# Radiation Dose Reduction in Cancer Imaging with New-Model CT Scanners: A Quality of Care Evaluation

## TL;DR

Upgrading to new CT scanners significantly reduces radiation doses in cancer patients without affecting image quality.

## Contribution

Demonstrates that newer CT scanners reduce radiation exposure in oncology imaging while maintaining diagnostic quality.

## Key findings

- New CT scanners reduced radiation doses (CTDI and DLP) in all phases except unenhanced.
- Image quality metrics (SNR and CNR) remained stable, with improved CNR at the aorta with new scanners.

## Abstract

This study aimed to assess whether replacing computed tomography (CT) scanners with new models reduced the radiation doses in oncological patients, even in a setting with optimized protocols. It also evaluated the impact on the objective image quality before and after scanner replacement. This study included 14,601 chest and abdomen CT scans. The results showed significant reductions in the radiation doses (CTDI and DLP) with the new-model CT scanners in all CT phases except the unenhanced phase. The image quality, as assessed by the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), showed no significant variation at the liver or aorta across the scanners; however, the CNR was elevated at the aortic level with the newer systems. These results indicate that upgrading CT scanners may allow for reduced radiation exposure without compromising the image quality.

Background/Objectives: The primary aim of this study was to evaluate whether the replacement of roughly one-decade-old computed tomography (CT) scanners with new-model CT scanners were associated with an additional reduction in the radiation dose delivered to oncological patients, in a radiological setting where the optimization of protocols had already reached very low radiation doses. An exploratory secondary objective was to evaluate the potential differences in the objective image quality between the CT scans obtained before and after the installation of the new-generation CT scanners. Methods: Chest and abdominal CT examinations conducted for oncologic purposes were retrospectively selected from two time periods—prior to scanner replacement (2022) and following an upgrade (2024)—after five CT systems in our radiology department were replaced. We extracted and compared the CT dose index (CTDI) and dose length product (DLP) for each CT phase. For the objective image quality evaluation, we calculated the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) at the center of the liver and the aorta. An appropriate statistical analysis was performed and a p-value < 0.05 was considered significant. Results: We included 14,601 CT acquisitions, of which 9013 (61.7%) were performed before and 5588 (38.3%) after the replacement of the CT scanners. There were significantly lower values for the CTDI and DLP with the new CT scanners compared to the old ones. The CTDI with the new CT scanners was significantly lower in all phases (p-value = 0.002 for unenhanced phase, and p < 0.001 for arterial, portal venous, and delayed phases). The DLP using the new CT scanners was significantly lower in the arterial, portal venous, and delayed phases (p < 0.001), and it was not significantly different in the unenhanced phase (p = 0.36). There was no significant difference in the SNR at the liver level (p = 0.72) or at the aorta level (p = 0.51). There was no significant difference in the CNR at the liver level (p = 0.24), whereas the CNR was higher with the new CT scanners at the aorta level (p = 0.03). Conclusions: The transition to new-model CT scanners resulted in a significant reduction in the radiation dose delivered by chest and abdomen CT scans, without compromising the objective image quality.