Structured alkali halides for medical applications

Schmitt, B.; Fuchs, M.; Hell, Erich; Knüpfer, W.; Hackenschmied, P.; Winnacker, A.

doi:10.1016/s0168-583x(02)00656-0

Cited by 40 publications

(24 citation statements)

References 7 publications

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“…If this reasoning holds true, it is expected that a thin dosimeter made of KCl: Eu 2+ , with a thickness of much less than the range of low-energy secondary electrons in the material, would provide significantly lower energy dependence than radiographic film and would have an overall dose response close to water. Modern thin film techniques, for example, tape casting 31 or vacuum evaporation, 32,33 are capable of producing dosimeters in such thin layers. Note that our experiments ͑data not shown͒ demonstrate that current KCl: Eu 2+ dosimeters are easily able to detect sub-cGy dose using, for example, a 5 mW He-Ne yellow laser.…”

Section: Discussionmentioning

confidence: 99%

Quantitative megavoltage radiation therapy dosimetry using the storage phosphor KCl:Eu2+

et al. 2009

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This work, for the first time, reports the use of europium doped potassium chloride ͑KCl: Eu 2+ ͒ storage phosphor for quantitative megavoltage radiation therapy dosimetry. In principle, KCl: Eu 2+ functions using the same photostimulatated luminescence ͑PSL͒ mechanism as commercially available BaFBr 0.85 I 0.15 :Eu 2+ material that is used for computed radiography ͑CR͒ but features a significantly smaller effective atomic number-18 versus 49-making it a potentially useful material for nearly tissue-equivalent radiation dosimetry. Cylindrical KCl: Eu 2+ dosimeters, 7 mm in diameter and 1 mm thick, were fabricated in-house. Dosimetric properties, including radiation hardness, response linearity, signal fading, dose rate sensitivity, and energy dependence, were studied with a laboratory optical reader after irradiation by a linear accelerator. The overall experimental uncertainty was estimated to be within Ϯ2.5%. The findings were ͑1͒ KCl: Eu 2+ showed satisfactory radiation hardness. There was no significant change in the stimulation spectra after irradiation up to 200 Gy when compared to a fresh dosimeter, indicating that this material could be reused at least 100 times if 2 Gy per use was assumed, e.g., for patient-specific IMRT QA. ͑2͒ KCl: Eu 2+ exhibited supralinear response to dose after irradiation from 0 to 800 cGy. ͑3͒ After x ray irradiation, the PSL signal faded with time and eventually reached a fading rate of about 0.1% / h after 12 h. ͑4͒ The sensitivity of the dosimeter was independent of the dose rate ranging from 15 to 1000 cGy/ min. ͑5͒ The sensitivity showed no beam energy dependence for either open x ray or megavoltage electron fields. ͑6͒ Over-response to low-energy scattered photons was comparable to radiographic film, e.g., Kodak EDR2 film. By sandwiching dosimeters between low-energy photon filters ͑0.3 mm thick lead foils͒ during irradiation, the over-response was reduced. The authors have demonstrated that KCl: Eu 2+ dosimeters have many desirable dosimetric characteristics that make the material conducive to radiation therapy dosimetry. In the future, a large-area KCl: Eu 2+ -based CR plate with a thickness of the order of a few microns, created using modern thin film techniques, could provide a reusable, quantitative, high-resolution two-dimensional dosimeter with minimal energy dependence.

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Section: Discussionmentioning

confidence: 99%

Quantitative megavoltage radiation therapy dosimetry using the storage phosphor KCl:Eu2+

et al. 2009

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“…The two effusion-cell sources were placed on each side of a vacuum chamber and operated at different temperatures according to the desired composition ratio of Tl to CsI inside the scintillator. Conditions such as deposition rate, chamber vacuum pressure, heat treatment temperature, and Tl doping concentration affect the microstructures and scintillation properties of CsI:Tl films [11][12]. CsI:Tl scintillator was deposited onto the substrate in a vacuum chamber at 150°C and 10 -3 Torr at low deposition rate (< 3 µm/min) and Tl doping concentration (0.1 mol%) with substrate plate rotation.…”

Section: Deposition Of Csi:tl Filmsmentioning

confidence: 99%

A TiO₂-Coated Reflective Layer Enhances the Sensitivity of a CsI:Tl Scintillator for X-ray Imaging Sensors

Kim¹,

Kim²,

Kwon³

et al. 2014

Journal of the Optical Society of Korea

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Columnar-structured cesium iodide (CsI) scintillators doped with thallium (Tl) are frequently used as x-ray converters in medical and industrial imaging. In this study we investigated the imaging characteristics of CsI:Tl films with various reflective layers-aluminum (Al), chromium (Cr), and titanium dioxide (TiO 2 ) powder-coated on glass substrates. We used two effusion-cell sources in a thermal evaporator system to fabricate CsI:Tl films on substrates. The scintillators were observed via scanning electron microscopy (SEM), and scintillation characteristics were evaluated on the basis of the emission spectrum, light output, light response to x-ray dose, modulation transfer function (MTF), and x-ray images. Compared to control films without a reflective layer, CsI:Tl films with reflective layers showed better sensitivity and light collection efficiency, and the film with a TiO 2 reflective layer showed the best properties.

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“…1 These NIPs have the potential to replace the granular image plates in medical diagnostics. 2 Offering a high lateral resolution combined with a high sensitivity 3 and a dynamic range of several orders of magnitude, the CsBr:Eu NIPs are especially useful for mammography.…”

Section: Introductionmentioning

confidence: 99%

Creation of storage centers in CsBr:Eu2+ needle image plates by vacuum ultraviolet radiation

Weidner

Batentschuk

Osvet

et al. 2009

Journal of Applied Physics

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In this study, the photostimulated luminescence of the CsBr: Eu 2+ needle image plates ͑NIPS͒ after vacuum ultraviolet ͑VUV͒ irradiation and their photoluminescence under VUV and UV excitation were investigated. It was shown that the photostimulable storage centers arise almost exclusively due to irradiation of the CsBr:Eu NIPs in the spectral lines of creation of the 4p 5 5s anion excitons, and not in the region of interband transitions of CsBr. The explanation of the results is based mainly on the radiative and nonradiative decay of the self-localized e +Br 2 − excitons.

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Structured alkali halides for medical applications

Cited by 40 publications

References 7 publications

Quantitative megavoltage radiation therapy dosimetry using the storage phosphor KCl:Eu2+

Quantitative megavoltage radiation therapy dosimetry using the storage phosphor KCl:Eu2+

A TiO₂-Coated Reflective Layer Enhances the Sensitivity of a CsI:Tl Scintillator for X-ray Imaging Sensors

Creation of storage centers in CsBr:Eu2+ needle image plates by vacuum ultraviolet radiation

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Structured alkali halides for medical applications

Cited by 40 publications

References 7 publications

Quantitative megavoltage radiation therapy dosimetry using the storage phosphor KCl:Eu2+

Quantitative megavoltage radiation therapy dosimetry using the storage phosphor KCl:Eu2+

A TiO2-Coated Reflective Layer Enhances the Sensitivity of a CsI:Tl Scintillator for X-ray Imaging Sensors

Creation of storage centers in CsBr:Eu2+ needle image plates by vacuum ultraviolet radiation

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A TiO₂-Coated Reflective Layer Enhances the Sensitivity of a CsI:Tl Scintillator for X-ray Imaging Sensors