Automatic current selection with iterative reconstruction reduces effective dose to less than 1 mSv in low-dose chest computed tomography in persons with normal BMI

Abstract

Most of the recent studies have used fixed tube current while few investigators use automatic current selection (ACS) with iterative reconstruction (IR) techniques to reduce effective dose (ED) to < 1 mSv in low-dose chest computed tomography (LDCCT). We investigated whether image quality of lungs as produced by a fixed tube current (FTC) of 35 mAs can be maintained with ED < 1 mSv produced by ACS with IR techniques in LDCCT. A total of 32 participants were included. The LDCCT was performed by a FTC 35 mAs (with a kilovoltage peak of 120 kVp) in 16 participants (Group A), and by a DoseRight ACS in 16 participants (Group B). Their images were improved by IR technique. The ED was estimated by multiplying the individual dose length product (DLP) by the dose conversion factor. The image quality was assessed by the CT number, noise levels, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of the regions of interest in the apex, upper lobe, and lower lobe of lung regions in the CT images. A t-test was used to evaluate the LDCCT image quality between the groups. The ED was significantly 49.2% lower in Group B than in Group A (0.71 ± 0.05 mSv vs 1.40 ± 0.02 mSv, P < .001). However, noise level, SNR, and CNR were not significantly different between Groups A and B, indicating the image quality was similar between two groups, or our setting parameters for DoseRight ACS with IR technique can achieve the image quality as good as obtained on the FTC 35 mAs with IR techniques. Our results suggest that the DoseRight ACS with IR technique reduces ED to lower than 1 mSv (averagely 0.71 mSv) yet maintains an image quality as good as produced by FTC 35 mAs with IR technique in normal BMI persons. The ACS setup thus is more preferable than the FTC to achieve the ALARA (as low as reasonably achievable) principle.

Diagnostic accuracy of ultra-low-dose chest computed tomography in an emergency department

“…Furthermore, we used a fixed tube current and therefore, the radiation dose was not adjusted to the individual patient. Recently, Chen et al (22) successfully performed ULD chest CT using automatic tube current modulation, but they included only patients with normal range BMIs (22).…”

“…Recently, Chen et al. (22) successfully performed ULD chest CT using automatic tube current modulation, but they included only patients with normal range BMIs (22).…”

Supplemental minimal‐activity PET/CT to validate ambiguous findings with less than 1 mSv: Proof of concept

“…With MA‐PET, the radiation dose could be lowered by factor 10 compared to a standard whole‐body PET/CT 15 . As a result, a moderate radiation exposure similar to a low‐dose‐CT of the chest could be accomplished 16 . Even the combination of initial standard PET/CT and supplemental minimal‐activity PET/CT is in the accepted range of equivalent doses for single PET scans.…”

Recommendations for reducing exposure to medical X‑ray irradiation (Review)

“…Another study demonstrated that automatic current selection setup was more effective than the fix tube current according to the ALARA principle. These findings suggest that the automatic current selection with iterative reconstruction technique can reduce the effective dose to an average of 0.71 mSv (reduction of radiation dose by ~50%), whereas it can maintain an image quality comparable to that obtained with the fixed-tube-current of 35 mAs with iterative reconstruction technique in individuals with a normal body mass index ( 52 ). It is noteworthy that different organs have different risks of radiation-induced cancer.…”