Room: Room 202
Purpose: Current methods of evaluation of dose distributions for total skin electron therapy (TSET) include diodes, OSLDs, TLD, or film measurements at point locations. Real time whole body Cherenkov light signal can be obtained for patients undergoing total skin electron beam therapy using a new innovative imaging technique acquired with gated-intensified camera (Dose Optics LLC). By calibrating and correcting the Cherenkov intensity, patient specific dose distributions can be projected onto a 3D surface mesh of the body for evaluation of matched fields, coverage, and uniformity during treatment.
Methods: A 3D surface mesh of the body was obtained for patients from outside the treatment room using a Structure Sensor 3D Scanner mounted to motorized tripod located at ~2 m from patient prior to each field being delivered, which allows documenting 3D body contours and positions. Using Rhinoceros 3D, the corrected Cherenkov intensity is projected onto the acquired 3D surfaces meshes for each field. Next, the cumulative dose (from 2-day cycles with 3 dual-fields per day) is determine as a function of positioning angle with respect to the gantry head. All of the 3D body contours acquired for each position are superimposed to generate a whole average body contour during the treatment, and the cumulative dose for entire treatment is superimposed on the patientâ€™s surface.
Results: By normalizing the Cherenkov images to the umbilicus point, a 2D dose map can be obtained per each patient posture using OSLD measured dose at umbilicus, which is used to construct the cumulative dose distribution for patient treatments. Planar mapping is used to project Cherenkov intensity distributions onto the patient using the TSET frame for alignment and scaling purposes.
Conclusion: This study allows for cumulative dose coverage and uniformity, for the first time, to be evaluated on a patient specific basis during TSET.