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183 Cards in this Set
- Front
- Back
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The measurement of the scanner’s performance through quality testing procedures and evaluation of the test results |
Quality Assurance |
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Two most frequently used standards for quality assurance assessment |
CT number calibration test and CT number standard deviation test |
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What are the acceptable limits for CT number calibration |
+/- 3 HU |
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If the measured value is not within the limits for the CT number calibration test, what must happen? |
The scanner must be recalibrated |
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Daily checks for quality assurance are usually carried out by who |
The technologist |
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Monthly checks for quality assurance are usually done by who |
The engineer |
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What type of tests would the engineer do on the scanner |
software upgrades, calibration, preventative maintenance |
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Annual checks for quality assurance are carried out by who |
The physicist |
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Phantoms of standardized human shape or test objects of a particular shape, size and structure used to help evaluate the performance of scanners |
test phantoms |
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What is the CT number of water |
0 |
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Concerns the linear relationship between the calculated CT number and the linear attenuation coefficient of each element of the object. |
Linearity |
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Relates to the requirements for the CT number of each pixel in the image of a homogeneous object to be the same within narrow limits over various regions of the object. |
Uniformity |
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the local statistical fluctuation in the CT numbers of individual picture elements of a homogeneous ROI. |
Image Noise |
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determines the minimum size of detail visualized in the plane of the slice |
Spatial resolution |
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How do you evaluate the accuracy of the position of the patient couch |
by moving the loaded couch a defined distance relative to the gantry and subsequently moving it back to the start position |
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specify the types of information that patients must be given so that they can make an informed decision about having medical care, diagnostic studies or treatment |
Informed consent |
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In order for consent to be valid, what two thing must there be |
1. patient must be considered competent to make the decision 2. The decision must be voluntary |
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What happens if the patient refuses the treatment |
the procedure should be terminated |
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What does HIPAA stand for |
Health Insurance Portability and Accountability Act |
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protects an individual's personal and health information that is created, maintained, filed, used or shared. |
HIPAA |
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What does PHI stand for |
Protected Health Information |
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What does PHI include |
a person’s name, address, birth date, age, phone number, email address, medical records, diagnosis, x-rays, photos, prescriptions, lab and test results, billing records, claim data, and referral authorizations. |
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What should be done if there is a discrepancy between what is on the order and what the patient says |
NEVER take it upon yourself to decide what should be scanned, ALWAYS check with the ordering physician and radiologist. |
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When is the only time a CT scan will be performed on a pregnant patient |
If the benefit outweighs the risk |
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X-rays can penetrate tissues and cause damage to the body in what two ways |
1. By breaking electron bonds and forming ion pairs in tissue when passing through the body. 2. Photons can cause damage by directly disrupting the DNA bonds within the nuclei of cells |
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most common form of measuring radiation |
RAD: Radiation Absorbed Dose |
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1 Gy = ? Rads |
100 rads |
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Typical skin radiation dose for a head CT is |
1-5 rads |
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Typical skin radiation dose for a body CT is |
2-6 rads |
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Typical skin radiation dose for a CT localizer is |
0.005 - .1 rads |
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What is CTDI? |
CT Dose Index |
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an indicator of radiation dose which includes radiation located within the intended slice thickness |
CTDI |
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What is MSAD |
Multiple Slice Average |
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an indicator of radiation dose which corrects the CTDI by factoring in gaps or overlaps between the slices or helices due to the selected table increments or pitch |
MSAD |
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help to differentiate adjacent anatomical structures and delineate abnormalities |
Contrast Media |
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What are the four categories of contrast agents |
1. Intravenous 2. Intrathecal 3. Intra-articular 4. Oral |
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Contrast is injected directly into the bloodstream |
Intravenous |
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Agents injected into the spinal subarachnoid space during a myelogram |
Intrathecal |
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Agents are injected into the joint space to allow better visualization of the joint |
Intra-articular |
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Contrast agents usually swallowed by the patient in order to better visualize the GI tract |
Oral |
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Which type of contrast agent will best help differentiate organs from intenstines |
Oral contrast agents |
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Intravenous contrast media contains what to help increase the attenuation of x-ray photons |
Iodine |
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The contrast that is perfused through the tissues will appear |
White |
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Examples of some intravenous contrast is |
isovue, omnipaque, optiray |
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Each molecule of ionic or non ionic contrast contains how many iodine atoms |
three |
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Non-Salt chemical compounds that also contain three atoms of iodine |
Non ionic contrast |
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Salt consisting of sodium and or meglumine with three iodine atoms |
Ionic contrast |
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The propensity of an iodinated contrast medium to cause fluid from outside the blood vessel to move into the bloodstream |
Osmolality |
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What are the 2 Groups of IV Contrast based on osmolality |
1. LOCM- Low osmolar contrast medium or 2. HOCM- High osmolar contrast medium |
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What type of IV contrast solutions will cause a net movement of water from within the tissue into the vascular space |
Hypertonic |
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Is non- ionic contrast media is considered a low osmolar contrast medium or high osmolar contrast medium |
Low osmolar contrast medium (LOCM) |
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What type of contrast medium osmolality is better tolerated by patients |
Low osmolar contrast medium |
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All ionic contrasts are considered what type of osmolar contrast mediums |
High osmolar contrast mediums (HOCM) |
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The measure of the thickness of the liquid |
Viscosity |
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Routine Transit time for Water Soluble iodinated contrast |
30-90 minutes |
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may NOT be used in cases suspected for perforation because it can be toxic to the peritoneum |
Barium Sulfate |
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What are examples of negative contrast agents |
Air, water, CO2, effervescent granules(fizzies) |
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What are some advantages of using air as a contrast medium |
1. Increased palatability and improved patient comfort 2. Better demonstration of the enhancing bowel wall 3. Does not interfere with 3D applications |
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when swallowed they add negative contrast in the form of gas to the stomach and proximal small bowel allowing for better visualization of the structures |
Effervescent Granules |
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Reactions that last briefly, tend to cause minor discomfort and generally do not require treatment |
Minor reactions |
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What are some examples of minor reactions |
Nausea, Chills, Vomiting, Itching, Headache, Sweating |
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more serious reaction, may require treatment |
Moderate reactions |
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What are some examples of moderate reactions |
Moderate Hives, Change in pulse rate, Hypo/hypertension, Laryngospasm, Wheezing, Bronchospasm, Facial Edema |
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How can you minimize reactions |
Use non-ionic contrast, Warming the contrast to reduce viscosity , or Pre-Medicate patients with an anti-histamine and or steroid |
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These lab values are used to indicate renal function |
Blood Urea Nitrogen (BUN) and Creatinine |
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the rate by which creatinine is filtered from the blood stream. It is calculated using the patient’s creatinine level, age, sex and race. |
Glomerular Filtration Rate (GFR) |
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A normal BUN is |
7-25 mg/dl |
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A normal Creatinine is |
0.5 to 1.5 mg/dl |
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At what level for the GFR is it OK to inject |
GFR of 60 or above |
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What must you do if the patient's GFR is between 30 and 60 |
Must get rad approval to inject contrast |
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At what GFR level do you not inject unless the patient is on dialysis |
GFR of 30 or below |
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measure of blood coagulation |
Prothrombin Time (PT) |
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Normal Prothrombin Time (PT) is |
12 to 15 seconds |
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detects abnormalities in blood clotting ability |
Partial Thromboplastin Time (PTT) |
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Normal Partial Thromboplastin Time (PTT) is |
25 to 35 seconds |
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during venipuncture, these veins should only be used if there is a lack of venous access to the vessels at the elbow, or cubital fossa. |
veins in the hand |
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If you have to use the vein in the hands during venipuncture, what adjustments must be made |
a smaller catheter must be used (22 g) and a slower rate must be used (1.5 ml/s). |
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The injection should be monitored for at least how many seconds |
10-15 seconds |
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The infiltration of the contrast agent outside the blood vessel |
Extravasation |
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what are the 3 separate enhancement phases of tissue enhancement as the contrast passes through the circulatory system |
1. Bolus Phase 2. Non- Equilibrium Phase 3. Equilibrium Phase |
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When does the Bolus Phase of tissue enhancement begin |
just after the contrast is injected |
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What is the first phase of tissue enhancement by contrast |
Bolus Phase |
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During this phase the bolus moves through the arteries and away from the heart. |
Bolus Phase |
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phase of tissue enhancement by contrast that follows the bolus phase |
Non- Equilibrium Phase |
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The contrast starts to disburse into the capillaries and then into the veins during this phase of tissue enhancement |
Non- Equilibrium Phase |
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Final phase of tissue enhancement by contrast |
Equilibrium Phase |
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The agent’s concentration in the veins becomes similar to the concentration in the arteries and the difference in soft tissue structures becomes diminished during this phase of tissue enhancement |
Equilibrium Phase |
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How long after the start of contrast to the liver is the hepatic Artery Phase |
20 to 40 seconds |
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How long after the start of contrast to the liver is the Portal Venous Phase |
60 to 90 Seconds |
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Why would contrast be used for a head CT |
to enhance certain structure - structures which are highly vascularized appear more dense following the administration of contrast |
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Why would contrast be used for a neck CT |
IV contrast allows for the differentiation of blood vessels and lymph node |
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why would contrast be used for a chest CT |
evaluation of masses, lymphoma, hilar or cardiac masses, to visualize the vessels |
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What type of CT exams would require IV and oral contrast |
Abdomen and pelvis CT exams |
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Performed to differentiate liver lesions with arterial blood supplies from those with venous blood supplies |
Bi-phasic liver exam |
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What are some clinical indications for a head CT scan |
evaluations of trauma, stroke, headaches, tumors, congenital abnormalities, hydrocephalus, metastatic lesions, endocrine pathology, bony abnormalities, contraindication for MRI |
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When would you use contrast for a head CT |
arteriovenous malformation, suspected neoplasm, attention to the pituitary gland, to indicate a disruption of the blood brain barrier |
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When do you never use contrast for a head CT |
trauma cases |
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What is the patient position for a head CT |
head first, supine |
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What should you do on a head CT to avoid radiation to the orbits and dental fillings |
angle 15 degrees above the IOML |
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How thick are the axial slices for a head CT |
5mm slices |
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What kVP is used for head CT |
120-140 kVp |
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How much mAs is used for a head CT |
300 mAs |
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What would you use for your WW and WL on a standard soft tissue algorithm for a head CT |
WW of 100, WL of 35 |
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What would you use for your WW and WL on a bone algorithm for a head CT |
WW of 3,000, WL of 400 |
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How much of a delay is there if a head CT is performed with contrast |
5 minute delay |
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If a head CT is performed with contrast, how much do you use and at what rate is it administered |
100 mL of contrast at 2-3 mL/sec |
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What are the clinical indications for a CT of the orbits |
trauma, foreign body, mass, visual disturbances, swelling, cellulitis |
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When would you use contrast for a CT exam of the orbits |
used for suspected mass/visual disturbances, swelling (not from trauma), abscess, cellulitis |
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What is the patient position for a orbital CT |
head first, supine |
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For a CT image of the orbits, axial images are acquired between what landmarks |
parallel to the IOML, collected from the top of the maxillary sinus through the upper orbital rim |
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For a CT image of the orbits, coronal slices extend from what two structures |
from the sphenoid sinus to the anterior globe |
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The standard/ soft tissue algorithm used for a orbital CT is |
WW of 400, WL of 40 |
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The bone algorithm used for a CT exam of the orbits is |
WW of 3,000 , WL of 400 |
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What are the clinical indications for a CT of the sinuses |
sinusitis, mass, headache |
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When would contrast be used in a sinus CT |
for a suspected neoplasm |
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For a sinus CT, axial images are acquired from what two landmarks |
parallel to the hard palate through the superior aspect of the frontal sinuses |
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For a sinus CT, coronal reformats extend between what two structures |
from the dorsum sella through the anterior aspect of the frontal sinus |
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The standard/soft tissue algorithm used for a sinus CT is |
WW: 400 , WL: 40 |
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The bone algorithm used for a sinus CT is |
WW: 3,000 WL: 400 |
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How thick are the slices for a sinus CT |
3mm slices |
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What are the clinical indications for a CT of the facial bones |
trauma, mass, swelling, abscess, cellulites |
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When would contrast be used for a CT of the facial bones |
abscess, swelling, cellulitis |
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What is the patient position for a CT of the facial bones |
head first, supine |
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Axial slices of the facial bones are taken through what structure for a facial bone CT |
through the superior aspects of the cranium |
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How thick are the slices for a CT of the facial bones |
0.5- 3mm slices |
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What WW and WL would be used for the standard/soft tissue algorithm for a CT of the facial bones |
WW of 400, WL of 40 |
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What WW and WL would be used for the bone algorithm for a CT of the facial bones |
WW of 3,000 , WL of 400 |
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What are the clinical indications for a CT scan of the pituitary |
adenomas, or when a patient cannot have an MRI |
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When would you use contrast for a CT scan of the pituitary |
Almost always use contrast |
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patient position for a CT scan of the pituitary |
head first, supine |
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Axial slices for a CT scan of the pituitary extend from what structures |
From the roof of the sphenoid sinus through the dorsum sella |
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Coronal slices for a CT scan of the pituitary extend from what structures |
extends from the anterior clinoid to the dorsum sella |
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How thick are the slices for a CT of the pituitary |
0.5 to 2 mm |
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What WW and WL would be used for the standard/soft tissue algorithm for a CT of the pituitary |
WW of 200 , WL of 50 |
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What WW and WL would be used for the bone algorithm for a CT of the pituitary |
WW of 2500, WL of 300 |
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When is CT preferred for an exam of the tempmandibular joints |
trauma or bony erosion |
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What is the patient position for a CT exam of the temporomandibular joints |
head first, supine |
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How thick are the slices for a CT of the TemporoMandibular Joints |
2mm |
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What WW and WL would be used for the standard/soft tissue algorithm for a CT of the TMJ |
WW of 180, WL of 40 |
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What WW and WL would be used for the bone algorithm for a CT of the TMJ |
WW of 2500 , WL of 300 |
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Cerebral aneurysms are present in what percent of the general populations |
5% |
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What is the main concern with aneurysms |
risk of rupture |
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Ruptured aneurysms result in about what percent mortality |
30-40% |
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Second leading cause of death in the United States |
Cerebral vascular disease |
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Most common cause of permanent disability in the U.S |
Cerebral vascular disease |
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What is administered if the patient shows signs of a stroke |
tPA- tissue plasminogen activator |
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tPa needs to be given within how many hours of the onset of symptoms of a stroke |
within the first three hours |
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The CT scan needs to be performed within how many minutes after the tPa is administered |
within 20 minutes |
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CTAs of the brain are used to identify and evaluate what |
Aneurysms, Intracranial thrombosis, Traumatic Cerebrovascular injury, Arteriovenous malformation, or Stenosis |
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monitors vessel opacification during contrast administration and automatically begins the scan once a predetermined HU value of attenuation w/in the target vessels is reached |
Automatic Triggering or bolus tracking software |
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How much contrast is used for CTAs of the circle of willis |
50-75 mL @ a rate of 3-5 mL/sec |
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What are the clinical indications for a CT soft tissue neck |
evaluation of tumors, inflammation, infection, developmental anomalies, lymphadenopathy |
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When would contrast be used in a CT soft tissue neck |
Almost always performed with IV contrast |
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why is contrast always used when performing a CT scan on the soft tissue neck |
helps to differentiate blood vessels and vascular tumors from lymph nodes |
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How much contrast is used and at what rate for a CT soft tissue neck |
75 mL of contrast @ 2-3mL/sec |
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What is the delay for a CT scan of the soft tissue neck with contrast |
30 second delay |
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Why is there a delay for a CT scan of the soft tissue neck with contrast |
the lymph nodes to not enhance immediately |
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What is the patient position for a soft tissue neck CT scan |
head first, supine |
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What WW and WL would be used for the standard/soft tissue algorithm for a CT of the soft tissue neck |
WW of 300, WL of 40 |
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CTA Neck is used to show what structures |
Carotids |
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For a CTA of the carotids, what is the patient position? |
head first, supine |
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What is included in the CTA of the carotids |
Includes from the aortic arch to the base of the skull |
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How much contrast is used to view the carotids and at what rate |
75 mL @ 3-5 mL/sec |
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How thick are the slices to visualize the carotids during a CTA |
0.5- 1.5 mL |
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Why are CT exams of the spine usually performed |
to evaluate trauma, intra-spinal tumors, disk herniation, spinal infection, spinal stenosis, metastatic disease, and fractures |
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Usually soft tissue concerns of the spine are sent where |
to MRI |
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Where would an exam of the entire spinal column most likely be taken |
X-ray |
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Why isn't it practical to perform a CT exam of the entire spinal column |
CT is rarely used for surgery studies and has a much higher dose than x-ray |
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How is the patient positioned for a CT exam of the cervical spine |
Head first and supine, Patient’s arms should be down by their side, and Shoulder’s should be lowered as much as possible |
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Why is an AP localizer used for CT images of the spine |
to make sure the spine is straight |
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Why is a lateral localizer taken when performing a CT of the spine |
allows the tech to adjust the angle of the slices to the disk space |
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What is the patient sometimes asked to do during an exam of the spine to minimize motion artifacts |
refrain from breathing and swallowing |
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What mAs is typically used for CT images of the spine |
200- 500 mAs |
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What WW and WL would be used for the standard/soft tissue algorithm for a CT of the cervical, thoracic, or lumbosacral spines |
WW of 300, WL of 40 |
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What WW and WL would be used for the bone algorithm for a CT of the cervical, thoracic, or lumbosacral spines |
WW of 2,000 , WL of 300 |
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What is the patient position for a CT exam of the thoracic spine |
head or feet first, supine |
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What is the patient position for a CT exam of the lumbosacral spine |
head or feet first, supine. Arms over the head or up by the chest and You can also place a wedge under the patient's knees for comfort and to reduce lordosis |
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Typical pediatrics dose for IV contrast |
2mL per kg |
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If you have to use a vein in the hand for venipuncture, what should be changed |
Smaller catheter must be used, and a slower rate must be used |
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At what rate do you inject contrast for routine exams |
2-4 ml/sec |
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At what rate do you inject contrast for routine exams |
2-4 ml/sec |
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At what rate do you inject contrast for CTA exams |
4-6 ml/sec |
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Reaction that occurs due to the total volume of contrast injected and the rate at which it is injected |
Chemotoxic reactions |
