Image Receptors 1

Question 1

types of film?

Answer 1

direct action film

indirect action film

Question 2

types of digital film?

Answer 2

solid state sensor

PSP’s

Question 3

what is direct film?

Answer 3

dental intra oral

xrays act directly on silver halide crystals on film emulsion

Question 4

what is an indirect film?

Answer 4

extra oral

light from intensifying screens act on silver halide crystals in film emulsion

Question 5

what is DR?

Answer 5

solid state CCD, CMOS sensor

Question 6

what is CR-PSP?

Answer 6

latent image produced by interaction of xrays with phosphor layer of plate
scanned by laser to produce image

Question 7

PSP action when in a patients mouth?

Answer 7

phosphor layer absorbs and stores xray energy in the electrons of the phosphor crystals

Question 8

PSP action when taken to scanner?

Answer 8

plate inserted into scanner
plate scanned by red laser
light released
light detected by photomultiplier tube

Question 9

how is an image produced from a PSP plate?

Answer 9

light = electrical signal
relayed to computer - digital image
residual energy trapped in electrons after scanning
image on plate erased by exposing PSP to bright light
plate ready to re use

Question 10

what state is a psp plate in when acted on by an xray?

Answer 10

stable excited state

Question 11

what happens to the stable excited state plate when acted on by red laser?

Answer 11

unsatble excited state

Question 12

how is the unstable excited plate turned back to a normal imaging plate?

Answer 12

scanner collects blue light and converts to an image

Question 13

layers of a CCD plate?

Answer 13

back cover + cable to PC
silicon wafer - light to electrical signal
scintillator layer - x ray energy to light

Question 14

how is an image produced from a CCD plate?

Answer 14

x rays hit scintillator layer = light
light hits photosensitive cells in silicon layer = pixels of image
electrons released in each cell = charge that is converted to a voltage = electrical signal = image

Question 15

what is the signal the computer receives made up of?

Answer 15

lines of pixels

each pixel connected to its neighbour

Question 16

how does CMOS work?

Answer 16

similar except photocells are electrically isolated

charge to volatge signal is made up of each individual cell instead of lines

Question 17

what gives the better quality image?

Answer 17

CCD

Question 18

what is cheaper?

Answer 18

CMOS

Question 19

what is more reliable?

Answer 19

CCD

Question 20

what uses less power?

Answer 20

CMOS

Question 21

advantages of digital images?

Answer 21

no chemicals
easily archived
easy image transfer
image can be manipulated
reduced pt dose

Question 22

disadvantages of digital images?

Answer 22

expensive
reduction in resolution because of pixel size
archiving = problem because of back up

Question 23

how are x rays stored at a dental practice?

Answer 23

local storage
PC
back up = CD, DVD, hardrive

Question 24

where is PACS stationed?

Answer 24

locally - NHS Tayside

nationally - Livingstone