Figure 5

Relative efficiency as a function of sample volume for five different isotopes: ¹⁸F, ¹¹C, ¹²⁵I, ^99mTc, and ⁵¹Cr. Energy windows are indicated in the figure. (a) Data acquired in a window centered on the lower photopeak; (b) data acquired in a wide window encompassing both the lower photopeak and the coincidence sum peak; and (c) data acquired in a window including only the coincidence sum peak. The dashed lines indicate unity and are intended to aid interpretation of the data.