Comparison of image quality between a novel mobile CT scanner and current generation stationary CT scanners

Early diagnosis and survival outcomes in silicosis: a retrospective cohort study of 11,809 patients in Guangdong Province, China (1956-2020)

Introduction

Silicosis, a progressive occupational lung disease caused by silica dust exposure, remains a global public health challenge due to limited therapeutic options. Early diagnosis is hypothesized to improve survival outcomes, yet evidence linking diagnostic stage to mortality remains scarce. This study aimed to evaluate the association between early diagnosis and survival in silicosis patients and assess the impact of delayed diagnosis on mortality.

Methods

A retrospective cohort study analyzed 11,809 silicosis patients diagnosed between 1956 and 2020 in Guangdong Province, China. Data were extracted from occupational disease registries, multi-sectoral databases, and provincial monitoring systems. Exclusion criteria included ambiguous diagnosis dates, pre-adolescent exposure, and missing variables. Cox proportional hazards models adjusted for covariates (sex, age, region, industry, exposure duration) were used to assess mortality risks across stages I-III. Survival curves, temporal trends, and subgroup analyses were performed.

Results

Most patients (77.8%) were diagnosed at stage I, with median survival times declining sharply across stages: 27 years (stage I), 20 years (stage II), and 11 years (stage III) (p < 0.001). Adjusted mortality risks increased progressively: stage II (HR = 1.42, 95%, CI: 1.33-1.51) and stage III (HR = 2.42, 95%, CI: 2.17-2.70)compared to stage I. Temporal analysis revealed peak diagnoses in 1963 and the early 1980s, stabilizing post-2006. Subgroup analyses confirmed staging as an independent prognostic factor across industries and exposure durations (p < 0.001).

Discussion

This study demonstrates that early diagnosis significantly prolongs survival in silicosis patients, with advanced stages correlating with exponentially higher mortality. The findings underscore the urgent need for systematic early screening, such as high-resolution CT, and stricter occupational health policies to reduce silica exposure. Despite limitations, including unmeasured confounders like smoking status, this research provides critical evidence to inform global strategies for mitigating silicosis through timely detection and workplace safety reforms.

Qualitative and Quantitative Assessment of Noncontrast Head CT Quality on a Newer-Generation Portable Scanner

OBJECTIVE

Portable computed tomography (CT) scanners allow bedside brain imaging in critically ill patients without the risks of transport, but historically these scanners have demonstrated image quality inferior to that of fixed scanners. In this study, the quality of head CT examinations using a newer-generation portable scanner, the On.site, was compared with that of an older-generation portable scanner, the CereTom, as well as to that of fixed CT scanners.

METHODS

Head CT examinations performed on the On.site scanner were retrospectively compared with those conducted on the same patient within 24 hours using the CereTom scanner or fixed scanners. A similar analysis was also carried out between the CereTom and fixed scanners. Three neuroradiologists rated the images qualitatively. Quantitative assessment included signal difference to noise ratio (SdNR) and noise magnitude in the cerebrospinal fluid, bone, and pons.

RESULTS

The On.site scanner had higher image quality scores than the CereTom scanner (P<0.001) and was 10 to 20 times less likely to produce subpar images. Mean noise in the pons was slightly higher with On.site than with CereTom (P=0.014). Fixed scanners had higher qualitative scores than the On.site scanner, but there was no significant difference between the scanners in the probability of producing subpar images. The CereTom scanner had significantly lower qualitative scores than fixed scanners, and significantly increased probability of producing subpar and nondiagnostic images (P<0.001). The SdNR was lower with the On.site scanner than with the fixed scanners (P<0.001). Noise magnitude measures were higher with On.site than with fixed scanners (P<0.001 for all).

CONCLUSIONS

The On.site scanner had significantly better qualitative image quality than the CereTom scanner and had a much lower probability of producing subpar or nondiagnostic images. Although the On.site scanner had inferior qualitative and quantitative image quality compared with the fixed scanners, there was no significant difference in the probability of producing subpar or nondiagnostic images. This may indicate a decreased need to transport sick patients out of the neurological intensive care unit for imaging in the future.

State-of-the-art mobile head CT scanner delivers nearly the same image quality as a conventional stationary CT scanner

The use of mobile head CT scanners in the neurointensive care unit (NICU) saves time for patients and NICU staff and can reduce transport-related mishaps, but the reduced image quality of previous mobile scanners has prevented their widespread clinical use. This study compares the image quality of SOMATOM On.Site (Siemens Healthineers, Erlangen, Germany), a state-of-the-art mobile head CT scanner, and a conventional 64-slice stationary CT scanner. The study included 40 patients who underwent head scans with both mobile and stationary scanners. Gray and white matter signal and noise were measured at predefined locations on axial slices, and signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were calculated. Artifacts below the cranial calvaria and in the posterior fossa were also measured. In addition, image quality was subjectively assessed by two radiologists in terms of corticomedullary differentiation, subcalvarial space, skull artifacts, and image noise. Quantitative measurements showed significantly higher image quality of the stationary CT scanner in terms of noise, SNR and CNR of gray and white matter. Artifacts measured in the posterior fossa were higher with the mobile CT scanner, but subcalvarial artifacts were comparable. Subjective image quality was rated similarly by two radiologists for both scanners in all domains except image noise, which was better for stationary CT scans. The image quality of the SOMATOM On.Site for brain scans is inferior to that of the conventional stationary scanner, but appears to be adequate for daily use in a clinical setting based on subjective ratings.