Flashcards in Lecture 1: Be a radiology tech in 2 years Deck (51)
Bayesian Analysis plus clinical example
pretest probability affects post-test probability. If you have a strong clinical suspicion of fracture but XR is negative, request further testing.
x ray attenuation: definition, function of what 3 variables?
X ray photons are "absorbed" by matter; amount of attenuation depends on: thickness, density of material (function of atomic number), and x ray beam kVp (peak kilovoltage/energy)
Xray: does an object of high density appear darker or brighter?
X ray radiolucency: define
Allows x ray to pass through without absorption, penetrates most easily. Appears dark on XR
X ray radiodensity: define
Absorbs x ray beams, appears bright on XR
Name a highly radiolucent material
Name a material class with high radiodensity
Which is more radiolucent: bone or water?
Which is more radiolucent: contrast or bone?
Which is more radiodense: contrast or bone?
Which is more radiodense: bone or fat?
Picture archiving and communication system-a medical imaging technology which provides economical storage of and convenient access to images from multiple modalities (source machine types).
Digital Imaging and Communications in Medicine (DICOM) is a standard for handling, storing, printing, and transmitting information in medical imaging. It includes a file format definition and a network communications protocol.
A radiology information system (RIS) is a computerized database used by radiology departments to store, manipulate, and distribute patient radiological data and imagery. The system generally consists of patient tracking and scheduling, result reporting and image tracking capabilities.
A hospital information system (HIS) is an element of health informatics that focuses mainly on the administrational needs of hospitals
satisfaction of search
phenomenon in which the detection of one radiographic finding interferes with that of others; just because you found something doesn't mean you found everything
Hounsfield Units: what modality of imaging? Define.
Measure of attenuation of x ray beam in CT scan
Hounsfield units: reference values for water and air
Hounsfeld units: bone, blood, muscle, fat
bone=1000, blood=40, muscle=10-40, fat=-50--100
CT scan: 4 types of artifact
Motion, metal, partial volume averaging, beam hardening artifact
CT scan motion artifact: example
Cardiac motion (less of an issue with today's fast multislice scanners)
CT scan: Partial volume averaging artifact
More of an issue with thicker slices; a substance that occupies several voxels will get "averaged" and look larger and blurrier than it would if it was centered in 1 voxel
CT scan: metal artifact
Radiodense structures limits evaluation of adjacent structures, can be minimized by increasing kvp
CT scan: beam hardening artifact
Appears like an area of radiolucency (very dark area on scan), low energy portion of the spectrum filtered out,
Makes structures more radiodense, therefore brighter and easier to discern on scan. Administered orally, rectally, or intravenously.
CT contrast risks
allergic reactions (mild-rash; severe-HOTN, laryngeal swelling, CV collapse); renal failure (creatinine >1,5-1.8); contrast extravasation-contrast leaks out of a ruptured vessel
CT scan for pts on dialysis
IV CT contrast OK but not MRI contrast
CT scan advantages
fast, high resolution, can be reformatted after scan into 3D image in any plane (multiplanar reformatting MPR)
CT scan disadvantages
artifact, risks of IV contrast, RADIATION