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Cloutier E, Beaulieu L, Archambault L. On the use of polychromatic cameras for high spatial resolution spectral dose measurements. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac6b0e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 04/27/2022] [Indexed: 11/11/2022]
Abstract
Abstract
Objective. Despite the demonstrated benefits of hyperspectral formalism for stem effect corrections in the context of fiber dose measurements, this approach has not been yet translated into volumetric measurements where cameras are typically used for their distinguishing spatial resolution. This work investigates demosaicing algorithms for polychromatic cameras based spectral imaging. Approach. The scintillation and Cherenkov signals produced in a radioluminescent phantom are imaged by a polychromatic camera and isolated using the spectral formalism. To do so, five demosaicing algorithms are investigated from calibration to measurements: a clustering method and four interpolation algorithms. The resulting accuracy of scintillation and Cherenkov images is evaluated with measurements of the differences (mean ± standard deviation) between the obtained and expected signals from profiles drawn across a scintillation spot. Signal-to-noise ratio and signal-to-background ratio are further measured and compared in the resulting scintillation images. Finally, the resulting differences on the scintillation signal from a 0.2 × 0.2 cm2 region-of-interest (ROI) were reported. Main results. Clustering, OpenCV, bilinear, Malvar and Menon demosaicing algorithms respectively yielded differences of 3 ± 5%, 1 ± 3%, 1 ± 3%, 1 ± 2% and 2 ± 4% in the resulting scintillation images. For the Cherenkov images, all algorithms provided differences below 1%. All methods enabled measurements over the detectability (SBR > 2) and sensitivity (SNR > 5) thresholds with the bilinear algorithm providing the best SNR value. Clustering, OpenCV, bilinear, Malvar and Menon demosaicing algorithms respectively provided differences on the ROI analysis of 7 ± 5%, 3 ± 2%, 3 ± 2%, 4 ± 2%, 7 ± 3%. Significance. Radioluminescent signals can accurately be isolated using a single polychromatic camera. Moreover, demosaicing using a bilinear kernel provided the best results and enabled Cherenkov signal subtraction while preserving the full spatial resolution of the camera.
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Alexander DA, Nomezine A, Jarvis LA, Gladstone DJ, Pogue BW, Bruza P. Color Cherenkov imaging of clinical radiation therapy. LIGHT, SCIENCE & APPLICATIONS 2021; 10:226. [PMID: 34737264 PMCID: PMC8569159 DOI: 10.1038/s41377-021-00660-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 10/01/2021] [Accepted: 10/08/2021] [Indexed: 05/08/2023]
Abstract
Color vision is used throughout medicine to interpret the health and status of tissue. Ionizing radiation used in radiation therapy produces broadband white light inside tissue through the Cherenkov effect, and this light is attenuated by tissue features as it leaves the body. In this study, a novel time-gated three-channel camera was developed for the first time and was used to image color Cherenkov emission coming from patients during treatment. The spectral content was interpreted by comparison with imaging calibrated tissue phantoms. Color shades of Cherenkov emission in radiotherapy can be used to interpret tissue blood volume, oxygen saturation and major vessels within the body.
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Affiliation(s)
- Daniel A Alexander
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
- DoseOptics LLC, Lebanon, NH, USA
| | - Anthony Nomezine
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
| | - Lesley A Jarvis
- Geisel School of Medicine, Dartmouth College, Hanover, NH, USA
- Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA
| | - David J Gladstone
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
- Geisel School of Medicine, Dartmouth College, Hanover, NH, USA
- Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA
| | - Brian W Pogue
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA
- DoseOptics LLC, Lebanon, NH, USA
- Geisel School of Medicine, Dartmouth College, Hanover, NH, USA
- Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA
| | - Petr Bruza
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA.
- DoseOptics LLC, Lebanon, NH, USA.
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LaRochelle EPM, Pogue BW. Theoretical lateral and axial sensitivity limits and choices of molecular reporters for Cherenkov-excited luminescence in tissue during x-ray beam scanning. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:JBO-200235R. [PMID: 33185051 PMCID: PMC7658603 DOI: 10.1117/1.jbo.25.11.116004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 10/21/2020] [Indexed: 05/03/2023]
Abstract
PURPOSE Unlike fluorescence imaging utilizing an external excitation source, Cherenkov emissions and Cherenkov-excited luminescence occur within a medium when irradiated with high-energy x-rays. Methods to improve the understanding of the lateral spread and axial depth distribution of these emissions are needed as an initial step to improve the overall system resolution. METHODS Monte Carlo simulations were developed to investigate the lateral spread of thin sheets of high-energy sources and compared to experimental measurements of similar sources in water. Additional simulations of a multilayer skin model were used to investigate the limits of detection using both 6- and 18-MV x-ray sources with fluorescence excitation for inclusion depths up to 1 cm. RESULTS Simulations comparing the lateral spread of high-energy sources show approximately 100 × higher optical yield from electrons than photons, although electrons showed a larger penumbra in both the simulations and experimental measurements. Cherenkov excitation has a roughly inverse wavelength squared dependence in intensity but is largely redshifted in excitation through any distance of tissue. The calculated emission spectra in tissue were convolved with a database of luminescent compounds to produce a computational ranking of potential Cherenkov-excited luminescence molecular contrast agents. CONCLUSIONS Models of thin x-ray and electron sources were compared with experimental measurements, showing similar trends in energy and source type. Surface detection of Cherenkov-excited luminescence appears to be limited by the mean free path of the luminescence emission, where for the given simulation only 2% of the inclusion emissions reached the surface from a depth of 7 mm in a multilayer tissue model.
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Affiliation(s)
| | - Brian W. Pogue
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, United States
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Rahman M, Brůža P, Langen KM, Gladstone DJ, Cao X, Pogue BW, Zhang R. Characterization of a new scintillation imaging system for proton pencil beam dose rate measurements. ACTA ACUST UNITED AC 2020; 65:165014. [DOI: 10.1088/1361-6560/ab9452] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Tendler II, Bruza P, Jermyn M, Soter J, Sharp G, Williams B, Jarvis LA, Pogue B, Gladstone DJ. Technical Note: A novel dosimeter improves total skin electron therapy surface dosimetry workflow. J Appl Clin Med Phys 2020; 21:158-162. [PMID: 32306551 PMCID: PMC7324701 DOI: 10.1002/acm2.12880] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 03/11/2020] [Accepted: 03/13/2020] [Indexed: 01/15/2023] Open
Abstract
PURPOSE The novel scintillator-based system described in this study is capable of accurately and remotely measuring surface dose during Total Skin Electron Therapy (TSET); this dosimeter does not require post-exposure processing or annealing and has been shown to be re-usable, resistant to radiation damage, have minimal impact on surface dose, and reduce chances of operator error compared to existing technologies e.g. optically stimulated luminescence detector (OSLD). The purpose of this study was to quantitatively analyze the workflow required to measure surface dose using this new scintillator dosimeter and compare it to that of standard OSLDs. METHODS Disc-shaped scintillators were attached to a flat-faced phantom and a patient undergoing TSET. Light emission from these plastic discs was captured using a time-gated, intensified, camera during irradiation and converted to dose using an external calibration factor. Time required to complete each step (daily QA, dosimeter preparation, attachment, removal, registration, and readout) of the scintillator and OSLD surface dosimetry workflows was tracked. RESULTS In phantoms, scintillators and OSLDs surface doses agreed within 3% for all data points. During patient imaging it was found that surface dose measured by OSLD and scintillator agreed within 5% and 3% for 35/35 and 32/35 dosimetry sites, respectively. The end-to-end time required to measure surface dose during phantom experiments for a single dosimeter was 78 and 202 sec for scintillator and OSL dosimeters, respectively. During patient treatment, surface dose was assessed at 7 different body locations by scintillator and OSL dosimeters in 386 and 754 sec, respectively. CONCLUSION Scintillators have been shown to report dose nearly twice as fast as OSLDs with substantially less manual work and reduced chances of human error. Scintillator dose measurements are automatically saved to an electronic patient file and images contain a permanent record of the dose delivered during treatment.
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Affiliation(s)
| | - Petr Bruza
- Thayer School of EngineeringDartmouth CollegeHanoverNHUSA
| | - Michael Jermyn
- Thayer School of EngineeringDartmouth CollegeHanoverNHUSA
- DoseOptics LLCLebanonNHUSA
| | - Jennifer Soter
- Thayer School of EngineeringDartmouth CollegeHanoverNHUSA
| | - Gregory Sharp
- Department of Radiation OncologyMassachusetts General HospitalBostonMAUSA
| | - Benjamin Williams
- Department of MedicineGeisel School of MedicineDartmouth CollegeHanoverNHUSA
- Norris Cotton Cancer CenterDartmouth‐Hitchcock Medical CenterLebanonNHUSA
| | - Lesley A. Jarvis
- Department of MedicineGeisel School of MedicineDartmouth CollegeHanoverNHUSA
- Norris Cotton Cancer CenterDartmouth‐Hitchcock Medical CenterLebanonNHUSA
| | - Brian Pogue
- Thayer School of EngineeringDartmouth CollegeHanoverNHUSA
- DoseOptics LLCLebanonNHUSA
| | - David J. Gladstone
- Thayer School of EngineeringDartmouth CollegeHanoverNHUSA
- Department of MedicineGeisel School of MedicineDartmouth CollegeHanoverNHUSA
- Norris Cotton Cancer CenterDartmouth‐Hitchcock Medical CenterLebanonNHUSA
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Andreozzi JM, Brůža P, Cammin J, Pogue BW, Gladstone DJ, Green O. Optical imaging method to quantify spatial dose variation due to the electron return effect in an MR-linac. Med Phys 2020; 47:1258-1267. [PMID: 31821573 PMCID: PMC7112467 DOI: 10.1002/mp.13954] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 11/21/2019] [Accepted: 11/26/2019] [Indexed: 11/12/2022] Open
Abstract
PURPOSE Treatment planning systems (TPSs) for MR-linacs must employ Monte Carlo-based simulations of dose deposition to model the effects of the primary magnetic field on dose. However, the accuracy of these simulations, especially for areas of tissue-air interfaces where the electron return effect (ERE) is expected, is difficult to validate due to physical constraints and magnetic field compatibility of available detectors. This study employs a novel dosimetric method based on remotely captured, real-time optical Cherenkov and scintillation imaging to visualize and quantify the ERE. METHODS An intensified CMOS camera was used to image two phantoms with designed ERE cavities. Phantom A was a 40 cm × 10 cm × 10 cm clear acrylic block drilled with five holes of increasing diameters (0.5, 1, 2, 3, 4 cm). Phantom B was a clear acrylic block (25 cm × 20 cm × 5 cm) with three cavities of increasing diameter (3, 2, 1 cm) split into two halves in the transverse plane to accommodate radiochromic film. Both phantoms were imaged while being irradiated by 6 MV flattening filter free (FFF) beams within a MRIdian Viewray (Viewray, Cleveland, OH) MR-linac (0.34 T primary field). Phantom A was imaged while being irradiated by 6 MV FFF beams on a conventional linac (TrueBeam, Varian Medical Systems, San Jose, CA) to serve as a control. Images were post processed in Matlab (Mathworks Inc., Natick, MA) and compared to TPS dose volumes. RESULTS Control imaging of Phantom A without the presence of a magnetic field supports the validity of the optical image data to a depth of 6 cm. In the presence of the magnetic field, the optical data shows deviations from the commissioned TPS dose in both intensity and localization. The largest air cavity examined (3 cm) indicated the largest dose differences, which were above 20% at some locations. Experiments with Phantom B illustrated similar agreement between optical and film dosimetry comparisons with TPS data in areas not affected by ERE. CONCLUSION There are some appreciable differences in dose intensity and spatial dose distribution observed between the novel experimental data set and the dose models produced by the current clinically implemented MR-IGRT TPS.
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Affiliation(s)
- Jacqueline M. Andreozzi
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755, USA
- Current: Department of Radiation Oncology, University of Florida, Gainesville, Florida 32608
| | - Petr Brůža
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755, USA
| | - Jochen Cammin
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | - Brian W. Pogue
- Thayer School of Engineering and Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755, USA
| | - David J. Gladstone
- Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03756, Geisel School of Medicine and Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755, USA
| | - Olga Green
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Tendler II, Hartford A, Jermyn M, LaRochelle E, Cao X, Borza V, Alexander D, Bruza P, Hoopes J, Moodie K, Marr BP, Williams BB, Pogue BW, Gladstone DJ, Jarvis LA. Experimentally Observed Cherenkov Light Generation in the Eye During Radiation Therapy. Int J Radiat Oncol Biol Phys 2019; 106:422-429. [PMID: 31669563 DOI: 10.1016/j.ijrobp.2019.10.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 10/10/2019] [Accepted: 10/18/2019] [Indexed: 12/29/2022]
Abstract
PURPOSE Patients have reported sensations of seeing light flashes during radiation therapy, even with their eyes closed. These observations have been attributed to either direct excitation of retinal pigments or generation of Cherenkov light inside the eye. Both in vivo human and ex vivo animal eye imaging was used to confirm light intensity and spectra to determine its origin and overall observability. METHODS AND MATERIALS A time-gated and intensified camera was used to capture light exiting the eye of a patient undergoing stereotactic radiosurgery in real time, thereby verifying the detectability of light through the pupil. These data were compared with follow-up mechanistic imaging of ex vivo animal eyes with thin radiation beams to evaluate emission spectra and signal intensity variation with anatomic depth. Angular dependency of light emission from the eye was also measured. RESULTS Patient imaging showed that light generation in the eye during radiation therapy can be captured with a signal-to-noise ratio of 68. Irradiation of ex vivo eye samples confirmed that the spectrum matched that of Cherenkov emission and that signal intensity was largely homogeneous throughout the entire eye, from the cornea to the retina, with a slight maximum near 10 mm depth. Observation of the signal external to the eye was possible through the pupil from 0° to 90°, with a detected emission near 2500 photons per millisecond (during peak emission of the ON cycle of the pulsed delivery), which is over 2 orders of magnitude higher than the visible detection threshold. CONCLUSIONS By quantifying the spectra and magnitude of the signal, we now have direct experimental observations that Cherenkov light is generated in the eye during radiation therapy and can contribute to perceived light flashes. Furthermore, this technique can be used to further study and measure phosphenes in the radiation therapy clinic.
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Affiliation(s)
- Irwin I Tendler
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
| | - Alan Hartford
- Department of Medicine, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire; Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire
| | - Michael Jermyn
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire; DoseOptics LLC, Lebanon, New Hampshire
| | - Ethan LaRochelle
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
| | - Xu Cao
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
| | - Victor Borza
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
| | - Daniel Alexander
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
| | - Petr Bruza
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
| | - Jack Hoopes
- Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire; Department of Surgery, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire
| | - Karen Moodie
- Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire
| | - Brian P Marr
- Department of Ophthalmic Oncology, Columbia University Medical Center, New York, New York
| | - Benjamin B Williams
- Department of Medicine, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire; Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire
| | - Brian W Pogue
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire; DoseOptics LLC, Lebanon, New Hampshire; Department of Surgery, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire
| | - David J Gladstone
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire; Department of Medicine, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire; Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire
| | - Lesley A Jarvis
- Department of Medicine, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire; Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire.
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