12.4 - Summary Of Sealed Sources
This table is based on the Assignment 07 question on sealed sources
Sealed Sources in Common Use
| Source | Decay Type | Emissions | HVL (Pb) | Half Life | Daughter | Construction | Sites | Indications |
|---|---|---|---|---|---|---|---|---|
| 192Ir | β- (95%) EC (5%) |
0.14 - 1.06 MeV γ (0.38 MeV Mean) |
2.5 mm | 73.8 days | Pt-192, Os-192 | Iridium/platinum alloy, in platinum case. Small wires or seed ribbons | Surface, interstitial, intracavity | HDR (prostate, gynae), LDR seeds (prostate) |
| 125I | EC | Mean 28 keV γ | 0.025 mm | 59.4 days | Te-125 | Iodine resin or implanted on silver wire. Titanium capsule. | Interstitial, eyeball | Permanent seed implants (prostate), uveal melanoma |
| 103Pd | EC | Mean 21 keV γ | 0.008 mm | 17.0 days | Rh-103 | Palladium plated graphite pellets and lead marker. Titanium shell to form seeds. | Interstitial, eyeball | Permanent seed implants (prostate), uveal melanoma |
| 137Cs | β- | 0.662 MeV | 5.5 mm | 30.2 years | Ba-137 | Caesium powder or microspheres, doubly encapsulated in stainless steel | Intracavity, interstitial | Low dose rate temporary implants |
| 90Sr 90Y | β- | 2.24 MeV β- | N/A | 28.9 years (90Sr), 64 hours (90Y) | 90Zr | Plaque, seeds | Surface (eyeball); intravascular | Treatment of pterygium of the eye, or intravascular treatments |
Uncommon Sealed Sources
| Source | Decay Type | Emissions | HVL (Pb) | Half Life | Daughter | Construction | Sites | Indications |
|---|---|---|---|---|---|---|---|---|
| 60Co | β- | 1.17 MeV, 1.33 MeV | 11 mm | 5.26 years | 60Ni | Encapsulated spheres | Most applications | High energy photons pose radiation protection issues; lower dose rate than 192Ir |
| 198Au | β- | 0.412 MeV gamma | 2.5 mm | 2.7 days | Hg-198 | 2.5 mm gold grains/seeds surrounded by platinum shell | Interstitial, surface | Infrequent use due to short half life, lower dose, radiation protection |
Historical Sealed Sources
| Source | Emissions | HVL (Pb) | Half Life | Daughter | Construction | Sites | Indications |
|---|---|---|---|---|---|---|---|
| 226Ra | 0.047 - 2.45 MeV γ Mean 0.83 MeV |
12 mm | 1,600 years | 222Rn | Powder loaded into encapsulated gold foil cells, encapsulated in platinum as needles | All applications | Not used due to broad spectrum, radiation protection issues (esp. Radium gas) |
| 222Rn | 0.047 - 2.45 MeV γ Mean 0.83 MeV |
12 mm | 3.83 days | 218Po | No specific data available on gaseous sources | N/A | N/A |
