Week 1: Intro, Power injector and communication Flashcards
Limitations of general radiography
- Superimposition
- Unable to distinguish between 2 similar tissues
Advantages of CT
- Eliminate Superimposition
- Differentiate small differences - Image Quality
Window Setting for the Brain
WW= 100, WL=30
Window Setting for Soft Tissue
WW: 350-500, WL: 50
Window Setting for the Lungs
WW= 1500, WL= -600
Window Setting for the Liver
WW= 150, WL=30-70
Window Setting for Pelvic Bone
WW= 1800-2000, WL=400-600
What does the number of pixels do
determines the resolution of the image by being signed a number
What does more pixels do to a CT image?
gives higher resolution and better image quality
How is depth of an image determined
by slice thickness
How is a voxel determined
by the pixel area and slice thickness
What does a Voxel Represent
a volume of tissue within the patient
What does Siemans call preliminary image (Scout, tomogram etc)
Topogram
What does GE call preliminary image (Scout, tomogram etc)
Scout
What does Toshiba call preliminary image (Scout, tomogram etc)
Scanogram
Common matrix size
512
ipsilateral
on the same side
Rostral
towards the nose
contralateral
on the opposite side
thenar
the fleshy part of the hand at the base of the thumb
volar
pertaining to the palm of the hand or the flexor surface of the wrist or sole of the foot
Why do we use a power injector
- faster injection time (better contrast enhancement)
-large bolus injections (single large quantity) - delivery of precise flow rates
- consistent and easily reproducible injection
- programmable
- can be used for many indications
control panel of power injector
displays injection parameters (flow rate, rise, total volume, pressure and delay)
power injector syringe
sterile, removable, varying capacities available, can be both reusable and disposable
heating device of power injector
thermal sleeve placed over syringe set to 37 degrees. reduces viscosity of contrast and maintains temperature of preheated contrast medium.
flow rate
- rate contrast injected
- measured is cc/sec or ml/sec
factors affecting flow rate
procedure, vessel, pt type, nature of disease, viscosity of contrast medium (determined by heat or iodine content), catheter, injection pressure
total volume
-amount of contrast to be delivered
- flow rate x injection duration (V = cc/sec or ml/sec x sec)
- measured in cubic centimetres
rise (linear rise)
time it takes to reach desired flow rate, measured in seconds
injection pressure
- force needed for specific dose of contrast medium
- measured in pounds per square inch (psi), range is 100-1200psi
- dependent on size of vascular structure and type of catheter
delay
injection delay: allows for image acquisition to begin before contrast injection. useful in angiography imaging.
xray delay: injection of contrast begins before the acquisition of images. useful in lower extremity arteriography
