Imaging Cherenkov photons emitted during radiation therapy can provide real-time information of the external beam field. It is well established that Cherenkov emission is correlative to dose deposited; however, differential photon energies and tissue attenuation properties, along with complicated camera geometries, entangle this relationship and introduce variability in the Cherenkov emission-to-dose ratio from patient-to-patient. This study aims to better understand the effects of optical properties, skin color, and patient-specific geometries (i.e. angle of camera incidence and curvature) on the Cherenkov emission-to-dose relationship. To do so, a series of phantom experiments were conducted with tissuesimulating optical phantoms and an andromorphic breast phantom in which optical properties, curvature, and camera angle of incidence were all examined as a function of normalized Cherenkov emission-to-dose. To acquire clinical Cherenkov data along with patient skin color, Cherenkov images and OSLD measurements for the ground-truth surface dose were collected weekly on 13 whole-breast radiotherapy patients, alongside high-resolution 3D color and texture scans. Phantom results suggest there to be a moderately strong correlation between dose percent error and patient curvature (R2 = 0.57), as well as angle of camera incidence (R2 = 0.56). Initial patient results suggest there to be a correlation between the redness of a patient’s skin, and the Cherenkov emission-to-dose ratio, with higher amounts of redness correlating to lower Cherenkov signal. By better characterizing these trends, we are potentially able to find generalizable optics-based corrections that improve the accuracy in mapping Cherenkov emission to real-time skin dose.
The emergence of the Halcyon linear accelerator has allowed for increased patient throughput and improved treatment times for common treatment sites in radiation oncology. However, it has been shown that this can lead to increased surface dose in sites like breast cancer compared with treatments on conventional machines with flattened radiation beams. Cherenkov imaging can be used to estimate surface dose by detection of Cherenkov photons emitted in proportion to energy deposition from high energy electrons in tissue. Phantom studies were performed with both square beams in reference conditions and with clinical treatments, and dosimeter readings and Cherenkov images report higher surface dose (25% for flat phantom entrance dose, 5.9% for breast phantom treatment) from Halcyon beam deliveries than for equivalent deliveries from a TrueBeam linac. Additionally, the first Cherenkov images of a patient treated with Halcyon were acquired, and superficial dose was estimated.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.