Table 3.

EC-associated radioactivity (IR) needed to deposit 10 000 cGy for beta particle emitters confined to endothelium.

Nuclide	10 000 cGy at tumor edge			10 000 cGy per endothelial cell
	kBq∕cm	Radioactive atoms per cm	Radioactive atoms per ECa	kBq∕cm	Radioactive atoms per cm	Radioactive atoms per ECa	Tumor edge dose (cGy)
Y-90	91.6	3.05×1010	1.69×106	4.56	1.52×109	8.43×104	498
Re-188	340.2	3.00×1010	1.67×106	16.1	1.42×109	7.90×104	474
P-32	16.1	2.87×1010	1.59×106	0.81	1.44×109	8.02×104	502
I-131	38.0	3.79×1010b	2.11×106b	0.71	7.08×108b	3.93×104b	187
Cu-67	130.0	4.17×1010	2.32×106	2.12	6.81×108	3.78×104	163
P-33	68.4	2.17×1011	1.20×107	0.16	5.07×108	2.81×104	24

^aEstimated by assuming each endothelial cell is a compressible sphere, 10 μm in diameter.

^bMust be multiplied by ∼20 to correct for low specific activity of ¹³¹I.