RESUMO
BACKGROUND: Recent clinical studies indicate that intravascular brachytherapy (IVB) can reduce the rate of restenosis substantially after angioplasty procedures. However, no clinical guidelines exist for optimal therapy. METHODS: The members of the IVB Subcommittee of the American Brachytherapy Society (ABS) identified the areas of consensus and controversies in IVB to issue the ABS perspective on IVB, based on analysis of published reports and the clinical experience of the members in brachytherapy. RESULTS: IVB is still experimental. The long-term efficacy, toxicity, the target tissue, and dose required for IVB are not established. The ABS recommends that IVB procedures must be performed, with careful attention to radiation-related issues, in the context of controlled multidisciplinary clinical trials with the approval of the institutional review board, the Nuclear Regulatory Commission, the Food and Drug Administration, and under an Investigational Device Exemption. The therapeutic radiologist, with a qualified radiation physicist, is responsible for dose prescription and delivery and needs to be present during the IVB procedure as part of this multidisciplinary team. The long-term outcome from these studies should be reviewed critically and published in peer-reviewed journals. The ABS endorsed the dosimetric guidelines of the American Association of Physicists in Medicine Task Group 60 (AAPM TG-60) report. The ABS recommends that dose specification be defined clearly; to allow comparisons between studies, the dose should be prescribed at 2 mm from the source for intracoronary brachytherapy and at an average luminal radius of +2 mm for peripheral vascular brachytherapy. The prescription doses at the above point is generally in the 12-18 Gy range. Comprehensive procedures for quality assurance, radiation protection, and emergencies should be in place before initiating an IVB program. Higher energy beta sources, lower energy gamma sources, dose-volume histograms, and correlation of three-dimensional reconstructions of delivered dose with patterns of failure are areas for further research. CONCLUSION: The ABS perspective on IVB is presented to assist the interventional team in developing protocols for the use of IVB in the prevention of restenosis. Long-term outcome data with a standardized reporting system are needed to establish the role of brachytherapy in preventing vascular restenosis. Endovascular brachytherapy is a new and evolving modality, and these recommendations are subject to modifications as new data become available.
