Final answer:
The percentage of radiotracer uptake that is unlikely to be viable is not specified, but technetium-99m is commonly used for diagnostic purposes due to its selective localization and suitable physical properties for imaging.
Step-by-step explanation:
In the context of radioactive tracers used in medical diagnostics, the percentage of radiotracer uptake that is unlikely to be viable is not explicitly identified in the provided excerpts. However, when examining bone cancer, radiotracers like technetium-99m (Tc-99m) are utilized for their ability to be selectively located in active bone cells. Technetium-99m's appeal in diagnostic medicine stems from its properties, including a relatively short half-life of about six hours, which allows it to remain in the body temporarily, and a decay into Tc-99 with a low-intensity gamma emission, minimizing radiation damage. The emitted gamma radiation has a sufficient range to exit the body, thereby allowing an external detector to measure the concentration of the tracer. Areas with less radiotracer uptake could indicate a lack of viability; however, specific percentages of uptake that correlate to non-viability are not provided and would typically require analysis by a medical professional interpreting the imaging results.