Sensors and Digital Imaging pt. 1

Question 1

The X-ray film market is expected to register a CAGR of —% over the forecast
period 2020-2025.

Answer 1

5.4

Question 2

film packet contents (2)

Answer 2

lead foil
black cardboard

Question 3

intraoral film size

Answer 3

 0 - pediatric
 1 – PA , pediatric
 2 - Standard
 4 - occlusal

Question 4

film composition (4)

Answer 4

supercoat- thin layer of hard plastic
emulsion- gel and AG - halide crystal
adhesive
base- plastic

Question 5

Chemicals used to form

Answer 5

elemental Ag from
silver halide salt

Question 6

Chemical changes are (3) dependent

Answer 6

time, temperature
and concentration

Question 7

what is a digital image?

Answer 7

Digital image can be conceived as a table with columns and rows,with
each cell (aka pixel) being assigned a number value which is then
assigned a gray intensity. The composite collection of pixel values
are used by a computer’s software processing ability to construct an
image for visual display

Question 8

pixel
definition

Answer 8

derived from the words PEL (picture element).
A px (pixel) is the smallest portion of a sensor, image or
display that is capable of being recorded and then printed or
displayed.

Question 9

Large amounts of information can
be stored in a small amount of
space
 Convenience of space saving is
exponential for (2)

Answer 9

physical and
financial considerations

Question 10

general steps in digital image formation (4)

Answer 10

X-ray shadow
Shadow image
detected by
digital sensor
Numerical pixel
values sent to the
computer
Digital image
on the computer
screen

Question 11

Pixels are

Answer 11

electrified

Question 12

Each pixel has a

Answer 12

pre-exposure electrical charge

Question 13

X-ray photons that make it to the sensor change the

Answer 13

electric charge in those pixels

Question 14

The thicker/denser the body part adjacent the sensor, the

Answer 14

less the x-photons can affect
the electrical charge

Question 15

The net effect is that there is a shadow of electric charges on the sensor reflective of the
—- of the body part.

Answer 15

thickness/density

Question 16

Electric charge value of each pixel is converted to a

Answer 16

numerical value
i.e, digitized

Pixel values sent to the computer for processing

Question 17

The computer assigns a
to each number

Answer 17

gray value

The gray values are displayed in a
visual format on a display monitor

Question 18

different types of dental digital radiography (3)

Answer 18

historic (indirect)
indirect (semidirect)
direct

Question 19

Historic(Indirect)
(3)

Answer 19

Flatbed scanner
Slide scanner
Digital cameras

Question 20

Indirect(Semidirect)
(1)

Answer 20

Phosphor Storage Plate (PSP)[aka Photostimulable Phosphor Storage Plate (PPSP)]

Question 21

Direct
(2)

Answer 21

Charge-Coupled Device
(i.e., CCD)
Complementary Metal Oxide Semiconductor
(i.e., CMOS)

Question 22

indirect digital radiography
* Loss or alteration of information due to-

Answer 22

partial volume averaging

Question 23

• The first film-like sensor was introduced in 1994
(2)

Answer 23

• Hybrid system
• Photostimulable phosphor (PSP) plate

Question 24

components of a semidirect digital system (6)

Answer 24

Laser scanner
Screen monitor
CPU, Server, or PACS
Printer- EPR- PACs
X-ray source
PSP plate

Question 25

skipped
principle of PSP detector

Answer 25

→ X-ray
→ PSP plate coated with crystalline
halide emulsion made up of BaFBrEu2+
i.e. Europium doped Barium Fluorobromide
producing a latent image of ionized phosphors
→ scanned with red laser beam
→ emits fluorescent light from excitation of
valence electrons in ionized fluorophophors
→ intensified by a photomultiplier tube
→ light intensity is converted to digital data
expose to strong light to erase residual
images by neutralizing charges in ionized
fluorophophors
reuse

Question 26

skipped
PSP plates and accessories (air techniques)
(3)

Answer 26

ScanX PSP plates
available in same
sizes as dental
film
Barrier Envelopes
Plate Transfer Box

Question 27

skipped
PSP plate scanners (3)

Answer 27

ScanX (Air techniques)
ScanX Intraoral (Air techniques)
DenOptixScanX (Gendex Dental Systems)

Question 28

components of direct digital system

Answer 28

Analog-to-Digital Converter for CCD only
Screen monitor
CPU, Server, or PACS
Printer- EPR- PACs
Digital interface cord
CCD/CMOS
X-ray source

Question 29

skipped
sensor components (4)

Answer 29

electronic substrate
CMOS imaging chip
fiber optic face plate (FOPO)
CSI scintillator

Question 30

CCD/CMOS area
Sensors have:
(2)

Answer 30

1) External Size
2) Internal Active Area – the portion of the sensor
producing the image.