Radiation safety and protection measures are important to minimize radiation exposure for patients and dental staff. Early pioneers in dental radiography suffered health effects from excessive radiation doses. Radiation can come from natural sources like cosmic rays and radioactive elements in the ground, or man-made sources like medical imaging. Protection techniques include using thyroid collars and lead aprons for patients, fast film, rectangular collimation, and selecting proper exposure factors. Proper handling and processing of films is also needed to avoid retakes and reduce unnecessary radiation exposure.

1. RADIATION SAFETY AND PROTECTION
PART-1

2. INTRODUCTION
• Many of the early pioneers in dental radiography
suffered from adverse effects of radiations.
• Resulting into loss of fingers , limbs and ultimately
their lives due excessive doses of radiation.
• Hence radiation protection measures need to be
taken to minimize radiation exposure to both
patients and dental radiographer before during and
after exposure to X-rays

3. Sources of Radiation Exposure
Sources
NATURAL
MAN MADE
Cosmic Sources
Terrestrial Sources
A,External sources
B,Internal sources

4. NATURAL RADIATION
• Background radiation from cosmic and terrestrial
sources yields an average annual effective dose of about
2.4 millisieverts (mSv) worldwide.

5. Cosmic Sources
Cosmic radiation includes
• Energetic subatomic particles,
• Photons from the sun and supernova and
• To a lesser extent, the particles and photons (Secondary cosmic
radiation) generated by the interactions of primary cosmic
radiation with atoms and molecules of the earth’s atmosphere.
Exposure from cosmic radiation
• At sea level - 0.24 mSv per year
• At an elevation of 1600 m - 0.50 mSv per year.

6. External sources
Soil
Terrestrial Sources
Internal sources
Radon and other
radionuclides that
are inhaled or
ingested.

7. External Radiation:
• Soil - Radioactive nuclides like potassium 40 Radioactive
decay products of uranium 238 and thorium 232.
• The average terrestrial exposure rate is about 0.5 mSv per
year

8. INTERNAL SOURCES:
Radionuclides that are taken up from the external environment by
ingestion.
Radon:
• A decay product in the uranium series,
• It is the largest single contributor to natural radiation (1.2 mSv ).

9. MAN-MADE RADIATION
3 major groups:
• Medical diagnosis and treatment,
• Consumer and industrial products and sources,
• other minor sources.
It is estimated that the average doses from medical exposures are
comparable to natural background exposure.

10. • The hazards of radiation are now well documented and the
radiation protection measures can be used to minimize the
dental exposure of both the patient and the dental
radiographer.

11. Radiation Protection can be
• 1.patient protection
• 2.operator protection
• 3.environment protection

12. PATIENT PROTECTION
• Patient protection techniques can be used before, during and after exposure.
• BEFORE EXPOSURE :
1.Prescribing dental radiographs.
2.Proper equipment.
• DURING EXPOSURE :
1. Thyroid collar
2. Lead apron,
3. Fast film,
4. Film holding devices
5.Exposure factor selection
6. Proper technique
7.source to skin distance
• AFTER EXPOSURE :
• 1.Proper film handling
2.Proper film processing:

13. 1. Prescribing dental radiographs:
The first important step in limiting the amount of x-radiation
received by the dental patient is proper prescribing or ordering
of dental radiographs.

14. • The dentist uses professional judgment to make decisions about
the number, Type & frequency of dental radiographs.
• Every patient’s dental condition is different & consequently every
patient should be evaluated for dental radiographs on an
individual basis.
• A radiographic examination should never include a
predetermined number of radiographs nor should radiographs
should be taken at predetermined time intervals.

15. 2.PROPER EQUIPMENT
• The dental x-ray tube must be equipped with appropriate
aluminum filters, lead collimators & position indicating devices.

16. FILTRATION:
• The purpose of aluminum disks is to filter out longer wavelength,
low energy x-rays from x-ray beam.
• Filtration of the x-ray beam results in a higher energy & more
penetrating useful beam.
1. Inherent filtration: filtration resulting from absorption of X-ray
as they pass through
a. Glass wall of the x-ray tube
b. Insulating oil and
c. Barrier Material - usable beam outside the tube enclosure
• Inherent filtration of dental x-ray machine is approximately 0.5
to 1.0 millimeter of aluminum.

17. • 2. Added filtration:
• Refers to placement of Al disk in the path of X-ray beam between
collimator and tube head seal which is added externally.
• It should try to absorb maximum low energy photon.
• Aluminum disks can be added to the tube head in 0.5 mm
increments
3.Total filtration:
• Inherent filtration + Added filtration.
• According to state and fedral law regulation the required thickness
of total filtration should be
• 1.5mm of aluminum to 70KVp
• 2.5mm for all higher voltages.

18. • WEDGE FILTER
• This filter is like sledge
• Occasionally used in diagnostic radiology to obtain film of
more uniform density
• Used when the part being examine is thinner than other side
within the field.
• Less radiation is absorbed by thinner part of filter so more is
available for thicker part.

19. COLLIMATION:
• Collimator is used to restrict the size & shape of
x-ray beam & to reduce patient exposure.
• Scattered radiation minimized by collimating the beam.
• It reduces Pt exposure and improves image quality
• Types : 1.tubular
2.slit type
3.round
4.rectangular

20. collimated
beam
collimator
target
(x-ray source)
front views side view
Collimation
2.75 inches (7 cm) = maximum diameter of circular beam or maximum length
of long side of rectangular beam at end of PID.

21. • The collimator may have either a round or rectangular opening.
• When using a circular collimator, federal regulations require that
the x-ray beam be collimated to a diameter of no more than 2 3/4
inches as it exits from position indicating device & reaches the
skin of the patient.
• These have larger diameter then that of size 2 films-increased
exposure to pt

22. • Since a rectangular collimator decreases the radiation dose by
up to fivefold as compared with a circular one, radiographic
equipment should provide rectangular collimation for
exposure of periapical and bitewing radiographs. (ADA,
2006).

23. POSITION INDICATING DEVICE:
appears as an extension of the x-ray tube head & is used to direct the
x-ray beam
There are three basic types of PID’s
1. conical
2. rectangular
3. round.
• Of the three types of PID the rectangular type is most effective in
reducing patient exposure.

24. To limit of the size of the x-ray beam.
A rectangular position-indicating device (PID) –
• Has an exit opening of 3.5 × 4.4 cm (1.38 × 1.34 inches)
reduces the area of the patient’s skin surface exposed by 60%
over that of a round (7 cm) PID.
• Make aiming the beam difficult (cone cutting), a film-
holding instrument is recommended

25. • Alternatively, film and sensor positioning devices with
rectangular collimators may be used with round aiming
cylinders .

27. DURING EXPOSURE:
• A thyroid collar, lead apron, fast film, film holding devices
are all used to limit the amount of radiation received by
patient.

28. 1. THYROID COLLAR: the thyroid collar is a flexible lead shield
that is placed securely around the patient’s neck to protect the
thyroid gland from scatter radiation.
• it is recommended for all intra oral films , however it is not
recommended for extra oral films.

29. 2. LEAD APRON: it is a flexible shield placed over the patients
chest & lap to protect the reproductive & blood-forming tissues
from scatter radiation;
the lead prevents the radiation to reach the radiosensitive
organs.

30. 3. FAST FILM:
Film of a speed slower than E-speed should not be used for
dental radiographs. (ADA, 2006)
Currently different film's which are used are
• F-speed or in-sight.,
• E-speed film or ektaspeed, &
• D-speed film or ultra speed.
Clinically, film of speed group E is almost twice as fast (sensitive)
as film of group D and about 50 times as fast as regular dental
x-ray film.

31. • The current F-speed films require about 75% the exposure of
E-speed film and only about 40% that of D-speed.
• Multiple studies have found that F-speed film has the same
useful density range, latitude, contrast, and image quality as D-
and E-speed films and can be used in routine intraoral
radiographic examinations without sacrifice of diagnostic
information.

32. • Current digital sensors offer equal or greater dose savings
than F-speed film and comparable diagnostic utility.

33. Extraoral radiography :
• Rare-earth intensifying screens are recommended...
combined with high-speed film of 400 or greater. (ADA,
2006)
• Compared with the older calcium tungstate screens, rare
earth screens decrease patient exposure by as much as 55%
in panoramic and cephalometric radiography.

34. • Unlike digital intraoral imaging, there is no significant dose
reduction to be gained by replacing extraoral screen-film systems
with digital imaging.
• Image resolution with digital systems is comparable to that
obtained with rare earth screens matched with appropriate film.

35. 4. FILM HOLDING DEVICES:
a. stabilize the film.
b. reduces the chance of movement.
c. prevents unnecessary radiation.

36. 5.Exposure factor selection:
• Exposure factor selection also limits the amount of x-
radiation exposure a patient receives.
• The dental radiographer can control the exposure factors by
adjusting the kilo voltage peak, mill amperage, & time settings
on the control panel of the dental x-ray machine.
• Operating potential of dental x-ray machine should range
between 70 to 90kvp, keeps patient exposure to minimum.

37. 6. Proper technique:
Proper technique helps to ensure the diagnostic quality of films
& to reduce the amount of exposure a patient receives.
ALL RETAKES MUST BE AVOIDED…

38. 7.Source-to-Skin Distance:
• Use of long source-to-skin distances of 40 cm, rather than short
distances of 20 cm, decreases exposure by 10 to 25 percent.
• Distances between 20 cm and 40 cm are appropriate, but the
longer distances are optimal. (ADA, 2006).
• As the x-ray beam will be less divergent.
• The use of a longer source-to-object distance also results in a
smaller apparent focal spot size and thereby theoretically
increases the resolution of the radiograph

39. AFTER EXPOSURE:
1. Proper film handling:
• Proper film handling is necessary to produce diagnostic
radiographs and to limit the patient exposure to radiation.
2. Proper film processing:
• Improper film processing can render films non-diagnostic, there
by requiring retakes and needlessly exposing the patient to excess
radiation

40. THANK YOU..