Optimization of CT parameters to reduce radiation dose in SPECT/CT bone scans while preserving diagnostic quality

Minimizing patient radiation exposure while maintaining diagnostic accuracy is essential in hybrid imaging modalities such as SPECT/CT. This study aimed to develop and validate a reduced-dose CT protocol for bone SPECT/CT imaging by optimizing CT acquisition parameters to lower radiation exposure without compromising image quality.

A two-part study was performed. The first part was a phantom study using a Jaszczak model, which evaluated multiple CT current and slice thickness combinations to identify the optimal image quality with minimized radiation dose. The second part was a clinical trial conducted to compare 20 patients scanned using the optimized protocol (40 mA) with 40 patients previously scanned using the standard protocol (60 mA) as historical controls. The SPECT parameters remained unchanged. Quantitative metrics (CR, COV, SNR, and CTDIvol) and blinded qualitative assessments were used.

The optimized CT protocol reduced patient dose (median CTDIvol: 3.04 vs. 4.08 mGy, p < 0.001) without statistically significant differences in SPECT image quality (median Likert score: 3 in both groups) or diagnostic metrics.

The proposed 40 mA CT protocol reduces radiation dose in bone SPECT/CT imaging while preserving diagnostic confidence and is suitable for clinical implementation.