Dose rate table for a P-32 intravascular brachytherapy source from Monte Carlo calculations

Studies of intravascular brachytherapy to prevent restenosis following angi oplasty have shown many promising results. Accurate dose rate tables based on detailed models of the brachytherapy sources are necessary for treatment planning. This work will present an away and along dose rate table for a 2 7 mm long catheter based P-32 beta source. MD-55-2 radiochromic film has be en exposed at five different depths (0.5 mm-4 mm) in a polystyrene phantom using a 27 mm long Guidant 32P beta source. The total dose to the active re gion of the film was determined using the absolute detector response of the MD-55-2 radiochromic film. The Monte Carlo code MCNP4B2 was also used to c alculate the dose to the active region of the film using a detailed model o f the source, encapsulation, and radiochromic film. The dose to film calcul ations showed good agreement with the measurements presented in this work w ith an average difference of 7%. The Monte Carlo calculations were also ver ified against previously published depth dose in water measurements determi ned using radiochromic film and plastic scintillator. The depth dose calcul ations in water showed good agreement with the previously published measure ments with the calculations being about 2.5% lower than the film measuremen ts and about 2.5% higher than the scintillator measurements. This work then uses the verified Monte Carlo code to present a dose rate table for the 32 P intravascular beta source. (C) 2001 American Association of Physicists in Medicine.