Measurement of Two-Dimensional Photon Beam Distributions Using a Fiber-Optic Radiation Sensor for Small Field Radiation Therapy

Lee, Bongsoo; Jang, Kyoung Won; Cho, Dong Hyun; Yoo, Wook Jae; Shin, Sang Hun; Kim, Hyung Sik; Yi, Jeong-Han; Kim, Sin; Cho, Hyosung; Park, Byung Gi; Moon, Jooho; Kim, Siyong

doi:10.1109/tns.2008.2002579

Cited by 22 publications

(9 citation statements)

References 17 publications

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“…exhibit a nearly sharp falloff at the field edges, as expected for all detectors. Indeed, because of scattered radiation and convolution effect between field and detector geometries, a perfect falloff cannot be achieved. Both effects are usually gathered in the penumbra region.…”

Section: Resultsmentioning

confidence: 99%

High spatial resolution inorganic scintillator detector for high‐energy X‐ray beam at small field irradiation

et al. 2020

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Purpose Small field dosimetry for radiotherapy is one of the major challenges due to the size of most dosimeters, for example, sufficient spatial resolution, accurate dose distribution and energy dependency of the detector. In this context, the purpose of this research is to develop a small size scintillating detector targeting small field dosimetry and compare its performance with other commercial detectors. Method An inorganic scintillator detector (ISD) of about 200 µm outer diameter was developed and tested through different small field dosimetric characterizations under high‐energy photons (6 and 15 MV) delivered by an Elekta Linear Accelerator (LINAC). Percentage depth dose (PDD) and beam profile measurements were compared using dosimeters from PTW namely, microdiamond and PinPoint three‐dimensional (PP3D) detector. A background fiber method has been considered to quantitate and eliminate the minimal Cerenkov effect from the total optical signal magnitude. Measurements were performed inside a water phantom under IAEA Technical Reports Series recommendations (IAEA TRS 381 and TRS 483). Results Small fields ranging from 3 × 3 cm2, down to 0.5 × 0.5 cm2 were sequentially measured using the ISD and commercial dosimeters, and a good agreement was obtained among all measurements. The result also shows that, scintillating detector has good repeatability and reproducibility of the output signal with maximum deviation of 0.26% and 0.5% respectively. The Full Width Half Maximum (FWHM) was measured 0.55 cm for the smallest available square size field of 0.5 × 0.5 cm2, where the discrepancy of 0.05 cm is due to the scattering effects inside the water and convolution effect between field and detector geometries. Percentage depth dose factor dependence variation with water depth exhibits nearly the same behavior for all tested detectors. The ISD allows to perform dose measurements at a very high accuracy from low (50 cGy/min) to high dose rates (800 cGy/min) and was found to be independent of dose rate variation. The detection system also showed an excellent linearity with dose; hence, calibration was easily achieved. Conclusions The developed detector can be used to accurately measure the delivered dose at small fields during the treatment of small volume tumors. The author's measurement shows that despite using a nonwater‐equivalent detector, the detector can be a powerful candidate for beam characterization and quality assurance in, for example, radiosurgery, Intensity‐Modulated Radiotherapy (IMRT), and brachytherapy. Our detector can provide real‐time dose measurement and good spatial resolution with immediate readout, simplicity, flexibility, and robustness.

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Section: Resultsmentioning

confidence: 99%

High spatial resolution inorganic scintillator detector for high‐energy X‐ray beam at small field irradiation

et al. 2020

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“…Reaching efficient optical coupling between scintillators and conventional step index optical fibers remains a real challenge owing to the strong mismatch between the almost omnidirectional dipolar emission of luminescent particles and the noticeably low numerical aperture and weak guiding properties of the fibers. The approach followed so far consists of compensating this low coupling efficiency by considering large scintillating volume coupled to large core multimode fibers [10][11][12][13][14][15][16]. These techniques lead to modest resolution on the mm to cm range and a compactness weakly compatible with endoscopy.…”

Section: Introductionmentioning

confidence: 99%

Ultracompact x-ray dosimeter based on scintillators coupled to a nano-optical antenna

Xie¹,

Maradj²,

Suárez³

et al. 2017

Opt. Lett.

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High energy radiations are nowadays cornerstone in scientific, medical and industrial imaging and cancer therapy. However, their detection and dosimetry are restricted to systems of modest compactness that are not compatible with endoscopy. Here, we report the first experimental imaging and dosimetry of X-rays with an ultracompact sensor integrated at the end of a single mode optical fiber (125 µm full diameter). We realize such a dosimeter by coupling luminescent scintillators to a nano-optical antenna engineered at the end of the fiber and by detecting in-fiber outcoupled luminescence with a photon counter. Direct profile and real-time dosimetry of a X-ray focused beam reveals a spatial resolution of a few microns together with a sensitivity better than 10 3 X-photons/s/µm 2 at energies of 8-10 keV. Because the nano-optical platform is auto-aligned with respect to the fiber, the resulting dosimeter is plug-and-play, flexible, and it is suitable for ultralow footprint endoscopic investigations at higher X-ray energies. Our nano-optical approach thus offers the possibility of X-ray profiling and dosimetry in ultra-confined environments, opening up new avenues in the fields of X-ray imaging, real-time control of cancer radiotherapies and Curie therapies, medical and industrial endoscopy, etc. With this study, nano-optical antennas make a first key contribution to the development of X-ray sensing protocols and architectures.

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“…24 Similarly, fiber-optic sensors assembled in 2D arrays have been demonstrated to measure radiation field sizes down to 1.5×5 cm with a resolution of 5 mm. 25 However, the overall dimensions of these detectors are typically larger than 1 mm, limiting their utility for microbeam measurements.…”

Section: B Fiber-optic Detectorsmentioning

confidence: 99%

Fiber‐optic detector for real time dosimetry of a micro‐planar x‐ray beam

et al. 2015

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Purpose:Here, the authors describe a dosimetry measurement technique for microbeam radiation therapy using a nanoparticle‐terminated fiber‐optic dosimeter (nano‐FOD).Methods:The nano‐FOD was placed in the center of a 2 cm diameter mouse phantom to measure the deep tissue dose and lateral beam profile of a planar x‐ray microbeam.Results:The continuous dose rate at the x‐ray microbeam peak measured with the nano‐FOD was 1.91 ± 0.06 cGy s−1, a value 2.7% higher than that determined via radiochromic film measurements (1.86 ± 0.15 cGy s−1). The nano‐FOD‐determined lateral beam full‐width half max value of 420 μm exceeded that measured using radiochromic film (320 μm). Due to the 8° angle of the collimated microbeam and resulting volumetric effects within the scintillator, the profile measurements reported here are estimated to achieve a resolution of ∼0.1 mm; however, for a beam angle of 0°, the theoretical resolution would approach the thickness of the scintillator (∼0.01 mm).Conclusions:This work provides proof‐of‐concept data and demonstrates that the novel nano‐FOD device can be used to perform real‐time dosimetry in microbeam radiation therapy to measure the continuous dose rate at the x‐ray microbeam peak as well as the lateral beam shape.

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Measurement of Two-Dimensional Photon Beam Distributions Using a Fiber-Optic Radiation Sensor for Small Field Radiation Therapy

Cited by 22 publications

References 17 publications

High spatial resolution inorganic scintillator detector for high‐energy X‐ray beam at small field irradiation

High spatial resolution inorganic scintillator detector for high‐energy X‐ray beam at small field irradiation

Ultracompact x-ray dosimeter based on scintillators coupled to a nano-optical antenna

Fiber‐optic detector for real time dosimetry of a micro‐planar x‐ray beam

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