Table 5. Differences between Fluorescence- and Radioactivity-Based Image-Guided Surgery.

	fluorescence	radioactivity
Spatial resolution	μm–mm’s	>2 mm
Signal display	Video rate	Only numeric/acoustic (γ-probe) or static image (γ camera)
Acquisition time	<50 ms	>500 ms (γ-probe), multiple seconds (γ camera)
Compatibility with microscopic tissue evaluation	Fluorescence microscopy (<μm resolution)	Autoradiography (>mm)
Biodistribution	Qualitative (image intensity only; impacted by autofluorescence and tissue-based signal attenuation)	Quantitative (%ID/g)
Signal penetration depth through tissue	<10 mm	>10 mm
Noninvasive whole-body imaging (surgical roadmap)	n.a.	2D scintigraphy/3D (e.g., SPECT/CT, PET/CT)