Rapid Multisite Remote Surface Dosimetry for Total Skin Electron Therapy: Scintillator Target Imaging

Abstract

Verifying radiation-field uniformity in total skin electron therapy is important to ensuring adequate and effective treatment administration. This clinical study presents a novel, scintillation-based, opticalimaging technique for conducting surface dosimetry in patients undergoing total skin electron therapy. The system exceeded the ease of use of established dosimetry techniques at a similar level of accuracy. Purpose: The goal of this work is to produce a surface-dosimetry method capable of accurately and remotely measuring skin dose for patients undergoing total skin electron therapy (TSET) without the need for postexposure dosimeter processing. A rapid and wireless surface-dosimetry system was developed to improve clinical workflow. Scintillator-surface dosimetry was conducted on patients undergoing TSET by imaging scintillator targets with an intensified camera during TSET delivery. Methods and Materials: Disc-shaped scintillator targets were attached to the skin surface of patients undergoing TSET and imaged with an intensified, time-gated, and linear acceleratoresynchronized camera. Optically stimulated luminescence dosimeters (OSLDs) were placed directly adjacent to scintillators at several dosimetry sites to serve as an absolute dose reference. Real-time image-processing methods were used to produce background-subtracted intensity maps of Cherenkov and scintillation emission. Rapid conversion of scintillator-light output to dose was achieved by using a custom fitting algorithm and calibration factor. Surface doses measured by scintillators were compared with those from OSLDs. Results: Absolute surface-dose measurements for 99 dosimetry sites were evaluated. According to paired OSLD estimates, scintillator dosimeters were able to report dose with <3% difference in 88 of 99 observed dosimetry sites and <5% difference in 98 of 99 observed dosimetry sites. Fitting a linear regression to dose data reported by

Technical Note: Quality assurance and relative dosimetry testing of a 60Co total body irradiator using optical imaging

“…In turn, workflow time can be minimized and there exists the possibility for reducing human error by automating data processing and analysis. There also exists the possibility of utilizing this system for patient imaging by incorporation of a modified version of a previously described equalized background subtraction method …”

“…There also exists the possibility of utilizing this system for patient imaging by incorporation of a modified version of a previously described equalized background subtraction method. [13][14][15] ACKNOWLEDGMENTS This work was sponsored by NIH grants R44 CA199836, R01 EB023909, and P30 CA023106.…”

“…Previous studies have shown that optical imaging of scintillator light emission can be used to measure surface dose in both phantoms and patients undergoing radiotherapy . These served as motivation for adapting scintillator imaging for use in 60 Co irradiator commissioning and QA.…”

Experimentally Observed Cherenkov Light Generation in the Eye During Radiation Therapy

“…Specifications of the image processing workflow and triggering mechanism have been previously described. [18][19][20][21][22] Image data were transmitted via fiber optic cable from the camera to a computer outside of the linear accelerator vault for image processing. 20 Output of the camera (1600 Â 1200 pixel intensity maps, .raw format) was processed for real-time display using CDose software (DoseOptics); additionally, MATLAB (MathWorks, Natick, MA) was used for image analysis and processing.…”

Optical imaging method to quantify spatial dose variation due to the electron return effect in an MR‐linac

“…[33][34][35] Both light sources are known to be linearly proportional to deposited dose, although Cherenkov emission exhibits more energy-dependence. [36][37][38][39][40] However, by using camera systems to image volumes as opposed to the point measurements of fiber-based dosimeter systems, a relative dosimetry approach is possible, diminishing the need to separate the two signals.…”