Assessment of radiation dose reduction potential and clinical utilization of automatic tube current systems

Author(s): Allen Mhagama*, Peter Msaki

This study investigated the patient dose reduction potential and clinical utilization of Automatic Tube Current Modulation (ATCM) systems in CT examinations. Assessment of the effectiveness of ATCM was conducted using standard CT phantoms of diameters 16 cm and 32 cm, and water phantoms of diameters 20 cm and 22 cm, which were scanned with and without activating ATCM. Assessment of clinical utilization of the ATCM systems was conducted by investigating in real time practice on utilization of ATCM during patient scanning, and from information of scan parameters were extracted from CT database for 125 patients that underwent different routine examinations at six multislice CT scanners acquired by six hospitals. From the database, information about the operation and utilization of automatic tube current modulation systems during different examinations was obtained. This information included the activation/ deactivation status of the systems, reference image quality mAs, effective mAs, mAs per slice and CTDIvol. In the phantom study, systems were found to reduce radiation dose with marginal increase in image noise, and that they are more effective in reduction of radiation dose for smaller patients than the large ones. Direct observations and analysis of the informations extracted from CT database revealed that most technologists had limited knowledge about the operation and utilization of the ATCM systems of respective scanners. These limitations were attributed to lack of standardization of different types and versions of the ATCM systems that are, in addition, not userfriendly. Some technologists claimed that the diagnostic image qualities were low when the ATCM systems were activated for some examinations. The radiographers and radiologists should attend the in-service training programmes to learn on how to operate and effectively utilize the ATCM systems. The CT scanner manufacturers should produce the standard and more user-friendly ATCM systems during future designs.