rad w4 (9, 10, 11, 22)

10

radiographic image formation

• use -radiation to prod a representation of internal structs

• differential absorp of x-ray result in varying radiographic densities

• radiopaque structs (LIGHT)

• radiolucent structs (DARK)

• receptor = medium capturing image

• conventional = film

• modern systems = digital sensors

film comp ⭐

Consist of

1. polyester base

2. adhesive layer

3. emulsion

• contain gelatin & silver halidecrystals that absorb rad & store it)

• crystals resp for image formation

• create invisible image within emulsion on exposed film latent Image (invis til exposure)️️

film emulsion ⭐

film emulsion = coating attached to both sides of film base by the adhesive layer

• allow greater film sensitivity to x-rad

• consist of gelatin + silver halide crystals

• crystals absorb exposure & store E

• stored E forms pattern

• invis image within emulsion on film = latent image (top image)

film processing

• controlled chem sequence converting latent > diagnostic radiograph

• development, rinse, fixation, washing, drying

1. development

• chem rxn that reduces exposed crystals > black metallic silver

• this make dark areas on radiograph

• emulsion is softened/temp sens

2. rinsing

• rinse to remove developer sol’n & stop develop proc

3. fixation

• remove unexposed silver crystals

• this make white/clear areas on rad

• emulsion is hardened

4. wash

• remaining chem sol’ns removed in water bath

5. dry

manual vs. auto processing

1. manual = strict control of time & temp in darkroom environ

• check soln lvls

• stir soln

• check temp

• label film hanger

• turn on safelight/turn off whitelight

• close door

• load film hander

• set timer

• immerse in developer

• agitate film

• rinse thorough

• set timer

• immerse film in fixer

• wash

• dry

2. automatic = standardize time, temp, & chemical replenishment

• photo

processing errors

diagnostic one provide….

• proper density, contrast, detail, definition

• error = partial/full absence of image or obscure

1. Light film = underdeveloped

• low density

• lack develop time

• low dev temp

• depleted/contam dev soln

• bad timer/thermometer

2. Dark film = overdeveloped

• excess dev time

• high dev temp

• inaccurate timer/thermometer

3. Reticulation = damaged emulsion

• look cracked

• sudden change betw dev > bath water temp

4. Developer spots = dark spots

• dev sol’n contact film before processing

• clean work area

5. Fixer spots = white spots

• fixer sol’n contact film before processing

• clean area!

6. Yellow-brown stain

• not enough proc sol’ns OR insuff fixing/rinsing

• make sure film enough fixation/rinse time

• maybe expired

7. Developer cut-off = straight white border

• low lvl developer soln

• partial image

• film not completely immersed in dev soln (bc clipped at top of film rack)

• replenish soln & take not of film placement

8. Fixer cut-off = straight black border

• low lvl fixer soln

• unfixed portion of film

• film not completely immerse in fixer due to clipping

9. Overlapped film = white/dark areas where film overlap

• 2 films touch each other while process

• white area = underdev

• black area = unfixed

10. Air bubble = air trapped on film surface

• after place in processing solns

• fix = agitate film rack after placing in proc solns

11. Fingernail artifact = black crescent marks

• film roughly handled - damage film emulsion w nail

• should only handle film by edges

12. Fingerprint artifact = black fingerprints

• touch film w contam fingers of developer or fluoride

• before process, wash hands + clean area

13. Static electricity = thin black branching lines

• open film packet too quick OR opened packet prior to touch item like countertop/carpet

• open packet slowly

14. Scratched film = white lines

• film emulsion removed from base by film clip/hanger

• handle w care when put rack in proc solns

• avoid contact w other hangers

15. Light leak = exposed area look black

• white light exposure OR defective film packet

• dont unwarp in presence of light

• check packet for defects

16. Fogged film = look gray, lack detail/definition

• improper safe lighting

• light leaks in darkroom & film storage

• contam proc solns

• high dev temp

• expired film

• check bulb wattage of safelight & dark room for light leak

film mounting

purpose

• systematic approach for view/eval graphs

• placed in anatomic order

why

• quick/easy

• easy store/access

• determ L & R

• dec damage to film emulsion

• illuminate = better interpret

identif dot

• raised bump on corner

• should face xray beam during exposure

order

• bw > post PA > ant PA

key info

• label & date film prior to mounting

• mount immediately after process

• handle by edge

• dots up

• curve of spee upward toward distal

SKIPPED SLIDE 50 IDENTIFYING FEATURES

FFP = missing tooth structs

BB (biteblock) = close to fix

FDP (faulty develop/proc error) = only conventional

1/8 inch = cutoff apices or crown, move film to fix

OPNP = film tilted/positioned incorrect or jaw not parallel

• film not parallel to incisal-occl surfs of teeth

HA = beam not lined up w film at right hor angle

CC = film not covered by whole PID

RD (radiographic density) = fix mA, kdp, exposure time (8)

• Too dark → decrease mA, kVp, or exposure time.

• Too light → increase mA, kVp, or exposure time.

inc mA (quantity of xrays) = dark

inc kVp (E/penetrate power of xrays) = dark + change contrast

time = darker

if mA too high (dark) can compensate by dec time

changing one doesn’t affect each other

AC (apical cutoff) = fix film placement

FD (film damaged)

VA = pid too steep (should be +10)

• cause foreshortening (look short) (too steep more than 10)

• elongation (less than 10)

FR (film reversal) = film backwards

PP (processing problems)

• fixer cut off (dark area)

• fixer spots (fixer touch film b4 proc)

• Fixer removes unexposed silver halide crystals, preventing those areas from turning dark during development.

Unexposed = film look clear/white

Film exposed to light = film black

Overexpose = film dark from too high time, kVp, or mA

Underexposed = film appear light

• not enough time kVp or mA

Diagnostic BW & PA

for HA overlap contact look like thin radiopaque (white) overlap

should be radiolucent (dark)

More errors

double expose = fil exposed 2x

movement (blurred fuzzy part = PENUMBRA)

reversed film = tiretrack/waffle

ghost image = accesories not removed

led apron artifact = above collar bone

reverse smile line = chin tipped up (smile line curve downwards

Curve too steep = chin tilted DOWN

Teeth ant to focal trough

• teeth too FWD on bite block

• too ant to focal trough (curved 3d area where teeth appear clear/sharp)

• so ant teeth looks narrow + out of focus