title: Monte Carlo calculations of dose distribution for intramural delivery of radioisotopes using a direct injection balloon catheter.
abstract: OBJECTIVE
  A unique method of delivering radiation dose to the coronary vessel wall to prevent restenosis is by direct injection of radioactive compounds into the vessel wall using a specially designed angioplasty balloon catheter. The radiation dose distribution resulting from such intramural delivery was investigated using Monte Carlo simulations.
  
  
  METHODS
  The radioisotope source distribution was modeled for two configurations within the vessel wall: (1) uniform to a depth of 0.5 mm and (2) confined to discrete pools surrounding the delivery injection ports. Monte Carlo MCNP4B computer simulations were utilized to estimate the associated radiation dose distribution for the following radioisotopes: 188Re, 186Re, 32P, 153Sm, 111In, 123I, and 99mTc.
  
  
  RESULTS
  For the uniform case where the radioisotopes are distributed uniformly to the depth of 0.5 mm into the vessel wall, an essentially constant radiation dose is delivered within the source distribution. Outside of the source volume, the dose falls off at a rate depending on the emission properties of the particular radioisotope. The nonuniform case involving discrete pools of activity showed the dose distribution being confined largely to the regions surrounding the delivery ports with significant regions between these ports receiving very little dose.
  
  
  CONCLUSIONS
  Direct injection of selected radioisotopes into the arterial wall appears to represent a potentially effective method for delivering radiation dose for the prevention of restenosis. Sufficiently high doses may be obtained from relatively low activity and the dose falls off rapidly outside of the target area for certain radioisotopes.
authors.affiliation: Department of Radiology, University of Cincinnati, Cincinnati, OH 45267, USA. William.Kassing@uc.edu
authors.forename: William M
authors.initials: WM
authors.lastname: Kassing
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: McGoron
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Thomas
authors.forename: Howard R
authors.initials: HR
authors.lastname: Elson
authors.forename: David W
authors.initials: DW
authors.lastname: Pipes
mesh_terms: D000328:Adult; D001610:Beta Particles / Q000627:therapeutic use; D002404:Catheterization / Q000295:instrumentation*; D023903:Coronary Restenosis / Q000517:prevention & control; D004307:Dose-Response Relationship, Radiation; D016503:Drug Delivery Systems; D004583:Electrons / Q000627:therapeutic use; D005720:Gamma Rays / Q000627:therapeutic use; D006801:Humans; D007267:Injections; D009010:Monte Carlo Method; D017785:Photons / Q000627:therapeutic use; D011868:Radioisotopes / Q000008:administration & dosage*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012016:Reference Values; D016896:Treatment Outcome
chemical_list: D011868:Radioisotopes