Room: Exhibit Hall
Purpose: The aim was to investigate if the setup of breast cancer patients could be improved using surface guided radiotherapy, compared to the conventional method using lasers and skin markings.
Methods: Forty-seven patients, who received tangential or locoregional adjuvant radiotherapy, were positioned using a surface-based setup (SBS). Thirty-eight patients were positioned using the conventional laser-based setup (LBS). For the patient group positioned using a SBS, correction for posture was performed under guidance of a color map projected onto the patients' skin in real time. The surface tolerance for the color map was 5 mm. For both setup techniques the deviation of the breast position was measured using verification images. In total, 897 images were analysed. The frequency distributions of the deviations were analysed.
Results: The result showed a significant improvement in the interfractional variation of the setup deviation for SBS compared to the LBS (p<0.01), both for the tangential and the locoregional treatments.For patients who received tangential treatments, the percentage number of fractions where the setup deviation exceeded 4 mm in any direction, which is the threshold for online correction used in the clinic, were 16.2% for LBS and 4.6% for SBS. For patients who received locoregional treatments, the percentage number of fractions where the setup deviation exceeded 4 mm was 44%/31%/36% (in the vrt/lng/lat directions) for LBS and 7.5%/7.5%/27% for SBS.
Conclusion: Conventional laser-based setup can be replaced by surface-based setup, both for tangential and locoregional breast cancer treatments.
Funding Support, Disclosures, and Conflict of Interest: Declaration of interest: Our research is partly financially supported by C-RAD AB, Uppsala, Sweden, however, the authors alone are responsible for the content, analyses, and writing.