Mosby Random 3 Flashcards
Pixel dimension formula
FOV/matrix size
*remember to convert mm to cm if necessary
Controlling factors of temporal resolution
- gantry rotation speed
- reconstruction method
A voxel’s dimension may be decreased by
Decreasing the section width
Nephrographic phase
Enhancement between renal cortex and medulla reaches equilibrium, providing optimal sensitivity for parenchymal lesions
70-90 seconds after injection
The descending colon is on the ____ side
Left
PTs left; right side on the screen
After injection, the hepatic venous phase of contrast enhancement occurs at approx
60-70 seconds
The hepatic phase is also known as
Portal venous phase
Period of peak hepatic parenchymal enhancements during which contrast material redistributes from the blood into the extravascular spaces
Hepatic venous phase
Broadening of the SSP inherent to helical CT acquisition is said to negatively affect the
Longitudinal spacial resolution
Describes the degree to which PT movement during volumetric acquisition can negatively affect image detail
Longitudinal spatial resolution
Agatston scores
Minimal 1-10
Mild 11-100
Moderate 101-400
Extensive 400+
Each iliac artery bifurcates into the internal a external iliac arteries at about the level of
L5-S1
During a CTA brain, contrast is injected at 3-4 mL/sec, an adequate delay for optimal vessel opacification would be
12-20 seconds
Well opacified ureters indicate what phase
Excretory
What factors affect longitudinal spatial resolution?
Detector collimation
Detector pitch
Interpolation algorithm
An analytic method of CT image recon
Fourier transform method
Iterative methods of CT image recon
- simultaneous
- ray-by-ray correction
- point-by-point correction
In PTs who are right dominant, the posterior descending artery branches from the
Right coronary artery
During a CT scan, each sample of ray sum measurements made by the data acquisition system (DAS) is called a
View
The average CT value for blood is approx
+45 HU
Stanford type B dissecting aneurysms affect
Descending aorta
Stanford type A dissecting aneurysms affect
Ascending aorta
By CT criteria, a solitary pulmonary nodule may be defined as a focal area of increased density in the lung that is smaller than
3 cm
The type of MSCT detector array that contains midline narrow events flanked by wider detectors is called
Hybrid array
For a CTA chest peak pulmonary opacification should occur at approx
20-25 seconds
What it’s the primary interaction between x-ray photons and tissue during CT?
Compton effect
The ability of an object to attenuate the x-ray beam is assigned a value known as the
Linear attenuation coefficient
For MDCT, identified areas of calcium must demonstrate relative attenuation values greater than
+130 HU
How long should a PT pump and dump after contrast when breast feeding?
12-24 hours
The period of the cardiac cycled known as complete cardiac diastole
Relaxation of L & R ventricles
Relaxation of L & R atria
T wave of ECG
PTs whose posterior descending artery branches front the right coronary artery and whose left posterior ventricular branches arise from the left circumflex artery are said to be
Codominant
PTT
Partial thromboplastin time
