Intensity-Modulated Total-Body Irradiation

Total-body irradiation (TBI) is an important component of myeloablative and non-myeloablative conditioning regimens for allogeneic hematopoietic stem cell transplantation (HSCT). Historically, 2D treatment techniques were utilized to irradiate the entire body to the prescription dose. Technological advancements in radiotherapy planning and delivery in the past two decades are prompting a transition to intensity-modulated radiation therapy (IMRT) TBI, given its ability to deliver myeloablative doses to the whole body while reducing doses to radiosensitive organs. Such modern TBI treatment techniques include Volumetric-Modulated Arc Therapy (VMAT) TBI and helical TomoTherapy TM TBI. However, adoption of these modern techniques has been slow, as it is a significant undertaking due to the substantial increase in complexity of treatment planning and delivery. The focus of this chapter is to discuss these modern treatment techniques in greater detail to provide guidance on best treatment planning and delivery practices.