CT dose and image quality in the last three scanner generations

Area of Science:

• Medical Imaging
• Radiology
• Computed Tomography

Background:

• Filtered back projection (FBP) is a traditional CT image reconstruction method.
• Iterative reconstruction (IR) techniques offer potential for dose reduction and improved image quality in CT.
• New detector technologies, such as the Stellar detector, aim to further enhance CT performance.

Purpose of the Study:

• To compare radiation dose and image quality between filtered back projection (FBP) and iterative reconstruction (IR) in computed tomography (CT).
• To evaluate the impact of a minimal electronic noise detector (Stellar detector) on CT dose and image quality.
• To assess dose reduction and image quality improvements across different anatomical regions (bone, soft tissue, air).

Main Methods:

• A lung phantom was scanned using three different CT scanners with identical parameters across nine exposure levels.
• Images were reconstructed using filtered back projection (FBP) and iterative reconstruction (IR, SAFIRE level 3).
• The Stellar detector was utilized with one of the CT scanners, and dose length products (DLPs) were recorded. Image quality metrics and subjective assessments by radiologists were performed.

Main Results:

• Iterative reconstruction (IR) achieved average dose reductions of 30% (bone), 52% (soft tissue), and 80% (air) compared to FBP for equivalent image quality.
• The Stellar detector provided additional dose reductions of 27% (bone), 54% (soft tissue), and 70% (air).
• Both IR and the Stellar detector significantly improved contrast-to-noise ratio and allowed for greater dose reduction at the same image quality levels, with benefits amplified at lower dose settings.

Conclusions:

• The Stellar detector offers substantial radiation dose reduction (27%-70%), comparable to the benefits of using iterative reconstruction (IR) over filtered back projection (FBP).
• These advanced CT technologies enable significant dose savings while maintaining or improving image quality.
• The findings support the clinical utility of IR and novel detectors for optimized patient radiation safety in CT examinations.