Introduction:The study aimed to quantify the ionizing radiation exposure of patients with hematologic malignancy who underwent hematopoietic stem cell transplantation (HSCT).Methods:This was a retrospective evaluation of the adult patients who underwent allogeneic or autologous HSCT for hematologic malignities in a single center between January 2016 and September 2020. All radiological imaging procedures involving ionizing radiation screened study participants. The study period covered both the pre- and post-transplantation phases. A typical cumulative effective dose (CED) was used to calculate the exposed ionizing radiation in units of millisieverts (mSv).Results:A total of 120 patients (females 38.3%, mean age: 52.2±15.6 years) were included. Autologous HSCT was performed in 66 patients (55%), whereas 54 patients (45%) underwent allogeneic HSCT. Patients with acute myeloid leukemia and acute lymphoblastic leukemia comprised 53.7% and 31.5% of allogeneic HSCT, respectively. Autologous HSCT was mainly performed in patients with multiple myeloma (47%) and non-hodgkin lymphoma (34.8%). The median total CED was 11.85 mSv (interquartile range: 4.08-19.78). The median CED of allogeneic HSCT patients was significantly higher than that of the autologous HSCT group. The vast majority of the total CED (92.3%) comes from computed tomography imaging procedures. In the entire groups, 92 patients (76.7%) received a low dose (20-50 mSv) ionizing radiation.Conclusion:One-third of all HSCT patients received a moderate ionizing radiation dose. Allogeneic HSCT patients had significantly higher median CED than autologous counterparts.