Effective radiation dose and eye lens dose in dental cone beam CT: effect of field of view and angle of rotation

Abstract

The effect of the FOV and rotation angle on the effective dose in dental CBCT was quantified. The dominant effect of FOV height was demonstrated. A preliminary model has been proposed, which could be used to predict effective dose as a function of FOV size and position.

Maxillofacial cone beam computed tomography (CBCT) : aspetcs on optimisation

“…50 There were only two studies using a paediatric phantom corresponding to patients aged 10 years. 35,40 This is notable as CBCT is increasingly replacing two-dimensional imaging modalities, such as cephalometry and panoramic radiography, in adolescents aged 10-18 years undergoing orthodontic treatment. As the justification for an increased dose to this young patient group is unclear, 1 there is an urgent need to estimate effective doses in relation to diagnostic tasks when examining these patients.…”

“…35 Some CBCT units use 360°rotation; others use a smaller trajectory arc of between 180°and 220°as the coverage of 180°and the cone angle is sufficient for tomographic image reconstruction. 36 Images produced by partial rotation may, however, have more noise and reconstruction artefacts.…”

“…al. (Pauwels et al, 2014) used a SEDENTEXCT IQ phantom with four different inserts [air, low-density polyethylene (LDPE), polytetrafluoroethylene (PTFE) and aluminum (Al)] to measure CNR of CBCT images performed using different exposure setting of 3D Accuitomo ® 170, and concluded that the best optimal contrast at a fixed dose was found at the highest available kV setting. Hidalgo Rivas et al (Hidalgo Rivas et al, 2015) investigated 3D Accuitomo ® 170 CBCT examinations of the anterior maxilla in children and images were classified as acceptable/not acceptable related to a number of different diagnostic tasks and different exposure conditions.…”

“…As presented in Figure 4, there was a variation in reported dose estimates for the same CBCT unit with the same FOV dimensions. 10,14,20,25,35,39 As the description of technical parameters of the CBCT units examined was incomplete, it was difficult to evaluate which components of the CBCT units that produced the different results on effective doses in these studies. Besides, different phantoms, dosemeter types and number, exposure parameters and protocols were applied in these studies (Figure 4).…”

“…17,19 As presented in Table 2, the effective dose of CBCT was compared with those of other imaging modalities in eight studies: CT, 13,16,24,25,37,44 panoramic radiography 16,25,31,37,44,45 and cephalometry. 37 Risk estimations were presented in eight studies 12,18,23,25,27,30,35,45 mostly as comparisons with background radiation.…”