CT My registry review missed questions

Common kV ranges?

70-150 kV

What is ADC?

• conversion of data into digital values

  • Determines grayscale resolution

What plane parallel to metatarsals of foot?

oblique axial

Convulution

Removes blurring in image during back projection

Why prone for CT urinary tract?

Differentiate b/w stones and urinary tract

True or false: Gantry rotation affects contrast resolution

False

T or F: CYST is a indicator for renal arteries?

False

Whole body dose?

Effective dose

Slice thickness for CT Chest High Res?

>1mm

Major blood supply for liver? and minor

Portal vein 75% and hepatic artery 25%

5 parts of circle of willis?

1. Anterior cerebral arteries

2. Posterior cerebral arteries

3. Anterior communicating artery

4. Posterior communicating artery

5. Internal carotid arteries

What exam may require full expiration?

CT chest high resolution

Define: Spondylolysis

fx of pars interarticularis

Define: Spondylolisthesis

vertebra slipping out

Define: Spondlyosis

Hypertrophy of facet of a vertebra

Define: High Spatial frequency

objects w/ high variations in density

What does multi-segmental reconstruction impact?

Temporal resolution

What does atrial systole represent?

P wave and contractions of Left and Right atria

What does ventricular systole represent?

QRS wave and contraction of LEFT and RIGHT VENTRICLES

What is complete cardiac distole?

T WAVE and ventricular and atrial diastole.

Clinical indication for CT chest high res?

Bronchiectasis

Gantry angle for CT head?

Parallel to IOML

CTA runoff clinical indication

claudification

What can Iterative recon do to noise?

decreased noise

What level is Superior Mesenteric artery? (SMA)

L1

BUN values

8-22 mg/dL

Creatinine values

0.6- 1.2 mg/dL

PT values

11-16 sec

PTT values

25-38 sec

INR values

0.8-1.2

Platelet count values

150k-350k

absorbed dose unit of measurement? SI and conventional

Gray and RAD

Effective dose unit. SI and conventional

Sievert and REM

Unit of exposure

Roentgen or R

What is ability of a scanner to differentiate b/w small differences closely spaced objects?

Contrast resolution

What line for CT Orbit?

Parallel to IOML

What is parenteral route?

Any non-oral method of administrationP

How does patient motion appear?

Blurring, streaks, misregistration and step artifact

What level does spinal cord end?

L1 and L2

Biforcation of abdominal aorta level?

L4

Fly - through imaging is used in?

VR

Scan parameters for a skull?

through skull base and posterior fossa

Thymus is located in mediastinum. True or False

False

What is FWHM and what does it measure?

Full Width at Half Maximum… Effective section width

What phase of cardiac cycle is used in prospective gating?

R-R interval and 55-75%

How much contrast for CTA neck?

70mL

Define Gerota’s fascia

Connective tissue that surrounds kidneys

Where does Carina Bifucate?

T4

What level is Carina?

T4-T5

What type of contrast is used for CT enterography?

Neutral Oral

What factors effect temporal resolution

Rotation speed and Half scan

Common slice thickness for C-spines?

1mm

Where does saline flush reduce streaking in?

Superior Vena Cava

Slice thickness for CT neck is?

1-2mm

What homogenous mass b/w bladder and rectum has 3 layers?

Uterus

What angle to tilt gantry for CT neck?

Parallel to hard palate

Common slice size for lumbar?

2-5mm

Connective tissue that surrounds kidneys?

Gerotas fascia

Delay for CT Pancreas?

35-45 sec

Typical delay for CTA Brain?

15-20 sec

MTF Graph represents what?

Spatial resolution

A/P slice thickness?

2-5mm S

Slice thickness for CT head?

2-5mm

Total exposure w/ scan length consideration?

DLP

How can partial volume averaging be compensated?

Use of film and overlapping slices

Cone beam exposes?

entire row of detectors evenly

CT sinus images require what type of view?

Direct Coronal images

What contrast phase begins after 3 minutes?

Excretory

Adjusting voxels utilize what type of recon?

Retrospective

3 major sources of noise?

1. Quantum mottle 2. Component limitations 3. Recon algorithm

Partial volume averaging can be compensated by?

Acquiring thinner sections

Contrast amount for CTA brain?

60mL

What is the whipple procedure?

Resection of pancreas and duodenum

Delay for Enterography?

40-50 sec

What axis controls SFOV?

X and Y axis

What ensures beam falls on entire multirow of detector array?

Precollimator and helps determine slice thickness and beam width

Normal BUN/Creatinine ratio?

6:1 to 22:1

Beam width in longitudinal axis?

Z axis

Area has similar densities…utilize wide or narrow WW?

Narrow WW

valsalva maneuver during CT neck can distend?

Pyriform Sinuses

How to positively impact contrast resolution?

Increase scan time…Increase photon flux…decrease noise

3 jobs of Data Acquisition System.

1. measure the transmitted radiation 2. convert the measurements into binary data 3. Transmitting the binary data to the PC

What is mean transit time?

average time for blood to pass a given area

Normal PT range?

12-15sec

How is mA and KV calculated for AEC?

Scount images

Disorder linked to CFTR gene on 7th chromosome?

Cystic Fibrosis

When does equilibrium phase take place?

2-3 minutes

BPM for adults?

60-100

Shading relates to?

determining the appearance of 3D image

What happens after reformation of raw data?

detector undergoes convulation

ADC job?

Converts data into digital values and determines grayscale resolution

What can increase risk of adverse reactions of contrast?

Asthma, pheochromocytoma, multiple myeloma

Most common gantry aperature size?

70cm

How does COPD present?

Thickening of bronchial wall, air trapping and narrowing of trachea

As area of interest Decrease..What happens to spatial frequency?

Spatial freq increases.

What adds color, lighting and texture?

Rendering

What slice size to display ILD?

10-15mm

MSCT is effective b/c?

obtain images that are isotropic

Formula for PITCH?

Tablemovement (lp/mm) / 1 revolution

slice thickness for CT head?

2-5mm