Improving treatment geometries in total skin electron therapy: Experimental investigation of linac angles and floor scatter dose contributions using Cherenkov imaging

Andreozzi, Jacqueline M.; Brůža, Petr; Tendler, Irwin I.; Mooney, Karen; Jarvis, Lesley A.; Cammin, J.; Li, Harold; Pogue, Brian W.; Gladstone, David J.

doi:10.1002/mp.12917

Cited by 12 publications

(11 citation statements)

References 19 publications

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“…Optical imaging of Cherenkov emission from patients undergoing TSET has been previously described in the literature; Cherenkov emission is proportional to absorbed dose in tissue. However, as shown in both previous work and this study, it is highly influenced by optical properties [14][15][16] in tissues (see Fig. 1B and 2).…”

Section: Discussionsupporting

confidence: 84%

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

Tendler

Brůža

Andreozzi

et al. 2019

International Journal of Radiation Oncology*Biology*Physics

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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

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Section: Discussionsupporting

confidence: 84%

“…Correcting Cherenkov intensity to account for optical properties of tissue is crucial for realizing accurate optical-surface dosimetry. [13][14][15][16]…”

Section: Optical Imaging Methodsmentioning

confidence: 99%

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

Tendler

Brůža

Andreozzi

et al. 2019

International Journal of Radiation Oncology*Biology*Physics

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“…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.…”

Section: Methodsmentioning

confidence: 99%

Experimentally Observed Cherenkov Light Generation in the Eye During Radiation Therapy

Tendler

Hartford

Jermyn

et al. 2020

International Journal of Radiation Oncology*Biology*Physics

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“…The Cherenkov emission spectrum from MV radiation is composed of optical photons with a limited penetration in human tissue, and so irradiated tissue can be selectively excited with this light signal, which comes from the secondary electrons in the irradiated volume. Imaging the emitted light from the surface of tissue shows the entrance beam as projected on the patient's skin, which has motivated the concept of real‐time visualization of surface dose on patients during delivery of their external beam radiation therapy (EBRT) . However, there is also potential to use Cherenkov light for molecular sensing of the tissue to assist in adaptive radiotherapy based upon the tumor microenvironment, using diagnostically useful molecular sensors (e.g., tissue oxygen pO2, acidity pH, or protein labels and reporters) within critical planning target volume (PTV) structures.…”

Section: Introductionmentioning

confidence: 99%

Cherenkov‐excited luminescence scanned imaging using scanned beam differencing and iterative deconvolution in dynamic plan radiation delivery in a human breast phantom geometry

et al. 2019

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Purpose: The purpose of this study was to demonstrate high resolution optical luminescence sensing, referred to as Cherenkov excited luminescence scanning imaging (CELSI), could be achieved during a standard dynamic treatment plan for a whole breast radiotherapy geometry. Methods: The treatment plan beams induce Cherenkov light within tissue, and this excitation projects through the beam trajectory across the medium, inducing luminescence where there can be molecular reporter. Broad beams generally produce higher signal but low spatial resolution, yet for dynamic plans the scanning of the multileaf collimator allows for a beam-narrowing strategy by recursively temporal differencing each of the Cherenkov images and associated luminescence images. Then reconstruction from each of these size-reduced beamlets defined by the differenced Cherenkov images provides a well-conditioned matrix inversion, where the spatial frequencies are limited by the higher signal-to-noise ratio beamlets. A built-in stepwise convergence relies on stepwise beam size reduction, which is associated with a widening of the bandwidth of Cherenkov spatial frequency and resultant increase in spatial resolution. For the phantom experiments, europium nanoparticles were used as luminescent probes and embedded at depths ranging from 3 to 8 mm. An intensity modulated radiotherapy (IMRT) plan was used to test this. Results: The Cherenkov images spatially guided where the luminescence was measured from, providing high lateral resolution, and iterative reconstruction convergence showed that optimization of the initial and stopping beamlet widths could be achieved with 15 and 4.5 mm, respectively, using a luminescence imaging frame rate of 5/s. With the IMRT breast plan, the original lateral resolution was improved 2X, that is, 0.08-0.24 mm for target depths of 3-8 mm. In comparison, a dynamic wedge (DW) plan showed an inferior image fidelity, with relative contrast recovery decreasing from 0.86 to 0.79. The methodology was applied to a three-dimensional dataset to reconstruct Cherenkov excited luminescence intensity distributions showing volumetric recovery of a 0.5 mm diameter object composed of 0.5 lM luminescent microbeads. Conclusions: High resolution CELSI was achieved with a clinical breast external beam radiotherapy (EBRT) plan. It is anticipated that this method can allow visualization and localization for luminescence/fluorescence tagged vasculature, lymph nodes, or superficial tagged regions with most dynamic treatment plans.

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Improving treatment geometries in total skin electron therapy: Experimental investigation of linac angles and floor scatter dose contributions using Cherenkov imaging

Cited by 12 publications

References 19 publications

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

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

Experimentally Observed Cherenkov Light Generation in the Eye During Radiation Therapy

Cherenkov‐excited luminescence scanned imaging using scanned beam differencing and iterative deconvolution in dynamic plan radiation delivery in a human breast phantom geometry

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