ROENT MIDTERM Flashcards
FILM PROCESSING REFERS TO A
SERIES OF STEPS THAT PRODUCE A
VISIBLE PERMANENT IMAGE ON A
RADIOGRAPH
DENTAL FILM PROCESSING
Convert latent image on the film into
a visible image
To preserve the visible image so that
it is permanent and does not
disappear from the dental
radiograph
Aim of processing
FILM PROCESSING
- DEVELOPING
- RINSING
- FIXING
- WASHING
- DRYING
Main action of the developer is to
chemically reduce all the silver ions
in the exposed crystals of silver
bromide ( with a latent image) to
metallic silver
DEVELOPER SOLUTION
- A continuous, gentle rinsing for 30
seconds in water is necessary after
developing
Purpose:
- To dilute the developer and slows
down the development processing
- To remove alkali activator thus
preventing neutralization of acid
fixer
RINSING
- Used in the fixing process.
Purpose:
- To dissolve and remove the
underdeveloped silver halide crystals
causes the film to be dark and non
diagnostic
- To harden and shrink film emulsion
during the process
FIXING SOLUTION
- Films are dried with the help of x-ray
dryer in a dust free area. - While drying, films should not touch
each other to avoid sticking of the
film
Drying
- The objective of washing is to
remove residual processing
chemicals and silver salts from the
radiograph
Washing the film
Automatic Processor Advantages:
- Time saving
- Constant film quality is achieved,
due to fixed processing cycles - Need for dark room is eliminated
- Less floor space is required
- Chemicals can be replenished
automatically by machine - Large number of films can be
processed continuously
FUNCTION
Reducing agent
ACTION
Increases
reduction potential of crystals and brings
out contrast
HYDROQUINONE
Automatic Processor Disadvantages:
- Equipment is relaLvely expensive
- Strict maintenance and regular
change is required, dirty rollers
produce marked films - Films may get lost in the tank
FUNCTION
Alkaline activator
ACTION
Softens emulsion to reach crystals
SODIUM
CARBONATE
FUNCTION
Reducing agent
ACTION
Bring out gray shade
Elon
(monomethylparaaminophenol)
FUNCTION
restrainer
ACTION
Prevent
developer from reducing unexposed crystals
Potassium bromide
FUNCTION
preservative
ACTION
Prevents rapid oxidation of chemical
Sodium sulfite
FUNCTION
solvent
ACTION
Medium for dissolving chemicals
Water
FUNCTION
acidifier
ACTION
Neutralizes developer
Acetic or sulfuric acid
FUNCTION
Clearing Agent
ACTION
Clears unexposed silver halide
Ammonium thiosulfate/ Na thiosulfate
FUNCTION
hardener
ACTION
Shrinks and hardens emulsion
Aluminum chloride/sulfide k alum
- A well planned dark room makes the
processing easier, which should be at
least 4x5 feet (1.2x1.5m). - The room should be well venLlated
to supply fresh air for the comfort of
the individual working in the area.
DARK ROOM
Characteristics for darkroom:
a. Convenient locaLon and adequate
size
b. Ample working space with adequate
storage
c. LighLng
d. Temperature and humidity
controlled
e. Darkroom plumbing
f. Miscellaneous
- Two types of lighting are essential in
darkroom
I. Room lighting (white
illumination)
II. Safe lighting
General safety rules in darkroom
- Limit access to the darkroom. Only
approved persons with safety
training should be allowed to work
in the room - Keep the work area clean
- Wet and dry areas should be clearly
separated - Always segregate chemicals
- Do not store chemicals on the floor
- Do not eat, drink, or smoke in the
darkroom - Always wash hands with soap and
warm water after working with
chemicals
WAYS OF REDUCING RADIATION EXPOSURE TO THE PATIENTS
- ALARA CONCEPT (As Low As
Reasonably Achievable) - Digital radiography 80% dose
reduction
Safety measure for operator protection
- Only the operator and patient are
permitted in the x-ray room. - Operator will stand in a safe place:
- 6 feet away not in direct beam
- behind an appropriate barrier
- outside the room if you cannot get
6 feet away - Never hold the film or tubehead
during exposure.
TRAID OF RADIATION SAFETY
- TIME
- DISTANCE
- SHIELDING
The exposure time is related to
radiation exposure and exposure
rate ( exposure per unit time) as
follows: Exposure = exposure rate x
time
TIME
The exposure to the individual
decrease inversely as the square of
distance. This is known as the
inverse square law, whish is stated
mathematically as: I = 1/D2
DISTANCE
A person standing twice as far from
the x-ray machine will be receive
one forth the radiation
Inverse square law
Materials such as concrete, lead will
attenuate radiation (reduce its
intensity) when they are placed
between the source of radiation and
the exposed individual.
Shielding
Types of Room shielding
a) X-ray equipment room shielding
b) Patient waiting room shielding
Includes all the radiation passing through the tube housing, other than the useful
radiation.
Leakage radiation
Type of radiation to be considered for
effective shielding
- Useful beam
- Leakage radiation
- Scattered radiation
Type of shielding
- Xray tube shielding (source
shielding) - Room shielding
a) X-ray equipment room shielding
b) Patient waiting room shielding
c) Control room shielding - Personal shielding
- Patient shielding
Which has undergone a change in direction
during passage through matter.
Scattered radiation
Radiation passing through the tube aperture, previously called primary beam
Useful beam
- X rays produced in the tube are
scattered in all directions - The x ray tube housing is lined with
thin sheets of lead to protect both
patients and personnel from leakage
X-ray tube shielding (source
shielding)
The control room of an x-ray
equipment is secondary protective
barrier which has two important
aspects:
a) The wall and viewing window of
the control booth should have lead
equivalents of 1.5mm.
b) The location of control booth,
should not be located where the primary beam falls directly, and the
radiation should be scattered twice
before entering the booth.
Shielding of x-ray control room
They are designed to protect
individuals located outside the x-ray
rooms from unwanted radiation.
- 2mm lead ≅25 mm layer of high
quality barium plaster ≅ 150 mm of
concrete ≅ 225 mm of solid bricks
Room Shielding (Structural
Shielding)
Should be used as and when necessary
which comprise of:
- Lead Aprons
- Eye glasses with side shields
- Hand gloves
- Thyroid shields
Shielding Apparel
- Personnel should remain in the
radiation environment only when
necessary (step behind the control
booth, or leave the room when
practical) - The distance between the personnel
and the patient should be maximized
when practical.
Personnel Shielding
- Aprons are shielding apparel
recommended for use by radiation
workers. - These aprons protect an individual
only from secondary (scattered)
radiation, not the primary beam.
Shielding Apparel Lead
Care of the Lead Apparel
It is important that lead aprons are not
abused, such as by:
a) Dropping them on the floor
b) Piling them in a heap
c) Improperly draping them over the back of
a chair
- Radiation protection of the patient
involves both technical and medical
decisions. - The technical decisions related to
the choice of the appropriate
equipment and to the technique.
Patients Shielding
- Patient waiting areas are provided
outside the x-ray room. - Red Light and warning place card is
provided at a conspicuous place
outside the x-ray room
Patient Waiting Area
- Dental personnel and patients are at
increased risk for acquiring
tuberculosis, herpes viruses, upper
respiratory infections, and hepatitis
strain A through E.
Infection control
Key steps in Radiographic Infection Control
Apply universal precautions:
- Wear gloves during radiographic
procedures - Disinfect and cover x-ray machine,
working surfaces, chair and apron. - Sterilize non disposable instruments
Use barrier – protected film sensor
or disposable container
- Prevent contamination of processing
equipment
