CASSETTE-BASED EQUIPMENT PT2

READER

With CR systems, no chemical processor or darkroom is necessary. Instead, following exposure, the cassette is fed into a __ that removes the imaging plate and scans it with a laser to release the stored electrons.

"Light Amplification of Stimulated emission of Radiation"

LASER

LASER

a device that creates and amplifies a narrow, intense, beam of coherent light

Helium laser beam or solid-state laser, raster

It scans the plate with red light in a __ pattern and gives energy to the trapped electrons

active, blue

Extra energy allows the trapped electrons to escape the __ layer into lower energy level where they emit __ light

Translation

term for the parallel plate movement of the plate through the scanner

PHOTOMULTIPLIER

The scan process produces lines of light intensity information detected by a __ that amplifies light and sends it to a digitizer.

more, more

The __ angled the beam is, the __ elliptical the shape of the beam

middle, edges, spatial resolution

The output of the screen would differ from the __ to the __, resulting in differing __ __ and inconsistent output signals

Analog

a device or system that represents changing values as continuously variable physical quantities

phosphor storage center
digitizer
squares (matrix)
brightness

In the process of digitizing the light signal, each __ is scanned, and the released electrons enter a __ that divides the analog image into __ and assigns each square in the matrix a number based on the __ of the square

pixel or picture element

Each square is called a __

512 × 512 to 1024 × 1024 for CT
2500 × 2500 for radiograph

The typical number of pixels in a matrix ranges from about __ for CT but can be as large as __ for radiograph

more, greater

The __ pixels there are, the __ greater the image resolution

position (spatial location) and by intensity (gray level)

The image is digitized both by __ and __

bit depth

Each pixel contains bits of information, and the number of bits per pixel that define the shade of each pixel is known as __

10 or 12

Some CR systems have bit depths of __, resulting in more shades of gray.

0 (20) and 4096 (212)

Each pixel can have a gray level between __ and __

SPATIAL RESOLUTION

The amount of detail present in any image

thinner, higher

The __ the phosphor layer, the __ the resolution

dynamic range

However, because the __, or the number of recorded densities, is much higher, the difference in resolution is more difficult to discern.

densities

More tissue __ on the digital radiograph are seen, giving the appearance of more detail

phospors
width and intensity
speed
200

The __ emit light according to the __ and __ of the laser beam as it scans the plate, resulting in a relative "__" that is roughly equivalent to a __ speed film/screen system.

photostimulable luminescence (PS)

CR system "speeds" are a reflection of the amount of __ given off by the imaging plate while being scanned by the laser.

computer

Once the imaging plate has been read, the signal is sent to the __ where it is preprocessed.

monitor
(post-processing)
quality control (QC)
picture archiving and communications system (PACS)

The data then goes to a __ where the technologist can review the image, manipulate it if necessary (__), and send it to the __ station and ultimately to the __