Ultraviolet ray irradiation duration for the pre-exposure of Gafchromic EBT2

Abstract The strength and density change of the ultraviolet (UV) ray of Gafchromic EBT2 were investigated. Previous studies suggested that UV-A rays can be substituted for the x-ray double-exposure technique to correct Gafchromic EBT2’s non-uniformity error. In this study, we aimed to determine the appropriate strength of UV-A rays for irradiating an active layer that would correct the non-uniformity error of Gafchromic EBT2. UV-A rays with a wavelength of 375 nm were used to irradiate Gafchromic EBT2 in various durations, and the resulting density change was investigated. To correct Gafchromic EBT2’s non-uniformity error, a pre-irradiation with a UV-A lamp was conducted at a distance of 72 cm for 30 min. To determine the most appropriate irradiation duration, a UV light-emitting diode generating UV-A of 375 nm was used to irradiate the Gafchromic EBT2 film with varying durations of 1, 2, 3, 4, 5, 10, 15, 20, 25, and 30 min at a distance of 5.3 cm. A 12.7 diameter region of interest was set by the irradiation area, and a histogram of pixel values was created. The condition options were decided based on two important requirements: 1) no zero values of the mode and seconds exist, and 2) the 1/10 value of the mode intersects both histogram sleeves. In the case of Gafchromic EBT2, the irradiation strength was 85.43 mJ/cm2 for one minute in which the pixel value of mean ± SD was 255.34 ± 213.29. The irradiation duration of 4 min was the border duration of the above two conditions. When a UV ray of 375 nm wavelength is used to irradiate Gafchromic EBT2 as a substitute for x-ray exposure, the 4-min pre-irradiation duration (341.74 mJ/cm2) is demonstrably sufficient.

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Determining optimum wavelength of ultraviolet rays to pre-exposure of non-uniformity error correction in Gafchromic EBT2 films

Polish Journal of Medical Physics and Engineering ◽

10.2478/pjmpe-2018-0002 ◽

2018 ◽

Vol 24 (1) ◽

pp. 11-14

Author(s):

Toshizo Katsuda ◽

Rumi Gotanda ◽

Tatsuhiro Gotanda ◽

Takuya Akagawa ◽

Nobuyoshi Tanki ◽

...

Keyword(s):

Light Emitting Diode ◽

Region Of Interest ◽

Ultraviolet Rays ◽

X Rays ◽

Double Exposure ◽

Light Emitting ◽

Gafchromic Films ◽

Color Density ◽

Gafchromic Ebt2 Film ◽

Exposure Technique

Abstract Gafchromic films have been used to measure X-ray doses in diagnostic radiology such as computed tomography. The double-exposure technique is used to correct non-uniformity error of Gafchromic EBT2 films. Because of the heel effect of diagnostic x-rays, ultraviolet A (UV-A) is intended to be used as a substitute for x-rays. When using a UV-A light-emitting diode (LED), it is necessary to determine the effective optimal UV wavelength for the active layer of Gafchromic EBT2 films. This study evaluated the relation between the increase in color density of Gafchromic EBT2 films and the UV wavelengths. First, to correct non-uniformity, a Gafchromic EBT2 film was pre-irradiated using uniform UV-A radiation for 60 min from a 72-cm distance. Second, the film was irradiated using a UV-LED with a wavelength of 353-410 nm for 60 min from a 5.3-cm distance. The maximum, minimum, and mean ± standard deviation (SD) of pixel values of the subtraction images were evaluated using 0.5 inches of a circular region of interest (ROI). The highest mean ± SD (8915.25 ± 608.86) of the pixel value was obtained at a wavelength of 375 nm. The results indicated that 375 nm is the most effective and sensitive wavelength of UV-A for Gafchromic EBT2 films and that UV-A can be used as a substitute for x-rays in the double-exposure technique.

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A GaN UV Light Emitting Diode

IEEE/LEOS 1995 Digest of the LEOS Summer Topical Meetings. Flat Panel Display Technology ◽

10.1109/leosst.1995.763984 ◽

2005 ◽

Author(s):

A.I. Akinwande ◽

B.L. Goldenberg ◽

R.D. Horning ◽

J. King

Keyword(s):

Uv Light ◽

Light Emitting Diode ◽

Light Emitting

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Suppression of “volcano” morphology and parasitic defect luminescence in AlGaN-based deep-UV light-emitting diode epitaxy

Results in Physics ◽

10.1016/j.rinp.2019.102285 ◽

2019 ◽

Vol 13 ◽

pp. 102285 ◽

Cited By ~ 1

Author(s):

Chia-Yen Huang ◽

Tsung-Yen Liu ◽

Shih-Ming Huang ◽

Kai-Hsiang Chang ◽

Tsu-Ying Tai ◽

...

Keyword(s):

Uv Light ◽

Light Emitting Diode ◽

Light Emitting ◽

Deep Uv ◽

Defect Luminescence

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Chromaticity Study of Curcumin Dye Extracted from Curcuma longa L. Using for UV Light down Conversion for White Light Emitting Diode

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.290.183 ◽

2019 ◽

Vol 290 ◽

pp. 183-189

Author(s):

Mahmood Al Shafouri ◽

Naser Mahmoud Ahmed ◽

Zainuriah Hassan ◽

Munirah Abdullah Almessiere

Keyword(s):

White Light ◽

Uv Light ◽

Light Emitting Diode ◽

Curcuma Longa ◽

Color Temperature ◽

Light Emitting ◽

Chromaticity Coordinates ◽

Major Factors ◽

Color Rendering ◽

Down Conversion

In thus study, Turmeric phosphor dye was extracted from Curcuma Longa L. via a simple technique using silica gel. The phosphor was used for light down-conversion of UV light for the manufacture white light emitting diode (WLED). The UV-LED was analyzed over 395nm wavelengths. The characteristics of the white light chromaticity were controlled by tuning the current and phosphor concentration. An optimum color rendering index (CRI) value of 63.4 was obtained. The chromaticity coordinates (CIE) and correlated color temperature (CCT) were measured for various currents and phosphor concentrations. The white phosphor exhibited CIE value of 0.355,0.338 and CCT of 4567 K. The concentration of phosphor and amount of applied current were confirmed to be major factors that control the intensity of white light emitted from the sample, where CIE and CRI of the emitted light steadily increased with the concentration of phosphor and current. Thus, phosphor concentration has a critical effect on conversion efficiency. Key words: Turmeric, phosphor, WLED, curcumin

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High Sensitivity of NO Gas Sensors Based on Novel Ag-Doped ZnO Nanoflowers Enhanced with a UV Light-Emitting Diode

ACS Omega ◽

10.1021/acsomega.8b01882 ◽

2018 ◽

Vol 3 (10) ◽

pp. 13798-13807 ◽

Cited By ~ 17

Author(s):

You-Ting Tsai ◽

Shoou-Jinn Chang ◽

Liang-Wen Ji ◽

Yu-Jen Hsiao ◽

I-Tseng Tang ◽

...

Keyword(s):

Gas Sensors ◽

Uv Light ◽

Light Emitting Diode ◽

High Sensitivity ◽

Light Emitting ◽

Doped Zno

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Visible-Light-Driven Photocatalytic Activity of Magnetic BiOBr/SrFe12O19 Nanosheets

Nanomaterials ◽

10.3390/nano9050735 ◽

2019 ◽

Vol 9 (5) ◽

pp. 735 ◽

Cited By ~ 3

Author(s):

Taiping Xie ◽

Jiao Hu ◽

Jun Yang ◽

Chenglun Liu ◽

Longjun Xu ◽

...

Keyword(s):

Magnetic Properties ◽

Electron Microscope ◽

Visible Light ◽

Uv Light ◽

Light Emitting Diode ◽

Active Species ◽

Composite Catalyst ◽

Light Emitting ◽

Transmission Electron ◽

Visible Light Driven

Magnetic BiOBr/SrFe12O19 nanosheets were successfully synthesized using the hydrothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and UV-visible diffused reflectance spectra (UV-DRS), and the magnetic properties were tested using a vibration sample magnetometer (VSM). The as-produced composite with an irregular flaky-shaped aggregate possesses a good anti-demagnetization ability (Hc = 861.04 G) and a high photocatalytic efficiency. Under visible light (λ > 420 nm) and UV light-emitting diode (LED) irradiation, the photodegradation rates of Rhodamine B (RhB) using BiOBr/SrFe12O19 (5 wt %) (BOB/SFO-5) after 30 min of reaction were 97% and 98%, respectively, which were higher than that using BiOBr (87%). The degradation rate of RhB using the recovered BiOBr/5 wt % SrFe12O19 (marked as BOB/SFO-5) was still more than 85% in the fifth cycle, indicating the high stability of the composite catalyst. Meanwhile, after five cycles, the magnetic properties were still as stable as before. The radical-capture experiments proved that superoxide radicals and holes were main active species in the photocatalytic degradation of RhB.

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Effects of Impurity Doping on the Luminescence Performance of Mn4+-Doped Aluminates with the Magnetoplumbite-Type Structure for Plant Cultivation

Materials ◽

10.3390/ma12010086 ◽

2018 ◽

Vol 12 (1) ◽

pp. 86 ◽

Cited By ~ 5

Author(s):

Xiaoshuang Li ◽

Zikun Chen ◽

Bo Wang ◽

Ruizhao Liang ◽

Yongting Li ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Light Emitting Diode ◽

Octahedral Complex ◽

X Ray Diffraction ◽

Paramagnetic Resonance ◽

Light Emitting ◽

X Ray ◽

Color Changes ◽

Plant Cultivation ◽

Impurity Doping

Mn4+ activated LaMgAl11O19 (LMA/Mn4+) with red emitting phosphor was obtained by sintering under air conditioning. The X-ray diffraction pattern Rietveld refinement results reveal that three six-fold coordinated Al sites are substituted by Mn4+ ions. Furthermore, the chemical valence state of manganese in the LMA host was further confirmed through X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). Photoluminescence emission (PL) and excitation (PLE) spectra of LMA/Mn4+ as well as the lifetime were measured, and the 663 nm emission is ascribed to the 2Eg→4A2g from the 3d3 electrons in the [MnO6]8− octahedral complex. The emission spectrum matches well with the absorption of phytochrome. Temperature-dependent PL spectra show that the color changes of the phosphor at 420 K are 0.0110 for Δx and −0.0109 for Δy. Moreover, doping Zn2+ and Mg2+ ions in the host enhances the emission intensity of Mn4+ ions. These results highlight the potential of LMA/Mn4+ phosphor for a light-emitting diode (LED) plant lamp.

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