Exhibit Hall | Forum 1
Purpose: Consideration of radiation dose is important for potentially high volume screening procedures such as CT Colonography (CTC). Our group previously presented a tin filtration-based CTC protocol that reduced CT dose index (CTDI(vol)) while maintaining image noise. The purpose of this study is to evaluate the potential reduction in CT dose indices as well as organ and effective dose for patients undergoing CTC using the tin-filtered spectrum when compared to the standard 120 kVp protocol.
Methods: This IRB-approved study included 88 patients (weight: 45-111 kg) who underwent a CTC examination for screening purposes. Each patient was imaged in both supine and decubitus positions, randomly assigned to one position with a 120 kVp protocol and the other position with a 100 kVp with tin-filtration (100Sn) protocol. The 100Sn protocol was selected so that it would result in equivalent image noise to a 120 kVp exam. The CTDI(vol), dose length product (DLP), effective dose, and organ doses from 120 kVp and 100Sn were compared for each patient.
Results: Compared to 120 kVp, the 100Sn protocol had a mean difference of -36.7% (CI: [-39.4%, -33.9%]) and -36.9% (CI: [-39.6%, -34.3%]) for CTDI(vol) and DLP, respectively. The corresponding percent differences in effective, colon, liver, stomach, and skin doses were -30.4% (CI: [-34.8%, -26.1%]), -31.8% (CI: [-35.9%, -27.4%]), -31.4% (CI: [-35.8%, -26.7%]), -31.0% (CI: [-35.6%, -26.4%]), and -35.1% (CI: [-37.7%, -34.2%]), respectively. All organ dose reductions were more than 25% (with 95% confidence).
Conclusion: Use of tin filtration has the potential to reduce patient organ and effective dose by more than 25%. Further study is needed to ensure that there is no loss in diagnostic efficacy.
Funding Support, Disclosures, and Conflict of Interest: This project is supported by a research grant from Siemens Healthineers.