KEY POINTS
- Phantom and Monte Carlo feasibility study testing whether Cherenkov photons from megavoltage photon beams could track motion of a small gold implant in water.
- Simulations used 6 megavolt, 10 megavolt flattening filter-free, 10 megavolt, and 15 megavolt beams, with an 8 × 12 × 0.25 mm³ gold implant in a water phantom.
- Cherenkov light yield upstream of the gold implant increased by 6.12%, 7.16%, 9.11%, and 7.01% for 6 megavolt, 10 megavolt flattening filter-free, 10 megavolt, and 15 megavolt beams, respectively.
- Experiments used a 10 megavolt flattening filter-free beam at 2400 monitor units per minute with sinusoidal, sawtooth, and sharkfin motion patterns of ±20 mm amplitude.
- For static beams, positional accuracy was <0.70 mm with repeatability <0.2 mm; during volumetric modulated arc therapy delivery, accuracy was <0.50 mm for Arc A and <0.70 mm for Arc B.
CLINICAL TAKEAWAY
This study shows that Cherenkov light imaging can track a moving gold implant with submillimetre accuracy in a controlled water-phantom setup, including during volumetric modulated arc therapy delivery. The concept is attractive because it would not add imaging dose, but clinical translation is far from proven. The main limitations are substantial: water is optically much easier than tissue, visible Cherenkov photons attenuate in biological tissue, and the current single-camera setup provides only two-dimensional tracking.