Estimation of radiation dose received during treatment of in-stent restenosis using ionizing radiation

Angioplasty is a widely accepted procedure for the treatment of coronary artery disease. However, restenosis of the treated vessel occurs in 30% of patients within 6 months. Intravascular brachytherapy (IVB) is used to inhibit the formation of new tissue growth at the vessel treatment site. IVB protocols using either gamma ray or beta particle emitting isotopes have been tested and approved. However, very little data are available on resultant whole-body dose and the potential for long-term radiation effects.

Using thermoluminescence dosimetry (TLD) devices, specifically lithium fluoride (LiF) doped with Mg, Cu, and P, the radiation dose on the surface of patients undergoing IVB was measured. The TLDs were positioned on the body to obtain a measure of the gamma dose at selected anatomic locations. Additionally, the skin dose from fluoroscopy was estimated.

Measurements indicate that the average body dose on the skin surface from all TLDs, clinical requirements, and gamma source configurations varies from 0.95 mSv (95 mrem) at the head to 27.06 mSv (2706 mrem) at the sternal notch. For beta sources, the dose varied from 0.11 mSv (11.4 mrem) at the head to 0.49 mSv (49.5 mrem) at the sternal notch. The fluoroscopy contribution of dose to the body dose (15-min exposure time) was 0.10 mSv (10 mrem) at the head and 2.57 mSv (257 mrem) to the sternal notch.

The results suggest that surface skin exposures from gamma sources used in IVB pose acceptable risks considering the medical benefits of the procedures.