High-pitch, 120 kVp/30 mAs, low-dose dual-source chest CT with iterative reconstruction: Prospective evaluation of radiation dose reduction and image quality compared with those of standard-pitch low-dose chest CT in healthy adult volunteers

• Published in: PloS one 2019-01, Vol.14 (1), p.e0211097-e0211097
• Main Authors: Lim, Hyun Kyung, Ha, Hong Il, Hwang, Hye Jeon, Lee, Kwanseop
• Format: Article
• Language: English
• Subjects: Adult; Aged; Algorithms; Analysis; Aorta; Biology and Life Sciences; CAT scans; Chest; Computed tomography; Confidence intervals; Dosimeters; Dosimetry; Electric potential; Engineering and Technology; Exposure; Feasibility studies; Female; Health aspects; Humans; Image filters; Image quality; Image reconstruction; Infrared radiation; Lung cancer; Lungs; Male; Mathematical analysis; Mediastinum; Medical imaging; Medicine and Health Sciences; Middle Aged; Muscles; Parenchyma; Physical Sciences; Prospective Studies; Quality; Radiation; Radiation Dosage; Radiation effects; Radiation Exposure; Radiation therapy; Radiographic Image Interpretation, Computer-Assisted; Research and Analysis Methods; Setting (hardening); Signal to noise ratio; Thorax - diagnostic imaging; Tomography; Tomography, X-Ray Computed - instrumentation; Tomography, X-Ray Computed - methods; Voltage; Volunteers
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0211097

Objective of this study was to evaluate the effectiveness of the iterative reconstruction of high-pitch dual-source chest CT (IR-HP-CT) scanned with low radiation exposure compared with low dose chest CT (LDCT). This study was approved by the institutional review board. Thirty healthy adult volunteers (mean age 44 years) were enrolled in this study. All volunteers underwent both IR-HP-CT and LDCT. IR-HP-CT was scanned with 120 kVp tube voltage, 30 mAs tube current and pitch 3.2 and reconstructed with sinogram affirmed iterative reconstruction. LDCT was scanned with 120 kVp tube voltage, 40 mAs tube current and pitch 0.8 and reconstructed with B50 filtered back projection. Image noise, and signal to noise ratio (SNR) of the infraspinatus muscle, subcutaneous fat and lung parenchyma were calculated. Cardiac motion artifact, overall image quality and artifacts was rated by two blinded readers using 4-point scale. The dose-length product (DLP) (mGy∙cm) were obtained from each CT dosimetry table. Scan length was calculated from the DLP results. The DLP parameter was a metric of radiation output, not of patient dose. Size-specific dose estimation (SSDE, mGy) was calculated using the sum of the anteroposterior and lateral dimensions and effective radiation dose (ED, mSv) were calculated using CT dosimetry index. Approximately, mean 40% of SSDE (2.1 ± 0.2 mGy vs. 3.5 ± 0.3 mGy) and 34% of ED (1.0 ± 0.1 mSv vs. 1.5 ± 0.1 mSv) was reduced in IR-HP-CT compared to LDCT (P < 0.0001). Image noise was reduced in the IR-HP-CT (16.8 ± 2.8 vs. 19.8 ± 3.4, P = 0.0001). SNR of lung and aorta of IR-HP-CT showed better results compared with that of LDCT (22.2 ± 5.9 vs. 33.0 ± 7.8, 1.9 ± 0.4 vs 1.1 ± 0.3, P < 0.0001). The score of cardiac pulsation artifacts were significantly reduced on IR-HP-CT (3.8 ± 0.4, 95% confidence interval, 3.7‒4.0) compared with LDCT (1.6 ± 0.6, 95% confidence interval, 1.3‒1.8) (P < 0.0001). SNR of muscle and fat, beam hardening artifact and overall subjective image quality of the mediastinum, lung and chest wall were comparable on both scans (P ≥ 0.05). IR-HP-CT with 120 kVp and 30 mAs tube setting in addition to an iterative reconstruction reduced cardiac motion artifact and radiation exposure while representing similar image quality compared with LDCT.