Technetium-99m's Ideal Properties for Medical Imaging

Steps:

• Identify half-life: Technetium-99m has a 6-hour half-life, short enough to limit radiation exposure after scanning.
• Determine radiation type: It emits gamma rays, which penetrate tissues for external detection.
• Evaluate suitability: Short half-life allows quick decay, reducing patient dose; gamma emission enables clear imaging without biological damage.
• Compare options: Only short half-life with gamma matches these needs for safe, effective scans.

Why D is correct:

• Short half-life minimizes prolonged radiation exposure (per inverse square law for dose reduction), while gamma rays penetrate tissues for detection in nuclear medicine imaging protocols.

Why the others are wrong:

• A: Long half-life increases unnecessary exposure; alpha particles lack penetration for imaging.
• B: Long half-life causes extended radiation risk despite gamma's suitability.
• C: Alpha radiation is stopped by skin, preventing external scan detection.

Final answer: D