Effects of reduced kVp and contrast volume on dose and image quality in canine abdominal CT

Abstract

Importance: Lower peak kilovoltage (kVp) can reduce radiation dose and increase iodine conspicuity, but veterinary CT protocols integrating kVp reduction with iodine-dose reduction are not well defined. Objective: To evaluate the effects of reduced kVp and reduced iodinated contrast volume on radiation dose and image quality in canine abdominal CT. Methods: A phantom study (0%–10% iodine dilutions) at 120, 100, and 80 kVp quantified the relationship between iodine concentration and CT attenuation. Eight healthy Beagle dogs underwent multiphase abdominal CT at 120, 100, and 80 kVp (1-week intervals) with weightbased contrast volumes adjusted using phantom-derived slope ratios. Radiation output (CTDIvol, dose-length product) and quantitative image quality (attenuation, background noise, signal-to-noise ratio [SNR], contrast-to-noise ratio [CNR]) were assessed, along with blinded qualitative scoring by 2 readers. Results: Compared with 120 kVp, CTDIvol decreased by 41% at 100 kVp and 74% at 80 kVp, with similar proportional decreases in dose-length product. Lower kVp increased iodinerelated attenuation, permitting iodine-dose reductions (17% at 100 kVp; 34% at 80 kVp). Quantitative noise increased and SNR decreased at 80 kVp, particularly in delayed-phase images; qualitative noise scores were significantly worse at 80 kVp, whereas overall qualitative image quality did not differ across protocols. Conclusions and Relevance: In dogs, a 100 kVp protocol reduced radiation output and iodine dose while maintaining diagnostic image quality, supporting 100 kVp as a practical optimization strategy for clinical abdominal CT.