Several studies have been performed that include dosimetry of CBCT equipment. The literature review conducted by the SEDENTEXCT project and published in the Provisional Guidelines document 11 studies in which dosimetry for CBCT was performed and in which effective dose was calculated using tissue weighting factors taken from ICRP (2007). included
Table 1 shows the reported effective doses for a range of dental CBCT units along with comparative data for conventional imaging techniques. Table 2 presents the effective dose for conventional imaging and conventional multi-slice CT (MSCT) imaging. The majority of studies were based on thermoluminescent (TLD) dosimetry techniques using anthropomorphic phantoms. They showed significant variation in methodology, especially with respect to the type of phantom used and TLD number and positioning. The effect of the number and position of the TLD dosimeters on the accuracy of the assessment has not been assessed.
Life is a risky business. Among the many risks to which we are prone, we are all constantly exposed to normal background radiation, which averages about 2400 µSv (European Commission, 2001) each year (average world figures). Medical exposures (of which dental radiology contributes a small fraction) add substantially to this figure, with wide variation from country to country. With this in mind, a panoramic radiograph may be associated with an effective dose the same as 1-5 days’ additional background radiation, while the dental CBCT risk could result in an effective dose equivalent to a few days up to a couple of months of background radiation, depending on the type of the machine and clinical protocol used.
Exposure to ionising radiation is associated with risks of various types. In diagnostic radiology, in particular with the low doses seen in dental and maxillofacial radiology, the radiation risk is of a very small increase in risk of cancer.
Table 1: The range of effective dose from dental CBCT in μSv. Studies are divided into those in which “dento-alveolar” CBCT (fields of view smaller than the facial region) and “craniofacial” CBCT, in which the field of view routinely includes at least the maxilla and mandible.
|
Dental CBCT unit
|
Effective dose (μSv)
|
References
|
||
|
|
Dento-alveolar
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Craniofacial
|
Dento-alveolar
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Craniofacial
|
|
NewTom
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41-75
|
30-78
|
Ludlow et al 2003
|
Ludlow et al 2006 Okano et al 2009
Silva et al 2008
Ludlow et al 2003
Ludlow et al 2008
Mah et al 2003
Tsiklakis et al 2005
|
|
Accuitomo/ Veraviewepocs
|
11-102
|
|
Okano et al 2009
Loftag-Hansen et al 2008
Hirsch et al 2008
Loubele et al 2008
|
|
|
Galileos
|
|
70-128
|
|
Ludlow et al 2008
|
|
Promax
|
488-652
|
|
Ludlow et al 2008
|
|
|
Prexion
|
189-388
|
|
Ludlow et al 2008
|
|
|
i-CAT
|
34-89
|
48-206
|
Roberts et al 2009
Loubele et al 2008
|
Ludlow et al 2006
Roberts et al 2009
Loubele et al 2008
Ludlow et al 2008
Mah et al 2003
|
|
CB MercuRay
|
407
|
283-1073
|
Ludlow et al 2008
|
Ludlow et al 2006
Okano et al 2009
Ludlow et al 2008
|
|
Illuma
|
|
98-498
|
|
Ludlow et al 2008
|
Table 2: Effective dose from conventional dental imaging techniques in μSv
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|
Effective dose (μSv)
|
References
|
|
Intra-oral radiograph
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<8.3*
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European Commission 2004*
|
|
Panoramic radiograph
|
2.7 - 23
|
Ludlow et al 2006
Okano et al 2009
Silva et al 2008
Palomo et al 2008
Garcia-Silva et al 2008
|
|
CT maxillo-mandibular
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180 - 2100
|
Ludlow et al 2006
Okano et al 2009
Silva et al 2008
Loubele et al 2005
|
|
CT maxilla
|
1400
|
Ludlow et al 2006
|
*no data available calculated subsequent to ICRP2007
References
European Commission. Radiation Protection 125: Low dose ionizing radiation and cancer risk. 2001. Office for Official Publications of the EC: Luxembourg. http://europa.eu.int/comm/environment/radprot/publications.
European Commission. Radiation Protection 136. European Guidelines on Radiation Protection in Dental Radiology. Luxembourg: Office for Official Publications of the European Communities, 2004. Available from: http://ec.europa.eu/energy/nuclear/radioprotection/publication/doc/136_en.pdf
Garcia Silva MA, Wolf U, Heinicke F, Gründler K, Visser H, Hirsch E. Effective dosages for recording Veraviewepocs dental panoramic images: analog film, digital, and panoramic scout for CBCT. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008; 106: 571-577.
Hirsch E, Wolf U, Heinicke F, Silva MA.Dosimetry of the cone beam computed tomography Veraviewepocs 3D compared with the 3D Accuitomo in different fields of view. Dentomaxillofac Radiol 2008; 37: 268-273.
ICRP Publication 103. The 2007 Recommendations of the International Commission on Radiological Protection. 2007. Annals of the ICRP: 37.
Lofthag-Hansen S, Thilander-Klang A, Ekestubbe A, Helmrot E, Gröndahl K. Calculating effective dose on a cone beam computed tomography device: 3D Accuitomo and 3D Accuitomo FPD. Dentomaxillofac Radiol 2008; 37: 72-79
Loubele M, Bogaerts R, Van Dijck E, Pauwels R, Vanheusden S, Suetens P, Marchal G, Sanderink G, Jacobs R.Comparison between effective radiation dose of CBCT and MSCT scanners for dentomaxillofacial applications. Eur J Radiol 2008; Jul 16 [Epub ahead of print].
Loubele M, Jacobs R, Maes F, Schutyser F, Debaveye D, Bogaerts R, Coudyzer W, Vandermeulen D, van Cleynenbreugel J, Marchal G, Suetens P. Radiation dose vs. image quality for low-dose CT protocols of the head for maxillofacial surgery and oral implant planning. Radiat Prot Dosimetry 2005; 117: 211-216.
Ludlow JB, Davies-Ludlow LE, Brooks SL.Dosimetry of two extraoral direct digital imaging devices: NewTom cone beam CT and Orthophos Plus DS panoramic unit. Dentomaxillofac Radiol 2003; 32: 229-234.
Ludlow JB, Davies-Ludlow LE, Brooks SL, Howerton WB. Dosimetry of 3 CBCT devices for oral and maxillofacial radiology: CB Mercuray, NewTom 3G and i-CAT. Dentomaxillofac Radiol 2006; 35: 219-26.
Ludlow JB, Ivanovic M. Comparative dosimetry of dental CBCT devices and 64-slice CT for oral and maxillofacial radiology. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008; 106: 106-114.
Mah JK, Danforth RA, Bumann A, Hatcher D.Radiation absorbed in maxillofacial imaging with a new dental computed tomography device. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003; 96: 508-513
Okano T, Harata Y, Sugihara Y, Sakaino R, Tsuchida R, Iwai K, Seki K, Araki K. Absorbed and effective doses from cone beam volumetric imaging for implant planning. Dentomaxillofac Radiol 2009; 38: 79-85.
Palomo JM, Rao PS, Hans MG. Influence of CBCT exposure conditions on radiation dose. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008; 105: 773-82.
Roberts JA, Drage NA, Davies J, Thomas DW.Effective dose from cone beam CT examinations in dentistry. Br J Radiol 2009; 82: 35-40.
Silva MA, Wolf U, Heinicke F, Bumann A, Visser H, Hirsch E. Cone-beam computed tomography for routine orthodontic treatment planning: a radiation dose evaluation. Am J Orthod Dentofacial Orthop 2008; 133: 640.e1-5.
Tsiklakis K, Donta C, Gavala S, Karayianni K, Kamenopoulou V, Hourdakis CJ. Dose reduction in maxillofacial imaging using low dose Cone Beam CT. Eur J Radiol 2005; 56: 413-417.
