Estimating the CTDIvol with helical acquisitions: Results from a national generalizability study

• Published in: Medical physics (Lancaster) 2024-12
• Main Authors: Barreto, Izabella L, Gress, Dustin A, Leon, Stephanie M, Schwarz, Bryan C, Kobistek, Robert J, Mahesh, M, Tomlinson, James A, Dillon, Chad M
• Format: Article
• Language: English
• ISSN: 2473-4209; 2473-4209
• DOI: 10.1002/mp.17543

While many clinical computed tomography (CT) protocols use helical scanning, the traditional method for measuring the volume CT Dose Index (CTDIvol) requires modifying the helical protocol to perform a single axial rotation. This modification can present challenges and mismatched settings across various scanner models.BACKGROUNDWhile many clinical computed tomography (CT) protocols use helical scanning, the traditional method for measuring the volume CT Dose Index (CTDIvol) requires modifying the helical protocol to perform a single axial rotation. This modification can present challenges and mismatched settings across various scanner models.This study investigates the generalizability of a helical methodology for estimating CTDIvol across a diverse range of participants, CT scanner models, and protocol parameters.PURPOSEThis study investigates the generalizability of a helical methodology for estimating CTDIvol across a diverse range of participants, CT scanner models, and protocol parameters.A web-based platform collected axial and helical CTDIvol measurements from 24 medical physicists who submitted 569 data sets obtained using four CT protocols on scanners from seven CT manufacturers. Various parameters were tested for tube voltage (70-140 kVp), rotation time (0.25-1.50 s), beam width (8-80 mm), and pitch (0.29-3.0) settings. Measurements from the two methodologies were assessed for reproducibility using three repeated exposures and then compared to each other and to the scanner-displayed CTDIvol. Agreement between the methodologies was assessed using Bland-Altman analysis, linear regression, paired t-tests, and a paired two one-sided tests (TOST) procedure with equivalence margins of 5% of the mean protocol CTDIvol. The impact of beam width and pitch on measurement accuracy was assessed using linear regression analysis and an independent t-test.METHODSA web-based platform collected axial and helical CTDIvol measurements from 24 medical physicists who submitted 569 data sets obtained using four CT protocols on scanners from seven CT manufacturers. Various parameters were tested for tube voltage (70-140 kVp), rotation time (0.25-1.50 s), beam width (8-80 mm), and pitch (0.29-3.0) settings. Measurements from the two methodologies were assessed for reproducibility using three repeated exposures and then compared to each other and to the scanner-displayed CTDIvol. Agreement between the methodologies was assessed using Bland-Altman analysis, linear regressi