Exposure of the operator to ionizing radiation during intracoronary radiation therapy

This study examined the radiation exposure levels and safety of medical personnel during intracoronary radiotherapy procedures. The data of 34 stenosis patients from a total of 42 irradiated patients who participated in the Seoul National University Hospital Postangioplasty Rhenium (SPARE) trial were analyzed. Intracoronary radiotherapy was delivered to the patient immediately after angioplasty ballooning. The prescribed dose was 17 Gy to the media of the diseased artery and was delivered via a Re-188 filled balloon catheter. Dosimetry was carried out with a Geiger-Müller counter at eight different points. The selected maximum and whole-body exposed doses to the operator were 10 cm and 40 cm from the patient's heart. Median delivered activity was 111.6 MCi, with an average treatment time of 576 seconds. Average exposed dose rates at 10 cm and 40 cm from the patient's heart level were 47.2 mrem/hour and 29.6 mrem/hour, respectively, and average exposed doses per treatment were 7.0 mrem and 4.9 mrem, respectively. Exposure levels measured were much lower than the recommended limit of 50 mSv for radiation workers or 1 mSv for the general population, as recommended by the International Commission on Radiological Protection. This study proves that the method of intracoronary radiotherapy currently adopted and which is the basis of this trial is safe with respect to radiation protection.