Conversion coefficients for the estimation of effective doses in intraoral and panoramic dental radiology from dose-area product values

Looe, Hui Khee; Eenboom, F.; Chofor, N; Pfaffenberger, A.; Steinhoff, Malte; Rühmann, Antje; Poplawski, Alicia; Willborn, K.; Poppe, Björn

doi:10.1093/rpd/ncn172

Cited by 21 publications

(22 citation statements)

References 16 publications

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“…There has been a very few reports about those in dental radiology. Looe et al25,26 suggested the conversion coefficients for the estimation of effective dose of the intraoral, panoramic, and lateral cephalometric radiography. However, the conversion coefficient for CBCT remains unknown.…”

Section: Introductionmentioning

confidence: 99%

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

2014

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PurposeTo determine the conversion coefficients (CCs) from the dose-area product (DAP) value to effective dose in cone-beam CT.Materials and MethodsA 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×179 mm), P mode (154 mm×154 mm), I mode (102 mm×102 mm), and D mode (51 mm×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.ResultsFor the C mode, the P mode at the maxilla, and the P mode at the mandible, the CCs were 0.049 µSv/mGycm2, 0.067 µSv/mGycm2, and 0.064 µSv/mGycm2, respectively. For the I mode, the CCs at the maxilla and mandible were 0.076 µSv/mGycm2 and 0.095 µSv/mGycm2, respectively. For the D mode at the maxillary incisors, molars, and mandibular molars, the CCs were 0.038 µSv/mGycm2, 0.041 µSv/mGycm2, and 0.146 µSv/mGycm2, respectively.ConclusionThe CCs in one CBCT device with fixed 80 kV ranged from 0.038 µSv/mGycm2 to 0.146 µSv/mGycm2 according to the imaging modes and irradiated region and were highest for the D mode at the mandibular molar.

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Section: Introductionmentioning

confidence: 99%

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

2014

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“…Conversion coefficients between DAP and effective dose have been determined for intraoral, panoramic and cephalometric radiography. [22][23][24] For CBCT, the conversion between DAP and effective dose is far more complicated, as the irradiated field size and positional factors need to be taken into account, which may complicate interpretation of this index. 25 A study by LofthagHansen et al 16 converted DAP values to effective dose using conversion factors determined for panoramic radiography.…”

Section: Discussionmentioning

confidence: 99%

Dose distribution for dental cone beam CT and its implication for defining a dose index

Pauwels

Theodorakou²,

Walker³

et al. 2012

Dentomaxillofacial Radiology

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6 Listing of partners on www.sedentexct.euObjectives: To characterize the dose distribution for a range of cone beam CT (CBCT) units, investigating different field of view sizes, central and off-axis geometries, full or partial rotations of the X-ray tube and different clinically applied beam qualities. The implications of the dose distributions on the definition and practicality of a CBCT dose index were assessed. Methods: Dose measurements on CBCT devices were performed by scanning cylindrical head-size water and polymethyl methacrylate phantoms, using thermoluminescent dosemeters, a small-volume ion chamber and radiochromic films. Results: It was found that the dose distribution can be asymmetrical for dental CBCT exposures throughout a homogeneous phantom, owing to an asymmetrical positioning of the isocentre and/ or partial rotation of the X-ray source. Furthermore, the scatter tail along the z-axis was found to have a distinct shape, generally resulting in a strong drop (90%) in absorbed dose outside the primary beam. Conclusions: There is no optimal dose index available owing to the complicated exposure geometry of CBCT and the practical aspects of quality control measurements. Practical validation of different possible dose indices is needed, as well as the definition of conversion factors to patient dose.

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“…The quantity used in this study to describe patient doses resulting from different kinds of dental radiation examinations is the product of the air kerma and the area of the radiation field (P KA ), as suggested and used by Helmrot and Alm Carlsson (4) , LofthagHansen et al (5) and Looe et al (6,7) . P KA values can be measured by a suitably calibrated P KA meter (KAP meter) (4) .…”

Section: Methodsmentioning

confidence: 99%

Methods for monitoring patient dose in dental radiology

Helmrot

Thilander-Klang

2010

Radiation Protection Dosimetry

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Different types of X-ray equipment are used in dental radiology, such as intra-oral, panoramic, cephalometric, cone-beam computed tomography (CBCT) and multi-slice computed tomography (MSCT) units. Digital receptors have replaced film and screen-film systems and other technical developments have been made. The radiation doses arising from different types of examination are sparsely documented and often expressed in different radiation quantities. In order to allow the comparison of radiation doses using conventional techniques, i.e. intra-oral, panoramic and cephalometric units, with those obtained using, CBCT or MSCT techniques, the same quantities and units of dose must be used. Dose determination should be straightforward and reproducible, and data should be stored for each image and clinical examination.It is shown here that air kerma-area product (P KA ) values can be used to monitor the radiation doses used in all types of dental examinations including CBCT and MSCT.However, for the CBCT and MSCT techniques, the methods for the estimation of dose must be more thoroughly investigated. The values recorded can be used to determine diagnostic standard doses and to set diagnostic reference levels for each type of clinical examination and equipment used. It should also be possible to use these values for the estimation and documentation of organ or effective doses. (7)

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Conversion coefficients for the estimation of effective doses in intraoral and panoramic dental radiology from dose-area product values

Cited by 21 publications

References 16 publications

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

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

Dose distribution for dental cone beam CT and its implication for defining a dose index

Methods for monitoring patient dose in dental radiology

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