Clinical Validation of Three-View Cherenkov-Convert-Dose In Total Skin Electron Therapy
Abstract
Purpose
Cherenkov imaging enables non-invasive, real-time visualization of superficial dose during radiation therapy. In TSET using the Stanford standing technique, dose uniformity is highly sensitive to daily patient positioning. This study aims to experimentally determine Cherenkov-to-dose conversion ratios and correction factors for side-view cameras and to clinically validate side-view Cherenkov imaging as a quantitative tool for 3D surface dose assessment in TSET patients.
Methods
A stereo Cherenkov imaging system consisting of one frontal and two lateral cameras was used for Cherenkov imaging during TSET delivery. Phantom experiments were performed to determine Cherenkov-to-dose conversion ratios for the side-view cameras relative to the frontal view. The frontal Cherenkov signal was converted to absolute dose using clinical in vivo dosimetry (IVD) measurements at the umbilicus. Patient-specific Monte Carlo (MC) simulations based on reconstructed 3D models were used to generate reference surface dose distributions. Vertical correction factors were derived from the ratio of Cherenkov intensity to MC reference dose and applied to the multi-view Cherenkov images for patients, with validation performed against clinical IVD measurements.
Results
Cherenkov correction factors followed a one-dimensional height-dependent trend, with larger corrections required at locations farther from the radiation isocenter. After applying patient-specific corrections, the average difference between Cherenkov-derived dose and IVD at the shin decreased from 43% to 1% based on a cohort of 29 patients. Incorporation of side-view Cherenkov images further improved agreement with reference MC dose on the patient’s lateral surface, reducing the average difference from 16% to 6% based on a cohort of 8 patients. Analysis of a total cohort of 40 patients is ongoing.
Conclusion
Patient-specific correction factors improve the quantitative accuracy of Cherenkov imaging in TSET. Incorporation of multi-view Cherenkov images reduces discrepancies between Cherenkov-derived dose and IVD at lateral sites. This approach shows promise for Cherenkov-based surface dose assessment during TSET.