Dosimetry and MIRD for Re-188 Liquid Balloons / 대한핵의학회잡지

Re-188 is suitable for endovascular liquid-balloon brachytherapy for the prevention of restenosis after angioplasty. Re-188 was concentrated to 3700 MBq/ml and labeled with DTPA. According to dosimetric calculation, it took 420 seconds using Re-188 solution with concentration of 3700 MBq/ml to irradiate 17.6 Gy to the target at 1 mm from the balloon surface. Software was made to estimate the irradiation time. MIRD calculation with dynamic bladder model yielded the whole body dose of Re-188-DTPA as 0.005mGy/MBq in case of balloon rupture and release of the whole amount into the blood.

Intracoronary Radiation Therapy Using Re-188 after percutaneous Coronary Angioplasty / 대한핵의학회잡지

Percutaneous coronary angioplasty is well established therapeutic modality in the management of coronary artery disease. However, the high restenosis rate of 30 to 50% limits its usefulness. The principal mechanism of restenosis, ntimalhyperplasia, is the proliferative response of vessel wall to injury, which consists largely of smooth muscle cells. A large body of animal investigations and a limited number of clinical studies have established the ability of ionizing radiation to reduce neointimal proliferation and restenosis rate significantly. Human studies have been reported that intravascular radiation after first restenosis inhibits a second restenosis. Encouraged by these reports, we are also conducting a double blind, placebo-controlled, randomized trial to evaluate this new therapeutic modality in patients with coronary artery stenosis. The objective of our trial is to determine the safety and efficacy of catheter-based solutional beta emitting radioisotope system in preventing restenosis after angioplasty. This review describes the vascular brachytherapy systems and isotopes that have been utilized in the initial clinical trials performed in this area of post PTCA coronary restenosis. The results of many worldwide ongoing clinical trials will determine whether this new technology will change the future practice of vascular intervention.

Dosimetry and Medical Internal Radiation Dose of Re-188-DTPA for Endovascular Balloon Brachytherapy Against Restenosis after Coronary Angioplasty / 대한핵의학회잡지

PURPOSE: Liquid beta emitter filled in angioplasty balloon could be used to perform endovascular balloon brachytherapy to prevent coronary artery restenosis. We investigated the dosimetry for Re-188-DTPA liquid-filled balloon and medical internal radiation dosimetry in case of balloon leakage. MATERIALS AND METHODS: We estimated radiation dose from an angioplasty balloon (20 mm lengfh, 3 mm diameter cylinder) to the adjacent vessel wall using Monte Carlo EGS4 code. We obtained time-activity curves of kidneys in normal dog and calculated Tmax, T1/2. Using MIRDOSE3 program, we estimated absorbed doses to the major organs (kidneys, bladder) and the whole body when we assumed that balloon leaked all the isotope contained. RESULTS: The radiation dose was 17.5 Gy at the balloon surface when we applied 3,700 MBq/ml of Re-188 for 100 seconds. Fifty percent of the energy deposited within 1 mm from the balloon surface. The estimated internal dose to the whole body was 0.005 mGy/MBq and 18.5 mGy for the spillage of 3,700 MBq of Re-188. CONCLUSION: We suggest that Re-188-DTPA can be used for endovascular balloon brachytherapy to inhibit coronary artery restenosis after angioplasty with tolerable whole body radiation dose in case of balloon rupture.