The Value of Low-dose Multi-slice Computed Tomography protocol of the Chest at Mzuzu Central Hospital, Malawi

To evaluate low-dose Computed Tomography (LDCT) chest vs. routine CT chest for image quality and diagnosis in suspected lung lesions, aiming to optimize LDCT protocol.

We retrospectively analyzed 85 patients with suspected lung lesions who underwent non-contrast enhanced (NCE) CT chest at Mzuzu Central Hospital from July 2023 to April 2024. The study divided patients into routine dose (43 patients, 120 kV, 300 mAs) and low-dose groups (42 patients, 120 kV with automatic tube current modulation) based on a transition point on February 16th, 2024. Both groups used filtered back projection (FBP) reconstruction with a 1mm layer thickness. Data were analyzed for signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and radiation dose parameters on AVW post-processing workstation, and for background noise and image quality on PACS.

(1) Objective evaluation revealed significantly higher SNR and CNR (6.58 ± 1.70, 175.96 ± 26.06) in the routine dose group compared to the low-dose group (4.17 ± 1.02, 141.23 ± 19.04) (P < 0.001). Additionally, the routine dose group had significantly higher CTDIvol, DLP, and ED [(9.95 ± 0) mGy, (372.84 ± 25.52) mGy·cm, (5.22 ± 0.37) mSv] compared to the low-dose group [(5.76 ± 1.12) mGy, (211.48 ± 50.64) mGy·cm, (2.96 ± 0.71) mSv] (P < 0.001). (2) Subjective evaluation showed no significant difference in scoring for background noise and overall image quality between the routine dose group [(1.95 ± 0.21) points, (4.09 ± 0.42) points] and the low-dose group [(1.93 ± 0.26) points, (3.98 ± 0.34) points] (P > 0.05).

The image quality of LDCT protocol is comparable to that of routine dose, while radiation dose is significantly reduced. The image quality meets the requirements for imaging diagnosis of lung lesions, and this protocol can be widely promoted in clinical practice.