Oral and maxillofacial radiology
Comparative dosimetry of dental CBCT devices and 64-slice CT for oral and maxillofacial radiology

https://doi.org/10.1016/j.tripleo.2008.03.018Get rights and content

Objectives

This study compares 2 measures of effective dose, E1990 and E2007, for 8 dentoalveolar and maxillofacial cone-beam computerized tomography (CBCT) units and a 64-slice multidetector CT (MDCT) unit.

Study design

Average tissue-absorbed dose, equivalent dose, and effective dose were calculated using thermoluminescent dosimeter chips in a radiation analog dosimetry phantom. Effective doses were derived using 1990 and the superseding 2007 International Commission on Radiological Protection (ICRP) recommendations.

Results

Large-field of view (FOV) CBCT E2007 ranged from 68 to 1,073 μSv. Medium-FOV CBCT E2007 ranged from 69 to 560 μSv, whereas a similar-FOV MDCT produced 860 μSv. The E2007 calculations were 23% to 224% greater than E1990.

Conclusions

The 2007 recommendations of the ICRP, which include salivary glands, extrathoracic region, and oral mucosa in the calculation of effective dose, result in an upward reassessment of fatal cancer risk from oral and maxillofacial radiographic examinations. Dental CBCT can be recommended as a dose-sparing technique in comparison with alternative medical CT scans for common oral and maxillofacial radiographic imaging tasks.

Section snippets

Materials and Methods

Doses for the following CBCT units were investigated: NewTom 3G (QR, Verona, Italy); CB Mercuray (Hitachi Medical of America, Twinsburg, OH); Promax 3D (Planmeca OY, Helsinki, Finnland); Prexion 3D (Terarecon, San Mateo, CA); Galileos (Sirona, Charlotte, NC); Classic i-CAT (Imaging Sciences International, Hatfield, PA); Next Generation i-CAT (Imaging Sciences International); and Iluma (Imtec Imaging, Ardmore, OK). Dose for the 64-slice MDCT was measured using the Somatom Sensation

Results

Table V provides equivalent doses for the weighted tissues and organs that receive direct exposure during maxillofacial imaging. Two dosimeter runs on the same Next Generation iCAT unit in landscape mode were available. The mean dosimeter exposure for each run was found to vary by less than 2%. An average of the values from the 2 runs is presented in table V. It is noteworthy that salivary gland contribution to effective doses range from 1 mSv to more than 17 mSv depending on the radiographic

Discussion

Revision of tissue-weighting factors in the 2007 ICRP recommendations is made possible by the availability of cancer incidence data that was not available when the 1990 guidelines were published. The 1990 ICRP cancer risks were computed based on mortality data. Incidence data provides a more complete description of cancer burden than mortality data alone, particularly for cancers that have a high survival rate. Much of the cancer incidence data comes from the Life Span Study of Japanese atomic

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