1. RADIATION
PROTECTION
Dr. Nidhi Yadav
Mds 2nd year
Department of Oral Medicine
& Radiology

2. CONTENT
S:
● .
● .
● .
• Introduction.
• Sources of radiation .
• Dose limit by NCRP & ICRP rules.
• Principles of radiation protection
• Radiation protection technique
• Personnel protection
• Radiation monitoring consideration of
pregnant women.
• Dosimetry
• TLD
• Conclusion.
• References.

3. Introduction
 Radiation is transmission of energy from space and matter.
 There are several forms of radiation, including ionizing and nonionizing.
 X-rays are the ionizing radiation used extensively in medical and dental
practice.
 Were discovered in 1895, and their immediate use brought numerous
benefits to the science and medicine, but also caused a number of
irreversible biological effects in patients, researchers, physicians, and other
exposed individuals.

4. Christensen's Physics of Diagnostic Radiology

5. The principle of radiation protection is to do those things that will minimize
exposure of patient and dental personnel and still provide benefits for the patient
from use of diagnostic radiography.
Protection in general
For a given radiation source the amount of radiation at any point in the beam depends upon
the distance from the point to the source of radiation (intensity is inversely proportional to
the square of the distance) and the nature of thickness of the material through which the
radiation is passed.
In addition, the average person is exposed to an additional 0.76–1.01 mSv per year from
other sources, such as global fall out, occupational exposure, treatment and diagnostic
radiation procedures and other miscellaneous causes
Dental And Maxillofacial Radiology-2nd ed. -Freny R Karjodkar

6. Sources of radiation exposure
● Background Radiation
● Medical Exposure
● Consumer Products
● Other Sources
Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh.

7. Natural radiation
1) Cosmic sources
2) Terrestrial sources
-external radiation
-internal radiation
(radon and radionucliotides)
Man made radiation
1)Medical Diagnosis And
Treatment
2)Consumer And Industrial
Products
3) Other Minor Sources
Dental And Maxillofacial Radiology-2nd ed. -Freny R Karjodkar

8. Background radiation
Radon and Its Progeny
Radon and its decay
products may become
attached to dust particles that
can be inhaled and deposited
on the bronchial epithelium in
the respiratory tract.
Space Radiation
Radiation from space
comes from the sun or
from cosmic rays.
It is composed primarily
of protons, helium nuclei,
and nuclei of heavier
elements as well as
other particles generated
by the interactions of
primary space radiation
with the earth’s
atmosphere.
Internal
Radionuclides
Greatest internal
exposure comes
from foods
containing uranium
and thorium and
their decay products,
primarily potassium
40 but also rubidium
87, carbon 14,
tritium, and others
Terrestrial
Radiation
comes from exposure
from radioactive
nuclides in the soil,
primarily potassium
40 and
the radioactive decay
products of uranium
238 and thorium 232.
73% 7%
9%
11%
Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh.

9. Natural background radiation contributes 3.1 mSv on average per year. Most exposure comes from radon, but there are significant
contributions from space, ingested radionuclides, and terrestrial sources including external radionuclides in the soil and building materials.
(Data from National Council on Radiation Protection and Measurements: Ionizing radiation exposure of the population of the United States,
NCRP Report 160, Bethesda, MD, 2009, National Council on Radiation Protection and Measurements.)

10. MEDICAL EXPOSURE
 The average doses from medical exposures are comparable to natural background exposure.
 CT contributes more than half of medical exposure.
 In contrast to background radiation exposures, which affect everyone relatively uniformly, the
distribution of medical exposures is highly skewed with older and sicker individuals receiving
most medical exposures.
 Dental x-ray examinations, although made relatively frequently, are responsible for only
0.26% of the total exposure from medical imaging.
Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh.

11. ● Exposure from cigarette smoking, building materials, air travel, mining and
agriculture, and combustion of fossil fuels. As more people travel
frequently above the protection of the earth’s atmosphere, cosmic
radiation becomes a more significant contributor to exposure.
Consumer products

12. Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh.

13. Data from National Council on Radiation Protection and Measurements: Ionizing radiation exposure of the population of the United
States, NCRP Report 160, Bethesda, MD, 2009, National Council on Radiation Protection and Measurements

17. Dose limits, exposures, and
risk
Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh.

18. Recognition of the harmful effects of radiation and the risks
involved with its use led
The National Council On Radiation Protection And
Measurements (NCRP) &
The International Commission On Radiological Protection (ICRP)
to establish guidelines on limitations on the amount of radiation
received by both occupationally exposed individuals and the
public
● The NCRP recommends a DRL (diagnostic reference levels) of 1.6 mGy entrance skin
dose for intraoral periapical and bitewing radiography. The NCRP further recommends an
achievable dose of 1.2 mGy for intraoral radiography. These standards require that most
users of D-speed film convert to E/F-speed film or a digital system.

19. Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh.

20. Patient exposure
Patient dose from dental radiography is usually reported as effective dose, a measure of the
amount of radiation received by various radiosensitive organs during the radiographic
examination.
Typical effective doses from common dental intraoral, extraoral, and medical examinations.
The equivalent exposure in terms of days of natural background radiation is shown.
Dental exposures are a small fraction of the annual average background exposure
Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh.

22. Risk estimates
 The data for the cancer risk from radiation exposure involve exposures many times larger than
those involved with dental radiology
 The very low incidence that may result from dental exposure is impossible to detect by direct
measurement.
 Radiation-induced cancers are clinically and histologically indistinguishable from cancers
induced by other causes.
 The time between radiation exposure and the development of cancer may be years to decades,
during which time individuals may be subjected to many other carcinogens
Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh.

23. Sources of radiation in a dental radiology department
• Primary beam is defined as radiation originating
from the focal spot
• Scattered or secondary radiation is the radiation
originating from the irradiated tissues of the patient
• Leakage or stray radiation is the radiation from the X-
ray tube head housing
• Scattered radiation is the radiation from filters and
cones
• Scattered radiation is the radiation coming from the
objects other than the patient such as the walls and
furniture’s that the primary beam may strike.
Dental And Maxillofacial Radiology-2nd ed. -Freny R Karjodkar

24. The means of protection can be divided into:-
Protection for the operator
Protection for the patient Protection for the environment
Dental And Maxillofacial Radiology-2nd ed. -Freny R Karjodkar

25. The two most
important
sources of X-rays
to which the
operator is
exposed to
Primary x-ray beam
Scattered radiation
originating from the
irradiated tissues of the
patient.
Other Sources of Lesser Importance Include
• Leakage radiation through the tube head housing
• Scattered X-ray from filters, cones
• Scattered radiation coming from objects other than the
patient, such as walls and furniture that the primary beam
may strike.
Freeman JP, Brand JW. Radiation doses of commonly used dental radiographic surveys. Oral Surg Oral Med Oral Pathol. 1994;77(3):285-9

26. Protection against primary beam
It is defined as radiation emitted by the focal spot of the target
 Effort must be made so that the operator can leave the room or take a suitable
position behind a barrier or wall during exposure
 Dental operatory should be designed and constructed to meet the minimum
shielding requirements
Position distance rule—which states that the operator should stand at
least six feet away from the source of radiation or the operator should
be at an angle of 90°– 135°, with respect to the direction of the
central ray, (This rule takes advantage of the inverse square law to
reduce the intensity and also considers that in this position the
patient’s head will absorb the most scattered radiation
Dental And Maxillofacial Radiology-2nd ed. -Freny R Karjodkar

27. Behind a barrier, made of suitable material, If there is no shield or barrier the operator
should use a lead apron
The film should never be held by the operator. Ideally film holding devices should be
used. If correct retention and placement is still not possible a parent or any other
individual responsible for the patient must hold the film in position
There should be no use of fluorescent mirrors in the oral cavity at the time of exposure
Avoid holding the X-ray tube head of the machine. The suspension arms should be
adequately maintained to prevent housing movement and drift.
Behind a barrier, made of suitable material, If there is no shield or barrier the operator
should use a lead apron
The film should never be held by the operator. Ideally film holding devices should be
used. If correct retention and placement is still not possible a parent or any other
individual responsible for the patient must hold the film in position
There should be no use of fluorescent mirrors in the oral cavity at the time of exposure
Avoid holding the X-ray tube head of the machine. The suspension arms should be
adequately maintained to prevent housing movement and drift.

28. Protection from secondary and scattered
radiation:
[Secondary radiation is defined as the radiation emitted by a substance through which X-rays are
passing. Scattered radiation is defined as that radiation that has under gone change in direction
during passage through a substance].
Use of high speed films
Replace the short plastic cone with an open ended lead lined cone
Adequate filtration of the primary beam
Use of collimator, to reduce the diameter of the beam
Use of film badge/TLD badge/pocket dosimeter, for personnel
radiation monitoring, to avoid accumulated over exposure
Dowd SB, Tilson ER. Practical Radiation Protection and Applied Radiology, 2nd edition, philadelphia; WB Saunder, Philadelphia; 1999.

29. X-ray scatter (collimation, kVp, air gap, thickness, anti-scatter grids) factors every technologist should know.

30. Protection for the
Patient
Patient dose from dental radiography is usually reported as the amount of radiation
received by target organs. One of the most common measurements is the skin or
surface exposure. Other target organs commonly reported include the bone marrow,
thyroid glands and gonads.
Dental And Maxillofacial Radiology-
2nd ed. -Freny R Karjodkar

31. Mean active bone marrow
dose:
● The dose derived as a specific dose relevant to a particular stochastic effect,
e.g. leukemia. It is that dose of radiation that is averaged over the entire bone
marrow
Thyroid dose:
● Particular concern has been expressed over the exposure of thyroid because
it has one of the highest radiation induced cancer rates
Gonadal dose:
● Radiographs that involve the abdomen result in the highest dose to the
gonads. As a general category the dental X-ray examinations result in a
generally insignificant dose to the gonads.

33. Reducing dental exposure
Principle of
justification
Principle of
optimization
Dose
limitation
Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh. Page 33

34. Principle of
justification
ADA has issued guidelines recommending which radiographs to make and how
often to repeat them:
 Make radiographs only after a clinical examination.
 Order only those radiographs that directly benefit the patient in terms of
diagnosis or treatment plan.
 Use the least amount of radiation exposure necessary to generate an
acceptable view of the imaged area
Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh. Page 33

35. ALAR
A
Principle of optimization
Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh. Page 33
States that all exposure to radiation must be kept to minimum ,or “as low as reasonably
achievable.”
To provide protection for both patient and operator, every possible method of reducing
exposure to radiation should be employed to minimize risk.
The dosage for individuals occupationally exposed in the operation of dental x-ray
equipment was found to be even less, 0.20 mSv, or 0.4%of the allowable limit.

36. ALADA
ALARA ALADAIP
AS LOW AS
REASONABLY
ACHIEVABLE.”
AS LOW AS DAIGNOSTICALY
ACCEPTABLE BIENG
INDICATED –ORIENTED AND
PATIENT SPECIFIC
AS LOW AS
DAIGNOSTICALY
ACCEPTABLE”
ALADAIP Introduced in 2017 in the position
statement paper of DIMITRA PROJECT
(dentomaxillofacial paediatric imaging :an
investigation towards low dose radiation induced
risk
ALADAIP, beyond ALARA and towards personalized optimization for paediatric cone-beam CT
Anne Caroline Oenning, Reinhilde Jacobs, Benjamin Salmon

37.  This principle applies to dentists and their staff who are exposed occupationally but not to
patients because there are no dose limits for individuals exposed for diagnostic purposes.
 Many of the steps described in the following sections that optimize exposures of the patient
also reduce exposure to dentists and their staff.
Dose
limitation
Recommendation of the American Dental
Association (ADA) Council on Scientific
Affairs
Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh. Page 33

38. Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh. Page 33

39. Patient selection
criteria
Radiographic screening for the purpose of detecting disease before clinical
examination should not be performed.
A thorough clinical examination, consideration of the patient history, review of
any prior radiographs, caries risk assessment and consideration of both the
dental and the general health needs of the patient should precede radiographic
examination (ADA 2012).
The ADA has published radiographic selection
criteria—clinical or historical findings that identify
patients for whom a high probability exists that a
radiographic examination would provide information
affecting their treatment or prognosis
Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh

40. Radiation protection
techniques:
With proper protection techniques ,the amount of x-radiation received
by patient can be minimized.
The protection techniques should be followed Before, during and
after the x-ray exposure
Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh. Page 33

41. Conduct of the
examination:
● When the decision is made that a radiographic examination
is justified, the way in which the examination is conducted
greatly influences patient exposure to radiation. It is divided
into:
Dental And Maxillofacial Radiology-2nd ed. -Freny R Karjodkar

42. • Film and Digital Imaging
• Intensifying Screens and Film
• Source-to-Skin Distance
• Rectangular Collimation
• Filtration
• Leaded Aprons and Thyroid
Collars
• Film and Sensor Holders
• Kilovoltage
• Milliampere-Seconds
• Film Processing
• Interpreting the Images
Dental And Maxillofacial Radiology-2nd ed. -Freny R Karjodkar

43. Before Exposure:

44. Patient selection criteria
 Radiographs should be prescribed after evaluation of
patient needs that includes clinical dental history
assessment
•
•
 Principle of justification is satisfied here which means the
dentist to do more good than harm.
health history review
clinical examination
an evaluation of susceptibility
to dental diseases.
Dental And Maxillofacial Radiology-2nd ed. -Freny R Karjodkar

45. Proper Equipment:
Dental x-ray tube head should be equipped with appropriate Aluminium filters,
lead collimator, and position indicating device.
Dental And Maxillofacial Radiology-whtie and faroah

46. Filtration
 The purpose of filtration is to remove the low energy
photons selectively from the x-ray beam.
 The federal govt. has designated the specific amount
of filtration, expressed as minimum half value layer,
required for dental x ray machine operating at
various kilovoltage.
 1.5 mm Al total filtration when operation from 50 to
70 kVp
 and with 2.5 mm Al total filtration when operating
above 70kVp.
Dental And Maxillofacial Radiology-2nd ed. -Freny R Karjodkar

47. In a radiologic examination the x-ray beam is filtered by absorbers at three different
levels. Beginning at the x-ray source, these are as follows:
1. The x-ray tube and its housing (inherent filtration)
2. Sheets of metal placed in the path of the beam (added filtration)
3. The patient
INHERENT FILTRATION
Filtration resulting from the
absorption of x rays as they pass
through the x-ray tube and its
housing is called inherent filtration.
Contains -glass envelope enclosing
the anode and cathode, the
insulating oil surrounding the tube,
and the window in the tube housing.
Inherent filtration is measured in
aluminum equivalents, which
represent the thickness of aluminum
ADDED FILTRATION
Added filtration results from absorbers
placed in the path of the x-ray beam.
Ideally, a filter material should absorb all
low energy photons and transmit all high
energy photons.
Christensen's Physics of Diagnostic Radiology

48. Collimation of the beam

49.  Collimation helps to control the size and shape of the X-ray beam, allowing
only the useful beam to emerge; (Useful beam is defined as that part of the
primary radiation which is allowed to emerge through the collimating
device).
 In intraoral machines there are fixed collimators and in extraoral machines
there are adjustable collimators.
 The beam should be limited to as small as an area possible for a particular
radiographic examination.
 The recommended beam size is not more than 2 ¾˝ in diameter at the
patient’s face, when the source film distance is 18 cm or more .
 Collimation decreases the risk of radiation, minimises scattered radiation
and decreases the fog, with a sharper image and better contrast
Dental And Maxillofacial Radiology-whtie and faroah
Collimation of the beam
The federal regulations (in USA) require that the diameter of a collimated X-ray beam be
restricted to 2.75 inches at the patient’s face

50. Source-to-Skin
Distance
Two standard focal source-to-skin distances have evolved over the years for
use in intraoral radiography, one 20 cm (8 inches) and the other 41 cm (16
inches
Use of the distance results in a reduction in exposed tissue volume because
the x-ray beam is less divergent .
Distances between 20 cm and 40 cm are appropriate, but the longer
distances are optimal (ADA 2006).
Use of long source-to-skin distances of 40 cm, rather than short distances of
20 cm, decreases exposure by 10 to 25 percent.
Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh. Page 34

51. Position indicating device
• These help to minimize the volume of tissue
irradiated in intraoral radiography, it is necessary to
increase the target film distance by using longer
position indicating devices to direct the X-ray beam.
• One of the most widely used PID is the long open
ended cylinder.
• This instrument reduces the more divergent rays
that are inherent in the use of the short target film
distance
• If a change is made in the technique from short cone
to long cone, it is important to simultaneously
reduce the size of the collimator aperture.
Compared to the short (8 inch) PID, the longer (16 inch) PID is preferred
because it produces less divergence of the X-ray beam Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh. Page 34

52. During
exposure

53. Leaded Aprons and Collars
 If all the NCRP recommendation are followed thoroughly, the use of
a leaded apron on patients is not required .
 If any of the recommendations is not implemented ,then a leaded
apron should be used.
 The radiation protection provided by a lead apron is approximately
0.25- to 1-mm thick lead.
 An apron with 0.5-mm thickness can attenuate approximately 90%
or more of the scatter radiation.
 Lead glasses with 0.5- or 0.75-mm thickness can reduce more than
95% of scatter radiation
Radiation safety: a focus on lead aprons and thyroid shields in interventional pain management Bo Kyung Cheon, Cho Long Kim, Ka Ram Kim, Min Hye

54.  Thyroid shielding with a leaded thyroid shield
or collar is strongly recommended for children
and pregnant women ,as these patients are
susceptible to radiation effects
 Thyroid collars 0.5-mm lead equivalent
thickness for neck and thyroid protection.
Radiation safety: a focus on lead aprons and thyroid shields in interventional pain management Bo Kyung Cheon, Cho Long Kim, Ka Ram Kim, Min Hye
The thyroid gland is more susceptible to radiation
exposure during dental radiographic exams given
its anatomic position, particularly in children.
Protective thyroid collars and collimation
substantially reduce radiation exposure to the
thyroid during dental radiographic procedures.
Because every precaution should be taken to
minimize radiation exposure, protective thyroid
collars should be used whenever possible (ADA
2012)

55. Kilovoltage
The operating potential of
dental X-ray machine must
range between 50 and 100
kilovolt peak but should range
between 60 and 80 kVp.
Milliampere-seconds:
The operator should set
the amperage and time
setting
for exposure of dental
radiographs of optimal
quality.
Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh. Page 34

56. After exposure

57. Film processing
 Dental radiographs should be processed by
manufacturers’ instruction regarding time
,temperature and chemistry should be
followed
 Proper film handling.
 Proper processing
 Proper interpretation.
 Time-temperature processing is the best way to ensure
optimal film quality. To help ensure optimal mage
quality, the dental assistant should follow the film
manufacturer’s recommendation for processing solution
Moores BM. Radiation safety management in health care - the application of quality function deployment.
Radiography,2006, (12): 291-304.

58. Protecting personnel:
 First, every effort should be made so that the
operator can leave the room or take a position
behind a suitable barrier or wall during exposure of
the image.
 NCRP recommendation states that walls must be of
sufficient density or thickness that the exposure to
non-occupationally exposed individuals is not
greater than 100mGy per week.
Moores BM. Radiation safety management in health care - the application
of quality function deployment. Radiography,2006, (12): 291-304.

59. HPA-RPD-065: recommendations for the design of x-ray facilities and
the quality assurance of dental cone beam CT (computed

60. Protection for the Environment
• Primary beam should never be directed at any
one other than the patient.
• Patient should be positioned such that the X-ray
beam is aimed at the wall of the room and not
through a door or other opening where people
may be located.
• Walls made of 3˝ of concrete, 3˝ × 16˝ of steel or
1 mm of lead will suffice to protect adjacent
rooms, even if the work load in the radiology
department is high.
If it is not possible to incorporate
lead or barium into the walls,
they can be lined with lead
plywood, 0.25 mm of lead
sandwiched between layers of
wood. – Primary barrier should
be incorporated in any part of the
floor or ceiling of the room at
which the beam is fired

61. If leaving the room or making use of some other barrier is
impossible, strict adherence to the position-and-distance rule: the
operator should stand at least 6 feet from the patient, at an angle
of 90 to 135 degrees to the central ray of the x-ray beam .
Essentials of Dental Rad. & Radiology. -3rd ed. –
Eric Whaites.

62.  Second, the operator should never hold films in place.
Ideally, film-holding instruments should be used.
 If correct film placement and retention are still not possible,
a parent or other individual responsible for the patient
should be asked to hold the film in place and, of course, be
afforded adequate protection with a leaded apron.
 Under no circumstances should this person be one of the
office staff.
Essentials of Dental Rad. & Radiology. -3rd ed. –Eric Whaites.

63.  Third, the radiographic tube housing should
never be stabilized by the operator or patient
during the exposure.
 Suspension arms should be adequately
maintained to prevent housing movement
and drift.
Essentials of Dental Rad. & Radiology. -3rd ed. –Eric Whaites.

64. Quality assurance
may be defined as any planned
activity to ensure that a dental
office will consistently produce
high quality images with the
minimum exposure to patients
and personnel.
Continuing education
Practitioners should stay informed
of new information of radiation
safety as well as development
materials and techniques to improve
radiographic practice.
Essentials of Dental Rad. & Radiology. -3rd ed. –Eric Whaites.

65. Radiation monitoring
Equipment monitoring :
Dental x-ray machines should be
monitored for any leakage radiation.
It can be monitored by use of film
device obtained from state health
department or the manufacturers
Personnel monitoring:
The best way to ensure that personnel are
following office safety rules such as those
described previously is with personnel-
monitoring devices.
Three main devices for monitoring and
measuring radiation dose:
1) Film badges
2) Thermoluminescent dosimeters
3) Ionization chambers
Essentials of Dental Rad. & Radiology. -3rd ed. –Eric Whaites.

66. Film badges
 They consist of a blue plastic frame
containing a variety of different metal
filters and a small radiographic film which
reacts to radiation .
 They are most commonly used.
 provide a permanent record of dose
received.
 Can measure the type and energy of
radiation encountered.
 Inexpensive
Essentials of Dental Rad. & Radiology. -3rd ed. –Eric Whaites.

67. Thermo luminescent dosimeters
Used for personal monitoring of whole body and/or extremities.
They contain materials such as lithium fluoride which absorb the
radiation and then release the energy in the form of light when heated.
The intensity of emitted light is proportional to radiation energy
absorbed originally
They should be worn for 1-3 months.
Read –out measurement are easily automated and rapidly produced.
Essentials of Dental Rad. & Radiology. -3rd ed. –Eric Whaites.

68. Ionization chambers:
 They are used for personal monitoring
and by physicists to measure radiation
exposure.
 Radiation produce ionization of the air
molecules inside the closed chamber,
which results in a measurable
discharge and hence a direct read out.
 Most accurate method of measuring
radiation dose.
 Direct read out gives immediate
information.
Essentials of Dental Rad. & Radiology. -3rd ed. –Eric Whaites.

69. Maximum accumulated dose
 Occupationally exposed workers must not exceed an
accumulated lifetime radiation dose called maximum
accumulated dose.
 MAD for occupationally exposed person is
MAD=(N-18)X5 rems/yr
MAD=(N-18)X0.05 sv/yr
Essentials of Dental Rad. & Radiology. -3rd ed. –Eric Whaites.

70. Dose received from dental radiography:
 The foetal dose from a dental X ray exam has
been estimated to be between 0.3 μSv - 1μSv .
 This is less than the estimated daily natural
background dose received by the foetus.
Yoon I, Slesinger TL.Radiation Exposure In Pregnancy staetperals 8July

71.  If the patient is pregnant the possibility of obtaining
information from a non-radiological investigation should
be considered.
 If the radiological examination is considered essential it
should be performed and due consideration should be
given to optimisation.
 It is essential to have pregnancy warning signs in the
waiting rooms.
 NCRP guidelines equivalent dose limit per month after
pregnancy is known is 0.5mSv.
 ICRP : 2 mSv.
Yoon I, Slesinger TL.Radiation Exposure In Pregnancy staetperals 8July

72.  The risk to the foetus from a few µSv of
radiation exposure arising from a dental
radiographic procedure is extremely small.
 The cancer risk to the unborn child resulting
from a 10 µSv foetal dose is several thousand
times less than the background risk of
childhood cancer.
 The risk of inducing a genetic abnormality is
an even smaller fraction of the background
risk of genetic disorder.
Yoon I, Slesinger TL.Radiation Exposure In Pregnancy staetperals 8July

73. Dosimetry
• Dosimetry” refers to the science by which radiation dose is determined by
measurement, calculation, or a combination of measurement and calculation.
• The technical name for radiation dose is “absorbed dose”; it is the amount of radiation
energy that is deposited in tissue divided by the mass of the tissue.
• The absorbed dose is the most important physical factor that influences the response of
tumors and the rest of the body to radiation.
Society of nuclear and molecular medicine

74. Dose: It is amount of radiation at a given point or the amount of energy absorbed
per unit mass at the site of interest.
Erythema dose: It is that dose which produces in one sitting a reversible reddening
of the skin (3–4 Gy).
Exposure: It is a measure of radiation quantity, the capacity of the radiation to ionize air.
The SI unit of exposure in air is kerma (Kinetic Energy Released in Matter) and is expressed in
units of dose gray (Gy), where 1 Gy equals 1 joule/kg. It has replaced the Roentgen (R), the
traditional unit of radiation exposure measured in air.
Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh. Page 33

75. ABSORBED DOSE
Absorbed dose is a measure of the total energy absorbed by any type of ionizing radiation per
unit of mass of any type of matter. The SI unit is the gray, where 1 Gy equals 1 J/kg. The
traditional unit of absorbed dose is the rad (radiation absorbed dose), where 1 rad is equivalent
to 100 ergs per gram of absorber; 1 Gy equals 100 rad
THE EQUIVALENT DOSE (HT)
is used to compare the biologic effects of different types of radiation on a tissue or organ.
Particulate types of radiation have a high LET and are more damaging to tissue than radiation
with low LET. SI unit=sievert (Sv). For diagnostic x-ray examinations, 1 Sv equals 1 Gy. The
traditional unit of equivalent dose is the rem (roentgen equivalent man); 1 Sv equals 100 rem
EFFECTIVE DOSE
The effective dose (E) is used to estimate the risk in humans. It is hard to compare
the risk from a dental exposure with, for example, the risk from a radiographic chest
examination because different tissues with different radio sensitivities are exposed.
The unit of effective dose is the Sv
RADIOACTIVITY
The measurement of radioactivity (A) describes the decay rate of a sample of radioactive material. The SI
unit is the becquerel (Bq); 1 Bq equals 1 disintegration per second
Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh.

76. Dental And Maxillofacial Radiology-2nd ed. -Freny R Karjodkar

77. • There are three procedural types of radiology:
• Analog, Computed (CR), and Digital (DR). Analog is the “old school” way, which involves developing film to show
the captured image.
• Computed radiology utilizes an imaging plate-cassette type system, rather than film, to capture images.
• Digital radiology is a method that completely digitizes the process. Although most of the industries that use x-rays
have moved to computed and digital processes, some still use the traditional analog process. And it is this old
school method that creates x-ray waste.
Waste management
X-Ray Waste Disposalby Samanatha Erickson | May 1, 2019 | Medical Waste 101

78. The Analog x-ray process produces the following wastes:
X-ray Fixer – Classified as a hazardous waste due to a high concentration of silver.
X-ray Developer – Contains hydroquinone, which is toxic until used. Once it has been used, it is safe to dispose of as regular
safe to dispose of as regular municipal garbage.
X-ray Film – Depending on how much silver is on the film, it can be considered hazardous waste.
Lead aprons and Lead dental foil – Both of these items contain lead and are considered hazardous waste.
waste.
• The Resource Conservation and Recovery Act gives the Environmental Protection Agency (EPA) the authority to regulate
hazardous waste.
• The EPA regularly conducts inspections at facilities that use x-rays, usually every 18 months to 2 years. Among other things,
the EPA makes sure to check radiation emissions.
• Every facility is supposed to have a certified Medical Physicist inspect their equipment annually to help control emissions.
• The EPA also checks for the proper disposal of any x-ray waste.
X-Ray Waste Disposalby Samanatha Erickson | May 1, 2019 | Medical Waste 101

79. • So how does one dispose of x-ray waste properly? Let’s go over each type of x-ray waste, one by one.
• X-ray Fixer Disposal: This should not be flushed or poured down the drain. Instead, x-ray fixer should be put in a
x-ray fixer should be put in a Chemical Recovery Cartridge (CRC), with proper labeling and care.
• X-ray Developer Disposal: While used x-ray developer is considered safe, unused developer poses major
developer poses major hazardous risks. The best practice for disposing of unused developer is to put it into a
separate labeled container, and send it back to its manufacturer.
• X-ray Film Disposal: Spent x-rays usually do not have toxic amounts of silver, so they can be recycled for their
they can be recycled for their silver content
• Lead aprons and Lead dental foil Disposal: These items can be recycled as well. While lead is hazardous,
While lead is hazardous, these items do not contain that much of it.
X-Ray Waste Disposal by Samanatha Erickson | May 1, 2019 | Medical Waste 101

80. Take home message
 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
 A strict adherence to the radiation protection principles, dose limitation of NCRP &
ICRP techniques and a close monitoring of the amount of radiation exposure is
recommended to avoid radiation induced hazards.

81. References:
 Oral Radiology – Principle & Interpretation - 6th ed. –White & Pharaoh.
 Essentials of Dental Rad. & Radiology. -3rd ed. –Eric Whaites.
 Dental Radiography. - Principle & Technologies - 3rd ed. – Haring, Jansen.
 Dental And Maxillofacial Radiology-2nd ed. -Freny R Karjodkar
 European guidelines on radiation protection in dental radiology 2004
 Moores BM. Radiation safety management in health care - the application of
quality function deployment. Radiography,2006, (12): 291-304.
• Schandorf C, Tetteh GK. Analyses of dose and dose distribution for patients undergoing selected X-ray
diagnostic procedures in Ghana. Radiation Protection Dosimetry, 1998, 76 (4): 249-256.
• Society of nuclear and molecular medicine
• Yoon I, Slesinger TL.Radiation Exposure In Pregnancy staetperals 8July 2022
• X-Ray Waste Disposal by Samanatha Erickson | May 1, 2019 | Medical Waste 101