Ytterbium-169

Overview 

Ytterbium-169 (¹⁶⁹Yb) was explored as a potential radioisotope for LDR and HDR applications due to it’s low average energy (93keV). The lower energy allows for reduced shielding and opens the potential for small directionally shielded sources or applicators. A ¹⁶⁹Yb LDR source, the GAMMAclip, was developed by Source Production & Equipment Co (New Orleans, LA).

Quick Facts 

• Half life: 32.03 days
• Average Energy: 93keV (Excluding <10keV photons)
• Exposure Rate Constant¹
  • \(\Gamma_{\delta} = 1.80\frac{R \\ cm^2}{mCi-h}\)
• Air Kerma Rate Constant¹
  • \(\Gamma_{AKR} = 0.427 \frac{cGy \ cm^2}{h \ MBq}\)
• Roentgen-to-rad conversion factors (\(f_{med}\))
  • \(f_{soft tissue} = 0.922 \frac{cGy}{R}\)
  • \(f_{bone} = 2.12 \frac{cGy}{R}\)
• Lead attenuation¹
  • First HVL = 0.2mm
  • First TVL = 1.6mm
• Decay Mode: Electron Capture