Exploring the effectiveness of CARE Dose 4D and CARE kV Automatic Exposure Control Systems in CT: A Slim and Obese Phantom Study
Joanna Kidoń-Szołtysek, Aleksandra Klimas, Marcin Dybek, Leszek Wojciuch, Aneta Kawa-Iwanicka, Krzysztof S. GołbaAbstract
Introduction
Radiology strives to minimise radiation exposure while maintaining diagnostic image quality. AEC systems achieve this by optimising radiation doses across different patients and anatomies. The purpose of our study was to evaluate the performance of AEC using Siemens CARE Dose4D and CARE kV options for both slim and obese adult phantoms. We focused on assessing how different parameter settings affect radiation dose and image quality.
Material and methods
Examinations were performed on a dual-source CT scanner using a slim and obese anthropomorphic phantom and a Catphan phantom. Parameters such as mAs modulation strength, reference kV values, quality reference mAs values, dose optimisation settings and CARE kV option were adjusted. The collected data included mA modulation, CTDI vol , effective mAs, quality reference mAs, reference mAs, kV values, and the relative standard deviation of HU values.
Results
The quality reference mAs serves as the baseline target for image quality and is influenced by the CARE kV mode, thereby designating the reference mAs (‘off ’ matches the baseline exactly; ‘on’ scales with the reference kV; ‘semi’ scales inversely with the reference kV). The effective mAs represents the final value influenced by all forms of modulation. For the slim phantom, the effective mAs remained lower than the reference mAs, while for the obese phantom, it was higher. The adjusted reference mAs values appear independent of phantom size. mA modulation curves reflect the link between CTD Ivol and AEC. Regardless of the phantom’s body type, CTDIvol decreased/increased when dose-saving optimiser levels, quality mAs ref , and kV ref were changed. Higher modulation strength lowers the dose for slim phantoms, but raises it for obese phantoms. Slim phantoms produce a lower relative standard deviation than obese ones.
Conclusions
Radiologists and medical physicists must understand the mechanics of the AEC system in CT scanners. This knowledge is essential for ensuring consistent image quality and minimising patient exposure.