Evaluation of Effective Patient Dose in Paranasal Sinus Imaging: Comparison of Cone Beam CT, Digital Tomosynthesis and Multi Slice CT

Abstract

Cone-beam CT (CBCT) and digital tomosynthesis are becoming interesting tools for paranasal sinus imaging. In present study, the effective dose of these new techniques was compared with the effective dose of multi slice CT (MSCT) acquisitions.

An anthropomorphic Rando phantom was fitted with 156 calibrated thermoluminescent dosimeters (TLD) in positions representative for the radiosensitive organs and tissues according to the 2007 recommendations of the International Commission of Radiological Protection. CBCT (Imaging Sciences International, I-CAT), digital tomosynthesis (GE, Definium 8000/VolumeRAD), low-dose and standard dose MSCT (GE, Lightspeed 16) acquisitions of the Rando phantom were obtained. For all imaging systems, the Rando phantom was positioned and exposed in a similar way as for patient paranasal sinus imaging on that specific system. Afterwards exposure, TLDs were read out and TLD readings were converted into organ doses.

Independent of the applied imaging techniques, the salivary glands, the brain and the thyroid are receiving the highest equivalent doses for the paranasal sinus imaging. The effective dose for the CBCT and the digital tomosynthesis examinations were 30μSv and 65 μSv respectively. For the MSCT examination, effective doses of 200μSv and 1400 μSv were found for the low-dose and the standard CT protocol.

Paranasal sinus imaging with CBCT and digital tomosynthesis showed a large dose reduction compared to low-dose and standard MSCT. When comparing the two new imaging techniques, CBCT could acquire high quality images at less than half the dose of the digital tomosynthesis system.