Room: Karl Dean Ballroom B1
Purpose: Total Skin Electron Therapy (TSET) has been widely used in treating cutaneous lymphoma and leukemia. Cherenkov imaging has been used to extract and analyze dose distribution in radiation therapies, including TSET, based on the linear relationship between the Cherenkov light intensity and dose deposition on the same materials. However, the tissue optical property is different for different patients. The same dose can generate different amount of Cherenkov intensity from different patientsâ€™ bodies. This study focuses on the dependence of Cherenkov signals to tissue optical property. The conversion ratios are derived in this study to convert Cherenkov to dose for different patients.
Methods: Tissue phantoms are created with different tissue optical properties. The optical properties, which are absorption (Âµ_a) and scattering (Âµ_s') coefficient, are measured using a diffuse reflective spectroscopy contact probe for these phantoms, and the values of diffuse reflectance vs. wavelengths are calculated. The phantoms are placed in the center of the TSET patientâ€™s location and irradiated with electron beams with different amounts of dose. The conversion ratios of dose to Cherenkov are derived from the response curve for each phantom and compared with the values of diffuse reflectance. Measured tissue optical properties on patients will be analyzed to correlate the Cherenkov intensity and in-vivo dosimetry.
Results: The response curve of Cherenkov signal to dose for individual phantom verifies the linear relationship between Cherenkov light intensity and dose. The conversion ratios from Cherenkov to dose are also linear related to the diffuse reflectance. Thus, the Cherenkov signal can be converted to dose with different patients through the measurement of tissue optical property of their skin.
Conclusion: The study shows a dependence of the conversion ratio of Cherenkov to dose to the tissue optical property.