CT Quizzes

When a large set of transmission measurements is collected from the patient at different locations and is used to build up an image of internal anatomy, it is referred to as:

-tomography.

-image reconstruction from projections.

-pattern recognition.

-digital image processing.

Image reconstruction from projections

Data acquisition refers to:

-collecting X-ray transmission readings from the patient.

-subjecting data to computer processing.

-changing the data before they are displayed on a monitor.

-storing the data collected from the patient onto magnetic tapes or disks.

Collecting x-ray transmission from the patient

Determining tissue types in CT slices is referred to as volume formation.

T/F

False (Classification )

Which of the following refers to modifying CT data to make the images more useful to the observer?

-Image manipulation

-Image reconstruction

-Data collection

-Pattern recognition

Image Manipulation

In CT,

-a computer is used to reconstruct images of sectional anatomy.

-a computer is used to calculate radiation dose to the patient.

-a computer is not required because the physicist calculates the image, which the computer then prints out.

-special detectors are used to reconstruct sectional images.

A computer is used to reconstruct images of sectional anatomy

Who developed the first clinically useful CT scanner?

Hounsfield

All these elements can be used during data acquisition to reduce patient dose except:

-combined applications.

-ultrafast ceramic (UFC) detectors.

-decreased pitch.

-online dose modulation.

Decreased pitch

Which company pioneered the development of the first clinically useful CT scanner?

EMI

Which form of imaging primarily uses DSCT scanners?

Cardiac Imaging

Which acronym has been established by the Radiological Society of North America (RSNA) and the accepted term for use within the radiologic community and major American radiology journals?

CT

In the original experiments in CT, the apparatus took 9 hours to scan the object. T/F

False (9 days)

Which term describes the systematic motion of the X-ray tube as it rotates around the patient to collect X-ray transmission readings?

Scanning

QC tests in CT meet only quantitative criteria to indicate the scanner is in working condition. T/F

False (they meet both quantitative and qualitative)

Ambrose received the Nobel Prize in 1979 with Hounsfield. T/F

False ( Cormack did)

Who developed the first whole-body CT scanner?

Ledley

ALARA is an acronym for as low as reasonably achievable. T/F

True

Gas-ionization detectors (xenon gas) are used in the majority of commercial CT scanners today. T/F

False (most now days are scintillation detectors)

The first CT scanners' X-ray tube and detector movement was described as translate-rotate-stop-rotate because they moved in a straight line across the patient.

True

The radiation used by Hounsfield in his original experiments was:

gamma rays

Which type of high-speed CT scanner was first introduced to image the cardiovascular system without artifacts caused by motion of the heart?

EBCT (electron-beam)

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

-CT dose index (CTDI) and multiple-scan average dose (MSAD)

-Isometric curves

-Exposure doses

-Collective doses

CT dose index (CTDI) and multiple-scan average dose (MSAD)

CT fluoroscopy is a clinical tool allowing the reconstruction and display of images in real time with variable frame rates. T/F

True

The mathematical techniques used by the computer to reconstruct the CT image are known as:

Image reconstruction algorithms

CT has been applied to the study of internal log defects and Egyptian mummies. T/F

True

Processing images by computer is referred to as digital image processing. T/F

True

Conversion of the attenuation readings into a CT image is accomplished by reconstruction algorithms. T/F

True

The total number of X-ray transmission measurements is equal to the:

-total number of detectors.

-number of views in each scan.

-product of the number of views and the number of rays in each view.

-number of views divided by the number of rays in each view.

product of the number of views and the number of rays in each view

A limitation of conventional radiography is that it is qualitative rather than quantitative. T/F

True

A CT image of 12 bits per pixel means:

-each pixel can have a total of 4096 shades of gray.

-the matrix is 4096 X 4096.

- pixel size is 12 mm.

-the voxel size is 12 mm.

each pixel can have a total of 4096 shades of grey

A polychromatic beam is better known as a homogeneous beam. T/F

False (poly-heter)

(monoenergetic-homo)

CT is better at recording very small differences in tissue contrast compared to conventional tomography. T/F

True

A spiral or helical beam is used to scan the patient in slice-by-slice data acquisition.

False (spiral or helical is used to scan a volume of tissue rather than one slice at a time)

The most obvious difference between CT and radiography is that:

-CT shows cross-sectional images or transaxial anatomy.

-radiography uses sodium iodide detectors.

-a computer is used to produce the film in radiography.

-radiography shows cross-sectional images.

CT shows cross-sectional images or transaxial anatomy

The radiation beam produced from a conventional X-ray tube is:

heterogeneous

Data processing includes all of the following except:

-raw data preprocessing.

-analog to digital conversion.

-image reconstruction.

-image storage.

image storage

All of the following apply to computed tomography (CT) except:

-a computer is used to reconstruct cross-sectional images of the patient.

-mathematical methods are used to reconstruct images.

-X-ray film is used as the detector.

-special detectors are used to detect X-rays that have passed through the patient at multiple angles.

x-ray film is used as the detector

The field of view (FOV) is:

the reconstruction circle

Which of the following is used to calculate CT numbers?

-CT number = µ water + µ tissue / K

-CT number = ((µ tissue - µ water) X K)/ µ tissue

-CT number = ((µ water + µ tissue) X K)/ µ water

-CT number = ((µ tissue - µ water) X K) / µ water

CT number = ((µ tissue - µ water) X K) / µ water

The Compton effect occurs largely in soft tissues. T/F

True

The photoelectric effect occurs mainly in tissues with a low atomic number.

False (occurs mainly in tissue with a high atomic number)

The second step of data acquisition is scanning. T/F

False ( the first step is scanning)

In which of the following are slices taken at specific locations on the patient?

-Spiral CT

-Helical CT

-Conventional slice-by-slice CT

-Volumetric CT

conventional slice by slice

All of the following changes occur in the attenuation of a heterogeneous beam of radiation except:

-the beam quality.

-the beam quantity.

-the beam intensity.

-the beam direction.

the beam direction

Which of the following is not true of a homogeneous beam of radiation?

-All the photons have different energies

-All the photons have the same energy

-Equal thicknesses of the absorber remove equal amounts of radiation

-Equal thicknesses of the absorber remove different amounts of radiation

All the photons have different energies

Which of the following is a limitation of radiography?

-Image blur caused by patient breathing

-Contrast degradation because of low peak kilovoltage techniques

-The presence of ghost images caused by the tube movement

-Superimposition of structures

superimposition of structures

Which of the following obeys Lambert-Beer's law?

-A homogeneous beam of radiation

-A heterogeneous beam of radiation

-A polyenergetic beam of radiation

-A polychromatic beam of radiation

A homogeneous beam of radiation

If the FOV for an examination is 30 cm and the matrix size is 1024 X 1024, what is the approximate pixel size?

0.3 mm

The reduction of the intensity of a beam of X-rays as it passes through the patient is:

attenuation

CT overcomes the limitations of radiography and conventional tomography by achieving all of the following except:

-reducing the problem of superimposition.

-improving the contrast of the image.

-using quantitative detectors and a computer.

-reducing a patient's radiation dose.

reducing patient radiation dose

CT numbers are established by referencing the linear attenuation coefficient of air. T/F

False (Water)

Computers operate using the binary number system which operates with a base of 10. T/F

False ( 2,that is, 0 or 1)

An example of a local operation that causes image brightness to change slowly or at a constant rate is called:

-area processes.

-low spatial frequency.

-convolution.

-high spatial frequency.

low spatial frequency

An increase of matrix size (with no change in field of view (FOV)) will ____________ detail.

increase

The origin of digital image processing stems from:

-space program.

-General Electric.

-Hounsfield.

-the Mayo Clinic.

the space program

Which type of artifact will appear on a digital image as a result of poor sampling of the analog signal?

Aliasing

Which of the following represents the logical order in digitizing an image?

scanning, sampling, and quantization

A 10 X 10 matrix consists of ______ pixels.

100

The least complicated and most frequently used image processing technique is the:

-point operation.

-local operation.

-global operation.

-geometric operation.

point operation

A radiograph is an example of an analog image. T/F

True

Visible images include all of the following except:

-paintings.

-mathematical images.

-photographs.

-drawings.

mathematical images

The systematic method of collecting data from the patient is called:

data acquisition

The total number of gray levels is called:

the gray scale

Which of the following is the final step in digitizing an image?

quantization

The output digital image must first be converted into an analog signal. T/F

True

In which of the following is the brightness level of each pixel in a picture measured by a photomultiplier tube (PM)?

-Scanning

-Sampling

-Quantization

-Digital to analog conversion

sampling

Which of the following assigns integers to the brightness values measured by the PM?

-Scanning

-Sampling

-Quantization

-Analog-to-digital conversion

Quantization

Aliasing results in an artifact that appears as a moiré pattern in the image. T/F

True

Digital image processing techniques have been applied successfully in not only the space program but also in medical imaging. T/F

True

Digital image processing was first developed for NASA's work in lunar and planetary exploration. T/F

True

The sine wave is an example of an analog signal. T/F

True

Which of the following reduces the amount of data that makes up the image?

-Image enhancement

-Image restoration

-Image analysis

-Image compression

image compression

A digital image is a discrete function. T/F

true

The imaging system components are located in the:

-scanner room

-radiologist viewing area

-operator room

-computer room

scanner room

All of the following are major systems in the basic equipment configuration for computed tomography (CT) except:

-imaging system.

-computer system.

-image display, recording, storage, and communication system.

-dictation system.

dictation system

The purpose of the imaging system is to perform all of the following except:

-detect and measure the radiation passing through the cross-section.

-produce X-rays.

-store images for retrieval.

-shape and filter the X-ray.

store images for retrieval

What method of image compression results in the loss of no information during the compression process?

-Irreversible compression

-Lossy compression

-Permanent compression

-Lossless compression

lossless compression

The following are accessories for a CT scanner except:

-axial head holder.

-knee support pad.

-array processor.

-pediatric cradle.

-array processor

The ideal couch top (table top) of a CT scanner table has all of the following features except:

-low radiation absorption characteristics.

-excellent vibration-damping features.

-carbon fiber design.

-limited horizontal and vertical movements.

limited horizontal and vertical movements

In general, the tilting range of a CT gantry is about:

±12 degrees to ±30 degrees.

Which of the following is where images are stored in a filmless imaging department?

PACS

Quality control (QC) equipment is part of the equipment specifications for CT. T/F

True

The typical matrix size of a typical CT image is:

512 x 512 x 8 bytes deep.

All of the following are purposes of the image display, recording, storage, and communication system except:

-displays the output digital image.

-provides a hard copy.

-facilitates storage.

-enables scanning procedures.

Enable scanning procedures

Which of the following does the computer system perform?

-Detects radiation

-Image manipulation

-Display the output image

-Provides a hard copy

image manipulation

Most scanners have a gantry aperture of about:

70 cm

The computer room generally houses the film recording equipment. T/F

False (control room)

The design that incorporates the high-voltage generator on the rotating frame of the CT gantry eliminates:

-the need for long high-tension cables.

-the need for short high-tension cables.

-the detectors from within the gantry.

-the need for any cables.

long high tension cables

The opening in the gantry in which the patient is positioned during scanning is called the:

gantry aperture

CT workstation computers are classified as supercomputers for their processing capabilities and size. T/F

False (midrage comuters)

Software modules for CT scanners allow each of the following except:

-facilitate modification of existing packages.

-revise existing software.

-alternate analog signals into digital.

-update existing software.

alternate analog signals into digital

LAN networks connect computers separated by large distances. T/F

False (WAN)

Which of the following supports the patient during a CT examination?

The CT table or patient couch

Which of the following allows the technologist to devote more time to the scanning procedure and the needs of the patient?

-The television monitor

-Control functions

-Floppy disks

-The line printer

control functions

The concept of modular design in CT scanner development is intended to:

simplify upgrading of scanners.

Which of the following allows the technologist to alter picture contrast?

window controls

Hardware modules include all of the following except:

-back-projectors.

-array processors.

-analog to digital conversion cards.

-application systems packages.

application system packages

The X-ray generator for CT scanners is usually a:

high frequency unit

Which room generally houses the gantry and patient couch and should be large enough to accommodate gurneys and emergency equipment?

scanning room

Which of the following obeys Lambert-Beer's law?

-A homogeneous beam of radiation

-A heterogeneous beam of radiation

-A polyenergetic beam of radiation

-A polychromatic beam of radiation

a homogenous beam of radiation

In which of the following are slices taken at specific locations on the patient?

conventional slice by slice