Chapter 04: Data Acquisition Concepts

Which of the following refers to a method by which the patient is systematically scanned by the X-ray tube and detectors to collect enough information for image reconstruction?

a. Beam geometry

b. Data acquisition

c. Sampling

d. Projection reconstruction

b. Data acquisition

Which of the following refers to the size, shape, motion, and path traced by the X-ray beam as it scans the patient?

a. Beam geometry

b. Projection profile

c. Data acquisition

d. Detector tracing

a. Beam geometry

A single ray in computed tomography (CT) is:

a. a beam of X-rays emanating from the X-ray tube.

b. a single straight line path of an X-ray beam.

c. the total attenuation as measured by the detector.

d. a collection of beams gathered by the detector.

b. a single straight line path of an X-ray beam.

A view in CT is:

a. a specific way in which the patient is positioned with respect to the detectors.

b. the total attenuation as measured by the detector.

c. a collection of rays for one translation across the object.

d. a single straight line path of an X-ray beam.

c. a collection of rays for one translation across the object.

CT detectors generate a signal that represents the attenuation as the ray moves across the slice. This signal is called:

a. a view sample.

b. an acquisition sample.

c. a profile.

d. a data sample.

c. a profile.

The total number of data samples per scan or per slice in CT is the:

a. number of data samples per view times the number of views.

b. number of views.

c. number of detectors plus the number of data samples per detector.

d. number of data samples per view plus the number of views.

a. number of data samples per view times the number of views.

Which CT scanner is based on a fan-beam geometry and complete rotation of the X-ray tube and detectors?

a. First-generation scanner

b. Second-generation scanner

c. Third-generation scanner

d. Fourth-generation scanner

c. Third-generation scanner

Fourth-generation CT scanners are characterized by:

a. rotate-translate motion and parallel beam geometry.

b. rotate-translate motion and fan-beam geometry.

c. fan-beam geometry and continuous rotation of X-ray tube and detectors

d. fan-beam geometry and complete rotation of X-ray tube around a stationary ring of detectors

d. fan-beam geometry and complete rotation of X-ray tube around a stationary ring of detectors

Which of the following is classified as a high-speed CT scanner?

a. Third-generation scanner

b. Fourth-generation scanner

c. Spiral/helical CT scanner

d. Fifth-generation CT scanner

d. Fifth-generation CT scanner

In which scanner is the apex of the fan beam located outside the detector?

a. Third-generation scanner

b. Fourth-generation scanner

c. Fifth-generation scanner

d. Sixth-generation scanner

b. Fourth-generation scanner

In one type of fourth-generation CT scanner, the tilting action of the detector ring is referred to as:

a. slip-ring technology.

b. nutating.

c. spiral scanning.

d. helical scanning.

b. nutating.

Which scanner is based on slip-ring technology?

a. Third-generation conventional scanner

b. Fourth-generation conventional scanner

c. Spiral/helical scanner

d. Fifth-generation scanner

c. Spiral/helical scanner

Which scanner allows for continuous rotation of the X-ray tube while the patient moves simultaneously through the gantry aperture?

a. Third-generation conventional scanner

b. Fourth-generation conventional scanner

c. Spiral/helical scanner

d. Dynamic volume scanner

c. Spiral/helical scanner

Which scanner results in a volume of the patient being scanned during a single breath-hold (rather than a single slice of tissue)?

a. Spiral/helical scanner

b. Seventh-generation scanner

c. Second-generation scanner

d. First-generation scanner

a. Spiral/helical scanner

The scanner that uses an electron gun to "shoot" electrons toward a target ring is the:

a. fifth-generation scanner.

b. fourth-generation scanner.

c. third-generation scanner.

d. spiral/helical scanner.

a. fifth-generation scanner.

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

a. target rings.

b. slip rings.

c. spiral rings.

d. helical rings.

b. slip rings

Which generation of scanners, also called dual-source CT scanners, consists of two X-ray tubes and two sets of detectors?

a. Third generation

b. Fourth generation

c. Fifth generation

d. Sixth generation

d. Sixth generation

Compared with conventional CT scanners, slip-ring scanners offer all of the following advantages except:

a. removal of cable wraparound.

b. elimination of start-stop action.

c. capacity for interrupted acquisition protocols.

d. minimal interscan delays.

c. capacity for interrupted acquisition protocols.

Which X-ray generator is used in modern CT scanners?

a. Single-phase half-wave rectified

b. Single-phase full-wave rectified

c. High-frequency generator

d. Three-phase, six-pulse generator

c. High-frequency generator

Which of the following X-ray tubes is most likely used in spiral/helical CT scanners?

a. A tungsten target fixed anode tube

b. A tungsten target rotating anode tube

c. A molybdenum target rotating anode tube

d. A rotating anode tube with a rhenium tungsten disk

d. A rotating anode tube with a rhenium tungsten disk

All of the following are radiation beams produced by an X-ray tube designed for CT except:

a. homogeneous beam.

b. heterogeneous beam.

c. polychromatic beam.

d. polyenergetic beam.

a. homogeneous beam.

The main purpose of a filter used in CT is to:

a. reduce the intensity of the beam at the detector.

b. make the beam less uniform at the detector.

c. decrease the mean energy at the detector.

d. protect the patient.

d. protect the patient.

What style of filter is common in CT filtration because it compensates for the difference in beam path length through the axial plane of the object such that a more uniform fluence can be delivered to the detector?

a. Straight filter

b. Bowtie filter

c. Cone filter

d. Star filter

b. Bowtie filter

The purpose of collimation in CT is each of the following except:

a. create an homogenous beam.

b. to protect the patient.

c. to ensure a constant beam width at the detector.

d. to reduce scatter radiation.

a. create an homogenous beam.

What design of collimation is influenced by the size of the focal spot?

a. Prepatient collimation

b. Postpatient collimation

c. Predetector collimation

d. Postdetector collimation

a. Prepatient collimation

The slice thickness in CT is determined by the:

a. focal spot.

b. anode.

c. collimator height.

d. collimator width.

d. collimator width.

Which of the following refers to the ability of the CT detector to capture, absorb, and convert X-ray photons into electrical energy?

a. Efficiency

b. Stability

c. Response time

d. Dynamic range

a. Efficiency

Which detector characteristic refers to the steadiness of the detector response?

a. Efficiency

b. Stability

c. Response time

d. Dynamic range

b. Stability

The speed with which a CT detector can detect an X-ray event and recover to detect another event is the:

a. response time.

b. stability.

c. efficiency.

d. dynamic range.

a. response time

The ratio of the largest signal to the smallest signal measured by a CT detector is the:

a. response time.

b. dynamic range.

c. efficiency.

d. stability.

b. dynamic range.

The following crystals have been used in scintillation CT detectors except:

a. bismuth germinate.

b. calcium tungstate.

c. calcium fluoride.

d. sodium iodide (NaI).

b. calcium tungstate.

Which of the following is commonly used in gas-ionization CT detectors?

a. Xenon

b. Oxygen

c. Neon

d. Helium

a. Xenon

What detector innovation allows for acquisition of both low and high energies for every exposure in CT imaging?

a. Stellar detector

b. Third-generation detector

c. Photon counting detector

d. Dual-layer detector

a. Stellar detector

What category of multirow detector array utilizes an isotropic design?

a. Adaptive array detectors

b. Matrix array detectors

c. Unilateral array detectors

d. Identical array detectors

b. Matrix array detectors

The data acquisition system (DAS) performs each of the following functions except:

a. measures the transmitted radiation beam.

b. encodes these measurements into binary data.

c. powers the rotating components of the gantry.

d. transmits the binary data to the computer.

c. powers the rotating components of the gantry.

Which of the following methods does not affect sampling information?

a. Closely packed detectors

b. Milliamperage-seconds (mAs)

c. Slice thickness

d. Double-dynamic focus

c. Slice thickness

What provides doubling sampling by obtaining two overlapping slices for each detector row per 360-degree rotation?

a. z-flying focal spot technique

b. Double-dynamic focus

c. Quarter-shifted detection

d. Aliasing method

a. z-flying focal spot technique