Intravascular brachytherapy (IVBT) is a useful treatment modality for the recurrence of in-stent restenosis following drug-eluting stents (DES) or IVBT failure. The objective of this study was to measure the dose rate of Sr-90/Y-90 IVBT sources for comparison with that given by the manufacturer and to control the dose uniformities of these sources along the source axis. The dose rates of Sr-90/Y-90 beta sources were measured with a radiochromic film in a custom-made phantom. The films for calibration were irradiated using Co-60 photon beams. The results for the three sources were 4.5%, 2.3%, and 3.5% higher than the corresponding certificate values. Maximum and minimum of the dose rates varied within +/- 10% of those at source center; and maximum dose discrepancy for the first Sr-90/Y-90 source train was 8.2%; for the second source train, 7.1%; and for the third source train, 5.1%. Our study showed that the dose rates given by the manufacturer for the three Sr-90/Y-90 IVBT sources were reliable and dose uniformities were within +/- 10% along two thirds of the treatment length.