radiation safety and protection done by dr. Mohammed Saad ( BDS ) @ al sha'ab SDC Baghdad, Iraq 2015 MOH

1. Radiation Safety & Protection
Supervised by
Dr. Alaa Mahmoud
Done by
Dr. Mohammed Sa’ad & Dr. Marwan N. Natah

2. Acknowledgments
 The chief of Al Sha’ab specialized center Dr. Hassan A. Hassan
 The head of X-Ray’s department Dr. Alaa Mahmoud
 All my fellows dentists

3. Subjects Index
 Introduction
 Digital Radiography in Dentistry
 Sources of Radiation Exposure
 Dose Limit
 Safety Part
 References

4. Goal of this seminar

5. Introduction
 Dentists must be prepared to intelligently discuss
with patients the benefits and possible hazards
involved with the use of x rays and to describe
the steps taken to reduce the hazard. This
seminar considers sources of exposure, estimates
of risks from dental radiography, and means to
minimize exposure from dental examinations.

6. Digital Radiography in Dentistry

7.  Digital radiography was introduced in Dentistry in 1987. The technology has
been gaining in acceptance, and in 2005 more than 22% of dentists were using
digital radiography.

8. Sources of Radiation Exposure

10. Dose Limit
 Dose limits from man-made sources for members of the general
public, not occupationally exposed, have been established at
10% of that of occupationally exposed individuals. The
negligible individual dose, established by the NCRP, is
considered to be the dose below which any effort to reduce the
radiation exposure may not be cost-effective. In spite of the
NCRP ’ s endorsement of the no threshold hypothesis for
purposes of radiation safety, it is thought that the impact on
society of radiation exposure of this magnitude is negligible.
Dentists and their staff are occupationally exposed workers and
are allowed to receive up to 50 mSv of whole-body radiation
exposure per year. Although this is considered to present only a
minimal risk, every effort should be made to keep the dose to
all individuals as low as practical.

11. RISK ESTIMATES

12. Reducing Dental Exposure
 the first is the principle of justification. In making dental
radiographs this principle obligates the dentist to do more good
than harm.
 The second guiding rule is the principle of optimization. This
principle holds that dentists should use every means to reduce
unnecessary exposure to their patient and themselves.
 The third principle is that of dose limitation. Dose limits are
used for occupational and public exposures to ensure that no
individuals are exposed to unacceptably high doses.

13. Safety Part

14. Operator Location

15.  The operator of the dental unit must stand at least six feet from the useful
beam or behind a protective barrier. [Stand at an angle of from 90 to 135
degrees from the central ray. Do NOT stand in the path of the primary x-ray
beam.]
 If a protective barrier is used, it must have a viewing window to allow the
operator to see the patient.

17. Personnel Radiation Badges

18.  The individuals who operate only dental radiographic systems are exempt
from the radiation badge requirements

19. X-ray Tube Housing

20.  The tube housing must not drift from its set position during an exposure. The
tube housing must not be hand-held during an exposure by the operator or
the patient due to leakage radiation through the tube housing. If you note
problems with the tube housing, immediately report this to your supervisor so
that any instability of the suspension arm can be corrected.

21. Film and Digital Imaging
 Currently, intraoral dental x-ray film is available in three speed groups: D, E,
and F . Clinically, fi lm 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 ( Fig. 3-
3 ). The current F-speed films require about 75% the exposure of E-speed film
and only about 40% that of D-speed. Faster films are desirable from the
standpoint of exposure reduction. 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.
 Current digital sensors offer equal or greater dose savings than F speed film
and comparable diagnostic utility.

23. Required Distances

24. 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)

25. Intensifying Screens and Film or Digital
Imaging
 Contemporary intensifying screens used in extraoral radiography use the rare
earth elements gadolinium and lanthanum . These rare earth phosphors emit
green light on interaction with x rays. Compared with the older calcium
tungstate screens, rare earth screens decrease patient exposure by as much
as 55% in panoramic and cephalometric radiography. Unlike digital intraoral
imaging, there is no significant dose reduction to be gained by replacing
extraoral screen-fi lm systems with digital imaging. Image resolution with
digital systems is comparable to that obtained with rare earth screens
matched with appropriate film.

26. Lead aprons and shields

28. Collimators

30.  Collimators limit the size and shape of the useful beam which reaches the
patient. Rectangular collimators are recommended for periapical radiographs
as their use significantly reduces the area of the patient’s body that is
exposed to radiation.

31. Cones

32.  The ADA discourages the use of short, closed, pointed cones because of the
increased scatter radiation close to the face and adjacent areas of the
patient’s body.

33. Rectangular Collimation
 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).

35. System Speed
 Faster image receptor systems result in decreased radiation exposure to the
patient.

36. Film and Sensor Holders
 Film holders that align the fi lm precisely with the collimated beam are
recommended for periapical and bitewing radiographs. (ADA, 2006) Film or
digital sensor holders should be used when intraoral radiographs are made
because they improve the alignment of the fi lm, or digital sensor, with teeth
and x-ray machine. Their use results in a significant reduction in
unacceptable images.

38. Kilovoltage
 The operating potential of dental X-ray machines must range between 50 and
100 kilovolt peak but should range between 60 and 80 kVp. (ADA, 2006)

39. Film Processing
 Radiographs should not be overexposed and then underdeveloped, because
this practice results in greater exposure to the patient and dental health care
worker and can produce images of poor diagnostic quality. Dental radiographs
should not be processed by sight, and manufacturers ’ instructions regarding
time, temperature and chemistry should be followed. (ADA, 2006) A major
cause of unnecessary patient exposure is the deliberate overexposure of films
compensated by underdevelopment of the fi lm. This procedure results in
both needless exposure of the patient and in films that are of inferior
diagnostic quality (because of incomplete development). The use of machines
to process dental x-ray fi lm has become widespread. More than 90% of
dentists surveyed have reported using dental fi lm processors. Automatic fi lm
processors should be used in a darkroom.

40. References
American Dental Association Council on Scientifi c Affairs : The use of dental radiographs: update and
recommendations , J Am Dent Assoc 137 : 1304 - 1312 , 2006 .
2 Code of Federal Regulations 21, Subchapter J: Radiological health, part 1000, Offi ce of the Federal Register,
General Services Administration, Washington, DC, 1994.
Committee to Assess Health Risks from Exposure to Low Levels of Ionizing Radiations : Health risks from
exposure to low levels of ionizing radiation: BEIR VII , Washington, DC , 2006 , National Academy Press . 4 Hall EJ
, Giaccia AJ : Radiobiology for the radiologist , ed 6 , Baltimore , 2006 , Lippincott Williams & Wilkins .
5 Horner K , Rushton VE , Walker A et al : European guidelines on radiation protection in dental radiology: the
safe use of radiographs in dental practice , Radiat Protect 136 : 1 - 115 , 2004 .
6 National Council on Radiation Protection and Measurements : Control of radon in houses , NCRP Report 103,
Bethesda, Md , 1989 , National Council on Radiation Protection and Measurements . N 7 ational Council on
Radiation Protection and Measurements : Q uality assurance for diagnostic imaging , NCRP Report 99, Bethesda,
Md , 1990 , National Council on Radiation Protection and Measurements . N 8 ational Council on Radiation
Protection and Measurements : L imitation of exposure to ionizing radiation , NCRP Report 116, Bethesda, Md ,
1993 , National Council on Radiation Protection and Measurements
N 9 ational Council on Radiation Protection and Measurements : D ental x-ray protection , NCRP Report 145,
Bethesda, Md , 2003 , National Council on Radiation Protection and Measurements . N 0 1 ationwide Evaluation
of X-Ray Trends (NEXT), tabulation and graphical summary of the 1999 dental radiography survey , CRCPD
Publication E-03-6, Bethesda, Md , 2003 , Center for Devices and Radiological Health, U.S. Food and Drug
Administration . P1reston RJ : Radiation biology: concepts for radiation protection , H ealth Phys 88 : 545 - 556 ,
2005 . 12 Sources and effects of ionizing radiation , volume 1 : sources, New York , 2000 , UNSCEAR, UN
Publication . 13 Wall BF , Kendall GM , Edwards AA et al : What are the risks from medical X-rays and other low
dose radiation? Br J Radiol 79 : 285 - 294 , 2006 .

42. Thank You
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