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Improved Setup and Workflow for Brain Treatments On the Halcyon Linac by Using Surface Guided Radiation Therapy

E Flores-Martinez*, L Cervino , T Pawlicki , G Kim , UC San Diego, La Jolla, CA


(Wednesday, 8/1/2018) 9:30 AM - 10:00 AM

Room: Exhibit Hall | Forum 5

Purpose: To evaluate the workflow efficiency and patient setup accuracy when using surface guided radiation therapy (SGRT) for brain treatments with the Halcyon linac

Methods: A novel workflow for brain treatments with the Halcyon linac was implemented at our clinic. The new streamlined workflow included the use of SGRT with AlignRT (Vision RT Ltd) for patient setup. A comparison between 35 treatment fractions using SGRT before MVCBCT and 35 fractions without SGRT was performed. The workflow efficiency was evaluated by comparing the total treatment time including the time for patient setup in the treatment room, the time for acquiring and evaluating the MVCBT and finally the delivery of the treatment fields with and without SGRT. Setup position accuracy was evaluated by comparing the MVCBCT setup series for each fraction with the simulation CT. The absolute residual rotational errors for pitch, jaw and roll angles were calculated by importing the images into MIM Software and performing an automatic rigid registration with the CT.

Results: By using SGRT, an average reduction of 27% in the time for the acquisition and evaluation of setup fields was achieved. The mean times for the treatment fractions were 3.8±0.8 and 4.8±1.7 minutes with and without the use of SGRT respectively. Without the use of SGRT, the imaging fields were delivered more than once on 11.4% of the fractions, while re-imaging was not necessary on any fractions using SGRT. The mean absolute residual rotational errors for pitch, jaw and roll without SGRT where 1.20±0.83°, 0.71±0.57° and 0.93±0.84° respectively and 0.50±0.38°, 0.76±0.58° and 0.57±0.51° when using SGRT.

Conclusion: The use of pre-MVCBCT SGRT for patient setup allows for a more efficient workflow on brain treatments with Halcyon. The use of SGRT will result in an improved dose coverage by means of a reduction on the residual rotational errors


Surface Matching, Image-guided Therapy, Image Guidance


TH- External beam- photons: Development (new technology and techniques)

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