The Effects of Additional Filtration on Image Quality and Radiation Dose in Cone Beam CT: An In Vivo Preliminary Investigation.

Jan Houfrar,Manuel Nienkemper,Ciamak Abkai,Adith Venugopal,Bjorn Ludwig,Dirk Bister,Shivam Mehta

doi:10.1155/2022/7031269

Abstract

Purpose The aim of this study was to investigate the effect of reduced radiation doses on the image quality of cone-beam computed tomography scans and the suitability of such imaging for orthodontics, oral surgery, dental implantology, periodontology, and endodontology. Materials and Methods Cone-beam computed tomography scans of a live patient were performed using seven attenuation filters with increased thickness to decrease the effective radiation dose from 22.4 to 1.8 μSv, and the effects of different radiation doses on image quality were further analysed. Quantitative image quality was calculated using dedicated measures, such as signal and contrast-to-noise ratio and sharpness. A panel of five certified raters assessed the cone-beam computed tomography scans qualitatively. Nine anatomical structures relevant to dentistry were identified, and the overall acceptance was assessed. Results Linear reduction of the effective radiation dose had a nonlinear effect on image quality. A 5-fold reduction in the effective dose led to acceptable quantitative and qualitative image quality measures, and the identification rate of dental anatomical structures was 80% or greater. The use of less than 40% of the reference dose was unacceptable for all dental specialties. Conclusions The ideal radiation dose for specific diagnostic requirements remains a patient-related and specialty-related decision that must be made on an individual basis. Based on the results of this study, it is possible to reduce exposure in selected patients, and at the same time obtain sufficient quality of images for clinical purposes.

Highlights

Cone-beam computed tomography (CBCT) was introduced in 1998 [1] and has since been used in all dental disciplines [2, 3], and specific indications have been identified in orthodontics [4], oral surgery [5], dental implantology [6], periodontology [7, 8], and endodontics [9, 10]
Image noise was more pronounced for filters higher than F4; signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) markedly decreased for doses less than 10% of the reference dose
The use of filters F1F3, which were equivalent to 62–26% of the reference dose, was feasible and still resulted in reliable identification of anatomical structures

Summary

Introduction

Cone-beam computed tomography (CBCT) was introduced in 1998 [1] and has since been used in all dental disciplines [2, 3], and specific indications have been identified in orthodontics [4], oral surgery [5], dental implantology [6], periodontology [7, 8], and endodontics [9, 10]. The diagnostic value of an image is determined by the radiation dose and depends on the equipment on which the image is visualized, as well as the person who assesses the image [20–23]. Physical parameters, such as beam quality and dose, determine the image quality of radiographs [14, 24–28]. This study aimed to acquire CBCT images from a live patient using interchangeable filters and to reduce the effective radiation dose. We attempted to determine the effect of radiation doses on subjective image quality and assess the ability of such imaging to identify anatomical structures. The images used for this study were acquired with a commercially available CBCT machine that had been modified using seven copper filters

Methods

Results

Conclusion