Random Flashcards
Non-ionic contrast media has an average osmolality _______
750 mOsm/kg of water
What are some types of non-ionic contrast?
- iopamidol (Isovue)
- lohexol (omnipaque)
- Iopromide (ultravist)
True/false
Patient does can be reduced by using a technique termed partial scam or half scan which reduces the total rotation of the X-ray tube.
True
The use of partial scan or half scan technique allows the technologist to reduce the total rotation of the x-ray tube, reducing the scan time and subsequently the patient dose
The total quantity of radiation dose received by the patient from a CT scan series is termed _______
MSAD
Platelets are small cell fragments responsible for the clotting of blood. The normal range for an adult is between _______
150,000 to 400,000 platelets/mm 3 of blood
When a patient suffers from an a. Cardiac event CPR must be administered within a maximum of ___ minutes to avoid the risk of brain damage.
4
Iodine is commonly used in radiopaque contrast media because of its ____________
High atomic number
Iodine’s high atomic number causes it to attenuate a large portion of the primary beam. Introducing iodine into tissue changes the subject contrast of the enhanced atomic area.
Iodine is commonly used in radiopaque contrast media because of its ____________
High atomic number
Iodine’s high atomic number causes it to attenuate a large portion of the primary beam. Introducing iodine into tissue changes the subject contrast of the enhanced atomic area.
What are enteric precautions protecting against?
They protect against The spread of infection to indirect or direct contact with fecal matter. The use of gowns and gloves are included in enteric precaution a mask is not necessary
Benadryl is also known as
Diphenhydramine
Insufficient volume of circulating blood causes
Hypovolemic shock
Common S/S of hypovolemic shock
Pallor
HypOTension
Tachycardia
Oliguria
Mild reactions to IV contrast include
Nausea/vomiting
Mild urticaria
Warm flushed sensation
refers to the relationship between the x-ray tube and detectors during scout pictures
azimuth setting
0degree- ap or pa
Quantitive CT is moved used for the diagnosis of
osteoporosis
condition of excessive nitrogenous waste in the blood
azotemia
the adult spinal cords ends at about
L1-L2
IV contrast is usually excreted from a PT w normal kidney function in
1-2 hours
the average density in Hounsfield units of a renal cyst should be between
-20 to +20 Hounsfield unit
This specialized technique incorporates narrow section widths and a high-resolution algorithm for image reconstruction
high-resolution CT
What types of detectors are used in CT
scintillation
gas ionization
hemorrhage that occurs between the skull and the outermost meningeal covering of the brain (dura mater)
epidural hematoma
occur between the dura mater and the meninges
arachnoid hematoma
inner most layer of the meninges
pia mater
what is complete cardiac diastole?
period of relaxation of the heart; ventricular and atrial diastole (relaxation) indicated by T wave on ECG
where is the thymus gland located
anterosuperior portion of the mediastinum and is easily visible in patients before puberty
what is a hybrid array?
narrow detector positioned midline flanked by wider detectors
MSAD
multiple scan average dose
calculation of the avg cumulative dose to each section within an acquisition of multiple sections
sensitivity is also known as
contrast resolution
The total length of a CT scan may be calculated by
multiplying the scan time by the aperture size
avg density of a renal cyst
-20 to +20 hounsfield units
protect you from the spread of infection through indirect or direct contact with fecal matter
Enteric precautions
Gas accumulating within a degenerating intervertebral disk is termed
Vacuum phenomenon
Parenteral routes of medication administration include:
intramuscular, intravenous, intradermal, and subcutaneous.
Strict isolation precautions
refers to the precautions used with patients at risk of infection. This type of precaution technique was once referred to as protective or reverse isolation.
Which generation of scanners employ multi-row detector technology?
3rd gen
A CT examination of the liver shows an abnormal finding of reduced density what is it probably
fatty infiltrate
The CT technologist controls the energy level of x-ray photons by selecting the appropriate
tube voltage
A CT examination of a female pelvis reveals ascites present in an area posterior to the uterus and ovaries known as…
the cul-de-sac
Which cranial nerve would an acoustic neuroma be found?
8th
Area of the tube which allows the xray beam to pass through
Tube window
Increase in avg energy if the xray beam as it penetrates tissue
Beam hardening
How do you find slice thickness
Xray beam thickness/number of slices
What type of image noise can be most easily reduced by the tech?
quantum noise
The detectors of a PET system absorb and measure what type of radiation?
annihilation photons
the broadening of the slice sensitivity profile inherent to helical CT acquisition is said to negatively affect
longitudinal spatial resolution
describes the degree to which pt movement during volumetric acquisition can negatively affect image detail
longitudinal spatial resolution
a voxel’s dimension may be decreased by
decreasing the section width
names commonly given to high spatial frequency algorithms
bone, edge, detail
what composes the C.O.W.
anterior cerebral anterior communicating internal carotid posterior cerebral posterior communicating arteries
full width at half maximum of a slice sensitivity profile diagram indicates
effective section width
the ability of an object to attenuate the x-ray beam is assigned a value known as the
linear attenuation coefficient
in MSCT, the beam pitch is equal to the table feed per rotation divided by the
total collimation
The definition of absorption efficiency is
the percent of x-rays entering the chamber which collide with the detector atoms
An artifact from a faulty detector would appear on a localizer image as
A black line throughout the image, parallel to the long axis of the patient table
The CT image of the brain exhibiting a cupping artifact will appear brighter
At the periphery of the brain
The direction in which the streaks from the edge gradient effect eminate in what orientation from the structure being imaged?
Parallel to the direction of the sharp density difference interface.
the excretory phase of renal contrast enhancement occurs at approx
3-5 minutes
In PTs who are left dominant, the posterior descending artery branches from the
left circumflex artery
the process by which electrons are produced at the cathode of a CT x-ray tube is known as
thermionic emission
forumla for pixel dimension
DFOV/matrix size
Each 1% in contrast between adjacent objects amounts to a difference in pixel value of approx
10 HU
the early arterial phase of hepatic contrast enhancement occurs at approx
15-20 seconds
When choosing a window to display a CT image, the width defines the
range of CT numbers (pixels) to be displayed
what type of reconstruction was used in the first prototype CT scanner
iterative technique
Why is it recommended that data acquisition for a CTA of the pulmonary arteries be performed in the caudocephalad direction?
less streaking artifact from dense contrast in the superior vena cava
the equilibrium phase of hepatic contrast enhancement occurs at approx
120-180 seconds
CT images that have been reconstructed from a portion of the data acquisition process in the hopes of reducing PT motion artifacts are called
segmented images
the articulation between the distal tibia and fibula is called the
syndesmosis
the left and right brachiocephalic veins originate from
the superior vena cava
MRP images along the long axis of the optic nerve would be best described by what plane?
oblique sagittal
Which layer of the uterine wall brightly enhances after IV administration of an iodinated contrast agent?
myometrium
Prospectively gated cardiac CT data acquisition occurs only during the portion of the ECG termed the
T wave
ability of a fluid to flow
viscosity
systemic hypertension often leading to cerebral ischemia
vasovagal reaction
areas of a CT image containing abrupt changes in tissue density are electronically represented by
high spatial frequencies
Which phase of IV contrast provides the best gastric and intestinal wall enhancement?
portal venous
degree of CT section broadening that occurs along the z-axis during volumetric data acquisition is represented graphically by the
SSP
slice sensitivity profile
the liver has a dual blood supply and receives 25% of its blood from the
hepatic artery
75% portal vein
beam pitch is equal to
table feed per rotation divided by total collimation
areas of a CT image containing abrupt changes in tissue density are electronically represented by
high spatial frequencies
