This study assessed the ability of various
types of topograms, when used with an automatic tube current modulation (ATCM) technique,
to reduce radiation dose from computed tomography (CT) scans. Three types of
topograms were used with the ATCM technique: (i) anteroposterior (AP) topograms alone, (ii)
AP topograms followed by lateral topograms, and (iii) lateral topograms followed by AP topograms.
Various regions (chest, abdomen and whole-body) of a humanoid phantom were scanned at several
tube voltages (80, 100 and 120 kVp) with the selected topograms. Although the CT dose depended on
the order of topograms, the CT dose with respect to patient positioning depended on the
number of topograms performed. The magnitude of the difference in CT dose between number and
order of topograms was greater for the scans of the abdomen than the chest. These results
suggest that, for the Siemens SOMATOM Definition AS CT scanner, choosing the right combination
of CT scan conditions with the ATCM technique can minimize radiation dose to a patient.
J. Shim and M. Yoon
Department of Bio-Convergence Engineering, Korea University,
145, Anam-ro, Seongbuk-gu, Seoul, Republic of Korea
Department of Diagnostic Radiology, Severance Hospital,
50-1, Yonsei-ro, Seodaemun-gu, Seoul, Republic of Korea
Journal of Instrumentation