Sensors and Digital Imaging part 1

Question 1

dental film packet, D speed film:

Answer 1

slower- more radiation

Question 2

dental film packet, F speed film:

Answer 2

faster- less radiation

Question 3

film packet contents

Answer 3

moist/light proof sleeve, lead foil (protects from scatter radiation), and black, light-proof paper wrapper folded around film

Question 4

film composition:
1
2
3
4

Answer 4

1. supercoat- thin layer of hard plastic
2. emulsion- gel and Ag- halide crystal
3. adhesive
4. base-plastic

Question 5

during film processing, chemicals are used to form

Answer 5

elemental Ag from silver halide salt

Question 6

during film processing, chemical changes are ____, ___, and _____ dependent

Answer 6

time
temperature
concentration

Question 7

digital image can be conceived as a table with columns and rows, each cell (pixel) being assigned:

Answer 7

a number value which is then assigned a grey intensity

Question 8

in a digital image, the composite collection of pixel values are used by a

Answer 8

computer’s software processing ability to construct an image for visual display

Question 9

derived from the words PEL (picture element)

Answer 9

pixel

Question 10

smallest portion of a sensor, image or display that is capable of being recorded and then printed or displayed

Answer 10

px (pixel)

Question 11

what are the general steps in digital image formation

Answer 11

1. x-ray shadow
2. shadow image detected by digital sensor
3. numerical pixel values sent to the computer [pixel values assigned a number which ten corresponds to a gray scale value]
4. digital image on the computer screen

Question 12

pixels are electrified.
each pixel has a ___________ electrical charge

Answer 12

pre-exposure

Question 13

in digital image formation, x-ray photons that make it to the sensor change the

Answer 13

electrical charge in those pixels

Question 14

the ______the body part adjacent to the sensor, the ____ x-photons can affect the electrical charge

Answer 14

thicker/denser
less

Question 15

the net effect of digital image formation, is that there is a shadow of electrical charges on the sensor reflective of the

Answer 15

thickness/density of the body part
(step 2)

Question 16

during step 3 of digital image formation, the electric charge value of each pixel is read by computer chip and the electrical voltage is:

then, the pixel values are sent to the computer for:

Answer 16

converted to a numerical value
(digitized)

for processing

Question 17

the last step of digital image formation is when the computer assigns the gray value of each number to the

Answer 17

location on the X:Y grid axis of the sensor

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

Question 18

what are the different types of dental digital radiography

Answer 18

1. historic (indirect)
   flatbed scanner
   slide scanner
   digital cameras
2. indirect (semidirect)
   phosphor storage plate (PSP)
3. direct
   charge-coupled device (CCD)
   complementary metal oxide semiconductor (CMOS)

Question 19

loss or alteration of information due to partial volume averaging

Answer 19

indirect digital radiography

Question 20

the first film like sensory was introduced in 1994:

Answer 20

hybrid system
PSP plate: photostimulable phosphor PSP plate

Question 21

what are the components of semidirect digital system

Answer 21

1. xray source
2. psp plate
3. laser scaner
4. screen monitor
5. cpu, server, or PACS
6. printer EPR PACS

Question 22

what are the principles of PSP detector
1
2
3
4
5
6
7

Answer 22

1. xray
2. PSP plate coated with crystalline
3. scanned with red laser beam
4. emits fluorescent light from excitation of valence electrons in ionized fluorophophors
5. intensified by a photomultiplier tube
6. light intensity is converted to a digital data
7. expose to strong light to erase residual images by neutralizing charges in ionized fluorophophors

Question 23

PSP plate is coated with

Answer 23

crystalline halide emulsion made up of barium fluorobromide

Question 24

what is psp scanned with

Answer 24

red laser beam

Question 25

once PSP is scanned with red laser beam that emits fluoroscent light from excitation of of valence electrons in ionized fluorphophors it is then

Answer 25

intensified by a photomultiplier tube

Question 26

the light intensity of psp is converted to:

and then exposed to strong light to erase:
by neutralizing charges in ionized fluorophophors

Answer 26

digital data

residual images