Comparison of radiation doses using weight-based protocol and dose modulation techniques for patients undergoing biphasic abdominal computed tomography examinations

Abstract

Computed tomography (CT) of the abdomen contributes a substantial amount of man-made radiation dose to patients and use of this modality is on the increase. This study intends to compare radiation dose and image quality using dose modulation techniques and weight- based protocol exposure parameters for biphasic abdominal CT. Using a six-slice CT scanner, a prospective study of 426 patients who underwent abdominal CT examinations was performed. Constant tube potentials of 90 kV and 120 kV were used for all arterial and portal venous phase respectively. The tube current-time product for weight-based protocol was optimized according to patient's body weight; this was automatically selected in dose modulations. The effective dose using weight-based protocol, angular and z-axis dose modulation was 11.3 mSv, 9.5 mSv and 8.2 mSv respectively for the patient's body weight ranging from 40 to 60 kg. For patients of body weights ranging 60 to 80 kg, the effective doses were 13.2 mSv, 11.2 mSv and 10.6 mSv respectively. The use of dose modulation technique resulted in a reduction of 16 to 28% in radiation dose with acceptable diagnostic accuracy in comparison to the use of weight-based protocol settings.

Computed tomography automatic exposure control techniques in 18F-FDG oncology PET-CT scanning

“…Philips also advised against using ZDOM due to concerns that use of this system may result in the tube current being inappropriately low in smaller and less attenuating regions such as the head. As ACS was not utilized, weight-based CT protocols were developed using the methodology described by Livingstone et al [22]. On the basis of initial clinical experience with the system, DDOM was deactivated for all patients scanned with their arms down, as the downward modulation of tube current in the AP and posteroanterior (PA) projections was considered inappropriately large because of the presence of the arms resulting in a very high lateral : AP attenuation ratio (Philips protocol 1).…”

Effects of the Use of Automatic Tube Current Modulation on Patient Dose and Image Quality in Computed Tomography

“…These results were parallel to the results obtained from our study. In another study carried out by S. Livingstone et al (7) on contrast-enhanced biphasic abdominal examinations, dose reductions between 16% and 28% were achieved with the protocol using ATCM compared to fixed current protocols based on patient weight. According to the results of our study, dose reduction rates were observed approximately between 10% (group 3) and 35% (group 1) among the 3 groups when both phases were considered together (Table 5).…”

“…In the literature, studies carried on the abdominal CT examinations of adults report commonly that the use of AEC techniques leads to a considerable decrease in patient dose while keeping a reasonable image quality (6,7,8,9,10,11,12,13,14). This study aims to focus on the use of Z-DOM in contrast-enhanced biphasic abdominal examinations and to make evaluations on image quality and patient dose.…”

New and Evolving Concepts in CT for Abdominal Vascular Imaging

“…Despite these desirable gains, the low-kilovoltage technique is not frequently applied at most CT departments due to lack of familiarity with appropriate kilovoltage and milliamperage selections and other parameter adjustments that negatively affect the CT workflow (19). The kilovoltage selections can be based on body size (body mass index, abdominal girth, or total weight) and require end-user adjustments in other scanning parameters ( Table 2) (19)(20)(21).…”