Cherenkov Imaging with a Predicted Surface Dose Overlay for Treatment Verification

Cherenkov Imaging to Verify Radiation Treatment Delivery in Breast Cancer

Improved Cherenkov Imaging across a Wide Range of Skin Pigmentation Levels for the Inclusion of Diverse Patient Populations

Imaging Radiotherapy-Induced Cherenkov Emission in Color

This paper aimed to evaluate the integration of Cherenkov imaging into radiation therapy practices, focusing on its utility in enhancing treatment precision, patient safety, and clinical decision-making. The research highlights its application in quality and safety verification, breast treatment, and dose visualization, confirming the absence of radiation in unintended areas and its broader clinical impact. We employed 2 commercially available Cherenkov imaging systems, BeamSite and DoseRT, integrated with Varian and Elekta linear accelerators. The methodology involved real-time imaging during radiation therapy sessions for various treatments, capturing Cherenkov light with time-gated cameras synchronized with radiation pulses. Posttreatment, images were analyzed to assess treatment accuracy, dose distribution, and any deviations from the intended plan. Cherenkov imaging consistently provided high-quality images that allowed immediate visualization of the radiation dose distribution, detection of deviations in real time, and ensured no radiation was delivered to unintended areas. The results are presented, focusing on 5 main topics: quality and patient safety verification; breast treatment applications; dose visualization for treatment verification; verification of a negative dose in areas of concern; and observations with clinical impact. It was particularly beneficial in complex scenarios like breast cancer treatments and in cases where patient positioning was challenging. The technology facilitated immediate treatment adjustments, improved patient safety, and offered insights into treatment response without adding significant time to the clinical workflow. Cherenkov imaging has shown substantial promise in enhancing radiation therapy by providing real-time, visual feedback on treatment delivery. It complements traditional verification methods by offering continuous monitoring, which can lead to fewer treatment errors and better patient outcomes. The findings suggest that Cherenkov imaging should be considered for broader clinical adoption to elevate the standard of care in radiation oncology, although further refinement of image processing and camera positioning could enhance its effectiveness.

Daily Cherenkov Imaging to Monitor for Unintended Field Overlap During Bilateral Breast Radiotherapy.

Purpose: To develop a tissue model of Cherenkov radiation emitted from the skin surface during external beam radiotherapy. Imaging Cherenkov radiation emitted from human skin allows visualization of the beam position and potentially surface dose estimates, and our goal is to characterize the optical properties of these emissions. Methods: We developed a Monte Carlo model of Cherenkov radiation generated in a semi-infinite tissue slab by megavoltage x-ray beams with optical transmission properties determined by a two-layered skin model. We separate the skin into a dermal and an epidermal layer in our model, where distinct molecular absorbers modify the Cherenkov intensity spectrum in each layer while we approximate the scattering properties with Mie and Rayleigh scattering from the highly structured molecular organization found in human skin. Results: We report on the estimated distributions of the Cherenkov wavelength spectrum, emission angles, and surface distribution for the modeled irradiated skin surface. The expected intensity distribution of Cherenkov radiation emitted from skin shows a distinct intensity peak around 475 nm, the blue region of the visible spectrum, between a pair of optical absorption bands in hemoglobin and a broad plateau beginning near 600 nm and extending to at least 700 nm where melanin and hemoglobin absorption are both low. We also find that the Cherenkov intensity decreases with increasing angle from the surface normal, the majority being emitted within 20 degrees of the surface normal. Conclusion: Our estimate of the spectral distribution of Cherenkov radiation emitted from skin indicates an advantage to using imaging devices with long wavelength spectral responsivity. We also expect the most efficient imaging to be near the surface normal where the intensity is greatest; although for contoured surfaces, the relative intensity across the surface may appear to vary due to decreasing Cherenkov intensity with increased angle from the skin normal. This research was supported in part by a GAANN Fellowship from the Department of Education.

Total Skin Electron Therapy (TSET) utilizes high-energy electrons to treat cancers on the entire body surface. The otherwise invisible radiation beam can be observed via the optical Cherenkov photons emitted from interaction between the high-energy electron beam and tissue. Cherenkov emission can be used to evaluate the dose uniformity on the surface of the patient in real-time using a time-gated intensified camera system. Each patient was monitored during TSET by in-vivo detectors (IVD) as well as Scintillators. Patients undergoing TSET in various conditions (whole body and half body) were imaged and analyzed. A rigorous methodology for converting Cherenkov intensity to surface dose as products of correction factors, including camera vignette correction factor, incident radiation correction factor, and tissue optical properties correction factor. A comprehensive study has been carried out by inspecting various positions on the patients such as vertex, chest, perineum, shins, and foot relative to the umbilicus point (the prescription point).