Plan quality, treatment delivery accuracy, and efficiency
isodose, breast (green) and nipple (dark yellow), breast cancer
BREAST CANCER
Based on these promising validation results, we have fully implemented APBI treatment in our Halcyon RDS. The first patient who underwent APBI on our Halcyon received a total of 26 Gy in five treatments every day for a right breast cancer (Figure Demonstration of the Halcyon APBI‐VMAT plan for the right breast patient, the first treated with the Fast‐Forward trial (26 Gy in 5‐fraction, daily) in our center. The isodose lines and the DVH parameters are shown. The crosshairs show the isocenter location. Critical structures shown were heart (blue), ipsilateral (light pink) and contralateral (light green) lung, contralateral breast (green) and nipple (dark yellow). The GTV (red) and PTV (pink) received highly conformal and homogeneous dose while selectively sparing all the critical organs including the use of sector avoidance for the right arm.Figure Pre‐treatment PD VMAT QA pass rate was 99.2% with a 3%/2 mm gamma passing criteria. The net treatment time (from first beam‐on until last beam off, including second and third beam preparation) was about 2 min. Recorded overall door‐to‐door time for this patient on Halcyon was < 10 min. This patient was initially positioned using external body marks and in‐room blue lasers, followed by the automated one‐step patient setup via shifts from Halcyon's blue lasers to the yellow lasers and a 30‐s pre‐treatment free‐breathing kV‐iCBCT scan. An in‐house IGRT/SBRT clinical protocol was applied to co‐register the pre‐treatment kV‐iCBCT images with the planning CT scan (see Figure Axial, coronal, and sagittal views of Halcyon kV‐iCBCT images (see inset) co‐registered with planning CT images (see back of coronal and sagittal views) used for image‐guided APBI treatment on Halcyon. In addition to anatomical landmarks, the planned dose cloud was superimposed for this treatment. Halcyon kV‐iCBCT images were acquired in the treatment position on breast board. The 3D soft‐tissue matching was performed via auto‐registration of online kV‐iCBCT scan with the planning CT followed by manually fine‐tuning for more accurate patient setup corrections.Those 3DOF couch corrections were within the limits of departmental APBI IGRT protocol requirements for this patient (translational shifts within ± 3.0 mm in each direction). Figure 