Tumor Microdosimetry Projections for 111In-DTPA-hEGF Administered Subcutaneously to Athymic Mice Bearing MDA-MB-468 Human Breast Cancer Xenografts
| Compartment | Cumulative radioactivity in source compartment (ÃS, Bq · s) at the following %ID/g: | ||||
|---|---|---|---|---|---|
| 5 | 30 | 80 | |||
| Membrane | 154 | 924 | 2,464 | ||
| Cytoplasm | 500 | 3,003 | 8,000 | ||
| Nucleus | 115 | 690 | 1,840 | ||
| Total | 769 | 4,617 | 12,304 | ||
| Radiation dose to nucleus (cGy) | 88 | 529 | 1,402 | ||
Data were calculated by assuming administration of 5 single doses of 18.5 MBq of 111In-DTPA-hEGF (total, 92.5 MBq), with radiopharmaceutical proportioned into cellular compartments as previously reported (10) and by assuming 2 × 109 cells per gram of tumor. Cumulative radioactivity was calculated by dividing radioactivity in source compartment by decay constant for 111In (3 × 10−6 s−1) and by assuming rapid tumor uptake and no biologic elimination.