Abstract
Surface dosimetry is required for ensuring effective administration of total skin electron therapy (TSET); however, its use is often reduced due to the time consuming and complex nature of acquisition. A new surface dose imaging technique was characterized in this study and found to provide accurate, rapid and remote measurement of surface doses without the need for post-exposure processing.Disc-shaped plastic scintillators (1 mm thick × 15 mm ) were chosen as optimal-sized samples and designed to attach to a flat-faced phantom for irradiation using electron beams. Scintillator dosimeter response to radiation damage, dose rate, and temperature were studied. The effect of varying scintillator diameter and thickness on light output was evaluated. Furthermore, the scintillator emission spectra and impact of dosimeter thickness on surface dose were also quantified. Since the scintillators were custom-machined, dosimeter-to-dosimeter variation was tested. Scintillator surface dose measurements were compared to those obtained by optically stimulated luminescence dosimeters (OSLD).Light output from scintillator dosimeters evaluated in this study was insensitive to radiation damage, temperature, and dose rate. Maximum wavelength of emission was found to be 422 nm. Dose reported by scintillators was linearly related to that from OSLDs. Build-up from placement of scintillators and OSLDs had a similar effect on surface dose (4.9% increase). Variation among scintillator dosimeters was found to be 0.3 ± 0.2%. Scintillator light output increased linearly with dosimeter thickness (~1.9 × /mm). All dosimeter diameters tested were able to accurately measure surface dose.Scintillator dosimeters can potentially improve surface dosimetry-associated workflow for TSET in the radiation oncology clinic. Since scintillator data output can be automatically recorded to a patient medical record, the chances of human error in reading out and recording surface dose are minimized.
Highlights
Surface dosimetry is widely used in radiotherapy
Scintillator surface dose measurements were compared to those obtained by optically stimulated luminescence dosimeters (OSLD)
The primary purpose of this current study was to evaluate the physical characteristics of scintillator dosimeters that are essential for clinical total skin electron therapy (TSET) utilization
Summary
Surface dosimetry is widely used in radiotherapy. in the case of total skin electron therapy (TSET), treatment efficacy is dependent on administration of a uniform radiation field across the body (Hensley et al 2013). Ensuring effective treatment delivery requires measurement and verification of surface dose (Kumar et al 1977, Desai et al 1988). Multiple systems which provide estimates of the delivered dose within a small surface area for verification of beam delivery are available commercially. The most common limitation of these devices is the need to keep track of where each probe is placed, since dose is read out and inserted into the patient record manually. The labor and time involved in this process comes at a high resource cost, and so while many centers have them, most limit their use because of the high level of human involvement in the processes (Butson et al 1996, Marre and Marinello 2004, Bufacchi et al 2007, Ben et al 2013, Desrosiers 2014, Schüttrumpf et al 2018)
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