Program Information
Feasibility of Using TomoDirect for Pulsed Reduced Dose-Rate Radiotherapy
M Geurts, Department of Human Oncology, University of Wisconsin at Madison
Presentations
TU-H-BRC-4 (Tuesday, August 2, 2016) 4:30 PM - 6:00 PM Room: Ballroom C
Purpose: Pulsed reduced dose-rate radiotherapy (PRDR) is a technique used for treatment of recurrent disease where a planned treatment is split into 0.2 Gy pulses, each separated by three-minute intervals, to achieve a time averaged dose rate of 0.0667 Gy/min. This study investigated the feasibility of using TomoTherapy's fixed angle delivery feature (TomoDirect) to create high quality IMRT plans that meet the radiobiological constraints of PRDR.
Methods: Two plans (one craniospinal irradiation and a complex shaped temporal lobe re-irradiation) were created using a conventional technique and then TomoDirect. Plan quality was compared between techniques. Next, the dose rate to each voxel in the target was computed for each TomoDirect beam to verify that the time-averaged dose rate is less than 0.0667 Gy/min.
Results: The TomoDirect CSI plan provided improved target coverage and organ at risk sparing with a per-beam treatment time ranging from 21.6 to 43.5 seconds and mean time-averaged dose rate of 0.032 Gy/min. The TomoDirect temporal lobe plan showed equivalent plan quality to a non-PRDR TomoHelical IMRT plan with per-beam treatment times ranging from 43.7 to 44.9 seconds and a mean time-averaged dose rate of 0.052 Gy/min.
Conclusion: Our initial investigation suggests that TomoDirect PRDR is not only feasible but ideal for delivering superior conformality and target homogeneity to complex and large fields.
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