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

Abstract

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.

Dose optimization by altering the operating potential and tube current exposure time product in dental cone beam CT: a systematic review

“…Bechara et al 39 also encouraged case-bycase decision-making on exposure factors, as they found that when imaging endodontically treated root fractures using a 360°as opposed to 180°rotation did not improve sensitivity but did improve specificity by reducing artefact, which could potentially reduce the number of patients having to undergo unnecessary treatment. birpublications.org/dmfr Dentomaxillofac Radiol, 45,20150254 Dose optimization in dental CBCT using kV and mAs: systematic review Goulston et al…”

“…During the first "screening" stage, the primary author (RG) read the journal titles and full abstracts of the studies found, to see if they fitted the eligibility criteria; those that met the criteria went through to stage two, where the primary author read the full-text article to ensure the studies continued to meet the pre-defined eligibility criteria. Where the primary author was uncertain about the eligibility of a study, this was resolved by discussion Dentomaxillofac Radiol, 45,20150254 birpublications.org/dmfr Dose optimization in dental CBCT using kV and mAs: systematic review with the other authors. This occurred on three occasions, and on all three occasions, it was decided that the study being considered did not meet the eligibility criteria; so, these studies were excluded from the review.…”

“…Dentomaxillofac Radiol, 45,20150254 birpublications.org/dmfr Dose optimization in dental CBCT using kV and mAs: systematic review Dose optimization in dental CBCT using kV and mAs: systematic review Goulston et al Dose optimization in dental CBCT using kV and mAs: systematic review Goulston et al Actual teeth and skull A protocol that used a 0.3-mm voxel size and then reconstructed at 0.25-mm voxel size was considered the best to use, as it produced images that were of diagnostic quality but gave the patient a lower radiation dose. The position of the external root resorption can affect diagnosis using CBCT.…”

“…Dentomaxillofac Radiol, 45,20150254 birpublications.org/dmfr Dose optimization in dental CBCT using kV and mAs: systematic review Dose optimization in dental CBCT using kV and mAs: systematic review Goulston et al Measuring effective dose with thermoluminescent dosemeters for all the tissues in the head and neck is very time consuming and expensive, and owing to the wide range of different machines, results could not be generalized. 21,24 Therefore, international research and agreement is also needed to find a cost-and time-effective way of reliably calculating the dose that patients undergoing CBCT receive so that operators can know exactly how altering different exposure factors will impact both patient dose and resultant image quality.…”

“…Some have investigated possible conversion co-efficients that may allow DAP readings to be used to work out an estimation of effective dose. 45 Programs based on the Monte Carlo simulation, such as the one investigated by Koivisto et al, 46 also need to be considered. These can be of value because they permit easy manipulation of exposure variables without performing time-consuming experiments in the field.…”