Chest CT Performed with 3D and z-Axis Automatic Tube Current Modulation Technique: Breast and Effective Doses

Rationale and Objectives. Chest computed tomographic (CT) scans are the most effective examinations for detecting lung cancer at ail early stage. In chest CT examinations. it is important to consider the reduction of radiation (lose. particularly to the mammary gland. The objective of this study was to assess breast doses and effective doses oil chest CT examinations between three-dimensional and z-axis automatic tube current modulation (ATCM) techniques. Materials and Methods. Absorbed close to the breast, lung. mediastinum, and skin was evaluated with ail anthropomorphic phantom and radiophotoluminescence glass dosimeters using two different CT scanners. The dosimeters were placed inside and outside the phantom. The phantom was scanned using three-dimensional and z-axis ATCM techniques after scanning localizer radiographs from the horizontal and vertical directions. After scanning, each or-an dose was calculated. Moreover, file dose-length product recorded in the dose reports was examined, and each effective dose was calculated. Results. Compared with z-axis ATCM, three-dimensional ATCM reduced breast dose by 0.7% to 18.6% and effective dose by 4.9% to 10.2%. In particular, three-dimensional ATCM reduced frontal breast dose. For other organs, three-dimensional ATCM reduced absorbed closes by 3.4% to 13.6% compared to Z-axis ATCM. Conclusion. Three-dimensional ATCM call reduce absorbed closes to the breast and other organs, in addition to reducing effective dose, compared to z-axis ATCM.