and shape)
