(Sunday, 7/14/2019)
Room: ePoster Forums
Purpose: To characterize the use of in-vivo optically stimulated luminescent dosimeter (OSLD) measurements as a primary verification of dose delivered during total skin electron therapy (TSET).
Methods: Data from 31 patients treated with total skin electron therapy (TSET) were retrospectively analyzed in order to characterize the accuracy and reliability of OSLD measurements taken in-vivo during treatment. Departmental clinical practice guidelines incorporate ten OSLD measurements during the patient’s first fraction to characterize dose delivered across the entire treatment field and to establish sites requiring supplemental dosage. Right hip and umbilicus readings are averaged and utilized to represent the primary prescription verification value (PPVV). For each patient, OSLDs were placed along the treatment plane at umbilicus, larynx, vertex, right shoulder, forearm, knee and hip as well as left dorsal hand, medial thigh, and dorsal foot. Prescription dose is 1200cGy in six fractions delivered via modified Stanford 6-field technique. Statistical analysis was performed in order to determine the consistency of this dosimetric validation method, and robustness of OSLDs in clinical practice.
Results: OSLD readings measured PPVV variation to 1.0% ± 7.6% on average (203cGy±15.4cGy, range 173-238cGy). Lowest average doses (160cGy±18.5cGy, range 127-193cGy) were measured on the left dorsal hand, as expected from positioning variations. Vertex OSLDs had the highest variability of 24.8% (190.2cGy±47.2cGy, range 84-258cGy). Overall, differences between the mean and median OSLD of all measurements (excluding the Vertex) were found be <5cgy.
Conclusion: OSLDs were shown to be a reliable and consistent in-vivo dosimetry method for the validation of prescribed dose for TSET at both the PPVV and multiple points of clinical importance.
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