Assessment of phantom dosimetry and image quality of i-CAT FLX cone-beam computed tomography

Abstract

Introduction Increasing use of cone-beam computed tomography in orthodontics has been coupled with heightened concern with the long-term risks of x-ray exposure in orthodontic populations. An industry response to this has been to offer low-exposure alternative scanning options in newer cone-beam computed tomography models. Methods Effective doses resulting from various combinations of field size, and field location comparing child and adult anthropomorphic phantoms using the recently introduced i-CAT FLX cone-beam computed tomography unit were measured with Optical Stimulated Dosimetry using previously validated protocols. Scan protocols included High Resolution (360° rotation, 600 image frames, 120 kVp, 5 mA, 7.4 sec), Standard (360°, 300 frames, 120 kVp, 5 mA, 3.7 sec), QuickScan (180°, 160 frames, 120 kVp, 5 mA, 2 sec) and QuickScan+ (180°, 160 frames, 90 kVp, 3 mA, 2 sec). Contrast-to-noise ratio (CNR) was calculated as a quantitative measure of image quality for the various exposure options using the QUART DVT phantom. Results Child phantom doses were on average 36% greater than Adult phantom doses. QuickScan+ protocols resulted in significantly lower doses than Standard protocols for child (p=0.0167) and adult (p=0.0055) phantoms. 13×16 cm cephalometric fields of view ranged from 11–85 μSv in the adult phantom and 18–120 μSv in the child for QuickScan+ and Standard protocols respectively. CNR was reduced by approximately 2/3rds comparing QuickScan+ to Standard exposure parameters. Conclusions QuickScan+ effective doses are comparable to conventional panoramic examinations. Significant dose reductions are accompanied by significant reductions in image quality. However, this trade-off may be acceptable for certain diagnostic tasks such as interim assessment of treatment results.

Effectiveness of thyroid gland shielding in dental CBCT using a paediatric anthropomorphic phantom

“…One study used TLDs, 11 while the other studies used optically stimulated luminescent dosemeters. 9,10 In all these studies, the location of the dosemeters in the phantom was determined by expert opinion. This study demonstrated most of the thyroid gland was located in the superior slice (Slice 9).…”

“…Several studies [1][2][3][4][5][6][7][8] have measured the organ and effective doses for a range of clinical protocols and dental CBCT machines. However, only three studies [9][10][11] have investigated the organ doses to young children using paediatric anthropomorphic phantoms. Since the majority of dental CBCT machines are not optimized for paediatric patients and do not offer paediatric-specific imaging protocols, the thyroid gland doses to young children are generally found to be higher than those of adolescent or adult patients owing to their smaller size.…”

A representative study of pediatric panoramic and cephalometric radiation exposure to organs of the head and neck

“…In children, their smaller cross-sectional area, the increased sensitivity of their tissues and organs to radiation, and their longer life expectancy, increases their cancer risk compared with adults [23]. A study by Ludlow et al, found that children are 2-5 times more sensitive to radiation carcinogenesis than adults [24]. The study also found that on average, the effective doses were 36% greater in child phantoms than adult phantoms [24].…”

“…A study by Ludlow et al, found that children are 2-5 times more sensitive to radiation carcinogenesis than adults [24]. The study also found that on average, the effective doses were 36% greater in child phantoms than adult phantoms [24].…”

Dosimetry in CBCT with Different Protocols: Emphasis on Small FOVs Including Exams for TMJ

“…Especially in Endodontics, high resolution images are a requirement that is obtained with small FOVs (7). This has particular importance, because it restricts the area of direct exposure to ROI, possibly reducing the radiation dose to the patient (8)(9)(10). However, as the device spins around the patient's head during scanning examination, tissues and structures outside the FOV are also irradiated.…”