Pilot study on image quality and radiation dose of CT colonography with adaptive iterative dose reduction three-dimensional.

Hesong Shen,Wenli Cai,Mingyue Luo,Jianping Qiu,Wenru Li,Shanshan Zhu,Dan Liang,Chaijie Duan,Qinghui Zhang

doi:10.1371/journal.pone.0117116

Abstract

ObjectiveTo investigate image quality and radiation dose of CT colonography (CTC) with adaptive iterative dose reduction three-dimensional (AIDR3D).MethodsTen segments of porcine colon phantom were collected, and 30 pedunculate polyps with diameters ranging from 1 to 15 mm were simulated on each segment. Image data were acquired with tube voltage of 120 kVp, and current doses of 10 mAs, 20 mAs, 30 mAs, 40 mAs, 50 mAs, respectively. CTC images were reconstructed using filtered back projection (FBP) and AIDR3D. Two radiologists blindly evaluated image quality. Quantitative evaluation of image quality included image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Qualitative image quality was evaluated with a five-score scale. Radiation dose was calculated based on dose-length product. Ten volunteers were examined supine 50 mAs with FBP and prone 20 mAs with AIDR3D, and image qualities were assessed. Paired t test was performed for statistical analysis.ResultsFor 20 mAs with AIDR3D and 50 mAs with FBP, image noise, SNRs and CNRs were (16.4 ± 1.6) HU vs. (16.8 ± 2.6) HU, 1.9 ± 0.2 vs. 1.9 ± 0.4, and 62.3 ± 6.8 vs. 62.0 ± 6.2, respectively; qualitative image quality scores were 4.1 and 4.3, respectively; their differences were all not statistically significant. Compared with 50 mAs with FBP, radiation dose (1.62 mSv) of 20 mAs with AIDR3D was decreased by 60.0%. There was no statistically significant difference in image noise, SNRs, CNRs and qualitative image quality scores between prone 20 mAs with AIDR3D and supine 50 mAs with FBP in 10 volunteers, the former reduced radiation dose by 61.1%.ConclusionImage quality of CTC using 20 mAs with AIDR3D could be comparable to standard 50 mAs with FBP, radiation dose of the former reduced by about 60.0% and was only 1.62 mSv.

Highlights

Colorectal cancer is the fourth leading cause of cancer death in China, and is usually diagnosed at an advanced stage with a subsequent poor prognosis [1]
Compared with 50 mAs with filtered back projection (FBP), radiation dose (1.62 mSv) of 20 mAs with AIDR3D was decreased by 60.0%
Image quality of CT colonography (CTC) using 20 mAs with AIDR3D could be comparable to standard 50 mAs with FBP, radiation dose of the former reduced by about 60.0% and was only 1.62 mSv

Summary

Introduction

Colorectal cancer is the fourth leading cause of cancer death in China, and is usually diagnosed at an advanced stage with a subsequent poor prognosis [1]. Detection and removal of the precursor lesion significantly reduces the incidence and mortality associated with this neoplasm. CT colonography (CTC) is likely to become a new imaging technique for colorectal cancer screening [2,3,4]. A potential obstacle to mass screening CTC is the concern about radiation exposure. Researchers continuously optimize CT scan protocols to reduce radiation dose while maintaining diagnostic image quality, with manufacturers improving hardware and software [5]

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Results

Conclusion