Objectives: The aim of the present study was to find out whether it was more effective to achieve a dose reduction in intraoral radiography with an increase in the tube potential setting (and a decrease of milliampere seconds) by an additional attenuation of the X-ray beam behind the film plane or by the use of digital radiography. A second aim was to find out if there were differences between the integral doses determined by two different detectors and two different phantoms.
Methods: The X-ray attenuation in this in vitro study was carried out using additional lead foils from the dental film packet fixed behind the film plane and with a metal film holder. The dose measurements were performed with two semiconductor detectors (Quart, Diados). Patient simulation was achieved by the Alderson phantom or by the use of a filter (6Al+0.8Cu). The absorbed doses were calculated by integrating an exponential function between the entrance dose and the body exit dose. In addition, organ doses were measured and the effective dose was determined according to the Implementation of the 1990 Recommendations of the ICRP (ICRP-60).
Results: The increase in tube potential levels did not provide a substantial reduction of the absorbed dose (90 kVp instead of 60 kVp: reduction to 92.4%), only a reduction of the entrance dose (by 30% to 35% at 90 kVp compared with 60 kVp). The use of three lead foils behind the film plane instead of one resulted in a 14.0% reduction of the absorbed dose (60 kVp); the use of a metal film holder resulted in a 27.8% reduction (60 kVp). When tube potential settings were increased, the dose reduction decreased. The absorbed dose was reduced to 52% when a storage phosphor plate was used instead of a film (60 kVp). It was possible to determine the amount of dose reduction with both the calculated absorbed dose and the effective doses. The integral doses obtained from the Alderson phantom showed values 5% higher than those obtained by the filter (r2=96.7%). For the comparison of the integral doses, the measurements performed with Quart had values higher by a factor of 1.139 than those performed with Diados.
Conclusions: Instead of increasing the tube voltage or using additional lead foils or metal film holders, a substantial dose reduction is provided by digital radiography or more sensitive films while a low tube potential level is maintained and the milliampere seconds setting is reduced.
1. www.icrp.org (homepage on the internet). Stockholm: International Commission on Radiological Protection 2003; International Commission on Radiation Protection 2004; Draft for Consultation; 2005 ICRP Recommendations (updated 2004 July 22; cited 2006 December 16). Available from: http://www.icrp.org/docs/2005_recs_CONSULTATION_Draft1a.pdf.
2. Jacobs R, Vanderstappen M, Bogaerts R, Gijbels F. Attitude of the Belgian dentist population towards radiation protection. Dentomaxillofac Radiol 2004; 33: 334–339.
3. Berge TI, Wohni T. Absorbed doses to discrete organs of the head and neck from four maxillary occlusal projections. Dentomaxillofac Radiol 1981; 10: 77–84.
4. Frey NW, Wuehrmann AH. Radiation dosimetry and intraoral radiographic techniques. II. Internal and external dose measurements. Oral Surg Oral Med Oral Pathol 1974; 38: 639–652.
5. Oishi TT, Parfitt GJ. Effects of varying peak kilovoltage and filtration on diagnostic dental radiographs. J Can Dent Assoc 1976; 9: 449–452.
6. Napier ID. Reference doses for dental radiography. Br Dent J 1999; 186: 392–396.
7. Jensen TW, Turek T. Improved radiography in endodontic practice: a procedure and an instrument. J Endod 1978; 4: 82–87.
8. Berkhout WE, Beuger DA, Sanderink GC, van der Stelt PF. The dynamic range of digital radiographic systems: dose reduction or risk of overexposure? Dentomaxillofac Radiol 2004; 33: 1–5.
9. Horner K, Hirschmann PN. Dose reduction in dental radiography. J Dent 1990; 18: 171–184.
10. International Electrotechnical Commission. Evaluation and routine testing in medical imaging departments. Part 3-4: Acceptance tests—imaging performance of dental X-ray equipment Berlin: Beuth, 2000. (IEC 61223-3-4).
11. International Commission on Radiological Protection. 1990 Recommendations of the International Commission on Radiological Protection. Ann ICRP 1991; 21: 1–201. (ICRP Publication 60).
12. Dula K, Mini R, van der Stelt PF, Lambrecht JT, Schneeberger P, Buser D. Hypothetical mortality risk associated with spiral computed tomography of the maxilla and mandible. Eur J Oral Sci 1996; 104: 503–510.
13. Frederiksen NL, Benson BW, Sokolowski TW. Effective dose and risk assessment from computed tomography of the maxillofacial complex. Dentomaxillofac Radiol 1995; 24: 55–58.
14. Velders XL, van Aken J, van der Stelt PF. Risk assessment from bitewing radiography. Dentomaxillofac Radiol 1991; 20: 209–213.
15. Altman DG. Practical statistics for medical research. London: Chapman and Hall, 1993.
16. Schmidt T, Pauly H, Hasl G. The integral dose in computerized tomography of the skull. Fortschr Röntgenstr 1982; 136: 157–165.
17. Medwedeff FM, Knox WH, Latimer P. A new device to reduce patient irradiation and improve dental film quality. Oral Surg Oral Med Oral Pathol 1962; 15: 1079–1088.
18. Kaeppler G, Dietz K, Reinert S. Influence of tube potential setting and dose on the visibility of lesions in intraoral radiography. Dentomaxillofac Radiol 2007; 36: 75–79.
19. Buchholz RE. No kilovoltage dilemma. Oral Surg Oral Med Oral Pathol 1967; 23: 459–461.
20. White SC. 1992 assessment of radiation risk from dental radiography. Dentomaxillofac Radiol 1992; 21: 118–126.
21. Gibbs SJ. Effective dose equivalent and effective dose: comparison for common projections in oral and maxillofacial radiology. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000; 90: 538–545.
22. Cederberg RA, Frederiksen NL, Benson BW, Sokolowski TW. Effect of the geometry of the intraoral position-indicating device on effective dose. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1997; 84: 101–109.
23. Avendanio B, Frederiksen NL, Benson BW, Sokolowski TW. Effective dose and risk assessment from detailed narrow beam radiography. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996; 82: 713–719.
24. Huumonen S, Kvist T, Gröndahl K, Molander A. Diagnostic value of computed tomography in re-treatment of root fillings in maxillary molars. Int Endod J 2006; 39: 827–833.
25. Ekestubbe A, Thilander-Klang A, Lith A, Gröndahl HG. Effective and organ doses from scanography and zonography: a comparison with periapical radiography. Dentomaxillofac Radiol 2004; 33: 87–92.