title: Characterization of a soft X-ray source for intravascular radiation therapy.
abstract: OBJECTIVE
  A soft X-ray device for intravascular radiation therapy of restenosis is characterized in terms of dose delivery for several artery configurations, including arteries with implanted stents, calcified plaque, and noncentered sources.
  
  
  METHODS
  The Monte Carlo code MCNP4B was used to determine the X-ray fluence and energy spectra for 15, 20, and 30-kV X-ray source generating voltages. Dose as a function of distance was calculated under a variety of artery conditions.
  
  
  RESULTS
  Calculated depth-dose profiles for the X-ray sources are within presumed artery dose tolerance limits for the range of generating voltages considered. Treatment times to deliver 8 Gy to the adventitia range from 2.7 minutes to 6.7 minutes for the 20-kV generating voltage and a 3-cm-long lesion, depending on the diameter of the artery. The does perturbation due to stent wires or calcified plaque is found to be more severe for the X-ray sources than for the radioactive sources. The effects of noncentering are found to be similar for radioactive sources and X-ray sources with generating voltages of 20 kV or higher.
  
  
  CONCLUSIONS
  The results of this study indicate that soft X-ray sources are suitable candidates for intravascular radiation therapy over a wide range of artery sizes, tissue compositions, and stent configurations.
authors.affiliation: Department of Nuclear Engineering, Massachusetts Institute of Technology, Cambridge, MA 02141, USA.
authors.forename: D P
authors.initials: DP
authors.lastname: Gierga
authors.forename: R E
authors.initials: RE
authors.lastname: Shefer
mesh_terms: D015906:Angioplasty, Balloon, Coronary; D002114:Calcinosis; D003327:Coronary Disease / Q000532:radiotherapy* / Q000628:therapy; D004307:Dose-Response Relationship, Radiation; D004583:Electrons / Q000627:therapeutic use; D006801:Humans; D009010:Monte Carlo Method; D055502:Secondary Prevention; D015607:Stents; D014964:X-Ray Therapy / Q000295:instrumentation*