Room: Exhibit Hall | Forum 7
Purpose: The time between initial diagnosis and the start of radiotherapy could be substantially reduced if CT simulation could be eliminated. We hypothesize such a workflow can be implemented if a suitable diagnostic volumetric scan exists in the PACS system. Contemporaneous with planning using the diagnostic image set, an immobilization mold is machined from polystyrene foam using the patientâ€™s surface contour extracted from the volumetric scan.
Methods: Under an IRB approved study, 5 volunteers were positioned comfortably on the couch of an MR scanner without immobilization and scanned from chest to upper thighs. Each volunteerâ€™s surface contour was extracted and used to machine a polystyrene mold with a landmark inscribed at the longitudinal position of the umbilicus. Each volunteer was rescanned in the mold 3 times to mimic treatment setup. Rigid registration of bony anatomy was used to quantify setup errors and immobilization performance. Subsequently, two patients received 24Gy single fraction paraspinal SBRT after being immobilized and planned with a similar approach. For both patients, diagnostic images obtained during CT myelogram for spinal cord localization served as the planning image set. The umbilicus was used for initial positioning, followed by CBCT image guidance.
Results: Setup and immobilization performance with volunteer molds was consistent with existing clinical spine SBRT data. Treatment of the first two patients went without issue. Translational and rotational setup errors were within the normal range. Room times were unremarkable.
Conclusion: For patients being treated to lower thoracic and lumbar sites, an expedited workflow achieved with the elimination of the CT simulation setup and the use of image guidance at treatment has been established. Extension of scope to other sites is feasible.
Funding Support, Disclosures, and Conflict of Interest: Authors have applied for a provisional patent for this technology
Not Applicable / None Entered.