Objective: The purpose of our study was to assess the effect on image quality and radiation dose of chest multidetector computed tomography (CT) examinations with low-kilovoltage protocols for adults.
Methods: This study was approved by the institutional review board of our medical center. Two hundred ten patients (83 women, 127 men; mean age, 56.1 years) requiring contrast-enhanced chest CT examination were randomly assigned to 1 of 3 protocol groups: (1) protocol A, the standard protocol, with 120 kilovolt (peak) (kV[p]) and 100 effective milliampere-second (eff mA s); (2) protocol B, with 100 kV(p) and 140 eff mA s; and (3) protocol C, with 80 kV(p) and 180 effm A s. Each group included 70 patients. Contrast material injection protocols were standardized for all groups. Three radiologists blinded to the CT parameters used assessed images in random order for 20 items/from 4 anatomical regions. They ranked the subjective image quality using a 4-point scale. The volume computed tomography dose index (CTDIvol) and dose length product (DLP) were displayed by the CT unit after the automatic exposure control-driven acquisition was recorded for each group; the differences were analyzed for statistical significance.
Results: When the overall agreement was pooled from the 3 observers, the qualitative score analysis revealed no significant difference between the 100-kV(p) and the standard protocols (P > 0.05). However, when the scores were compared between the 80-kV(p) and the standard protocols, a marginal significance (P = 0.054) was observed. When the patients in the group with an 80-kV(p) protocol were subcategorized according to body mass index (BMI), the image quality scores of all BMI subgroups, • of the 80-kV(p) protocol, were not significantly different from those of the standard protocol. However, an increase in the BMI tended to be associated with a decrease in the subjective image quality. The mean values of CTDIvol for 120-, 100-, and 80-kV(p) protocols were 5.042, 4.507, and 2.883, respectively. The mean values of DLP for each protocol were 187.5, 158.7, and 105.8, respectively. The CTDIvol and DLP of the low-kilovoltage protocols were significantly lower than those of the standard protocol (P < 0.01). The DLP of the 100- and 80-kV(p) protocols were reduced radiation exposure doses in 15.36% and 43.57%, respectively, as compared with the standard protocol.
Conclusions: The use of low-kilovoltage protocol resulted in a significant reduction in the radiation exposure at chest CT, with image qualities comparable with those of the standard protocols.