ABSTRACT
Objective:To compare the dose and image quality of selected photon shield (SPS) technique, organ-based tube current modulation (OBTCM) technique and the combination of these two techniques for reducing the organ dose in head CT examination for infants.Methods:Two anthropomorphic head phantoms (CIRS 1-yr-old and 5-yr-old) were scanned by using Reference mode, Reference + OBTCM mode, SPS mode and SPS + OBTCM mode, respectively. Radiation doses to the lens of the eye, the anterior of the brain, the posterior of the brain, noise level and CNR of orbit and brain in different phantoms were measured and compared by using different scanning modes.Results:Compared with Reference mode, the doses to the lens of the eye in 1-yr-old and 5-yr-old phantom decreased by (21.89 ± 0.01)% and (28.33 ± 0.34)%, respectively. In SPS mode, the reduction in doses to the lens of the eye in 1-yr-old and 5-yr-old phantom were (71.38 ± 1.30)% and (53.72 ± 2.42)%, respectively. In SPS + OBTCM mode, the reduction was (71.12 ± 2.54)% and (55.73 ± 1.90)%, respectively. There was significant difference in the noise level of orbit and brain in different phantoms under various scanning modes ( F=5.67-85.47, P< 0.05). The noise level in OBTCM mode compared with reference mode increased slightly (<1.45 HU) in various phantoms. SPS and SPS + OBTCM mode resulted in a small noise increase (<2.58 HU). There was no significant difference in CNR of different phantoms under various scanning modes ( P>0.05). Conclusions:SPS and SPS + OBTCM mode can significantly reduce the radiation dose of lens and the whole image plane in the head CT scan for infants, with maintaining the image quality.