Ch 1: Imaging Modalities and Digital Images

Question 1

Any component of the image that is extraneous to the representation of tissue structures; can be caused by a technique, technology, hardware, or software error

Answer 1

Artifact

Question 2

Uses a photostimulable or storage phosphor imaging plate.

Answer 2

Computed radiography (CR)

Question 3

Devices that convert x-ray energy to electron whole pairs in an amorphous selenium photoconductor, which are read out by a thin film transistor (TFT) array of Amorphous silicon (Am-Si); a form of radiography that uses x-ray sensitive plates to directly capture data during the patient examination, immediately transferring to the computer system without the use of an intermediate cassette

Answer 3

Digital radiography (DR)

Question 4

CT number representing absorption values of tissues; expressed on a scale of +1000 units for the maximum x-ray beam absorption of bone to -1000 units for the least absorbent air. Water is used as a reference material for determining CT numbers is, by definition, equal to 0.

Answer 4

Hounsfield Unit

Question 5

An imaging procedure that uses a strong magnetic field to maneuver proteins in the tissues of the body. Radiofréquence excitation of the protons results in energy absorption and subsequent re-emission of RF signals, which are detected and processed to reveal the magnetic characteristics of tissues in tens of a grayscale image. Pulse sequences specifically generate tissue contrast differences; typically, several sequences are acquired for a specific study.

Answer 5

Magnetic resonance imaging (MRI)

Question 6

is a type of nuclear medicine imaging uses small amounts of radioactive material to diagnose, evaluate or treat a variety of diseases.

Answer 6

Positron Emission Tomography (PET)

Question 7

is a nuclear medicine tomographic imaging technique using gamma rays. It is very similar to conventional nuclear medicine planar imaging using a gamma camera (that is, scintigraphy). but is able to provide true 3D information

Answer 7

Single-photon emission computed tomography (SPECT)

Question 8

is a noninvasive test that can be used to estimate the blood flow through your blood vessels by bouncing high-frequency sound waves off circulating red blood cells. A regular ultrasound uses sound waves to produce images, but can’t show blood flow.

Answer 8

Doppler US

Question 9

may refer to either the smallest discrete element of the physical display or to the smallest element of the image

Answer 9

Pixel

Question 10

the smallest 3-dimensional discrete element of the physical display or to the smallest 3-dimensional element of the image as employed in CT and other cross-sectional imaging modalities

Answer 10

Voxel

Question 11

the digitization of the spatial coordinates and is related to pixel size, reflective of matrix size and affects spatial resolution

Answer 11

Sampling

Question 12

the ability of the imaging modality to differentiate two objects. Low techniques will be unable to differentiate between two objects that are relatively close together.

Answer 12

Spatial resolution

Question 13

the ability of any imaging modality to distinguish between differences in image intensity. The inherent _____ of a digital image is given by the number of possible pixel values, and is defined as the number of bits per pixel value.

Answer 13

Contrast resolution