Home About us Editorial board Ahead of print Current issue Archives Submit article Instructions Subscribe Search Contacts Login 
  • Users Online: 256
  • Home
  • Print this page
  • Email this page


 
 Table of Contents  
ORIGINAL ARTICLE
Year : 2014  |  Volume : 26  |  Issue : 1  |  Page : 24-29

Estimation of the annual cumulative radiation dose received by the dentist in dental clinics in Chennai


1 Department of Oral Medicine and Radiology, Thai Moogambigai Dental College, Chennai, Tamilnadu, India
2 Department of Oral Medicine and Radiology, Bharati Vidyapeeth Dental College and Hospital, Pune, Maharashtra, India
3 Department of Oral Medicine and Radiology, Sree Balaji Dental College and Hospital, Chennai, Tamil Nadu, India
4 Department of Oral Medicine and Radiology, Priyadarshini Dental College and Hospital, Pandur, Tamil Nadu, India
5 Department of Oral Medicine and Radiology, Career Postgraduate Institute of Dental Sciences, Lucknow, Uttar Pradesh, India
6 Department of Oral Medicine and Radiology, Desh Bhagat Dental College and Hospital, Muktsar, Punjab, India

Date of Submission14-Jul-2014
Date of Acceptance26-Aug-2014
Date of Web Publication26-Sep-2014

Correspondence Address:
Shams Ul Nisa
Department of Oral Medicine and Radiology, Bharati Vidyapeeth Dental College, Katraj, Pune - 411 043, Maharashtra
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-1363.141835

Rights and Permissions
   Abstract 

Aim and Objectives: To estimate the annual cumulative radiation dose received by a dentist in a 'less than an ideally sized clinic' in Chennai. The objective of the study is to estimate the annual cumulative radiation dose received by the dentist at various distances and various angulations from the x-ray tube. Study Design: The head of a mannequin model was mounted on the dental chair to simulate a patient's head and three thermoluminescent dosimeter (TLD) chips were kept at various distances and various angulations, at a constant height. The standard conventional intraoral dental radiographic unit was used, which was kept stationary, with a constant voltage of 70 Kv, 8 mA current, and a constant exposure time of 0.3 seconds. Ninety-two TLD chips were exposed 20 times a day with constant horizontal angulations for a period of one year. The reading from the TLD chips was obtained on a computer through a TLD Badge Reader. Statistical Analysis: Post Hoc tests and One-way analysis of variance (ANOVA) were used. Results and Conclusion: A decreasing trend was obtained in the average radiation doses, as the distance increased from the x-ray source, and a highly significant difference in doses (P < 0.001%) was found between 4 and 5.5 feet (ft). We found a minimum average radiation dose at an angle of 60° to 80° and behind the tube. The purpose of this study was to create awareness among dental professionals, who had 'less than an ideally sized clinic'. We recommend that the dentist follow guidelines suggested by the National Council on Radiation Protection and Measurements (NCRP), USA. From this study, it is clear that most clinics are of sizes that do not permit this distance (6 ft), and hence, it is recommended that they use suitable barriers.

Keywords: Annual cumulative dose, dental clinics, radiation dose, thermoluminescent dosimeters


How to cite this article:
Selvamuthukumar SC, Nisa SU, Parthasarathy VK, Sahabudeen MA, Pamula R, Siddareddy NR. Estimation of the annual cumulative radiation dose received by the dentist in dental clinics in Chennai . J Indian Acad Oral Med Radiol 2014;26:24-9

How to cite this URL:
Selvamuthukumar SC, Nisa SU, Parthasarathy VK, Sahabudeen MA, Pamula R, Siddareddy NR. Estimation of the annual cumulative radiation dose received by the dentist in dental clinics in Chennai . J Indian Acad Oral Med Radiol [serial online] 2014 [cited 2018 Sep 25];26:24-9. Available from: http://www.jiaomr.in/text.asp?2014/26/1/24/141835


   Introduction Top


Dental radiography is a double-edged armament, capable of diagnosis of physical conditions that would otherwise be difficult to identify and its judicious use is of considerable benefit to the patient. One of the basic beliefs of radiation safety is the 'As Low As Reasonably Achievable (ALARA)' principle. In addition to this, in x-ray diagnostics, Thermoluminescent Dosimeters (TLD) are commonly used for determining absorbed doses to patients and operators. [1],[2],[3]

In reality, due to an enormous increase in real-estate prices the world over, dental clinics are becoming smaller and many more dentists are knowingly or unknowingly standing at a less-than-safe distance from the x-ray source. [4],[5]

In this study, the annual cumulative radiation doses were estimated, to see how much radiation a dentist would receive, without using a suitable barrier, while standing at less than the recommended safe distance from the x-ray source. Subsequently, a census was taken from among the practicing dentists in Chennai, by means of a questionnaire, and the information corroborated the fact that dental clinics are indeed smaller than ideal to allow taking radiographs from a safe distance.


   Materials and Methods Top


In the present study, a dedicated room of size 100 sq ft, with 30 cm wall thickness, a door with leaded glass, and a lead lining of thickness 1.7 inches, with a warning light outside, was used. The head of a mannequin model was mounted on the dental chair to simulate the patient's head. Ribbons were tied at various angulations with the help of a protractor and sellotape [Figure 1] and [Figure 2]. Three Calcium Sulfate: Dysprosium (Caso4: Dy) TLD chips were kept in a plastic sachet and mounted on the tied ribbons at various distances of 2, 4, and 5.5 ft and angulations of 0°, 20°, 40°, 60°, 80°, 90°, 140°, 160°, 180°, and behind the tube, respectively, at a constant height of 3.5 ft, with the help of sellotape. Two TLD chips were kept as the control in the room, as recommended by the Avanttec Laboratories [Figure 3]. The standard conventional Intraoral Dental Radiographic Unit was used, which was kept stationary with a constant voltage of 70 Kv, 8 mA current through a 5 Kv Servo voltage stabilizer, and a constant exposure time of 0.3 second. The x-ray beam was directed either to the maxilla or mandible with an intraoral Ekta Speed film placed in the lingual side of the lower posterior teeth and palatal side of the upper posterior teeth. Ninety-two TLD chips were exposed 20 times a day, with constant horizontal angulations at the rate of 10 exposures of radiation dose for the maxilla and 10 exposures of radiation dose for the mandible, for a period of one year. The TLD chips were kept in TLD cards and then loaded in a magazine [Figure 4]. The magazine was kept in a TLD badge reader and the TL dosimeter was heated with the help of a hot nitrogen gas (N2) jet to 285°C. The TL output was recorded using a photomultiplier tube. The badge reader read the TLD cards and gave the TL glow curve, which was an integral of the current output and was proportional to the dose received. The reading was obtained on a computer [Figure 5], [Figure 6], [Figure 7]. A questionnaire primarily pertaining to the clinic size, number of radiographs taken per day, position of the dentist in relation to the x-ray source, and the radiation protection measures employed while taking intraoral radiographs, was distributed to 100 practicing dentists, in Chennai, and their answers were taken in writing [Table 1].
Table 1: Results of the questionnaire distributed among one hundred dental practitioners

Click here to view
Figure 1: Schematic diagram showing placement of TLD cards

Click here to view
Figure 2: TLD cards kept at various distances and angulations from the head of the mannequin model

Click here to view
Figure 3: TLD chips used for different distances and angulations and for control

Click here to view
Figure 4: TLD chips in the TLD cards and inside the magazine

Click here to view
Figure 5: Nitrogen dispenser

Click here to view
Figure 6: TLD badge reader with magazine

Click here to view
Figure 7: Computer with TLD badge reader

Click here to view


Statistical analysis

Post Hoc Tests and One-way ANOVA were used.


   Results Top


The results of the questionnaire distributed among 100 dental practitioners in Chennai are shown in [Table 1] and Graph 1. [Additional file 1]

The cumulative radiation dose values were compared between different distances and angulations. With the glow curve, we found the maximum radiation dose at a distance of 2 ft and at a 180° angulation [Table 2].
Table 2: Cumulative radiation dose at different angulations and distances

Click here to view


The cumulative radiation dose values were compared between different distances. We found a decreasing trend in the average radiation doses as the distance increased from the x-ray source and maximum doses at 2 ft. A multiple correlation analysis was done using 'Post Hoc Tests', to compare parameters for multiple groups, which depicted an insignificant difference (P > 0.05%) between distances of 2 to 4 ft and 2 ft to 5.5 ft and a highly significant difference (P < 0.001%) between 4 and 5.5 ft [Graph 2]. [Additional file 2]

The cumulative radiation dose values were compared among different angulations. We found a decreasing trend in the average radiation dose at an angle of 60° and 80° and behind the tube, and the maximum dose at 180°. One-way ANOVA was used to compare parameters for multiple groups, which depicted an insignificant difference (P > 0.05%) among the different angulations [Graph 3]. [Additional file 3]

[Table 1] shows the distances at which dentists stand, area (in sq ft) of their clinics and protective measures used by dentists in Chennai. [Table 2] shows the cumulative radiation dose at different angulations and distances.


   Discussion Top


Sir Wilhelm Roentgen accidentally discovered x-rays, in 1895, when he produced an unintentional radiograph of his own hand. X-ray radiation is a form of energy that can pass through matter and disperse the energy that depends on the atomic structure of the object and the energy of the beam. Radiation damage to the tissue can be either direct or indirect. [6],[7]

Health physics is concerned with protecting people from the harmful effects of ionizing radiation, while allowing its beneficial use in the medical and dental fields. Dentists must be aware of safe practices during radiation procedures and use it at all times. A proper barrier can reduce the operator's radiation exposure during intraoral radiography to zero. In addition, when the barrier is not available, the dentist can stand at least 6 ft from the patient and in a location that is not in the path of the primary x-ray beam, during exposure. [4],[8],[9]

A controlled area is defined as the area around the x-ray equipment that staff should vacate during exposure. A dentist should ensure that they are well out of this area, 2-3 m away or out of the room, during radiography. This can be achieved by defining an area that the dentist does not normally enter during x-ray exposure. [4],[8],[9],[10]

Dosimetry is the determination of the quantity of radiation exposure or dose. Personnel dosimetry refers to the monitoring of radiation doses to individuals who are exposed to radiation during the course of their work. Dosimeters used for monitoring of personnel have a dose measurement limit of 0.1-0.2 mSv. [11],[12]

In the present study, a questionnaire was distributed among 100 dental practitioners in Chennai on the basis of the size of the dental clinic, number of radiographs taken per day, and use of protective measures while taking intraoral radiographs. A survey was taken from the North, South, East, West, and Central part of Chennai. On an average, 36-39% of the dentists had clinics that were between 100 and 300 sq ft in size. Seventy-eight never used any radiation protection, 17% used wall protection, and only 5% of the dentists used a lead shield during intraoral radiography [Table 1]. On an average, 87% of the dentists stood less than 4 ft away from the patient's head and the x-ray source, during exposure.

A similar survey was done by Jacobs et al., in 2004. [13] In their study, they concluded that the distance of the dentist from the radiation tube during exposure was an average of 2.2 m (7.2 ft) and 8% of the dentists assisted in holding the image receptor inside the patient's mouth. One-quarter of the dentists were standing behind a wall when taking radiographs.

A similar survey was done by Kaviani et al., in 2007. [14] In their study, they found that in 68.3% of the cases, the position-distance rule was used, indicating that this method was the most commonly used method. In 75.3% of the cases, dental practitioners did not use any protection.

In the present study, the average cumulative radiation dose at various distances from the x-ray source has been studied. It has been found that there is a decreasing trend in the average radiation dose as the distance increases from the x-ray source from 2 to 4 ft and 4 to 5.5 ft. A highly statistical significant difference (P < 0.001%) between 4 and 5.5 ft has been obtained. An insignificant statistical difference (P > 0.05%) between 2 to 4 ft and 2 to 5.5 ft has been obtained. The maximum average radiation dose has been found at a distance of 2 ft.

In the present study, the average cumulative radiation dose at different angulations from the x-ray source was studied. It was found that there was a decreasing trend in the average radiation dose from the angles of 0° and 180°, at various distances. The lowest radiation dose was obtained at an angle of 60°, 80°, and behind the tube, at 5.5 ft. The maximum radiation dose was found at an angle of 180°at 2 ft. A statistical insignificant difference (P > 0.05%) among the different angulations was obtained.

The findings of this study are consistent with the study done by Kuroyanagi et al., in 1998. [15] The result was obtained, by measuring the radiation dose of the spatial distribution of scattered radiation, which was not the same in the eight directions around the chair. According to their results, the preferred position suggested for the operator was 200 cm behind the patient and the radiation exposure was least in the region between 135° and 180° than those in the other directions. However, in our study, we found minimum exposure of an average radiation dose at angles of 60° and 80°, at a distance of 5.5 ft, and behind the tube, and the maximum dose at 180°. To the best of our knowledge, this is the first study done in India, second in world, and the results are more or less consistent with the study done by Kuroyanagi et al., in Japan.

According to Abbott, a good clinic design, with large rooms and appropriate wall thickness and materials, will help protect the dental personnel. [16] The staff should be at least 2 m away from the x-ray machine and the room should be designed in such a manner that the x-ray beam is never pointed toward the exit door where the staff are sheltering. [17] Monsour et al. [18] reported that the average number of radiographs taken each week by Australian dentists was 22.1 ± 14.5 intraoral films and 6.2 ± 7.8 extraoral films, whereas, the threshold level at which x-radiation could become harmful to an operator is calculated as 360 dental exposures per week of 0.5 second each. [19] Well-maintained, modern equipment is essential for diagnostically acceptable radiographs and for radiation safety. Machines that are more than 10 years old could need maintenance, upgrading or even replacement. All aspects of every machine, including the filtration, beam size, timer, and the like, should be checked regularly, to ensure proper functioning. [20]


   Conclusion Top


In the present study, the annual cumulative radiation dose at various distances and angulations was less than the maximum permissible dose. The principle of ALARA recognizes the possibility that no matter how small the dose, some stochastic effects may result. [1] The purpose of this study is to create awareness among dental professionals who have 'less than ideally-sized clinics', which do not allow them to stand in the safe zone when taking intraoral periapical radiographs. We recommend that the dentist follow the guidelines suggested by the National Council on Radiation Protection and Measurements (NCRP), USA, which states that the operator should stand at least 6 ft from the patient, at an angle of 90°-135° to the central ray of the x-ray beam. From this study, it is clear that most clinics are of sizes that do not permit this distance (6 ft), and hence, it is recommended that they use suitable barriers. The radiation dose can further be reduced with the use of faster films, to reduce the exposure time, electronically-controlled timers, to produce an optimum dose, and computers and digital imaging technology.

 
   References Top

1.Farman AG. ALARA still applies. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;100:395-7.  Back to cited text no. 1
[PUBMED]    
2.Ludlow JB, Davies-Ludlow LE, White SC. Patient risk related to common dental radiographic examinations: The impact of 2007 International Commission on Radiological Protection recommendations regarding dose calculation. J Am Dent Assoc 2008;139:1237-43.  Back to cited text no. 2
    
3.Bhatt BC. Application of thermoluminescent phosphors in medical physics. J Med Phys 2004;29:41-7.  Back to cited text no. 3
  Medknow Journal  
4.ADA Council on Scientific Affairs. An update on radiographic practices: Information and recommendations. ADA Council on Scientific Affairs. J Am Dent Assoc 2001;132:234-8.  Back to cited text no. 4
[PUBMED]    
5.Alcaraz M, Parra C, Martínez Beneyto Y, Velasco E, Canteras M. Is it true that the radiation dose to which patients are exposed has decreased with modern radiographic films? Dentomaxillofac Radiol 2009;38:92-7.  Back to cited text no. 5
    
6.Frommer HH, Fortier P. History of the American Academy of Oral and Maxillofacial Radiology. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;80:512-6.  Back to cited text no. 6
    
7.Langland OE, Langlais RP. Early pioneers of oral and maxillofacial radiology. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;80:496-511.  Back to cited text no. 7
    
8.Hirschmann PN. Radiation protection in dentistry. Br J Radiol 1978;51:837.  Back to cited text no. 8
[PUBMED]    
9.Grover SB, Kumar J, Gupta A, Khanna L. Protection against radiation hazards: Regulatory bodies, safety norms, dose limits and protection devices. Indian J Radiol Imaging 2002;12:157-67.  Back to cited text no. 9
  Medknow Journal  
10.Minder W, Osborn SB. Manual on Radiation Protection in Hospitals and General Practice. Vol.5. Personnel Monitoring Services. Geneva: World Health Organization; 1980. p. 56.  Back to cited text no. 10
    
11.Kron T. Thermoluminescence dosimetry and its applications in medicine--Part 1: Physics, materials and equipment. Australas Phys Eng Sci Med 1994;17:175-99.  Back to cited text no. 11
[PUBMED]    
12.Kron T. Thermoluminescence dosimetry and its applications in medicine - Part 2: History and applications. Australas Phys Eng Sci Med 1995;18:1-25.  Back to cited text no. 12
[PUBMED]    
13.Jacobs R, Vanderstappen M, Bogaerts R, Gijbels F. Attitude of the Belgian dentist population towards radiation protection. Dentomaxillofac Radiol 2004;33:334-9.  Back to cited text no. 13
    
14.Kaviani F, Esmaeili F, Balayi E, Pourfattollah N. Evaluation of X-ray protection methods used in dental offices in Tabriz in 2005-2006. J Dent Res Dent Clin Dent Prospects 2007;1:49-52.  Back to cited text no. 14
    
15.Kuroyanagi K, Hayakawa Y, Fujimori H, Sugiyama T. Distribution of scattered radiation during intraoral radiography with the patient in supine position. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998;85:736-41.  Back to cited text no. 15
    
16.Abbott P. Are dental radiographs safe? Aust Dent J 2000;45:208-13.  Back to cited text no. 16
[PUBMED]    
17.National Health and Medical Research Council. Code of Practice for Radiation Protection in Dentistry. Canberra: Australian Government Publishing Service; 1987. p. 1-63.  Back to cited text no. 17
    
18.Monsour PA, Kruger BJ, Barnes A, Sainsbury A. Measures taken to reduce X-ray exposure of the patient, operator, and staff. Aust Dent J 1988;33:181-92.  Back to cited text no. 18
[PUBMED]    
19.Smith NJ. Dental Radiography. 2 nd ed. Oxford: Blackwell Scientific Publications; 1988. p. 1-53.  Back to cited text no. 19
    
20.Monsour PA, Kruger BJ, Barnes A. X-ray equipment used by general dental practitioners in Australia. Aust Dent J 1988;33:81-6.  Back to cited text no. 20
[PUBMED]    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]
 
 
    Tables

  [Table 1], [Table 2]



 

Top
 
 
  Search
 
Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

   Abstract Introduction Materials and Me... Results Discussion Conclusion Article Figures Article Tables
  In this article
 References

 Article Access Statistics
    Viewed975    
    Printed21    
    Emailed0    
    PDF Downloaded178    
    Comments [Add]    

Recommend this journal


[TAG2]
[TAG3]
[TAG4]