Figure 4.

Beta detection better pinpoints the source of radiation than gamma detection. Beta and gamma measurements were taken at incremental distances from the tumors 1-hour following intravenous injection of radiolabeled ¹⁸F. Beta detection was nearly zero at distances > 5 cm from the source, while gamma emission was still detectable at 15 cm. Data from a representative animal is shown to demonstrate that at the spot over tumor, the beta counts are high, but after the probe is moved ~2 cm away from the tumor, counts are nearing zero. In contrast, the gamma probe detects emissions up to 10 cm away from the site of tumor.