A comparison of intravascular source designs based on the beta particle emitter 114mIn/114In. Line source versus stepping source.
BACKGROUND
Catheter-based intravascular brachytherapy (IVB) sources of the next generation will have to meet high demands in terms of miniaturization, flexibility, safety, reliability, costs and versatility. The radionuclide pair 114mIn/114In (half-life 49.51 days, maximum beta energy 2.0 MeV, average beta energy 0.78 MeV) is an attractive beta emitter for application in such a source.


METHODS
Since metallic indium is unfit for the manufacture of a brachytherapy source, the feasibility, safety and dosimetric properties of a design concept comprising a linear array of ceramic In2O3 spheres within a thin-walled, superelastic Ni/Ti capsule are investigated.


RESULTS
Neutron activation of enriched In2O3 spheres yields a specific activity sufficiently high for the manufacture of a stepping source, keeping treatment times limited to a few minutes. Although 114mIn/114In also emits some gamma radiation, the effective doses received by members of the medical staff are an order of magnitude lower than those received from fluoroscopy. The dose distributions about a 40-mm line source and a 5-mm stepping source (outer diameter 0.36 mm) are calculated using MCNP4C. Dose-volume histograms (DVHs) are calculated for the line source (centered and noncentered) and the stepping source (centered) using the geometry of a human coronary artery.


CONCLUSIONS
The results show that a centered stepping source with optimized dwell times delivers the most homogenous dose within the target volume.
Schaart
Dennis R
DR
Nucletron B.V., Waardgelder 1, 3905 TH, Veenendaal, The Netherlands. schaart@iri.tudelft.nl
Marijnissen
Johannes P A
JP
D015906:Angioplasty, Balloon, Coronary / Q000295:instrumentation; D001610:Beta Particles / Q000627:therapeutic use*; D001918:Brachytherapy / Q000295:instrumentation*; D002408:Catheters, Indwelling; D023903:Coronary Restenosis / Q000517:prevention & control; D004307:Dose-Response Relationship, Radiation; D004583:Electrons / Q000627:therapeutic use; D004867:Equipment Design; D005060:Europe; D005240:Feasibility Studies; D006801:Humans; D007205:Indium Radioisotopes / Q000008:administration & dosage* / Q000627:therapeutic use; D015918:Infusion Pumps, Implantable; D009010:Monte Carlo Method; D009501:Neutron Activation Analysis; D017785:Photons / Q000627:therapeutic use; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional; D014481:United States
D007205:Indium Radioisotopes