Room: Exhibit Hall | Forum 9
Purpose: Cherenkov video imaging provides verification during radiotherapy of beam shape across fractions for each patient. Rare occurrences can produce serious errors during external beam radiation therapy. Additionally, patients are subject to setup errors. This can lead to health risks such as damage to healthy tissue and under-dosing the tumor. Cherenkov imaging uses light emissions from secondary charged particles traveling faster than the phase velocity of light in a dielectric medium (tissue). These emissions show the radiation beam on the patient, providing real-time verification of treatment delivery.
Methods: A clinical study was undertaken using Cherenkov imaging to assess inter-fraction beam shape variation during whole breast radiation therapy. Consent was obtained for each patient and procedures were performed in accordance with IRB approval. Cumulative Cherenkov images were acquired for each beam, fraction, and patient. Live background images of patient anatomy were acquired simultaneously, allowing for live background subtraction. Thresholding was used to isolate the beam shape, and beam shapes were compared across fractions using DICE and mean distance to conformity (MDC). DICE represents percentage agreement (100% is perfect agreement), while MDC represents the average distance of deviation (0 mm is perfect agreement). Variation was calculated relative to the first fraction.
Results: Preliminary results are presented for a total of 26 fractions from 3 patients, each with multiple beams per fraction. Beam shape was in close agreement across fractions for all patients and beams, with a mean DICE > 90 % and mean MDC < 2 mm for each patient.
Conclusion: Cherenkov imaging is able to assess beam shape of delivered treatment during breast radiation therapy, and results indicate that inter-fraction beam shape is stable. This supports the potential of Cherenkov imaging for live daily treatment verification of the radiation beam on the patient, to catch and interrupt possible treatment delivery errors.
Funding Support, Disclosures, and Conflict of Interest: Funding Support: Prouty Pilot Grant; NIH SBIR for DoseOptics (R44CA199681). Conflict of Interest Disclosure: M.J. is employed by DoseOptics LLC. B.P. is president and a co-founder of DoseOptics LLC.