Rad 142 Unit 2

Front 1

Dynamic Range

Back 1

Range of exposure intensities that an image receptor can accurately detect.

*Film has limited dynamic range when compared to digital IRs

Front 2

Radiographic Film

Back 2

Serves as medium for image aquisition, processing and display

(more sensitive to light

less sensitive to x-rays)

Front 3

Automatic Film Processor

Back 3

Chemically converts latent image into manifest/visible image

(Developer, fixer, washer, dryer)

Hint 3

Front 4

Developer

Back 4

Converts latent to a manifest or visible image.

(Part of automatic Film Processor)

Front 5

Fixer

Back 5

Removes unexposed silver halide from film; stops development process and hardens the emulsion

(Part of automatic Film Processor)

Front 6

Washer

Back 6

Removes fixing solution from surface

(Part of automatic Film Processor)

Front 7

Dryer

Back 7

Removes majority of moisture from film

Front 8

Sensitometry

Back 8

Study of relationship between intensity of radiation exposure to a film and the amount of blackness(density) after processing.

Hint 8

Front 9

Sensitometry curve & characteristics

Back 9

Visually demonstrates relationship between intensity of radiation exposure and resultant optical densities.

Steeper slope = HIGH contrast/narrow latitude

Gradual slope = LOW contrast/wide latitude

Characteristics:

Toe - area of low density

Shoulder - area of high density

Straight line - region where changes in exposure have significant effect on density.

Hint 9

Front 10

Back 10

Developer over-replenishment & roller marks.

*Increased in density, vertical roller marks

Front 11

Back 11

Inadequate washing

*Brown stained appearance in overall radiograph

Front 12

Back 12

Reticulated film (caused by extreme temp. VERY Hot developer & cold water)

*crumbly radiograph w/ very fragile appearance and structure

Front 13

Back 13

Dirty processed rollers

* Roller marks, linear artifacts across radiograph

Front 14

Back 14

Overlapping films (put film before processor beeps/ready for new film)

*Emulsion from second film overlapping original film

Front 15

Back 15

Safelight fog exposure +2minutes

*Vertical faint line in center of film indicates portion had slightly higher density from being placed under safelight

Front 16

Capture vs Coupling vs Collection element

Back 16

COMPONENT OF DIGITAL RADIOGRAPHY CHART

Front 17

Computed Radiography

Back 17

Requires an Imaging plate in separate processing system

*Barium fluorohalide PSP

Front 18

Scanned Projection Radiography

Back 18

Developed by CT vendors to facilitate patient positioning imaging volume.

*Scanning motion required several seconds leading to motion blur

*Not widely used as diagnosirc imaging method

Front 19

Indirect DR

Back 19

Process by which x-rays are converted first to light then an electrical signal.

*Cesium Iodide/CCD or CMOS

*Cesium Iodide/a-Si (TFT)

*Gadolinium Oxysulfide/a-Si (TFT)

Front 20

CCD imaging characteristics

Back 20

High sensitivity - ability to detect and respond to very low levels of visible light.

Wide dynamic range - ability to respond to wide range of light intensities.

Size- very small

(INDIRECT DR)

Front 21

Direct DR

Back 21

Process by which x-rays are converted directly into an electrical signal

*Amorphous selenium (a-Se)

Front 22

CMOS

Back 22

Complementary Metal Oxide Semiconductor

*Special type of memory chip that retains info. from PC's hardware while off

*Uses scintillator that converts x-rays to light and placed in capacitor. Amplified within pixel converts light photons in electrical charges

Front 23

Computer

Back 23

Consists of Input, output and processing devices

Front 24

Input devices

Back 24

Keyboard, mouse, microphone, bar code readers, touch screens, image scanners.

Front 25

Output devices

Back 25

Monitors, printers, speakers

Front 26

Binary code

Back 26

Machine language of 1s and 0s

Front 27

Bit

Back 27

Single unit of data

Front 28

Byte

Back 28

Made up of 8 bits

Front 29

Motherboard

Back 29

Largest circuitry board, contains many important small components for computer functionality

Hint 29

Front 30

CPU

Back 30

Microprocessor, brains of the computer.

1. Read data from storage

2. Manipulate data

3. Moves data back to storage or sends to an external device

Hint 30

Front 31

BIOS

Back 31

(Input, output)

Contains simple set of instructions for computer.

- Runs start-up diagnostics

- Oversees basic functions of receiving and interpreting signals

- Acts as intermediary between system and hardware

Front 32

Memory

Back 32

Stores information being currently processed within CPU on temporary basis.

Ex: RAM

Front 33

Ports

Back 33

Connects on the PC that link peripherals.

Ex: charging port, USB

Hint 33

Front 34

Powersupply

Back 34

Delivers all electricity to PC

- Contains a fan to help keep the inside of the computer cool

Hint 34

Front 35

Hard Drive

Back 35

Main storage for programs and documents

Front 36

CD/DVD Drive

Back 36

Information may be burned onto disk, capacity depends on type of CD or DVD

Front 37

Analog to digital converter (ADC)

Back 37

Converts analog data to digital data to produce digital image via sampling and quantization

Front 38

Preprocessing

Back 38

Largely automatic, purpose is to improve image contrast and produce artifact free digital image

- to provide electronic calibration to reduce pixel-to-pixel, row-to-row and column-to-column response differences

Front 39

Digital Image preprocessing. Problems and solutions

Back 39

Defective pixel

Image Lag

Line noise

Front 40

Defective pixel

Back 40

-Dead of unresponsive pixel.

-Interpolate adjacent pixel signals

-Response of pixel surrounding defective pixel is averaged and value is assigned.

Front 41

Image Lag

Back 41

-Electronic latent image that remains

-offset correction

-application of an offset voltage before next image acquired.

Front 42

Line noise

Back 42

-voltage variants seen along each pixel that causes linear artifacts

-correct from dark reference zone

-application of voltage correction from a row or column of pixels in a dark zone

Front 43

Flat fielding

Back 43

Equalizes response of each pixel to uniform x-ray beam

-fixes inconsistent brightness / density caused by anode heel effect

Front 44

Histogram

Back 44

Graphic representation of data set of an image

Front 45

Histogram analysis

Back 45

Computer analyzes histogram using processing algorithms and compares it to pre-established histograms specific to anatomical part being imaged.

Front 46

Value of interest (VOI)

Back 46

Determines range of histogram data set that should be included in displayed image

Front 47

Look up table (LUT)

Back 47

Following histogram analysis, provides method of altering image to change display of digital image

Front 48

Post processing

Back 48

Computer software operations available to radiographer/radiologists that allow manual manipulation of displayed image

Front 49

Window level

Back 49

Adjusts brightness

Direct relationship w/ brightness

Front 50

Window width

Back 50

Contrast

-Inverse relationship w/ contrast.

*Narrow window width = increased contrast

*Wide window width = decreased contrast

Front 51

Electronic cropping, masking, shuttering

Back 51

Used to remove region of brightness that surrounds radiation exposed field that provides no useful information. (White border)

Front 52

Dose creep

Back 52

Result of technologist not adjusting exposure factors as frequently required in screen film Imaging due to the wide dynamic range of digital imaging

*Overexposing patients with intention of correcting images

*Relying on the system to fix an image through rescaling and use higher mAs

*Not changing factors between lateral and AP view when taken consecutively

Front 53

ET

Back 53

Target exposure index. Reference exposure obtains when an image is optimally exposed

Front 54

DI

Back 54

Deviation index.

Quantifies how much the actual EI varies from the target exposure index