Pulmonary nodule detection and volumetrical analysis with Low Dose protocols: Preliminary experience

Diagnostic accuracy of a Computed Tomography (CT) exam protocol is dependent both on physical parameters of the CT scanner both on radiologist visualization, so it is fundamental to perform a complete characterization of the "diagnostic system" to define optimal protocol. A psycho-physical approach was performed; a CT procedure that requires scanning repetition of the same anatomical district was analyzed, acquiring every CT image sets with a different Low Dose protocol. Images acquired from 20 patients were post-processing shuffled, codified and scored by expert radiologists. Matching this data with effective dose imparted to patient, it is possible to define an optimized CT protocol. The measurements accuracy was assessed by performing analysis of a dedicated phantom with synthetic nodules. Our CT volumetrical analysis show that optimal Low Dose protocol, associated with volume reconstruction algorithm, is accurate to determine nodule with a diameter of Φ > 1.0 cm and variations in nodule diameters of ΔΦ ≈ 5 mm.