MDCT of chest, abdomen, and pelvis using attenuation-based automated tube voltage selection in combination with iterative reconstruction: an intrapatient study of radiation dose and image quality.

OBJECTIVE

The purpose of this study was intrapatient comparison of image quality and radiation dose between MDCT scans of the chest, abdomen, and pelvis obtained with attenuation-based automated kilovoltage selection and sinogram-affirmed iterative reconstruction and scans obtained with standard kilovoltage selection and a filtered backprojection image reconstruction algorithm.

MATERIALS AND METHODS

One hundred one oncology patients who had undergone two chest, abdominal, and pelvis CT scans within 1 year were imaged with standard tube voltage selection of 120 kVp using a filtered backprojection reconstruction algorithm (protocol 1) and with attenuation-based automated tube voltage selection using an iterative reconstruction algorithm (protocol 2). Radiation dose parameters (volumetric CT dose index [CTDIvol], dose-length product, and effective dose) as well as image noise, signal-to-noise ratio, and contrast-to-noise ratio were compared. Two independent radiologists evaluated image quality and sharpness. Student t test, Fisher exact test, and Wilcoxon signed-rank test were used for analysis. A p value less than 0.05 was considered significant.

RESULTS

Mean ± SD CTDIvol values were 19.9 ± 4.43 mGy and 12.53 ± 4.79 mGy for protocols 1 and 2, respectively (p < 0.0001). Effective dose was 38.2% lower on average using protocol 2 compared with protocol 1 (12.08 vs 19.55 mSv; p < 0.0001). Objective image quality parameters were significantly better in protocol 2 (p < 0.0001). Both radiologists found the overall image quality and sharpness to be similar for both protocols (p > 0.05).

CONCLUSION

In patients undergoing CT examination of the chest, abdomen, and pelvis, the combination of attenuation-based automated tube voltage selection with iterative reconstruction significantly reduced radiation dose parameters and maintained objective image quality when compared with standard tube voltage selection associated with filtered backprojection reconstruction.