Linac-Based Total Marrow Irradiation (TMI)

Radiation (total body irradiation, TBI) combined with chemotherapy plays an important role as a conditioning regimen in patients with hematological malignancies. One of the limitations of TBI, however, has been the toxicity, mainly the pulmonary complications. Hence, maximizing the role of radiation while reducing the dose to limiting organs has been the primary goal of recent efforts. Linear accelerator can deliver conformal radiation dose to the shape of total marrow for patients of hematological malignancies using multileaf collimators and inverse planning techniques. Linac-based intensity-modulated total marrow irradiation (IM-TMI) has shown great potential to reduce severe complications associated with conventional radiation techniques, including TBI through limiting the undesirable dose to organs at risk (OARs). Furthermore, the improved delivery efficiency of volumetric modulated arc therapy (VMAT) can greatly facilitate clinical transition of TMI by providing adequate target coverage with selective normal organ sparing in a more efficient way.