Radiation dose reduction in temporal bone CT with iterative reconstruction technique.
OBJECTIVE
Iterative reconstruction of CT images is characterized by reduced image noise and may allow reduction in radiation exposure. We investigated the influence of an IRT technique on image quality and radiation dose savings when applied to temporal bone CT.


METHODS
Based on the typical image quality level of adult subjects using routine radiation dose and FBP, an exsomatized cadaveric head with CNR characteristics closest to the level of clinical subjects was identified. Cadaver acquisitions were performed at multiple levels of tube current exposure. Reconstructions were performed using FBP and IRT (iDose), with multiple iDose levels applied for each acquisition. Transverse and coronal reformations of all reconstructions were evaluated subjectively and objectively. Phantom tests were performed to validate the protocol optimizations with iDose, specifically the spatial resolution relative to routine dose acquisitions. Finally, the results of protocol optimization with iDose were clinically validated in 50 patients.


RESULTS
At the same radiation dose, the image CNR of iDose reconstructions was higher than that of FBP and progressively increased with higher iDose levels. The combination of 100 mAs/section and iDoseL5 was the lowest dose that met the requirements for diagnostic acceptability, with CNR slightly higher than our routine institution protocol of 200 mAs/section with FBP reconstruction. Spatial resolution characteristics were similar between FBP and iDose at all different strengths. The findings were consistent among the cadaver, phantom, and clinical acquisitions.


CONCLUSIONS
The iDose IRT can help reduce radiation dose of temporal bone CT by 50% relative to routine institution protocols with FBP, while maintaining diagnostic image quality.
Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing, China.
Y T
YT
Niu
D
D
Mehta
Z R
ZR
Zhang
Y X
YX
Zhang
Y F
YF
Liu
T L
TL
Kang
J F
JF
Xian
Z C
ZC
Wang
D000328:Adult; D000465:Algorithms; D005260:Female; D006801:Humans; D008297:Male; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013701:Temporal Bone / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*