Optimization of dental CBCT exposures through mAs reduction

Area of Science:

• Radiology
• Medical Imaging
• Cone-Beam Computed Tomography (CBCT)

Background:

• Cone-beam computed tomography (CBCT) utilizes varying exposure settings, impacting image quality and radiation dose.
• Optimizing exposure parameters like tube current-exposure time (mAs) is crucial for balancing diagnostic accuracy and patient safety.

Purpose of the Study:

• To evaluate the impact of reduced mAs on CBCT image quality across different scanners.
• To identify preliminary minimally acceptable mAs and contrast-to-noise ratio (CNR) values for CBCT.

Main Methods:

• Utilized PMMA and anthropomorphic skull phantoms scanned with four CBCT devices and seven exposure protocols.
• Measured contrast-to-noise ratio in air (CNRAIR) and assessed clinical image quality via radiologist scoring of anatomical landmarks.

Main Results:

• A hyperbolic relationship was observed between CNRAIR and mAs.
• Clinical image quality remained acceptable with moderate to large mAs reductions in several protocols, depending on application.
• Minimally acceptable mAs values ranged from 9 to 70, varying by criterion and clinical use.

Conclusions:

• Lower mAs levels can yield acceptable clinical CBCT image quality, even below recommended settings for specific patient groups.
• Device-specific variations prevent the establishment of universal minimally acceptable image quality values for CBCT.