2.2.1. Intro to Imaging Flashcards
What determines radiographic opacity?
- Material
- Density
- Thickness
What material appears BLACK on a radiograph?
What is this characteristic called?
AIR appears black b/c there’s no object to “cast a shadow”
Black areas are where the Xrays shine through = “lucent”
What is the term for a material that appears WHITE on a radiograph?
“Radioopaque” - this is when objects “cast a shadow”
Arrange in order from most lucent to most radioopaque:
titanium screw, adipose, bone, lung, soft tissue, muscle
(most lucent) lung - adipose - muscle - soft tissue - bone - titanium screw (most radioopaque)
Can you determine an object’s shape from a single radiograph?
If not, what’s the minimum you need?
NO!
You need two to determine shape (more can be a waste and cause unnecessary radiation exposure)
Name and describe the orientation of the three imaging planes.
- Sagittal = cuts the body longitudinally
- Coronal = cuts the body front-to-back
- Transverse = cuts the body parallel to the floor view
Order the steps of generating a radiographic image:
A. Electrons hit a tungsten target & are reflected off
B. Electrons are “boiled off” of the filament
C. Remaining electrons hit a film/sensor
D. Object of interest blocks electrons
E. A tungsten filament is heated
E, B, A, D, C
- A tungsten filament is heated
- Electrons are “boiled off” of the filament
- Electrons hit a tungsten target & are reflected off
- Object of interest blocks electrons
- Remaining electrons hit a film/sensor
Describe the basic concept of contrast radiography
Technique using a “contrast” (aka dye) to bring out the details in a radiographic image by giving contrast to a structure in question.
What does the term “echogenicity” refer to?
This term describes how a tissue/object/etc appears when examined via Ultrasound
- Hyperechoic = bright
- Hypoechoic = dim
- Echogenic = any tissue
- Anechoic = fluid, air
What is the specific term for image “density” in a CT scan?
“Attenuation”
What does a HIGH attenuation look like on CT scan?
LOW attenuation?
High = white
Low = black
List four advantages of CT scanning
- Rapid
- Low cost
- Readily available
- Great resolution (~1500x greater than XRay)
List four disadvantages of CT scanning
- Patient’s pathology may change from the time the scan was taken
- Volume averaging
- Radiation risk from multiple scans
- Equipment is expensive to procure
List four advantages of MRI scanning
- No radiation
- Rapid
- Low cost
- Generally available
List four disadvantages of MRI scanning
- Changing Pathology
- Potential for claustrophobia
- Metal in/on patient
- Magnetic Field and Radio Frequency cause interference and create inaccurate images