  The purpose of the present study was to evaluate radiation dose reduction and
image quality during CT scanning by using a new dose reduction fiber sheet
(DRFS) with commercially available bismuth shields. These DRFS were composed of
nano-barium sulfate (BaSO4), filling the gaps left by the large oxide bismuth
(Bi2O3) particle sizes. The radiation dose was measured five times at
directionss of 12 o'clock from the center of the polymethyl methacrylate (PMMA)
head phantom to calculate an average value using a CT ionization chamber. The
image quality measured CT transverse images of the PMMA head phantom depending
on X-ray tube voltages and the type of shielding. Two regions of interest in CT
transverse images were chosen from the right and left areas under the surface
of the PMMA head phantom and from ion chamber holes located at directions of 12
o'clock from the center of the PMMA head phantom. The results of this study
showed that the new DRFS shields could reduce dosages to 15.61%, 23.05%, and
22.71% more in 90 kVp, 120 kVp, and 140 kVp, respectively, than with a
conventional bismuth shield of the same thickness, while maintaining image
quality. In addition, the DRFS were produced to about 25% more thinness than
conventional bismuth. We concluded, therefore, that DRFS can replace the
conventional bismuth and may be utilized as a new shield.
