Radiation pneumonitis following Yttrium-90 radioembolization: A Korean multicenter study

To report the incidence of radiation pneumonitis after radioembolization. In this retrospective study, from May 2009 to July 2021, 782 consecutive patients underwent radioembolization in two institutes. Medical internal radiation dose dosimetry and partition dosimetry were used for glass and resin Yttrium-90-labeled microspheres ( Y-microspheres), respectively. Medical records and radiological findings were retrospectively evaluated with emphasis on the symptomatic radiation pneumonitis. Of the 732 patients with lung shunt study and follow-up, 13 (1.8%) had symptomatic radiation pneumonitis and six patients died due to radiation pneumonitis. Of the 721 patients whose lung doses were calculated, 10 patients who were treated with glass (n = 5) and resin (n = 5) Y-microspheres had radiation pneumonitis. No significant statistical difference between glass and resin Y-microspheres (p = 0.304) was noted in terms of radiation pneumonitis incidence. Among the patients with radiation pneumonitis, all five patients treated with glass Y-microspheres had estimated lung doses > 29 Gy, whereas five patients treated with resin Y-microspheres had relatively wide range of lung dose reaching much lower value (13.21Gy). The present study suggests that radiation pneumonitis after radioembolization may occur even though the manufacturer's instructions are followed.