. Author manuscript; available in PMC: 2009 Aug 2.

Published in final edited form as: J Nucl Med. 2009 May 14;50(6):999–1007. doi: 10.2967/jnumed.108.059576

TABLE 5.

Requirements for Metal Particulate Agents in CT: Required Number Would Scale Inversely with Density

Diameter of particle containing metal (nm)	$\frac{{(μ / ρ)}_{t} \cdot ρ_{t}}{{(μ / ρ)}_{a} \cdot ρ_{a}}$ for specific metal at specific keV	Particles per cm³ to be detected	Particles per cell to be detected
100	0.002 for gadolinium at 60 keV	4 × 10¹⁰	40 per cell
1,000	0.002 for gadolinium at 60 keV	4 × 10⁷	1 every 25 cells
10,000	0.002 for gadolinium at 60 keV	4 × 10⁴	1 every 25,000 cells
100	0.006 for iron at 30 keV	12 × 10¹⁰	120 per cell
1,000	0.006 for iron at 30 keV	12 × 10⁷	1 every 8 cells
10,000	0.006 for iron at 30 keV	12 × 10⁴	1 every 8,000 cells
100	0.001 for lead at 30 keV	2 × 10¹⁰	20 per cell
1,000	0.001 for lead at 30 keV	2 × 10⁷	1 every 50
10,000	0.001 for lead at 30 keV	2 × 10⁴	1 every 50,000 cells