Comparative assessment of image quality and radiation dose: spectral purification computed tomography (Sn100kV) with adaptive iterative reconstruction for tuberculosis follow-up.

BACKGROUND

During tuberculosis treatment, multiple chest computed tomography (CT) scans are required for follow-up, each with an effective radiation dose (ED) of approximately 7 mSv. If treatment outcomes are poor or complications arise, additional scans may be necessary, thereby increasing the cumulative radiation burden. This study aimed to evaluate the effects on image quality of low-dose CT using spectral purification technology, in combination with varying levels of sinogram-affirmed iterative reconstruction (SAFIRE) algorithms, with the goal of identifying the optimal SAFIRE level for imaging in follow-up of active secondary pulmonary tuberculosis in adults.

METHODS

A total of 90 patients diagnosed with active secondary pulmonary tuberculosis between January and May 2024 undergoing follow-up chest CT scans after treatment were randomly assigned to three groups: conventional dose scanning (Group A), optimal tube voltage scanning with intelligence (Group B), and low-dose scanning (Group C). In Groups A and B, images were reconstructed using SAFIRE level 3 (A3 and B3), while Group C images were reconstructed with SAFIRE levels 1 through 5 (C1 to C5). The overall image quality was evaluated, double-blind, independently by two senior radiologists. Radiation doses, subjective assessments of image quality, and objective image quality metrics were analyzed and compared across the groups.

RESULTS

The ED was significantly lower in Group C compared to Groups A and B (0.28±0.05 vs. 2.79±0.65 and 1.75±0.47 mSv respectively, P<0.001). Within Group C, image noise decreased and both the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) increased with higher SAFIRE levels. SNR was significantly higher in the C5 group compared to the C1 to C4 groups (P<0.05). Subjective assessments indicated significant differences in the visibility of lung fissures, peripheral bronchi, adjacent pulmonary vessels, pleura, and subpleural regions between different SAFIRE levels (P<0.05). The best subjective scores for visualization of parenchymal lesions, including patches and nodules, were at SAFIRE level 2, while images reconstructed at level 5 scored significantly lower (P<0.05). Consistency in subjective evaluations between the C1 to C5 groups was high (Kappa =0.682).

CONCLUSIONS

The combination of spectral purification technology with SAFIRE reconstruction effectively reduced radiation exposure and image noise, and maintained diagnostic adequacy during follow-up for patients with active secondary pulmonary tuberculosis.