Purpose: There has been recent interest in the use of brachytherapy for the possible prevention of restenosis after angioplasty. However, this field is unfamiliar to most interventional cardiologists. This article is meant to serve as an introduction to the principles of brachytherapy especially as it applies to intravascular brachytherapy. Because the intended audience is the interventional cardiologist, the details of physics, radiobiology, and radiation jargon has been kept at a minimum.
Methods: The main advantages of brachytherapy are that it can irradiate small volumes and conform to the target volume while sparing the surrounding normal tissues from the deleterious effects of irradiation. Various gamma- or beta-emitting radioisotopes can deliver the brachytherapy dose. In general, the beta emitters have fewer radiation exposure hazards, but the limited penetration of beta emitters can be a problem if deeper tissues need to be irradiated. Gamma sources can irradiate deeper but suffer from greater radiation exposure hazards. It should be remembered that the biological effects of radiation depend on a number of parameters, including the radiation modality, dose, dose rate, fractionation, treatment duration, dose prescription point, and the volume irradiated. The use of low energy isotopes, beta emitters, and remote-controlled afterloading has reduced the radiation exposure to the medical caregivers.
Conclusion: Intravascular brachytherapy is currently considered to be experimental. Those wishing to start a new intravascular brachytherapy program should comply with the required federal and state regulatory guidelines issued by the Nuclear Regulatory Commission, Food and Drug Administration, and their individual Institutional Review Board.