radiation protection protocols for dental professionals

1. RADIATION SAFETY AND
PROTECTION FOR
DENTAL RADIOGRAPHY
PREPARED BY
DR. NITIN SHARMA
Postgraduate Student
Dept. Of Oral Medicine & Radiology

2. Introduction
Licensed dentists play an important role in maintaining
radiation exposures of patients and staff as low as reasonably
achievable (ALARA). Greater numbers of intra-oral
radiographs are being requested and a wide range of other
dental radiographic examinations (panoramic, cephalometric)
are being performed on a routine basis with the addition of
advanced imaging modalities (CBCT). Individuals who operate
dental X-ray equipment must have a basic knowledge of the
inherent health risks associated with radiation and must have
demonstrated familiarity with basic rules of radiation safety.

4. Responsibilities of Licensed Dentist and X-ray
Machine Registrant
1. Registration of Dental Radiographic Equipment
All institutes who are possessing diagnostic x-ray
equipments are required to obtain Licence for operation
from AERB (Atomic Energy Regulatory Board).
To facilitate issuance of licence, AERB has launched an
e-governance application e-LORA(e-Licensing of Radiation
Applications).

6. 2. Radiation Protection – General Requirements
 Take all precautions necessary to provide reasonably adequate
protection to the health and safety of individuals.
 Provide radiation safety rules to dental personnel
 Individuals who requires use of X-rays
should be provided individual or
personnel monitoring devices.
 Assure that dental personnel do not
stand in the path of the useful
beam.

7.  Dental personnel must not expose any individual to the useful beam
for training or demonstration purposes
 In areas or rooms where X-ray equipment is used, post a sign (that
may include the radiation symbol) stating: CAUTION X-RAYS
 Dental X-ray equipment and imaging software should be operated
only by individuals adequately instructed in safe operating procedures
 Maximum permissible dose equivalent (MPD)
• Whole body (total effective dose equivalent) – 5 rem or 0.05Sv
• Skin and extremities (shallow-dose equivalent) – 50 rem or 0.5 Sv
• Lens of the eye (eye dose equivalent) – 15 rem or 0.15 Sv

8. Dental Radiographic Machine Requirements
A. X-ray Tube Housing : “DIAGNOSTIC TYPE TUBE HOUSING”
Leakage radiation does not exceed 100 mrems, or 1mSv, in
any one hour at a distance of 1 meter (39.37 inches)

9. B. Collimating Device
C. X-ray Beam Filtration
 Only the X-rays with higher energies can penetrate the tissue of
the patient’s face and react with the image receptor area.
 Low-energy X-rays that have no effect on image production and
are absorbed by the tissues, can cause tissue damage.

10. The regulations specify the minimum
total filtration as shown below:
Tube Operating Minimum Total
Potential (kV) Filteration
Below 50 0.5
50 to 70 1.5
71 and above 2.5
(“Aluminum-equivalent” is defined as
a substance equivalent to aluminium
in its ability to absorb preferentially
less penetrating radiation.)

11. D. Exposure Cord
The exposure switch must be permanently fixed in a safe shielded
location or must be long enough to permit the operator to make
exposures while positioned at least six feet from the patient.
E. Exposure Timer “Dead-man” type exposure switch

12. F. X-ray Tube Head and Flexible Arm Assembly
The flexible extension arm allows the X-ray tube head to be adjusted
to various positions required for dental radiography. The mechanical
support of the X-ray tube head and cone shall maintain the exposure
position without drift or vibration.

13. Patient Protection
 All individuals unnecessary to the dental radiographic examination
leave the X-ray room prior to making an exposure.
 Anyone who is in the X-ray room at the
time of exposure must be behind a protective
barrier or they can wear protective apron.
The apron should be preferably 0.5 mm of
lead or lead-equivalent but not less than 0.25
mm of lead or lead-equivalent thickness.
 The reduction in exposure resulting from placing 0.25 mm lead-
equivalent apron material in a primary X-ray beam of 100 kVp would
only be 60% as compared to 0.50 mm lead-equivalent apron that will
attenuate the beam by 85%.

14.  Lead-impregnated leather or vinyl aprons
must be used to cover the reproductive
organs of all patients who undergo dental X-
ray examinations.
 Aprons should be evaluated periodically (at least yearly) for tears and
cracks.
 Aprons should be properly hung because creases eventually become
cracks which allow radiation to penetrate.
 A specially designed lead-impregnated
thyroid collar can be used to protect the
thyroid gland from excessive and/or
unnecessary radiation during intraoral X-ray
exposures.

15. Responsibilities of Dental Personnel Operating
X-ray Equipment
A. Protect Patient from Unnecessary Radiation Exposure
 Use appropriate protective devices, such as protective aprons and a
protective lead collars.
 Rectangular collimation of the X-ray beam is highly recommended.
B. Use Fast Image Receptors
Patient exposure may be reduced by more than 50 percent by changing
to a faster film speed or to a digital image receptor.

16. Speed Ratings of Commonly Used Dental Films
Film Brand Speed Group
Kodak Ultra Speed D
AGFA-Dentus, Flow D
Kodak Intraoral E
AGFA-Dentus E/F
Kodak Insight, Flow F

17. C. Digital Receptors
 Digital receptors include rigid wired or wireless sensors such as the
charged-coupled device (CCD) and the complementary metal oxide
semiconductor (CMOS) and photostimulable phosphor plate (PSP) or
storage phosphor plate (SPP) receptors.
 It is estimated that digital radiography reduces patient radiation dose
by 75% compared with D speed film, 50% compared with E speed film
and approximately 40% compared with F speed film.
 Digital receptors cannot be sterilized so the clinician must use
careful disinfection and barrier coverage techniques to avoid cross-
contamination of the receptor.

18. D. Intensifying Screens
 With regard to film-based extraoral radiography, rare earth
intensifying screen phosphors are recommended to reduce radiation
exposure.
 Rare earth elements like lanthanum and gadolinium have replaced
calcium tungstate crystals in intensifying screens.
 When rare earth screens are combined with green light sensitive
film, exposure can be reduced approximately 55% for panoramic and
cephalometric radiographs.

19. E. Plan Dental Radiographic Procedures Carefully and Avoid
unnecessary retakes.
1. Five of the most important factors relating to the production of
quality radiographs are:
• Patient positioning and instruction
• Alignment of the X-ray beam and the film.
• Use of rectangular collimating device
• Selection of proper exposure factors (kV, mA, time, distance)
• Proper film or digital image processing
2. Long axis of the body part being radiographed should be
perpendicular to the main X-ray beam and parallel to the image
receptor

20. 3. Receptor holding instruments
with beam alignment devices
should be used.
4. Use an exposure time that is as short as possible to minimize the
radiation dose and motion artifact during exposure.
5. Ensure that the focal spot-to-film distance (FFD) is correct.

21. 6. All patient exposures procedures must be documented in the
patient’s record and the images should be properly labeled.
7. The diagnostic information obtained from the radiographic images
also should be recorded in a notation or formal report in the patient’s
record.
F. Using Proper Kilovoltage (kV)
Kilovoltage determines the penetrating
ability (quality) of the X-ray beam.
When a high kV is used in a film
system, there will be more shades of
gray (i.e., low contrast) than when low
kV is used.

22. G. Milliamperage (mA) and Time Setting
 Milliampere-seconds (mAs) determines the amount (quantity) of x-
radiation being produced which is calculated by multiplying the
milliamperage (mA) x time (in seconds) = mAs (milliampere-seconds).
 Set the mA at the highest setting and then establish the proper
timer settings. This technique results in the use of shorter time
settings, which are helpful in avoiding patient motion artifacts on the
radiograph.

23. Dental Radiographic Quality Assurance (QA) and
Quality Control (QC)
Quality assurance (QA) program should include the
X-ray and ancillary imaging equipment, education
of dental personnel to perform quality control
(QC), and preventive maintenance procedures.
DENTAL X-RAY MACHINE
The following parameters should be measured:
• X-rays output : Use radiation dosimeter to measure the intensity
radiation output.
• Collimator alignment should be checked.
• Beam energy : HVL (half-value layer) of the beam should be
measured to ensure that there is sufficient energy for film exposure.

24.  Timer : Electric pulse counter counts the number of pulses
generated by an X-ray machine during present time interval.
• Tube head stability : It should be stable when placed around the
patient’s head.
• Focal spot size : Measure the focal spot size as it may become
enlarged with excessive heat build in the X-ray machine.
SPINNING TOP TEST FOR TIMER ACCURACY
It consists of rotating radiopaque disc with a
hole or notch at the periphery of disc. Top is
spun by the operator and the exposure is made
when the top slows down at the speed of one
revolution per second. Each radiation impulse
produced by the X-ray machine makes an
image of the hole or notch.

25. COLLIMATION
 Four dental films are placed on a sheet of paper, crossed with edge
of cone crossing the middle of film. The outline of cone end and films
are marked on the paper.
 Radiopaque objects such as paper clips, coins, pins or nails are
placed on the film inside the X-ray beam and films are exposed with one
half of the exposure time used for an anterior radiograph.
 Radiographs are processed and relocated in their original position on
the paper using the image of the different radiopaque objects.

26. PINHOLE CAMERA TECHNIQUE FOR FOCAL SPOT ASSESSMENT
A piece of lead of 1 mm in thickness is placed
over the collimator opening in the base of the
cone. A small hole not larger than 0.5 mm in
diameter is made in the centre of lead.
A dental film is placed on a small box in the
middle of cone at the same distance from the
lead hole as the focal spot of the X-ray
machine. Exposure time of five impulses is
needed to produce a clear image of focal spot
on the radiograph.

27. DARKROOM
Safelight requires checking of the following:
• Types of filter : Type of filter which should be compatible with
the colour sensitivity of film used, i.e. blue, green, ultraviolet.
• Condition of filter : Scratched filter should be replaced.
• Watt of bulb : It should be not more than 25 W.
• Distance from work area : The distance from the work surface
should not be more than 4 ft.
Coin test/penny test
Place the coin on the film, turn on the safelight
and leave for approximately 1–5 min. Process the
film in the normal way. Fogging of the film due to
safelight will then be obvious when compared to
the clear area protected by the coin.

28. X-RAY FILM
Take an unexposed film from newly opened box and process it in
freshly prepared solution. The film is then viewed.
• Fresh film : It appears clearer with blue tint which means film is
properly stored and protected.
• Fogged film : It appears fogged, meaning that film has expired,
improperly stored or exposed to radiation.
PROCESSING
Developer Strength
The solution must reached optimum temperature of 20°C for manual
processing and 28°C for automatic processing.

29. Step-wedge film :
Step-wedge film is a device with small, graduated increase in the
thickness of its material.
Step wedge can be made in dental office by following
method :
• Tape six pieces of lead foil from the film packets on
the end of tongue blade.
• The first two pieces should be 1 in. long, second two
pieces ¾ in. long and third two pieces should be ½ in.
long.
• Tape these foil pieces in three steps, with one step
having six layers, second having four layers, and third
having two layers.
• Cut the excess foil from the side and tape the foil
layer to the tongue blade.

30. Step-wedge radiograph
 Take a radiograph of step wedge using known
exposure factors.
 Process the film in fresh solution and produce
a standard reference film with level of
increasing density.
 Repeat using the same exposure factor every
day as the solution becomes depleted.
 Compare it every day with standard reference
step wedge film to determine objectively any
decrease in blackening of the processed film
which would indicate deterioration of the
developer.

31. Fixer Strength
To monitor fixing following tests are carried out:
• Preparation of film : Unwrap one film and immediately place it in
the fixer solution. Check the time taken for clearing.
• Fast clearing : If the film clears in 2 min, the fixer is of adequate
strength.
• Slow clearing : If the film is not completely cleared after 2 min,
then fixer strength is not adequate.

32. Guidelines for Prescribing Dental Radiographs
Use of these guidelines should promote the appropriate use of X-rays,
by reducing overutilization and excessive radiation, and minimizing
underutilization of imaging with potential inadequate diagnosis
The guidelines categorize patients first by type of visit (new or
recall), then by dental status (child with primary or transitional
dentition, adolescent, or adult dentulous or edentulous). Lastly the
patient’s risk category for caries, periodontal disease or growth and
development assessment is considered.

36. A. Positive Historical Findings
1. Previous periodontal or endodontic
treatment
2. History of pain or trauma
3. Familial history of dental anomalies
4. Postoperative evaluation of healing
5. Remineralization monitoring
6. Presence of implants, previous implant-
related pathosis or evaluation for implant
placement

37. 1. Clinical evidence of periodontal disease
2. Large or deep restorations
3. Deep carious lesions
4. Malposed or clinically impacted teeth
5. Swelling
6. Evidence of dental/facial trauma
7. Mobility of teeth
8. Sinus tract (“fistula”)
9. Clinically suspected sinus pathosis
10. Growth abnormalities
B. Positive Clinical Signs/Symptoms

38. 11. Oral involvement in known or suspected systemic disease
12. Positive neurologic findings in the head and neck
13. Evidence of foreign objects
14. Pain and/or dysfunction of the temporomandibular joint
15. Facial asymmetry
16. Unexplained bleeding
17. Unexplained sensitivity of teeth
18. Unusual eruption, spacing or migration of teeth
19. Unusual tooth morphology, calcification or color
20. Unexplained absence of teeth
21. Clinical tooth erosion

39. Maximum permissible dose and maximum accumulated dose
 Dose limits have been established for occupationally exposed
persons, non-occupationally exposed persons (general public) and
occupationally exposed pregnant women.
 The maximum permissible dose (MPD) is the dose of whole body
radiation that is not expected to produce any significant somatic or
genetic effects in a lifetime.

41. GUIDELINES FOR SHIELDING OF X-RAY INSTALLATIONS
The adequacy of shielding depends on the material and thickness used
for this purpose. Different materials can be used for shielding.
However, brick or concrete are considered the best materials, as they
are easily available, economical, and have good structural strength.
DENTAL CBCT/OPG
DENTAL – INTRAORAL RADIOGRAPHY

42. Dental radiographic examinations are not without risk. X-
radiation has the potential to damage tissue through
either the indirect effect or direct effect of radiation.
The biologic effects of radiation are cumulative and every
effort must be taken to keep radiation exposures as low
as reasonably achievable. A variety of radiation safety and
protection measures can be employed to reduce exposure
to dental patients and minimize occupational exposure.