Affiliations: Shanghai Pneumology Hospital, Shanghai, P.R.
China | The 1st Affiliation Hospital of Hua-Xi Medical Center,
Shichuan, P.R. China | HealthONE Alliance, Denver, Colorado, USA
Note: [] Correspondence to: Zheng Huang, HealthONE Alliance, 5125
Stapleton Drive North, Denver, CO 80216, USA. Tel.: +1 303 3204061; Fax: +1 303
3204061; E-mail: zheng_huang@msn.com
Abstract: The aim of this study was to optimize CT scan protocol to minimize
patient exposure to ionizing radiation while maintaining CT image quality for
detecting pulmonary diseases. The absorbed dose and CT scan quality were
determined using dose phantoms at various tube current settings (7.5–115 mAs).
The relationship between the absorbed radiation dose and CT scan quality were
examined. For both 8-mm and 3-mm scanned slice thickness, the homogeneity of CT
scans was within the required range (< 4 HU) at tested tube settings (>
7.5 mAs). However, the noise level of CT scans remained within the acceptance
range (< 0.35%) only when the tube current was ≥ 25 mAs. The reduction
of tube current from 115 mAs to 40, 25 or 7.5 mAs could decrease the CT Dose
Index (CTDI) to 60, 70 or 85%, respectively. The evaluation of CT image
quality suggested that there was an inflection point at 25 mAs. When the spiral
chest CT scan was employed at a low tube current setting (i.e. 40 or 25 mAs),
it maintained satisfactory image quality and reduced the absorbed dose of the
patient, therefore protecting patients from ionizing radiation exposure.
