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oe1(光电查) - 科学论文

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出版时间
  • 2015
研究主题
  • Calibration process of OSL detectors
  • Iodine-131
  • OSL-BeO
  • Dosimetry of staff and patients
  • Optically Stimulated Luminescence (OSL)
应用领域
机构单位
  • Akdeniz University
72 条数据
?? 中文（中国） ▾

  • Design, fabrication and characterization of a windowless extrapolation chamber for low-energy X-rays: Experimental and Monte Carlo results

    摘要： Extrapolation chamber is a special parallel-plate ionization chamber, particularly suggested for low penetrating radiations. Its sensitive volume is varied through a change of the inter-electrode distance, ideally satisfying the Bragg-Gray cavity theory. A windowless extrapolation chamber was designed and constructed for low-energy X-rays, produced at the tube voltage of 70-100 kV. It consists of the following elements and innovation. The electrodes of the chamber are made of a homogenous block of graphite instead of a coating graphite layer to reduce the leakage current. Also, the entrance window has been eliminated to decrease the beam perturbation. To the best of our knowledge, this type of chamber has not been used in low energy X-rays before. The performance of the chamber was investigated in terms of its saturation curve, polarity effect, leakage current, linearity of response and short-term stability. It was also simulated using Monte Carlo method and in the worst case, the relative ionization current obtained in experiment differs about 4.5% with that in the simulation result. Moreover, the influence of chamber components on its response was examined. All of the results showed the feasibility of its use for detection of 70 - 100 kV X-rays.

    关键词： simulation,Low-energy X-rays,Monte Carlo,Extrapolation chamber,dosimetry

    更新于2025-09-23 15:21:01

  • Note: Complementary approach for radiation dosimetry with Ag <sup>+</sup> -activated phosphate glass

    摘要： Silver ion-activated phosphate glass (Ag+-glass) has a good potential for application to radiation dosimetry in various radiation fields due to its multifunctional properties as a detector. The Ag+-glass provides three independent signals of radiophotoluminescence, optical absorption, and nuclear track. The combination of these signals allows the dynamic range of the measured dose (10 μGy–10 kGy) and linear energy transfer (<10 keV/μm and >1 MeV/μm) to be widened.

    关键词： optical absorption,radiophotoluminescence,Ag+-activated phosphate glass,radiation dosimetry,nuclear track

    更新于2025-09-23 15:21:01

  • Assessment of image quality and exposure parameters of an intraoral portable X rays device

    摘要： Objective: To evaluate the exposure parameters, radiation protection, absorbed dose and radiographic image quality of the DIOX? intraoral portable radiography device. Materials and methods: The exposure parameters were measured using the Xi UNFORS detector. Operator exposure to secondary radiation was measured using the 1800cc ionization chamber coupled to the electrometer. The absorbed dose (D) in the patient was calculated using TLD-100H positioned in the Alderson RANDO anthropomorphic simulator. The quality of the radiographic digital image was assessed by comparing radiographic images obtained from two convencional devices (CS 2200- Carestream Health?; Heliodent plus- Sirona Dental Systems GMbH?) with the radiological simulator of the upper molar region (RMI) (Radiation Measurements Instruments), using three acquisition sensors : Kodak RVG 5000? and Kodak PSP?, Eastman Kodak Company, Rochester, NY, USA; EVO Micro Image?, Brazil. Results: The DIOX intraoral portable radiographic device demonstrated reliability in relation to the performance of the standard evaluated parameters, except for the diameter of the radiation field (5.8mm) less or greater. No evidence of device head radiation was detected. The Pb lead protection of the apparatus attenuates the secondary radiation, thus protecting the operator. However, it was observed that the region of the operator’s gonads was the most exposed during the measurements. In the Alderson RANDO anthropomorphic simulator, the highest value of D was in the region corresponding to the submandibular and lingual glands of the left side (0.568mGy). The image quality of the DIOX portable radiographic apparatus presented quality standards equivalent to those produced by the two conventional radiographic devices. Conclusion: The DIOX? intraoral portable radiography device demonstrated reliability in relation to the quality control and radioprotection criteria, according to international standards. Results obtained demonstrated the safe use of the DIOX? intraoral portable radiography device and indicated the need for debate and change in international sanitary oversight standards regarding the use of portable XR devices in dentistry.

    关键词： Radiation Protection,Radiography, Dental, Digital,Thermoluminescent Dosimetry

    更新于2025-09-23 15:21:01

  • Three-dimensional radiation dosimetry based on optically-stimulated luminescence

    摘要： A new approach to three-dimensional (3D) dosimetry based on optically-stimulated luminescence (OSL) is presented. By embedding OSL-active particles into a transparent silicone matrix (PDMS), the well-established dosimetric properties of an OSL material are exploited in a 3D-OSL dosimeter. By investigating prototype dosimeters in standard cuvettes in combination with small test samples for OSL readers, it is shown that a sufficient transparency of the 3D-OSL material can be combined with an OSL response giving an estimated >10.000 detected photons in 1 second per 1mm3 voxel of the dosimeter at a dose of 1 Gy. The dose distribution in the 3D-OSL dosimeters can be directly read out optically without the need for subsequent reconstruction by computational inversion algorithms. The dosimeters carry the advantages known from personal-dosimetry use of OSL: the dose distribution following irradiation can be stored with minimal fading for extended periods of time, and dosimeters are reusable as they can be reset, e.g. by an intense (bleaching) light field.

    关键词： optically-stimulated luminescence,silicone matrix,OSL,three-dimensional dosimetry,radiation dosimetry

    更新于2025-09-23 15:19:57

  • Remote Measurements of X-rays Dose Rate using a Cerium-doped Air-clad Optical Fiber

    摘要： Cerium doped silica glasses are attractive materials for radiation dosimetry. In this work, Ce-doped air-clad optical fiber has been fabricated for real-time X-ray dose rate measurements through the radioluminescence (RL) signal. The structural properties of the obtained material were studied using Raman spectroscopy. The presence of Ce3+ ions inside the sol-gel-derived silica core was confirmed using photoluminescence (PL) measurements. This optical fiber, with a high numerical aperture, was tested as active and guiding material in an all-fibered remote X-ray dosimeter configuration. We demonstrated that the response dependence of RL versus dose rate is linear from 52 mGy(SiO2)/s up to at least 1.5 Gy(SiO2)/s, allowing to monitor the dose rate evolution during an irradiation run. The presented results confirm the potentialities of this microstructured optical fiber to monitor ionizing radiations in harsh environments. They also pave the way towards an alternative to the widely used approach that uses a scintillator material at the end of a transport optical fiber.

    关键词： radioluminescence,cerium,Dosimetry,X-ray radiation,optical fiber

    更新于2025-09-23 15:19:57

  • Recent Advances in Silica Glass Optical Fiber for Dosimetry Applications

    摘要： In this paper, we review the highly promising silica glass, fabricated as doped and undoped optical fiber for intended use in radiation dosimetry. The dosimetry techniques reviewed here, underpinned by intrinsic and extrinsic defects in silica glass, focus on Thermoluminescence (TL), Optically Stimulated Luminescence (OSL) and Radioluminescence (RL), with occasional references to the much more established Radiation Induced Attenuation (RIA). The other focus in this review is on the various materials that have been reported earlier as dopants and modifiers used in silica glass optical fiber radiation dosimeters. This article also elaborates on recently reported optical fiber structures, namely, cylindrical fibers, photonic crystal fibers and flat fibers, as well as dimensions and shapes used for optimization of dosimeter performance. The various types of optical fiber radiation dosimeters are subsequently reviewed for various applications ranging from medical dosimetry such as in external beam radiotherapy, brachytherapy and diagnostic imaging, as well as in industrial processing and space dosimetry covering a dynamic dose range from μGy to kGy. Investigated dosimetric characteristics include reproducibility, fading, dose response, reciprocity between luminescence yield to dose-rate and energy dependence. The review is completed by a brief discussion on limitations and future developments in optical fiber radiation dosimetry.

    关键词： radioluminescence,thermoluminescence,Silica optical fiber,review,dosimetry

    更新于2025-09-23 15:19:57

  • Dual-Color Plasmonic Nanosensor for Radiation Dosimetry

    摘要： Radiation dosimeters are critical for accurately assessing the levels of radiation exposure of tumor sites and surrounding tissues and for optimizing therapeutic interventions as well as for monitoring environmental exposure. To fill the need for a simple, user-friendly and inexpensive dosimeter, we designed an innovative colorimetric nanosensor-based assay for detecting ionizing radiation. We show that hydroxyl radicals generated by ionizing radiation can be used to etch gold nanorods (AuNRs) and silver nanoprisms (AgNPRs), yielding reproducible color changes for radiation dose detection in the range of 50-2000 Rad, broad enough to cover doses used in hyperfractionated, conventional, and hypofractionated radiotherapy. This range of doses detected by this assay correlates with radiation induced DNA damage response in mammalian cells. Furthermore, this AuNR- and AgNPR-based sensing platform has been established in a paper format that can be readily adopted for a wide range of applications and translation.

    关键词： Radiation dosimetry,gold nanorods,silver nanoprisms,dual-color nanosensor,colorimetric detection

    更新于2025-09-23 15:19:57

  • Investigating energy deposition in glandular tissues for mammography using multiscale Monte Carlo simulations

    摘要： Purpose: To investigate energy deposition in glandular tissues of the breast on macro- and microscopic length scales in the context of mammography. Methods: Multiscale mammography models of breasts are developed, which include segmented, voxelized macroscopic tissue structure as well as nine regions of interest (ROIs) embedded throughout the breast tissue containing explicitly-modelled cells. Using a 30 kVp Mo/Mo spectrum, Monte Carlo (MC) techniques are used to calculate dose to mm voxels containing glandular and/or adipose tissues, as well as energy deposition on cellular length scales. ROIs consist of at least 1000 mammary epithelial cells and 200 adipocytes; specific energy (energy imparted per unit mass; stochastic analogue of the absorbed dose) is calculated within mammary epithelial cell nuclei. Results: Macroscopic dose distributions within segmented breast tissue demonstrate considerable variation in energy deposition depending on depth and tissue structure. Doses to voxels containing glandular tissue vary between 0.1 and 4 times the mean glandular dose (MGD, averaged over the entire breast). Considering microscopic length scales, mean specific energies for mammary epithelial cell nuclei are 30% higher than the corresponding glandular voxel dose. Additionally, due to the stochastic nature of radiation, there is considerable variation in energy deposition throughout a cell population within a ROI: for a typical glandular voxel dose of 4 mGy, the standard deviation of the specific energy for mammary epithelial cell nuclei is 85% relative to the mean. Thus, for a glandular voxel dose of 4 mGy at the centre of the breast, corresponding mammary epithelial cell nuclei will receive specific energies up to 9 mGy (considering the upper end of the 1σ standard deviation of the specific energy), while a ROI located 2 cm closer to the radiation source will receive specific energies up to 40 mGy. Energy deposition within mammary epithelial cell nuclei is sensitive to cell model details including cellular elemental compositions and nucleus size, underlining the importance of realistic cellular models. Conclusions: There is considerable variation in energy deposition on both macro- and microscopic length scales for mammography, with glandular voxel doses and corresponding cell nuclei specific energies many times higher than the MGD in parts of the breast. These results should be considered for radiation-induced cancer risk evaluation in mammography which has traditionally focused on a single metric such as the MGD.

    关键词： microdosimetry,cellular dosimetry,breast dosimetry,Mammography,Monte Carlo

    更新于2025-09-19 17:15:36

  • Evaluating the performance characteristics of some ion chamber dosimeters in high dose per pulse intraoperative electron beam radiation therapy

    摘要： Employing routine dosimetry protocols for intraoperative electron beam needs further refinements to obtain reliable results. In this regard, the performance of some cylindrical and parallel plate ion chambers for both relative and absolute dosimetry of intraoperative electron beam has been evaluated. Materials and methods: Four different ion chambers including Semiflex and PinPoint cylindrical chambers as well as Advanced Markus and Roos parallel plate ones were employed for PDD measurement and dose rate determination in reference condition of the electron beam produced by LIAC intraoperative accelerator. The results of PDD measurements were compared with those of Gafchromic EBT2 film. Specific recommendations were followed to determine the chamber correction factors including ks and kQ,Q0 for absolute dosimetry in intraoperative reference condition. Results: There was good agreement between PDDs measured by employed chambers and EBT2 film at all nominal energies. Nevertheless, Advanced Markus chamber had the best performance based on the gamma analysis results. Obtained kQ,Q0 and ks for studied ion chambers largely differed from expected values by TRS-398 protocol. The difference of measured dose rates at 12 MeV energy by investigated chambers was less than 1.1% and Advanced Markus had the best accordance with pre-set dose rate by manufacture. Conclusion: Results showed that ignoring the specific recommended procedures in determining the chamber correction factors causes the overestimation of the measured dose. Therefore, dedicated dosimetry protocol should be developed for high dose per pulse intraoperative electron dosimetry including all of the updated correction factors and deviations from routine ionometric electron dosimetry formalisms.

    关键词： Intraoperative electron radiotherapy,Ion chamber dosimeter,Reference dosimetry,Ionometric dosimetry

    更新于2025-09-19 17:15:36

  • A linear relationship for the LET-dependence of Gafchromic EBT3 film in spot-scanning proton therapy

    摘要： Radiochromic film is a valuable dosimetric tool, primarily due to its sub-millimeter spatial resolution. For accurate proton dosimetry, the dependence of film response on linear energy transfer must be characterized and calibrated. In this work, we characterized film under-response, or 'quenching,' as a function of dose-weighted linear energy transfer (LETd) in several proton fields and established a simple, linear relationship with LETd. We performed measurements as a function of depth in a PMMA phantom irradiated by a spot-scanning proton beam. The fields had energies of 71.3 MeV, 71.3 MeV with filter, and 159.9 MeV. At each depth (measurements taken in depth step sizes of 0.5-1 mm in the Bragg peak), we measured dose with a PTW Markus ion chamber and EBT3 radiochromic film. EBT3 under-response was characterized by the ratio of dose measured with film to that with ion chamber. LETd values for our experimental setup were calculated using in-house clinical Monte Carlo code. Measured film under-response increased with LETd, from approximately 10% under-response for LETd = 5 keV/μm to approximately 20% for LETd = 8 keV/μm. The under-response for all measurements was plotted versus LETd. A linear fit to the data was performed, yielding a function for under-response, U = [(-0.0251 ± 0.0010) μm/keV] × LETd + (1.02 ± 0.01). Finally, the linear relationship was applied to a film measurement within a spread-out Bragg peak (SOBP). Without correcting for LETd-dependence in the SOBP measurement, the discrepancy between film and Monte Carlo profiles was greater than 15% at the distal edge. With correction, the corrected film profile was within 2% and 1 mm of the Monte Carlo profile.

    关键词： dosimetry,film,LET,proton therapy

    更新于2025-09-19 17:15:36