converts a latent radiographic image to a visible one via chemistry

Developer - alkaline

     changes silver halide crystals into black metallic appearance

Fixer - acidic

     stops the action of the developer and preserves the image in film

Water - wash bath to rinse the chemicals from film and prevent cross contamination

affected by temperature (usu 95F), oxidation, usage, excessive light and age

MANUAL - 3 separate tanks (developer, wash and fixer)

AUTOMATIC - 90 sec to 3 min

Safelights

     matched to film sensitivity

Film ID system

Film bin

Thermometers and timers

Radiographic quality

Density

Contrast

Detail

Distortion

degree of blackness on film; primarily controlled by mA

differences between adjacent radiographic densities; primarily controlled by kVP; high/short black white or low/long scale gray

sharp edges to structures/clarity; motion and penumbra (blurring of edges); SID, OID

misrepresentation of size, shape and/or location of structures being imaged; foreshortening (not parallel) and elongation (CR is angled)

Radiation safety

     Units of measure

Roentgen (R) - exposure measured in air

rad (r) - radiation absorbed dose; exposure in soft tissue

rem - radiation equivalent man; occupational exposure

Radiation safety

     Effects

Potential to ionize matter

affects/changes matter on a cellular level (DNA)

Reparable damage:  cataracts

Irreparable damage:  Genetic mutations, cancer, life shortening

     Genetic - effecting offspring

     Somatic - effecting individual subjected to radiation

          erythema - reddening of skin

          swuamous cell carcinoma

Radiation safety

     Sources of in Radiology

Primary - primary beam  (cahtode > anode > out of machine)

Scatter - from patient, table  (lower energy)

Leakage - small amount from xray tube housing

Fluoroscopy - real time radiography - higher dose, continuous beam

Radioisotopes - nuclear medicine studies

Radiation safety

     Personnel monitoring devices

Film badges

Thermoluminescent Dosimeter (TLD) / OSL

     contains lithium/calcium fluoride crystals

     stores energy received from xrays

Pocket Dosimeter - instant readout

Radiation safety

     Protection Devices

Time

Distance - Inverse Square Law:  double the distance will decrease exposure by 4

Shielding

     lead aprons, thyroid shields, gloves

     lead/concrete walls

     filters

     collimation

Console

Transformer - converts low voltage AC electricity into high voltage DC that is utilized by teh xray tube

Xray tube - 2 main parts in a glass vacuum protected by metal housing

     Cathode - negative charge

          filament - tungsten wire

          focusing cup - concentrates electron beam

     Anode - positive charge

          tungsten disc - focal spot where electrons bombard

               Stationary - used in lower output machines

               Rotating - spinning creates greater area of focal spot/ higher output and heat capacities

generated when high speed electrons collide with matter

     electrons @ cathode

          amount controlled by mA selection

          speed of travel controlled by kV selection

collision of electrons with atoms of tungsten anode create xrys

amount is proportional to amount of electrons - mA

energy level (penetration) proportional to speed - kV

Collimator - lead shutters at right angles to one another (light and mirror); ability to focus xray beam to desired area

Filtration - absorbs low energy xrays

Transmitted

     low density; black; air, gas

Absorbed

     high density; white; bone, metal, contrast, foreign body

Scattered

     intermediate density; gray; tissue, organs, fat, fluids

Radiographic film

     Construction

Coating - protective layer

*Emulsion - two sided layer

     silver hallide crystals in gelatin

     amount of crystals determine film characteristics

Base - center supported layer/tinted

Radiographic film

     Types

     Speed

Non screen film; single sided emulsion

     direct xray exposure, dental

Screen film; double sided emulsion

     light xray exposure

High - large crystals / low detail

Medium - more commonly used

Slow - small crystals / high detail

composed of fluorescent phosphors in a plastic base

emit light when exposed to light

Speeds

     High/rapid - large phospors, decreased detail

     Fast/medium - most popular

     Slow/detail - small phospors, best detail