Work CT Flashcards
Through explanation of CT procedure & proper communication with pt is vital in ensuring that:
- breathing instructions are followed.
- misregistration doesnt occur.
- pt anxiety is kept at a minimum.
The lumen of needles used for injection of contrast media varies in diameter. The unit used to describe this diameter is called:
Gauge.
Direct contraindications to contrast material administration includes;
- prior life threatining reaction to contrast material.
- multiple myeloma.
What method is used to verify patient identity?
Check wrist band.
What are the advantages of automatic power injectors over manual bolus method of IV contrast administration?
- Increased tissue enhancement due to faster injection time.
- Uniform contrast administration are entire length of the study.
What interactions b/t x-ray beam and matter result in the largest amount of pt dose?
Photoelectric effect.
Examples of mild adverse reactions to contrast may include:
Nausea and warm flushed sensation.
What CT procedures require a pt to give informed consent?
any invasive procedure
ex: abdomen scan w/ IV contrast.
Medication given to sedate small kids ungoing CT exams:
Chloral hydrate.
Difference b/t ionic and nonionic contrast?
Non-ionic contrast media have a lower osmolality than ionic media.
What term describes an IV injection of medication or contrast agent in one complete dose over a short period of time?
Bolus.
Intrathecal injection before a lumbar spine place iodinated contrast material directly into what?
Subarachnoid space.
Abnormalities of the middle and inner ear may best be demonstrated using CT sections of what? (mm)
1-2mm
Prior to an IV injection of iodinated contrast material, the pt should be question regarding (pick 1 or more answers)
1. renal function.
2. allergic history.
3. cardiac history.
1, 2, and 3.
What is used to determine the biologic effect of IV contrast media, what term refers to the # of ions formed when a substance dissociates in solution?
Osmolality or osmotic concentration
- described as # of particles in solution per kilogram of water.
What laboratory values can be used to evaluated the renal function of the pt?
Blood Urea Nitrogen (BUN) and Creatinine.
What infection is acquired by a pt during their stay in a health care institution?
Nosocomial.
During CT exams, pts should be shielded above + below b/c of what?
Rotational nature of xray tube cause pt to get exposure from all sides.
Which of the following would be best suited for IV injection of contrast material with a power injection?
A. Butterfly needle.
B. Central venous line.
C. 23-gauage spinal needle.
D. Angiocatheter.
D. Angiocatheter.
What contrast material may be described as one that does not dissociate into charged particles in solution?
Non-ionic.
What technical factors exhibits a direct effect on pt dose?
Milliampere-seconds (mAs).
Which of the following injection control techniques is required at the site of an IV injection of iodinated contrast media?
A. Contact isloation.
B. Surgical asepsis.
C. Medical asepsis.
D. Enteric precuations
B. Surgical asepsis.
Retrospective image reconstruction facts
- algorithm, matrix size, and DFOV may be changed.
- scan (raw) data must be available.
- restrospective image recon may be used to adjust center of displayed image.
spiral resolution of a CT exam using the following parameters? Large focal spot, 10 mm sections, 512x512 mm matrix?
- change focal spot size.
- perform 5 mm sections.
What reduces scatter radiation reaching the detecors?
Post-patient & predetector collimation
What mathematical techniques used exclusively for image recon with spiral CT scanners?
Interpolation.
Pixles whose average coefficients are less than that of water have what types of CT # value?
NEGATIVE.
What technical parameters would greatly improve the quality of studies requiring multiplanar reformats?
Overlapping scans with narrow section thickness.
Quality control measurements to test accuracy and calibration of scanner should be performed?
Daily.
When an operator reduces the SFOV for a particular body part, what technical changes occur?
Smaller # detectors are activated.
Average CT # for blood is:
+45 HU.
What type of gas is commonly used for gas ionization CT detectors?
Edge gradient
PT collimation fact
Prepatient colimation directly controls slice thickness.
Increasing the pitch during a spiral CT exam adversely affects the spatial resolution along with:
Z-axis.
Simple cysts of the kidney have average attenuation values in the range of:
0 to 20 HU.
