Towards prospective identification of optimal scan parameters for CT-guided interventions: a phantom study

Area of Science:

• Medical Imaging
• Radiology
• Interventional Radiology

Background:

• CT-guided interventions demand a careful balance between radiation exposure and diagnostic image quality.
• Image quality is often quantified by contrast-to-noise ratio (CNR), which can be affected by scan parameters.

Purpose of the Study:

• To evaluate how tube voltage and tube load influence CNR in CT-guided interventions.
• To determine the optimal settings for various patient sizes and target tissues.

Main Methods:

• A modular multi-energy phantom (20cm and 35cm diameters) with bone, iodine-blood, and blood targets was used.
• Scans were performed at matched dose levels (1-10 mGy SSDE) using tube voltages from 80 to 140 kVp.
• CNR was measured as the primary metric for image quality assessment.

Main Results:

• In smaller phantoms, lower kVp improved CNR for high-contrast targets (iodine), while higher kVp benefited low-contrast imaging.
• In larger phantoms, increasing kVp consistently enhanced CNR across all tested materials.
• Example: Increasing kVp from 80 to 120 improved CNR from 6.5 to 8.6 for iodine-blood targets.

Conclusions:

• Optimal CT-guided intervention protocols require dynamic adjustment of tube voltage and load based on patient size and target tissue.
• Achieving the best CNR involves managing the trade-off between contrast enhancement and noise reduction at higher tube voltages.