Real-world data on the impact of dose reduction measures on radiation exposure in CT perfusion of the brain.

BACKGROUND

CT perfusion (CTP) imaging is a valuable tool for assessing cerebral blood flow. However, it is associated with high radiation doses, often exceeding those of non-contrast cranial CT. We evaluated the impact of different dose reduction approaches in CTP.

METHODS

We retrospectively included patients who underwent CTP in a stroke referral center. Imaging was performed using four different scanners. The protocols were iteratively optimized by decreasing the tube current time product through lowering the tube current while maintaining a constant tube rotation time. Additionally, the temporal sampling interval was increased from 1.5 to 3.0 s. Volume CT dose index (CTDIvol) was compared across the optimization steps. Effective doses were calculated and the theoretical lifetime cancer risk was estimated.

RESULTS

Radiation doses from 3812 cases with CTP (47.5% female, mean age 73 ± 14 years) were evaluated. Reducing the tube current by one third resulted in a dose decrease of 33.1%. Doubling the temporal sampling interval significantly reduced the dose by approximately half (47.3%-51.7%) across all scanners (all p < 0.001). Combining both adjustments on the same scanner led to an overall dose reduction of 67.7%. The lowest mean CTDIvol and effective dose across all scanners were 69.2 ± 0.2 mGy and 0.61 ± 0.08 mSv, respectively. The estimated additional lifetime cancer risk was reduced by up to 67.7%, with greater absolute benefits in younger patients.

CONCLUSION

Dose reduction measures allow for scanning CTP with exposure levels close to those of standard non-contrast CT.