Imaging Sci Dent.  2014 Mar;44(1):21-29. 10.5624/isd.2014.44.1.21.

Conversion coefficients for the estimation of effective dose in cone-beam CT

• Kim DS
• Rashsuren
• Kim EK

• KMID: 1974470
• DOI: http://doi.org/10.5624/isd.2014.44.1.21

Abstract

PURPOSE
To determine the conversion coefficients (CCs) from the dose-area product (DAP) value to effective dose in cone-beam CT.
MATERIALS AND METHODS
A CBCT scanner with four fields of view (FOV) was used. Using two exposure settings of the adult standard and low dose exposure, DAP values were measured with a DAP meter in C mode (200mm x 179 mm), P mode (154 mm x 154 mm), I mode (102 mm x 102 mm), and D mode (51 mm x 51 mm). The effective doses were also investigated at each mode using an adult male head and neck phantom and thermoluminescent chips. Linear regressive analysis of the DAP and effective dose values was used to calculate the CCs for each CBCT examination.
RESULTS
For the C mode, the P mode at the maxilla, and the P mode at the mandible, the CCs were 0.049 microSv/mGycm2, 0.067 microSv/mGycm2, and 0.064 microSv/mGycm2, respectively. For the I mode, the CCs at the maxilla and mandible were 0.076 microSv/mGycm2 and 0.095 microSv/mGycm2, respectively. For the D mode at the maxillary incisors, molars, and mandibular molars, the CCs were 0.038 microSv/mGycm2, 0.041 microSv/mGycm2, and 0.146 microSv/mGycm2, respectively.
CONCLUSION
The CCs in one CBCT device with fixed 80 kV ranged from 0.038 microSv/mGycm2 to 0.146 microSv/mGycm2 according to the imaging modes and irradiated region and were highest for the D mode at the mandibular molar.

Keyword

Radiation Dosage; Radiography, Dental; Cone-Beam Computed Tomography; Effective Dose

MeSH Terms

Adult
Cone-Beam Computed Tomography*
Head
Humans
Incisor
Male
Mandible
Maxilla
Molar
Neck
Radiation Dosage
Radiography, Dental

Figure

• 

  Fig. 1 DIAMENTOR M4-KDK (PTW, Freiburg, Germany) used for the measurement of DAP.

• 

  Fig. 2 Adult male ART head and neck phantom (A) and TLD-100 LiF chips (B) used for the measurement of effective dose.

• 

  Fig. 3 Ionization chamber of DAP meter is located at the tube side of CBCT machine for the measurement of DAP.

• 

  Fig. 4 Adult male ART head and neck phantom is positioned for CBCT taking.

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