DirectORGANS with SOMATOM go.Sim

Cancer care frequently includes radiation therapy as a component of treatment in the upfront curative intent setting as well as extensively in the setting of metastatic disease for palliation. The initiation of a course of radiotherapy includes an initial consultation with a radiation oncologist and, if inclusion of radiation therapy is recommended, the patient undergoes a simulation, most commonly with a CT scanner designed for radiation therapy. These images are then transferred to a radiation treatment planning system wherein the radiation target(s) and organs at risk (OARs) are delineated by the radiation oncologist. Subsequently, a radiation dosimetrist along with a medical physicist perform treatment planning and return the completed plan to the radiation oncologist for review. Once approved by the radiation oncologist, the plan undergoes quality control with medical physics and finally pretreatment review by radiation therapists. All the steps must occur in a timely fashion to allow appropriate early initiation of treatment delivery. We know from numerous studies, delays in initiation of radiation therapy portend poorer outcomes.¹ 

The time from simulation to start of radiation therapy varies significantly from center to center. This depends on the urgency of the clinical scenario. The above steps must be performed in a timely but also accurate and safe manner. The delineation of the radiation target(s) and OARs by the radiation oncologist (contouring time) contributes a significant amount of time to this process, which is handled differently by different radiation therapy centers. In practice, some of this workload is performed by medical dosimetrists, radiation oncologists, or radiation oncology residents. In my experience, contouring contributes most of the time between simulations to initiation of radiation therapy.