A study on radiation damage in doped BGO crystals

Zhu, R. Y.; Stone, Helen B.; Newman, H. B.; Zhou, Tianyu; Tan, Hao-Ran; He, C.F.

doi:10.1016/0168-9002(91)90493-a

Cited by 56 publications

(18 citation statements)

References 4 publications

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“…The sharp decline in scintillator sensitivity ͑ϳ17%͒ within the first few hundred cGy of radiation exhibited by the prototype would complicate clinical use of such a scintillator. Previous examinations of the effect of radiation on the performance of BGO have indicated widely varying resultsranging from negligible to significant effects [52][53][54][55][56][57][58][59][60][61][62] -possibly due to differences in the crystal quality and irradiation conditions. Some studies suggested the possibility that highenergy X rays knock out electrons from oxygen atoms, forming color centers that increase optical absorption in the BGO crystal.…”

Section: Summary and Discussionmentioning

confidence: 99%

High‐DQE EPIDs based on thick, segmented BGO and CsI:Tl scintillators: Performance evaluation at extremely low dose

et al. 2009

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Purpose: Electronic portal imaging devices ͑EPIDs͒ based on active matrix, flat-panel imagers ͑AMFPIs͒ have become the gold standard for portal imaging and are currently being investigated for megavoltage cone-beam computed tomography ͑CBCT͒ and cone-beam digital tomosynthesis ͑CBDT͒. However, the practical realization of such volumetric imaging techniques is constrained by the relatively low detective quantum efficiency ͑DQE͒ of AMFPI-based EPIDs at radiotherapy energies, ϳ1% at 6 MV. In order to significantly improve DQE, the authors are investigating thick, segmented scintillators, consisting of 2D matrices of scintillating crystals separated by septal walls. Methods: A newly constructed segmented BGO scintillator ͑11.3 mm thick͒ and three segmented CsI:Tl scintillators ͑11.4, 25.6, and 40.0 mm thick͒ were evaluated using a 6 MV photon beam. X-ray sensitivity, modulation transfer function, noise power spectrum, DQE, and phantom images were obtained using prototype EPIDs based on the four scintillators. Results: The BGO and CsI:Tl prototypes were found to exhibit improvement in DQE ranging from ϳ12 to 25 times that of a conventional AMFPI-based EPID at zero spatial frequency. All four prototype EPIDs provide significantly improved contrast resolution at extremely low doses, extending down to a single beam pulse. In particular, the BGO prototype provides contrast resolution comparable to that of the conventional EPID, but at 20 times less dose, with spatial resolution sufficient for identifying the boundaries of low-contrast objects. For this prototype, however, the BGO scintillator exhibited an undesirable radiation-induced variation in x-ray sensitivity. Conclusions: Prototype EPIDs based on thick, segmented BGO and CsI:Tl scintillators provide significantly improved portal imaging performance at extremely low dose ͑i.e., down to 1 beam pulse corresponding to ϳ0.022 cGy͒, creating the possibility of soft-tissue visualization using MV CBCT and CBDT at clinically practical dose.

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Section: Summary and Discussionmentioning

confidence: 99%

High‐DQE EPIDs based on thick, segmented BGO and CsI:Tl scintillators: Performance evaluation at extremely low dose

et al. 2009

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“…They are transparent, colorless, nonhygroscopic. The high γ-quantum detection efficiency, relatively short decay time and small afterglow provide a wide application of Bi 4 Ge 3 O 12 in high-energy physics and positron computer tomography [1,2]. The problem of the improvement of the resistance to radiation damage for scintillation crystals is very actual and connected with the production of high quality crystals.…”

Section: Introductionmentioning

confidence: 99%

“…They have not to contain impurities and structural defects that can be transformed into color centers or create spatial layers with changed properties under the influence of external factors, namely: irradiation, electric fields, temperature changes. The scientists try to solve this problem, as a rule, by technological means using chemical and physical purification of raw materials, the modification of available crystal growth methods and development of the new ones [3,4]. Investigation of the effect of impurities and radiation defects on the scintillation characteristics of Bi 4 Ge 3 O 12 crystals is another main line [4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Charge transport in bismuth orthogermanate crystals

Bochkova¹

2011

Semicond. Phys. Quantum Electron. Optoelectron.

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Abstract. Current-voltage relations in bismuth orthogermanate crystals with Ag, Pt, InGa electrodes have been measured in the modes of double and unipolar injection of charge carriers. It has been shown that Bi 4 Ge 3 O 12 is relaxation type semiconductor. The appearance of the regions with negative differential resistance or sublinear rise of the current in characteristics is connected with the injection of the minority charge carriers and recombination processes in the space charge layer.

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“…It is well known that the -ray induced damage in PWO crystals recovers under room temperature, leading to dose rate dependent radiation damage [7], [8]. The recovery of radiation damage was measured after these samples were irradiated at 30 rad/h in equilibrium.…”

Section: Gamma Ray Induced Radiation Damage In Pwo-ii Crystalsmentioning

confidence: 99%

“…The main consequence of -ray induced radiation damage in PWO crystals is radiation induced absorption which causes degradation of LT and LO. It may also affect crystal's light response uniformity (LRU) and cause an unrecoverable degradation of the energy resolution if the light attenuation length (LAL) is reduced significantly [6], [7]. The -ray induced absorption may also spontaneously recover, leading to dose rate dependent radiation damage [8], [9].…”

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confidence: 99%

A Study on Radiation Damage in PWO-II Crystals

Yang

Mao

Zhang

et al. 2013

IEEE Trans. Nucl. Sci.

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Abstract-We report in this paper an investigation on radiation hardness of 20 cm long PWO-II crystals produced at BTCP for the proposed PANDA experiment at FAIR. The optical and scintillation properties of PWO-II crystals, such as transmittance, light output and light response uniformity, were measured before and after -ray irradiations at different dose rates. PWO-II crystals are compared to PWO crystals used in the CMS experiment. Progresses are observed in the light output and the radiation hardness for PWO-II crystals. Its use for crystal calorimeters in future high energy physics experiments is discussed. To maintain crystal precision, a precision light monitoring system is mandatory to follow variations of crystal transparency in situ.

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A study on radiation damage in doped BGO crystals

Cited by 56 publications

References 4 publications

High‐DQE EPIDs based on thick, segmented BGO and CsI:Tl scintillators: Performance evaluation at extremely low dose

High‐DQE EPIDs based on thick, segmented BGO and CsI:Tl scintillators: Performance evaluation at extremely low dose

Charge transport in bismuth orthogermanate crystals

A Study on Radiation Damage in PWO-II Crystals

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