CT

Pitch directly relates to:

- patient dose - volume scanned

The range of CT numbers varies frkm

-1000 to +3000

The smaller the scan field size, the

-better resolution -less risk of motion -faster scan time

The CT console provides the radiographer access to

-data display -the software program -data acquisition

In order for CT X-ray to be measured, it must

-enter the detector -be absorbed by the detector material -be converted to electrical energy as a signal

The CT radiation beam is collimated

-pre-patient and post patient -at the tube exit -at the detector entrance

Compared with conventional computed tomography scanners, slip ring scanners offer the following advantages:

-removal of cable wraparound -elimination of start-stop action -continuous rotation of X-ray tube and minimal interscan delays

The computed tomography number for water is?

0

Which of the following pitch ratios is considered to be oversampling?

0.5-1

Calculate pitch for the following parameters: Couch movement of 10 mm/seconds and slice thickness per 360° rotation of 20mm

0.5:1

Approximately ?? of all head CT generally require intravenous contrast media

50% to 90%

An undesirable feature or density in the CT image not representative of anatomy is an:

Artifact

The reduction of the intensity of a beam of xrays as it passes through the patient is:

Attenuation

Which of the following is best used to describe patient dose in computed tomography?

CTDI & MSAD

The slice thickness in computed tomography is ultimately determined by the:

Collimator width

Who shared the Noble Prize in Medicine and Physiology with Hounsfield for his contributions to the computed tomography technique?

Cormack

The detectors convert the attenuation data into ?? signals

Electrical

True or False: The aperture houses the X-ray tube and the detector array

False

True or False: a pitch greater than 1 will result in an increase dose

False

Fourth generation CT scanners are characterized by:

Fan beam geometry and complete rotation of X-ray tube around a stationary ring of detectors

First generation CT scanned the ?? only

Head

The most recent generation of CT scanners use a ?? motion

Helical

A series of tissue density values that evolved for CT measurements are called ?? units

Hounsfield

Who developed the first clinically useful computed tomography scanner?

Hounsfield

The CTDI dose measurement

Is slice-based

The capability to create accurate reconstruction of patient data into alternative planes is termed:

Multiplanar reconstruction

What controls the actual thickness of the CT slices?

Prepatient collimator

Which of the following chest structures would not be located at the level of the jugular notch?

Pulmonary artery

The localization image produced by CT scanner is technically called an

Scanogram

Which generation of CT scanner used a fan beam and a translate-rotate acquisition pattern?

Second

In which of the following data acquisition methods is a volume of tissue scanned during a single breath hold while the couch moves continuously?

Spirical/helical computed tomography

With computed tomography scanner is based on a fan beam geometry and complete rotation of the X-ray tube and detectors?

Third generation scanner

Computed tomography sections are available as

Transverse, sagittal and coronal

True or False: Artifacts caused by patient motion are reduced with volume CT scanning as compared with earlier generation scanners

True

True or False: the number of shades of gray assigned to a CT image can be controlled by the technologist

True

Which material serves as the baseline for CT numbers?

Water

The gantry of the CT until contains the

X-ray tube

CT scan pitch uses all of the following technical parameters EXCEPT

acquisition mAs

What specifically do the CT detectors measure?

attenuation

The most obvious difference between computed tomography and radiography is that:

computed tomography shows cross-sectional images or transaxial anatomy

Sectional images are obtained from all of the following EXCEPT

conventional radiography

As the pitch increases, the image quality:

decreases

The pitch ratio is expressed as:

distance the table travels during 360 degrees/slice thickness

The CT radiographer usually varies the ?? to control the primary beam.

mA

Electromechanical devices made up of rings and brushes to transmit electrical energy across a rotating interface are called:

slip rings

All of the following apply to CT except:

x-ray film is used as the detector