Ch. 8 Digital Imaging

Question 1

acquiring images using x-rays & digitally displaying them on computer files

Answer 1

Digital imaging

Question 2

digital images that can be sent through a computer network to numerous computers inside and outside the medical facility

Answer 2

conventional radiography

Question 3

“cassette-based” digital imaging
- photostimuable phosphor plate that stores the latent image
- thick phosphor made of barium flurohalide with europium
-high resoultion IPs produce greater image resolution

Answer 3

Computed Radiography

Question 4

IP is exposed
CR reader scans the IP with a laser beam turning the energy into light
IP is erased with a white light

Answer 4

Process of viewing an image with Computed radiography

Question 5

CR reader unit, computer workstation, computer system, computer storage, printer

Answer 5

required items for Computed Radiography

Question 6

“Cassetteless” digital imaging
- uses flat-panel detectors made of a scintillation screen or a photoconductor to convert photons into electrical signals
- 2 conversion systems: indirect vs. direct

Answer 6

Digital Radiography

Question 7

2-step process where xray energy is converted into light and then into an electrical signal using a scintillator made of cesium iodide

Answer 7

Digital Radiography-Indirect Conversion

Question 8

collects the electric charges as a matrix of pixel size elements (Detector Elements)

Answer 8

Amorphous Silicon

Question 9

Takes the stored charge and converts it into digital values that are sent to the computer for processing/viewing

Answer 9

Analog-to-Digital Converter (ADC)

Question 10

no photodiode, but instead converts the light from the scintillator to the electric signal

Answer 10

Charged Coupled Device (CCD)

Question 11

converts light into electrons that are stored in capacitors
-most common semiconductor is silicon

Answer 11

Complementary Metal Oxide Semiconductor (CMOS)

Question 12

1-step process where detectors convert the xray energy directly into an electric signal through an amorphous selenium detector without light conversion

Answer 12

Digital Radiography- Direct Conversion

Question 13

how fast can DR images be processed?

Answer 13

3-5 seconds

Question 14

defects that cause a loss in information
-dust, scratches, interactions between materials can occur

Answer 14

dead pixels

Question 15

amount of detail/sharpness available
-larger matrix with smaller pixels = greater resolution

Answer 15

Spatial resolution

Question 16

ability to distinguish anatomical structures of similar subject contrast

Answer 16

contrast resolution

Question 17

the responce of the detector to different levels of radiation exposure

Answer 17

dynamic range

Question 18

the ability of the digital system to convert input electric signal into a useful image

Answer 18

Signal-to-noise ratio

Question 19

noise that occurs when there are not enough photons to provide a high-quality image

Answer 19

quantum mottle

Question 20

Histogram
Look-up table (LUT)
Window Level
Window Width
Electronic Cropping
Image Stitching
Image annotation
Edge Enhancement
Smoothing
Subtraction
Contrast Enhancement

Answer 20

Functions of the processing system (“editing” images)

Question 21

controls density (brightness)

Answer 21

Window level

Question 22

controls contrast

Answer 22

Window Width

Question 23

a graph of the minimum & maximum signals in the image

Answer 23

Histogram

Question 24

images are produced with uniform density & contrast regardless of the amount of exposure
-problems occur when too little/too much exposure is used resulting in loss of contrast & detail

Answer 24

rescaling

Question 25

measurement of light converted into a signal
-the base of exposure indicator number for all manufacturer’s systems designates the middle of the detector operating range

Answer 25

Exposure indicator (“Exposure Index”)

Question 26

a universally accepted standard for exchanging medical radiographic images within the institution and in many areas where the images are viewed

Answer 26

Digital Imaging Communications in Medicine (DICOM)

Question 27

provides methods for calibrating a particular viewing monitor display system for the purpose of presenting images consistently on different display monitors and printers

Answer 27

DICOM gray-Scale function

Question 28

a digital health record for every patient

Answer 28

Electronic Medical Record (EMR)

Question 29

ties x-ray exams to the patient’s EMR

Answer 29

Radiology Information System (RIS)

Question 30

image management system that consists of networked groups of computers, servers, and archives containing the images obtained in the department

Answer 30

Picture Archival and Communication Systems (PACS)

Question 31

Quantum Mottle
Moiré Pattern
Light spots
White Light
Histogram Analysis Error
Phantom/Ghost Images
Scratches/Tears
Extraneous Line Patterns
Fogging

Answer 31

Common artifacts seen on images