Increased prescription dose for large vessel intravascular brachytherapy

BackgroundMost randomized studies testing the effectiveness of IVBT were limited to vessels less than 4 mm diameter. In fact, it is now common to treat vessels larger than 4 mm. Accordingly, the authors instituted a prescription dose increase to 34 Gy at 2 mm from source center for vessels greater than 4.0 mm. The increase in prescription dose to 34 Gy at 2 mm from center is substantial, being 50% higher than the conventional maximum of 23 Gy.AimTo take a close look at group of patients treated to 34 Gy, and for whom follow‐up angiograms are available.MethodsTen patients treated for ISR with a prescription dose of 34 Gy and for whom follow‐up angiograms were available were studied. Beta‐radiation brachytherapy was performed with a Novoste Beta‐Cath System using a strontium‐90 (beta) source (Best Vascular, Springfield, VA). Source lengths of 40 or 60 mm were used. A dose of 34 Gy was prescribed at 2 mm from the source center.ResultsPatients were re‐catheterized from 2 to 21 months (median: 16 months) following IVBT, all for symptoms suggested of restenosis. All patients had some degree of ISR of the target vessel, but no IVBT‐treated vascular segment showed angiographic signs of degeneration, dissection or aneurysm.ConclusionThe authors' clinical impression, along with detailed review of the 10 cases, suggest that using a 34 Gy prescription dose at 2 mm from source center does not result in increased toxicity.