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RADIATION TECHNIQUE
DARKROOM
• A scientific laboratory
Where radiography starts and ends
OCCUPATIONAL SAFETY AND HEALTH AGENCY (OSHA)
• It requires RT to wear face mask
RATIONALE: fumes are carcinogenic
DARKROOM DISEASE
• Hypersensitivity to fumes
MAIN FUNCTION OF DARKROOM
• To prevent/protect film from exposure to white light and ionizing radiation during
handling and processing
EXPOSED FILM
• 2-8 times more sensitive to subsequent exposure than unexposed film
RATIONALE: it contains the latent image
LATENSIFICATION
• Increase in sensitivity after exposure to white light or ionizing radiation
IMPORTANCE OF PROCESSING ROOM
1
...
) SIZE
15ft x 9
...
) PROTECTS AGAINST RADIATION
Darkroom can be adjacent to exposure room only if:
CONCRETE: greater than 6 inches
HOLLOW BLOCKS: filled with cement
WOOD: with 1
...
) TOTALLY INSIDE
All automatic processor are located inside

ADVANTAGE: jammed films can be retrieved without exposure to white
light
DISADVANTAGES:
Increased heat/temperature, noise and humidity/moist
B
...
) BULK OUTSIDE
Only the feed tray is located inside
Used only when the darkroom is small
ADVANTAGES: almost no heat, noise and humidity
DISADVANTAGES:
Jammed films can’t be retrieved through white light
Repeat exposure when the films are exposed
4
...
) CLEANLINESS
Avoid SMOKING, EATING and DRINKING
RATIONALE: to prevent artifacts

EFFICIENT DARKROOM
Pertaining to cleanliness
Uncluttered counter tops
6
...
) ILLUMINATION
WHITE LIGHT ILLUMINATION
Overhead light
2-4 fluorescent lamps
48 inches/8 m2
PURPOSE:
Maintenance
Emergency cases
Cleaning
SAFELIGHT ILLUMINATION
DISTANCE: 3-4 ft
WATTAGE:
7
...
) COLORS OF WALL
PASTEL AND LIGHT: reflectance of safelight
ENAMEL AND EPOXY: easy to clean and durable
MATTE FINISH NOT GLOSSY: it will not reflect white light
NEON COLOR: prohibited
Bright Color vs Dark Color: bright color is the best choice
9
...
) DARKROOM ENVIRONMENT
Daily
Maintained clean, well ventilated, organized and safe
B
...
05 OD
Always check the DISTANCE, WATTAGE and FILTERS used
WRATTEN 6B: >550 nm
GBX 2: > 600 nm
ACCEPTABLE: 0
...
) AUTOMATIC PROCESSOR TEMPERATURE
Weekly
Greater than ± 0
...
5 oF
D
...
) DEVELOPER SOLUTION pH
Quarterly/Every 3 months/Weekly
NORMAL pH: 10-11
...
6-10
...
) FIXER SOLUTION
Quarterly/Every 3 months/Weekly
NORMAL pH: 4-4
...
2-4
...
) DEVELOPER SPECIFIC GRAVITY
Quarterly/Every 3 months/Weekly
Not greater than 0
...
) PROCESSOR CONTROL CHART MONITORING
Daily
Early in the morning
After the automatic processor reached its maximum capacity or has been
warmed up
Not greater than 0
...
2
Controls the toe of the characteristic curve
HYDROQUINONE
Film contrast indicator
Second to produced
Black tones
Dmax = greater than 1
...
) MONOCHROMATIC FILM
COLOR: Blue sensitive
GRAINS: Globular
SCREEN PHOSPHOR: Calcium tungstate (not specific emission)
Sensitive to spectrum wavelength of photons
2
...
) PANCHROMATIC FILM
Sensitive to all visible light spectrum
GRAIN TECHNOLOGY
1
...
) TABULAR GRAIN
Tabletop-like structure
Provides bigger surface
For green sensitive film
CALCIUM TUNGSTATE
Broad band colors (Blue, Indigo, Violet)
LINE EMISSION: not specific emission
RARE EARTH
OXYBROMIDE: Blue
OXYSULFIDE: Green
LANTHANUM: Blue
LINE EMISSION: specific emission
LANTHANIDE
ATOMIC #: 57-71
Yttrium: 39
Lanthanum: 57
Gadolinium: 64
GENERAL TYPES OF FILM
1
...
) SCREEN FILM
Indirect exposure o
Uses thinner emulsion
More sensitive to light
Light: 90-99%
X-ray: 1-10%
ADVANTAGES:
Decreased patient dose
Decreased developing time
DISADVANTAGES:
Increased quantum mottle
Blurred image
CLASSIFICATION OF FILM
ACCORDING TO USE
1
...
) THERAPY LOCALIZATION FILM
It serves as a guideline
Wide range of exposures
Direct exposure
Fine grain
ADVANTAGE: increase resolution
DISADVANTAGE: radiation is continuously emitted

SIMULATOR
It used in Cobalt 60
LETHAL DOSE
Dose required to kill cancer cells
TOLERANCE DOSE
It should be greater than lethal dose
TREATMENT FOR BREAST CANCER
Surgery – mastectomy
Radiation Therapy – regional
Chemotherapy – metastases
PALLIATIVE TREATMENT
Lengthening the life in short term basis
CURATIVE TREATMENT
Lengthening of life in long term basis
3
...
) VIDEO FILM
Single emulsion
It uses multiformat camera and laser camera
5
...
) CINE/ROLL FILM

Single emulsion film
With sprocket holes
Movie film
Angiographic film
Cardiac catheterization
Width – 16 mm & 35 mm
Image – 7 x 10 mm & 24 x 35mm
Uses tagaro viewer
Frame Rate – 30-60 frames/sec
100-300 rolls
Black and white
35% actual images
7
...
) COPY/DUPLICATING FILM
Reversal film
Single emulsion
It uses UV lamp and light
Black light bulb
9
...
) AUTOMATIC SERIAL CHANGER
Serial radiography
Angiography
Special procedure
Special protective coating
To prevent scratches
11
...
) POLAROID
Paper-based
Thermal paper
DSA and UTZ
13
...
) UNEXPOSED FILM
Stored in original packaging
RATIONALE: expiration date
Expired Film – Decreased Sensitivity/Loss Speed – Increased mAs
Age Fog/Expired Film – Loss Contrast – Poor Image Quality
2
...
) ARCHIVAL FILM
5 years/10 years
Can be sold
4
...
) GREEN FILM
The most precious in terms of Ag recovery
100% Ag recovery
Ag remain intact
VERTICAL/EDGE/STRAIGHT/UPRIGHT
Storage of film
RATIONALE:
To prevent film to stick to one another
To prevent pressure artifacts
STORAGE TEMPERATURE
10-21 O C/50-70O F
40-60% humidity
MAXIMUM STORAGE
30-45 days at 21 oC/70 oF
Greater than 1 year at 10 oC/50 oF
0 oC – stop film aging process
Film can be used but should be warm up to room temperature at 35 oC/85 oF
Increased Temperature – rapid aging process

ENVIRONMENT
Very important to film
POSSIBLE CONSEQUENCES OF STORING UNEXPOSED FILM IN ENVIRONMENT
WITH IMPROPER TEMPERATURE AND RELATIVE HUMIDITY
Temperature too high: increased fog level
Temperature too low: increased static discharges
Humidity too high: increased fog level
Humidity too low: increased static discharges
STATIC ARTIFACTS
Positive artifacts (black)
NECKLACE
Negative artifacts (white)
TEMPERATURE AND HUMIDITY
Inversely related
Increased Temperature – Increased Heat Fog – Increased Possibility of Static
Artifacts
PACKAGING OF FILM
Photo-inert photoethylene bag or metal foil
RATIONALE: to protect film from moisture and light
FILM STORED
Must be protected from:
Heat
Radiation
Chemical fumes
Pressure
EXPIRATION DATE
Adhere First In First Out (FIFO)
RATIONALE: to beat the expiration date
HANDLING OF FILM
AVOID:
Hand cream
RATIONALE: finger print marks (negative density mark)
Rubber gloves
RATIONALE: static artifacts (positive density marks)
Cotton gloves can be used
KINDS OF FOG THAT CAN
AFFECT THE FILM

1
...
) CHEMICAL/DEVELOPMENT FOG
Fumes
Contaminated developer solution (0
...
) SAFELIGHT FOG
Most common cause of fog
4
...
) SECONDARY RADIATION FOG
Increased kVp – Increased Scattered Radiation – Increased Fog
X-ray – polyenergetic heterogenous beam
20-150 energy/kVp
20-70 – produces scatter radiation
80-120 – remnant radiation
mAs
Controls quantity, amount and number of x-rays
APPEARANCE OF FOG
Gray shades

FACTORS THAT CONTROL SCATTER RADIATION

1
...
) PATIENT THICKNESS, SIZE AND DENSITY
Increased Thickness, Size and Density – Increased Scatter Radiation
3
...
or 14 x 17 in
...
or 8 x 10 in
...
) TOPCOAT/SUPERCOAT/OVERCOAT
A protective covering of gelatin that enclosed the emulsion
Composition: made up of gelatin
Purpose:
Prevent damage to sensitive emulsion layer
Protects the emulsion from scratches, pressure & contamination
Allows rough manipulation of x-ray film before exposure
2
...
) ADHESIVE/SUBSTRATUM LAYER
A thin coating located between the emulsion & base

Adheres one layer of the film
Purpose: allows emulsion & base to maintain proper contact & integrity
4
...
) SUPERIOR PHYSICAL/DIMENSIONAL STABILITY
Maintain its size and shape without contributing to image distortion
2
...
) FLEXIBLE & FRACTURE RESISTANT
It can be snap in the viewbox/negatoscope
4
...
) SEMIRIGID
6
...
) CHEMICAL MEMORY
Remain flat
8
...
) WATERPROOF

PARALLAX EFFECT
Apparent displacement of an image as seen in the radiograph

HISTORY OF FILM BASE

1
...
) CELLULOSE NITRATE
Standard base
Characteristic: flammable
3
...
) POLYESTER (1960)
Film base of choice
Ethylene glycol & dimethyl terapthalate
Characteristics:
More resistant
Superior dimensional stability
BASIC FILM TYPES ACCORDING TO CONSTRUCTION
1
...
) SINGLE-COATED
Films that have emulsion layer on one side only
HALATION
Reflection of screen light transmitted through the emulsion & base
The halo unsharpness that reduces resolution
Produced by the light photons that has already pass through the emulsion
layer for single coated film
FILM CHARACTERISTICS
1
...
0 above base fog
Increased Film Speed – Increased Sensitivity – Increased Density – Decreased
mAs – Decreased Dose
FACTORS AFFECTING FILM SPEED
Number of silver halide crystals
The number of sensitivity center per crystals
The concentration of crystals in the emulsion

The size & distribution of the crystals
FACTORS AFFECTING FILM SPEED IN INTENSIFYING SCREEN
Type/composition of phosphor
Thickness of phosphor
Size of phosphor
Reflectance used
2
...
) EXPOSURE LATITUDE
Margin of errors
Range of exposures that produce OD within straight line region of sensitometric
curve
Inversely proportional to film contrast
High contrast emulsion – narrow latitude
Few factors can be applied
Near to OD required
Low contrast emulsion – wide latitude
Many factors can be applied
PARTS OF THE CHARACTERISTIC CURVE
Base plus fog
Toe
Shoulder
Straight line portion
HUMAN EYE
It has a logarithm of response to OD
OD = Log10 (Io/It)
DENSITOMETER
It measures density
4
...
) SPECTRAL MATCHING
Correctly matching the sensitivity of the film to the color of emission of
intensifying screen
6
...
) RECIPROCITY LAW
OD on a radiograph is proportional only to the total energy imparted to the
radiographic film
Applicable only in direct exposure, but not in screen-film
FILM SENSITOMETRY
Quantitative measurement of the response of film to x-ray and exposure or
development and processing
Frequency:
Early morning when the processor reached its maximum capacity or has been
warmed up
SENSITOMETER
Optical step-wedge
A device that produces a constant simulated, predetermined x-ray exposure
X-ray machine is not utilized
PENETROMETER
Aluminum step-wedge

X-ray machine is utilized
CONTROL FILM/CONTROL BOX
The film used
Exclusively used for film sensitometry
AUTOMATIC PROCESSOR
Develop film
SENSITOMETRIC STRIP/STEP TABLET
Made by exposing successive areas on a film with one exposure
The image from least to maximum OD
11 or 24 strips
Dmax to Dmin
DENSITOMETER/TRANSMISSION DENSITOMETER
A device that measures the percentage of light transmittance
Base Density/Manufacturer’s Film Density: 0
...
1% (3 OD)
GRAPHING PAPER/CONTROL CHART
For plotting the H & D curve
Hurter & Driffield
OPTICAL DENSITY
Human eyes has a logarithm of response
Noticeable
Formula: Log10 (Ii/It) or Log10 (Io/It)
SENSITOMETRIC CURVE
The product of sensitivity
Film characteristic curve or H & D curve
Base Plus Fog: lowest portion (0
...
14 OD
BASE PLUS FOG
Inherent fog cause by processing conditions

Acceptable B+F: 0
...
25 density units above B+F
density and 2
...
) PROTECTIVE COATING
It gives physical protection to the delicate phosphor layer
It provides a surface which can be cleaned without damaging the phosphor
It helps prevent static
Transparent to x-ray
Size: 10-20 micrometer
2
...
) REFLECTIVE LAYER
Intercepts light photons headed in other direction & redirects them to the film
Shiny Substances: Magnesium oxide & Titanium dioxide
Size: 25 micrometer
Crystal Size: 5-15 micrometer
2x Film Speed – 2x Density – ½ mAs
4
...
) DETECTIVE QUANTUM EFFICIENCY
The ability of the phosphor to interact with x-ray
2
...
) SPECTRAL MATCHING
Specific color
4
...
) CALCIUM TUNGSTATE (CaWO4)
Introduced by Thomas Alba Edison
Scheelit: natural tungstate
2
...
) ZINC SULFIDE
For low kVp techniques
It was used for high resolution image quality
Decrease quantum mottle – Increase mAs
4
...
) CALCIUM TUNGSTATE (CaWO4): BLUE
2
...
) THICKER PHOSPHOR LAYER
Increase screen speed – Increase quantum mottle – Decrease recorded detail
Increase screen speed – Increase light emission – Increase density – Decrease
mAs – Decrease patient dose
2
...
) REFLECTIVE LAYER
2x screen speed – Increase quantum mottle – Decrease recorded detail
2x screen speed – 2x light emission – 2x density – Decrease mAs – Decrease
patient dose
3
...
) DYE IN PHOSPHOR LAYER
Same as above
INTENSIFICATION FACTOR
Intensifying action of the screen
A measure of screen speed

Formula:
Exposure w/o screens ÷ Exposure w/ screens
Increase IF – Increase intensifying action
SPEED VALUE
The most common method of designating screen speed
Formula: New mAs = (Old mAs x Old Relative Speed Value) ÷ New Relative
Speed Value
Fast speed – Increase light emission – Decrease sitting requirement
Slow speed – Decrease light emission – Increase sitting requirement
Decrease screen speed – Decrease light emission – Decrease density –
Increase mAs – Increase patient dose
Increase screen speed – Increase light emission – Increase density – Decrease
mAs – Decrease patient dose
Increase crystal size – Thicker phosphor – Increase screen speed
INTENSIFYING SCREEN SPEED
25 – Ultra Detail
50 – Slow/High Resolution/Detailed
100 – Standard/Medium/Par
200 – Fast/High Speed
300 – Ultrafast/Hi-plus
1200 – Rare Earth
RELATIVE SPEED
The ability of the screen to produce light and density
Formula: mAs1/mAs2 = relative speed2/relative speed1
WATER TEMPERATURE
>2
...
0o C/5o F than developer temperature
If water temperature is greater than developer temperature, developer activity
increases
90 SECONDS AUTOMATIC PROCESSOR
33
...
) POINT DEFECT
silver ions moves out from the cubical lattice formation

2
...
) LATENT IMAGE CENTER
Refers to clumping or grouping of silver ions
4
...
) LATENT/POTENTIAL IMAGE
Refers to the image that exists on film after it has been exposed but before it has
been processed
2
...
) DEVELOPER
Convert latent image to visible image
To amplify the amount of metallic silver on the film by increasing the number of
silver
To reduce the exposed SHC into metallic silver

A
...
2 OD
Hydroquinone
Builds up contrast slowly during development period
Principal component
Contrast indicator
Sensitive to light and temperature
PQ: for automatic processing
MQ: for manual processing
B
...
5 or 10-12
C
...
PRESERVATIVE/CYCON
Same with fixer
Prevent rapid oxidation of the reducing agent

Reacts with QUINONE (by produce of Hydroquinone which is a dye), capable of
staining the film and form colorless compound called HYDROQUINONE
MONOSULFATE
STABILIZER: to promote equilibrium of chemicals
ANTI-OXIDANT: prevents internal oxidation
pH = 3-4 (Preservative, Restrainer & Hardener)
E
...
) HARDENER/TANNING AGENTS
Dialdehyde/Glutaraldehyde
For automatic processing only
Added for developer solution to prevent swelling of emulsion
Reduces film transportation problems & preventing damage to the emulsion
Developer: weak/temporary hardener
Fixer: strong/permanent hardener
2
...
) SEQUESTERING AGENTS
Prevent precipitation of calcium sludge
Oily substance & precipitate of aluminum
EDTA: sodium salt of Ethylene Diamine Tetra Acetic Acid
CALGON: sodium hexametaphosphate
CHELATES: boric acid/salts
4
...
) ANTIFROTHANT/ANTI-FOAMING
Prevent bubble formation in the solution
Prevents aerial and external oxidation
Closefitting lids
Mixing paddle
Hose should not be used
6
...
) BUFFER
Developer: Sodium hydroxide/carbonate
Fixer: Acetic acid/Sulfuric acid
Maintains pH value of the solution
OXIDIZED DEVELOPER
Old or exhausted developer
Decrease reducing property (aerial/chemical oxidation)
Product of developing as increased monosulfate
All agent’s activity are decreased, except for Restraining Agent
REPLENISHMENT
Physical and chemical means of maintaining the level of processing
solution

REPLENISHER
A solution containing more reducing agents, activator and preservative but
without restrainer to maintain chemical activity of the processing solution to the
original & in proper dilution with water
MQ Replenisher: without restrainer
PQ Replenisher: with restrainer (BENZOTHIOSOLE)
FLOOD VOLUME REPLENISHMENT SYSTEM
25-50 pcs of 14x14 or 14x17 films developed/day
MICROSWITCH
A device located at the entrance of the automatic processor which controls the
replenishment rate of processing chemicals
Replenishment rate are normally established on the basis how much chemistry is
required per 14 in of film travel
Developer: 60-70 cc or 4-5 mL/in
Fixer: 100-110 cc or 6-8 mL/in
14x14 or 14x17 in: replenishment occurs
8x10 in: no replenishment occurs
Oxidized developer: many big films are developed
Overreplenishment: many big films are developed; increases density
FLOOD/TIMED/STANDBY/TITUS REPLENISHMENT SYSTEM
Donald Titus of Kodak
Replenish every 10 mins or 1 hour
<25-50 14 in films
No microswitch but with timer
Many films are replenished

SUPERADDITIVITY/SYNEGISM
Activity of each individual component of reducing agent in solution is less that the
activity when two components are combined
CLASSIFICATION OF DEVELOPER
1
...
) PQ DEVELOPER
Phenidone-hydroquinone developer
15 times more superadditivity than MQ developer combination
FACTORS AFFECTING DEVELOPMENT TIME
Temperature of the solution:
Increase temperature – Increase activity – Decrease time of development
Size of film:
Big film size – Longer DT
Size of grains of the film:
Larger/thicker SHC – Increase development time (Same as direct exposure)
Agitation: circulation system
Increase agitation – Increase interaction – Shorter DT
Exhaustion of the developer:
Decrease developer activity – Longer DT
2
...
CLEARING AGENT/FIXING AGENT
Sodium thiosulfate (Manual Processing)
Ammonium thiosulfate/hypo (Automatic Processing)
Dissolves unexposed AgBr crystals, thereby producing a permanent visible
image
Oxidized developer: strong ammonia odor

Hyporetention/Thiosulfate retention:
Silver sulfide stain
Pale yellow or brown color (brown stain)
WASHING
Very important to archival quality
Prevent hyporetention
THIO
Function is to dissolve silver
Thio silver sulfate: Ag enter to thio
Hyporetention
HYPOKIT
A chemical that is dropped to the film
Presence of thiosulfate = changes color
Many thiosulfate = brown color
Chemical used = acetic acid, silver nitrate & solvent

AMMONIUM THIOSULFATE VS SODIUM THIOSULFATE
Ammonium: for automatic processing; better than sodium
Fixes the film more rapidly than Na thiosulfate when present equivalent
concentration
Sodium: for manual processing
B
...
2-4
...
PRESERVATIVE / STABILIZER / CYCON / ANTI-OXIDANT
Sodium sulfite/Potassium sulfite
Maintains equilibrium of the chemical in the solution
Prevents internal oxidation
Prevent aerial oxidation of fixing agent
Prevent decomposition and precipitation of sulphur from the thiosulfate fixing
agent
Responsible in removing silver to thio
Oxidized developer: increase monosulfate
Oxidized fixer: increase sulfurization

D
...
SOLVENT
Water
SEQUESTERING/BUFFERING AGENT
Boric acid/salts
An anti-sludging agent which delay precipitation of Al hydroxide (alkaline)
Increases pH
Hyponeutralizer
Solution used between fixing stage and the final washing cycle to decrease the
washing time of the film to prevent hyporetention
Clearing
The process by which the fixing agent acts on the unexposed to form soluble
complexes which eventually diffuses out of the film into fixing solution
Fixing Time = 2x Clearing Time (OLD)
Fixing Time = Clearing Time + Hardening Time (NEW)
3
...
8o C/5o F of developer temperature
MAIN FUNCTION: to stabilize developer temperature
Change = 0
...
) DRYING
Final process
Removes 85-90% of moisture from the film so that it can be handle easily and
stored while maintaining quality of the diagnostic image
10-15% remaining
Consuming more electricity (60-80% electrical consumption)
Rationale:
Filament = 1500-2500 W
Air blower = 100-300 cu-ft/min
TEMPERATURE CONTROL

Tempering system
Increase and decrease in developing temperature can adversely affect the
quality of radiographic image
90 secs = 33
...
) Developer Tank
2
...
) Water Tank
CASCADE COMPARTMENT
2 wash tank
AUTOMATIC PROCESSOR
A device that has roller transport system
A device that comprises chemical tanks
A dryer system for processing of radiographic film
PROCESSING CYCLE/DRY-TO-DROP TIME
Time to process a single piece of film
45 seconds to 3
...
) VERTICAL TRANSPORT SYSTEM

Used in automatic processor
Advance the film through different stages
All rollers & feed tray
A
...
TRANSPORT/PLANETARY ROLLER
Vehicle transport
Moves the film through the chemical tanks and dryer
Size: 1 inch
C
...
CROSSOVER ROLLER
Moves the film from one tank to another
From fixer to developer
E
...
) RAPID PROCESSING
30 seconds
Useful for angiography, special procedure, surgery & emergency room
More concentrated chemicals
Higher developer and fixer temperature
2
...
) DAYLIGHT PROCESSING
2 minutes
Receive film in 15 seconds
Uses microprocessor
Advantages: no darkroom required & speed
RADIOGRAPHIC ARTIFACTS
Unwanted image
POSITIVE DENSITY ARTIFACT
Radiolucent appearance

Halfmoon marks: bending & kinking of film
Scratching/Abrasion: fingernail/scratch
Static discharge: sliding films over flat surface
Fogging: exposure to white light, ionizing radiation, heat, safelight fog & expired
film
Density outside collimation area: off-focused/off-skin radiation
NEGATIVE DENSITY ARTIFACT
Radiopaque appearance
Finger print: moisture on finger transferred to the film before exposure
Scratches/Abrasions: scrapping or removing emulsion
Foreign objects: some unintended object in the imaging chain
Non-specific decrease: dirty screens or cassette
SILVER RECOVERY
1
...
) METALLIC REPLACEMENT / DISPLACEMENT
Used of aluminum steel wool
Cartridge
Least expensive and simplest
3
...
) Photographic Industry: 30%
2
...
) Sterling Industry: 15%

PART IV

RADIOGRAPHY
Used of ionizing radiation
RADIOGRAPH
Image produced with good quality
TECHNICAL COMPETENCY
Operation of the control panel
Selection of appropriate accessories
Use of terminologies in evaluation of radiograph
Measurement
Evaluation of result
CHARACTERISTIC OF RADIOGRAPH
Exposure factor is adequate
Adequate penetration
Sufficient density and contrast
Field size selection is appropriate
No motion
Voluntary: good communication
Involuntary: decrease exposure time
KILOVOLTAGE PEAK (kVp)
Controls energy of the beam
Penetrating ability
Accelerates the electron
Wavelength of photon
Affects blackening of film by 15% rule
Affects the production of scattered radiation
Controls radiographic contrast
Affects exposure to patient
MILLIAMPERAGE (mA)
Number of electrons
Number of x-ray photons
Blackening
Influences focal spot blooming
Increase actual focal spot size when the tube current is increased
TIME (s)
Length of exposures
Number of photons exposing the patient with mA-timer relationship

DISTANCE
FFD/SID: distance from the focal spot to the recording medium
Affects blackening of film
Inverse square law

RADIOGRAPHIC QUALITY
A
...
GEOMETRIC ASPECT/SHARPNESS
Definition: clarity and sharpness of structural lines
Distortion: undesired change in the size and shape of the anatomic part
RADIOGRAPHIC DENSITY
Determines the amount of density on finished radiograph
Acceptable Range: 0
...
0 OD
Directly related to mAs
FACTORS AFFECTING DENSITY
Controlling factor: mAs
kVp, Distance, Grids, Film Screen Speed, Collimation, Anatomic Part, Anode
Heel Effect, Reciprocity Law, Generator Output, Filtration & Film Processing
FACTORS TO REMEMBER IN DENSITY
Increase mAs: great density
Fastest screen film combination: great density
Lowest grid ratio: great density
Direct exposure technique: least density
Shortest distance: great density
Longest time: great density
Highest kVp: great density
Smallest area of collimation: least density
INFLUENCING FACTORS
15% kVp rule
Increase Density: original kVp + 15%
Decrease Density: original kVp –15%
Maintain Density: original kVp + 15%, mAs ÷ 2
Decrease Patient Dose: original kVp + 15% and mAs ÷ 2
Increase Image Quality: original kVp – 15% and mAs x 2
ANODE HEEL EFFECT
Used long FFD and shortest/smallest field size

Anode Side: 75%
Cathode Side: 120%
Difference: 45%
INVERSE SQUARE LAW
Intensity of x-ray is inversely proportional to the square of distance
RECIPROCITY LAW
States that OD on a radiograph is proportional only to the total energy imparted
to the radiographic film
Accurate only on direct exposure
Fails in screen-film
RADIOGRAPHIC CONTRAST
To make detail visible
Attenuation and differential absorption
TYPES OF CONTRAST
1
...
) FILM CONTRAST
Inherent in the film base
Affects by film (IR), film type & direct/IS exposure

CHARACTERISTIC OF CONTRAST SCALE
1
...
) LONG SCALE
Large number of useful densities on the radiograph
Little change from one density to another
Low contrast, less contrast & wider latitude
High kVp technique
HIGH kVp
LOW kVp

Long scale contrast
Short scale contrast
Low contrast
High contrast
Less contrast
More contrast
Wide latitude
Narrow latitude

CONTRAST
Influencing factor: kVp
Grids, Collimation, OID, CM, Processing & Air-gap Technique
CASTS
Fiber glass: no increase in exposure factor
Wet Plaster: increase mAs 3x
Dry Plaster: increase mAs 2x
SPLINTS
Fiber glass: no increase in factor
Inflatable (Air): no increase in factor
Wood, Aluminum & Plastic: increase exposure if they are in the path of primary
beam

PATHOLOGY
1
...
) DESTRUCTIVE DISEASES
Decreases absorption characteristic
Decrease kVp
Active TB, Atrophy, Bowel obstruction, Cancer, Degenerative arthritis,
Emphysema, Osteoporosis & Pneumothorax

RADIOGRAPHIC DEFINITION/RECORDED DETAIL
Clarity and sharpness
Umbra: true image
Penumbra: geometric unsharpness; the blurred areas around the umbra
DISTORTION
Used to removed superimposition
Magnification:
Distortion in size
Increase FFD – Decrease OFD – Decrease magnification
Foreshortening/Elongation:
Irregular magnification
Distortion in shape
Affected by CR part-film alignment
RELATIONSHIPS
Increase mAs – Increase Density
Decrease mAs – Decrease Density
Increase kVp – Increase Density – Decrease Contrast
Decrease kVp – Decrease Density – Increase Contrast
Increase SID – Decrease Density – Increase Detail – Decrease Distortion
Decrease SID – Increase Density – Decrease Detail – Increase Distortion
Increase OID – Decrease Density – Increase Contrast – Decrease Detail –
Increase Distortion
Decrease OID – Increase Density – Decrease Contrast – Increase Detail –
Decrease Distortion
Increase Grid Ratio – Decrease Density – Increase Contrast
Decrease Grid Ratio – Increase Density – Decrease Contrast
Increase Film-Screen Speed – Increase Density –Decrease Detail
Decrease Film-Screen Speed – Decrease Density – Increase Detail
Increase Collimation – Decrease Density – Increase Contrast
Decrease Collimation – Increase Density – Decrease Contrast
Increase Focal Spot Size – Decrease Detail
Decrease Focal Spot Size – Increase Detail
Increase CR Angle – Decrease Density – Decrease Detail – Increase Distortion
CONTROL OF SCATTER RADIATION
PRODUCTION OF SCATTER RADIATION
TWO TYPES OF X-RAYS RESPONSIBLE FOR THE OPTICAL DENSITY &
CONTRAST ON A RADIOGRAPH
1
...
) X-rays that are scattered within the patient through Compton interaction
REMNANT X-RAYS

X-rays that exit from the patient
IMAGE-FORMING X-RAYS
X-rays that exit & interact with the image receptor
PROPER COLLIMATION
Effects:
Less scatter radiation
Reduces patient dose
Improves contrast resolution
THREE FACTORS CONTRIBUTE TO INCREASED SCATTER RADIATION
1
...
) Field Size
3
...
) Beam Restrictors
2
...
) APERTURE DIAPHRAGM
Simplest type
A flat piece of lead that has hole in it
2
...
) COLLIMATOR
Best type
Useful and accepted type of beam-restricting device
4
...
) GRID STRIPS/LINES
Radiopaque material
Purpose: it absorbs scattered radiation
Composition: lead (Pb)
Advantages:
Easy to shape
Inexpensive
High atomic number
High mass density
Characteristics: thin & high absorption properties
Size: 50 μm wide

2
...
) Grid Strip Thickness (T)
2
...
) Grid Height (h)
GUSTAVE BUCKY (1913)
He invented stationary grid
He demonstrated the technique for reducing the amount of scatter radiation that
reaches the IR

GRID CONTRUCTION CAN BE
DESCRIBED BY:
1
...
) GRID FREQUENCY

The number of grid strips per centimeter or inches
High Frequency: less distinct grid lines on a radiograph
Range: 25-45 lines/cm or 60/110 lines/inch

=

T = grid strips thickness/width
D = interspace width
High Frequency Grids:
Requires radiographic technique
Result: higher patient radiation dose
GRID P



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