Uptake Decrease of Proliferative PET Tracer 18FLT in Bone Marrow after Carbon Ion Therapy in Lung Cancer
The aim of this study was to investigate the change of 3′-[18F]fluoro-3′-deoxy-l-thymidine (18FLT) uptake in normal bone marrow (BM) after inevitable radiation. Twenty-one non-small cell lung cancer patients who received carbon ion radiotherapy (CIRT) were studied with 18FLT-positron emission tomography/computed tomography (PET/CT) at pre- and post-CIRT. Radiation dose was calculated by radiation planning. Irradiated BM was divided into three groups (<10% of maximum dose, 10–30%, and >30%). 18FLT uptake clearly decreased at >10% irradiated areas and mildly decreased at <10% areas. 18FLT uptake was lowest just after CIRT, somewhat increased at 3 months, and remained unchanged for more than 1 year. There was no significant difference between 10–30% and >30% areas. 18FLT revealed that BM function decreased by small dose such as <4.2–4.4 GyE/1 fraction of CIRT and is eradicated by >4.2–4.4 GyE/1 fraction.