Validation of a dual energy technique using a single source multidetector computed tomography scanner

One of the most recent advances in computed tomography is the use of dual energy (DECT). However, this technique typically requires high-end CT scanners. The purpose of this work was the implementation of a protocol that can be used to perform dual energy acquisition with a single source CT scanner (DE-SSCT) by performing two consecutive scans with different tube potential. A semi-anthropomorphic phantom was used. The phantom contained samples of iodine and calcium, and was scanned using both a SSCT and a dual source CT (DSCT). The DSCT system was operated in conventional SSCT mode (ie using only one source), but also in dual-energy mode (ie using both sources) for validation of the proposed approach. The proposed DE-SSCT approach partitioned the dose for each of the two consecutive scans, such that the volume CT dose index (CTDIvol) matched that of a routine SSCT examinations performed at 120 kVp. To characterize the performance of DECT, voxel by voxel CT number ratio (CTR) values between the CT numbers at high and low energy were calculated. Paired t-student test were used to compare mean CTR values. The CTR values for calcium and iodine obtained with the DSCT system operated in dual-energy mode were 1,69 and 2,10; and 1,68 and 2,05 using the DSCT system but with the proposed DE-SSCT method. CTR differences were statistically significant (p<;0.05). CTDIvol value for the proposed DE-SCCT operated at 80 and 140 kVp was 9.31 mGy. Further evaluation in a SSCT system that allowed operation at 80 and 135 kVp resulted in CTR values of 1,59 and 1,81 using the proposed DE-SSCT protocol. The mean CTR differences for calcium and iodine was statistically significant (p=0,002). CTDIvol obtained was 16.2 mGy. In conclusion, in a stationary phantom, DECT can be performed in a SSCT system with the use of two consecutive scans allowing calculation of material specific CTRs.