Room: Exhibit Hall | Forum 7
Purpose: To evaluate the possible clinical options for managing patients with breast cancer on the Halcyon (H) system and make comparisons with the Truebeam (TB) system.
Methods: The first clinical Halcyon-system was implemented in our institution in Sept.2017. Breast is one of the sites that present a dosimetric and delivery challenge due to the jawless 28x28cm2 MLC system, the single 6X-FFF mode available and the compulsory MV-imaging as part of its workflow. For this retrospective study 3 supine and 3 prone breast cases were planned with IMRT, RapidArc:RA, field-in-filed:FiF and irregular-surface-compensator:ISC (a utility that converts the FFF-beam into a flattened beam). These patients were managed originally by a TB-system either via FiF or RA delivery for the supine cases and FiF for all prone cases.
Results: We treat supine and prone breast is typically with FiF on a TB-system. For supine breast, the Halcyon ISC and IMRT were comparable with modestly higher heart dose and lower V5 that the TB RA and comparable mean lung dose. The Halcyon RA was less homogeneous than IMRT. Overall, the Halcyon IMRT was favored for supine cases. For prone breast, the Halcyon-system ISC and IMRT were comparable with modestly higher heart dose than the TB FiF. Overall, the Halcyon IMRT and ISC were more favorable. The delivery time for the Halcyon was half of the TB for most cases, due to faster MLC and gantry speeds.
Conclusion: The Halcyon system IMRT, RA, FiF and ISC were evaluated for supine and prone breast treatments and was compared to TB FiF and RA. For both supine and prone cases, the Halcyon IMRT and ISC were favored to RA and FiF of both Halcyon and TB systems. A faster delivery for Halcyon may enhance it clinical relevance for breast treatments.
Funding Support, Disclosures, and Conflict of Interest: Supported by Varian
Not Applicable / None Entered.
TH- External beam- photons: Development (new technology and techniques)