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- 2015
- Calibration process of OSL detectors
- Iodine-131
- OSL-BeO
- Dosimetry of staff and patients
- Optically Stimulated Luminescence (OSL)
- Akdeniz University
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Characteristics of CCD Based Optical CT Scanner for Therapeutic Radiation Dosimetry
摘要： A CCD camera and an LED light source were combined to fabricate a compact optical CT scanner for the therapeutic radiation dose evaluation of a polymer gel dosimeter. After the collimated beam emitted by the LED passed through aquarium, gel phantom, and telecentric lens, an image was collected by the CCD camera and reconstructed using MATLAB. By using a stepping motor and LabVIEW, the gel dosimeter was rotated at every 0.72o, and the time for collecting 500 slice images per a revolution was within 20 min. At a spatial frequency of 4.5 lp/mm of the optical CT scanner, the modulation transfer function value was 72%. The linear correlation coefficient of the optical CT scanner for the polymer gel dosimeter was 0.987.
关键词： Optical Computed Tomography Scanner,Polymer Gel,Dosimetry
更新于2025-09-10 09:29:36
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Percentage depth dose fragmentation for investigating and assessing the photon beam dosimetry quality
摘要： Aim: The purpose of this study is to introduce a new approach to assess the dosimetry quality of photon beam with energy and irradiation field size. This approach is based on percentage depth dose (PDD) fragmentation for investigating the dosimetry quality. Materials and methods: For the investigation of the dosimetry quality of 6 and 18 MV photon beams, we have proceeded to fragment the PDD at different field sizes. This approach checks the overall PDD and is not restricted to the exponential decay regions, as per the International Atomic Energy Agency Technical Reports Series No 398 and the American Association of Physicist in Medicine Task Group 51 recommendations. Results and discussion: The 6 MV photon beam deposited more energy in the target volume than the 18 MV photon beam. The dose delivered by the 6 MV beam is greater by a factor of 1·5 than that delivered by the 18 MV beam in the build-up region and the dose delivered by the 6 MV beam is greater by a factor of 2·6 than that delivered by the 18 MV beam in the electronic equilibrium and the exponential decay regions. Conclusion: The dose measured at different points of the beam is higher for 6 MV than for 18 MV photon beam. Therefore, the 6 MV beam is more dosimetrically efficient than the 18 MV beam. Using the proposed approach, we can assess the dosimetry quality by taking into account overall PDD not only in the exponential decay region but also in the field.
关键词： radiotherapy efficiency,fragmentation,photon beam energy,quality index,dosimetry quality
更新于2025-09-10 09:29:36
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Quantitative comparison of pre-therapy 99mTc-macroaggregated albumin SPECT/CT and post-therapy PET/MR studies of patients who have received intra-arterial radioembolization therapy with 90Y microspheres
摘要： Objective: The aim of our study was to compare yttrium -90 (90Y) dosimetry obtained from pre-therapy 99mTc-macroaggregated albumin (MAA) SPECT/CT versus post-therapy PET/MRI imaging among patients with primary or metastatic hepatic tumors. Materials and methods: Prior to 90Y radioembolization (RE), 32 patients underwent a scan using MAA mimicking 90Y distribution. After RE with 90Y microspheres, the patients were imaged on a PET/MRI system. Reconstructed images were transferred to a common platform and used to calculate 90Y dosimetry. The Passing-Bablok regression scatter diagram and the Bland and Altman method were used to analyze the difference between dosimetry values. Results: For MAA and PET/MRI modalities, the mean liver doses for all 32 subjects were 43.0 ± 20.9 Gy and 46.5 ± 22.7 Gy, respectively, with a mean difference of 3.4 ± 6.2 Gy. The repeatibility coefficient was 12.1 (27.0% of the mean). The Spearman rank correlation coefficient was high (ρ = 0.92). Although, there was a substantial difference in the maximum doses to the liver between the modalities, the mean liver doses were relatively close, with a difference of 24.0% or less. Conclusions: The two main contributors to the difference between dosimetry calculations using MAA versus 90Y PET/MRI can be attributed to the changes in catheter positioning as well as the liver ROIs used for the calculations. In spite of these differences, our results demonstrate that the dosimetry values obtained from pre-therapy MAA SPECT/CT scans and PET/MRI post-therapy 90Y studies were not significantly different.
关键词： MAA,90Y PET/MRI,Dosimetry
更新于2025-09-10 09:29:36
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Assessment of image quality and radiation dose in some models of digital radiography systems?–?A Pehamed FLUORAD A?+?D phantom study
摘要： Digital radiography (DR) systems have been recently introduced as a developed technology that is replacing conventional film–screen systems in many countries around the world. Ideal situation in radiography is to maximize the image quality while minimizing the patient dose. The purpose of this study was to compare image quality and radiation dose in different digital radiography systems. Four different digital systems are compared in terms of their image quality performance and dose area product (DAP). Images of Pehamed FLUORAD A + D phantom were obtained for each DR system. Image quality parameters (contrast resolution (CR), spatial resolution (SR), and contrast-to-noise ratio (CNR)) and DAP were significantly different between different digital systems. It was shown that all four quantities increased with increasing exposure parameters in all systems. Image quality parameters of the SEDECAL system were higher than that in other systems (p ≤ 0.05). At the stable DAP (100 mGy.cm2), means of CR, CNR, and SR in the SEDECAL system were 6.38 ± 0.797, 29.70 ± 0.85 and 3.10 ± 0.38 lp/mm, respectively. The results of this investigation can be taken into consideration in the selection and purchasing of new systems in order to preserve patients as well as radiographers from unnecessary radiation dose.
关键词： image quality,digital radiology,phantom,dosimetry
更新于2025-09-10 09:29:36
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Re-evaluation of the correction factors for the GROVEX
摘要： The GROVEX (GROssVolumige EXtrapolationskammer, large-volume extrapolation chamber) is the primary standard for the dosimetry of low-dose-rate interstitial brachytherapy at the Physikalisch-Technische Bundesanstalt (PTB). In the course of setup modifications and re-measuring of several dimensions, the correction factors have been re-evaluated in this work. The correction factors for scatter and attenuation have been recalculated using the Monte Carlo software package EGSnrc, and a new expression has been found for the divergence correction. The obtained results decrease the measured reference air kerma rate by approximately 0.9% for the representative example of a seed of type Bebig I25.S16C. This lies within the expanded uncertainty (k = 2).
关键词： dosimetry,ionisation chamber,extrapolation chamber,low-dose rate brachytherapy,primary standard
更新于2025-09-09 09:28:46
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Dynamic 3D measurement of modulated radiotherapy: a scintillator-based approach
摘要： With the rise of high-conformity dynamic radiotherapy, such as volumetric modulated arc therapy and robotic radiosurgery, the temporal dimension of dose measurement is becoming increasingly important. It must be possible to tell both ‘where’ and ‘when’ a discrepancy occurs between the plan and its delivery. A 3D scintillation-based dosimetry system could be ideal for such a thorough, end-to-end verification; however, the challenge lies in retrieving the volumetric information of the light-emitting volume. This paper discusses the motivation, from an optics point of view, of using the images acquired with a plenoptic camera, or light field imager, of an irradiated plastic scintillator volume to reconstruct the delivered 3D dose distribution. Current work focuses on the optimization of the optical design as well as the data processing that is involved in the ongoing development of a clinically viable, second generation dosimetry system.
关键词： dynamic radiotherapy,volumetric modulated arc therapy,plenoptic camera,robotic radiosurgery,3D scintillation-based dosimetry
更新于2025-09-09 09:28:46
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Enhanced method for determining the low-LET saturation dose of PRESAGE?
摘要： An accurate value for the saturation dose of PRESAGE? is important in elucidating the mechanism of the so-called quenching phenomenon in the 3-D dosimetry of proton beams. This quantity is difficult to obtain, because it involves measuring the optical density of a set of very highly attenuating samples. We present a novel method that makes use of the ability to irradiate microscopically-thin “slices” of a cuvette using microplanar beams from a synchrotron. Using the new method, we were able to measure optical densities of up to 50 cm-1 using a standard spectrophotometer, and we derived a value 14000 Gy for the saturation parameter D37.
关键词： 3-D dosimetry,synchrotron,quenching phenomenon,saturation dose,PRESAGE?,optical density,proton beams,microplanar beams
更新于2025-09-09 09:28:46
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THERMOLUMINESCENCE OF NEWLY DEVELOPED HIGHLY SENSITIVE α-Al2O3:C BY THE VERTICAL GRADIENT FREEZING METHOD
摘要： A highly sensitive α-Al2O3:C crystal was directly grown by the vertical gradient freezing (VGF) method using Al2O3 and graphite powder as the raw materials. The main thermoluminescence (TL) characteristics of α-Al2O3:C detectors grown by the VGF method and TLD-500K detectors were compared. The α-Al2O3:C grown by the VGF method shows good dosimetric properties, such as high TL sensitivity (152 times higher than that of the TLD-100 at heating rate of 1°C/s), an extremely low residual signal of 0.03%, a minimum measurable dose of 0.12 μGy and an excellent linear response within the dose range studied from 1 μGy to 10 Gy. The α-Al2O3:C detectors grown by the VGF method have a higher sensitivity and a better linear response compared to the TLD-500K detectors. Both kinds of α-Al2O3:C can be used in an unannealed form and to measure the very low dose in environmental monitoring and personnel dosimetry.
关键词： α-Al2O3:C,personnel dosimetry,dosimetric properties,vertical gradient freezing method,thermoluminescence,environmental monitoring
更新于2025-09-09 09:28:46
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X-Ray Thermoluminescence Dosimetry Characterization of Commercially Available CVD Diamond
摘要： High quality commercially available CVD diamonds are being tested in novel clinical high energy photons, hadron therapy, and high energy physics applications. In the present work, the authors report on the thermoluminescence (TL) and dosimetry properties of commercial synthetic CVD diamond sample from Element6, exposed to X-ray irradiation at dose rates of 3.9–120 Gy min?1 from 0.13 to 90 Gy. The TL glow curves are composed of four peaks with maxima at about 104, 150, 210, and 280 °C and activation energies of 0.78, 0.79, 0.81, and 1.0 eV, respectively. The dose response of the area under TL glow curves is linear at doses lower than 0.6 Gy, supralinear between 0.6 and 6 Gy and sublinear at higher doses. The samples exhibited a strong TL fading of the low temperature 104 °C peaks that fades away around 120 min after irradiation, which is accompanied by increasing of the 210 and 280 °C peaks. The measured TL cycle reproducibility was very good, in spite of the fading exhibited by the lower temperature peak, with values of 0.1–3.0% at different dose rates and doses. It is concluded that CVD commercially single crystal electronic grade diamond may be securely used in clinical radiotherapy.
关键词： dosimetry,fading,thermoluminescence,diamond CVD crystal,X-ray irradiation
更新于2025-09-09 09:28:46
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Performance characterisation of a real-time fiber dosimetry system using radiophotoluminescent glasses
摘要： We report the first demonstration of a real-time fiber-optic-coupled dosimetry system using Ag-activated phosphate glasses based on radiophotoluminescent (RPL) phenomena. The performance characterisation using real-time fiber RPL glass dosimetry is compared with that of real-time fiber plastic scintillation dosimetry. The inevitable build-up phenomena occurring in Ag-activated RPL glasses both during and after X-ray exposure were measured. The real-time RPL curves for the X-ray exposure region and the build-up region are analytically evaluated and fitted to the second-order polynomial functions and the sum of three exponentials, respectively. In addition, some resolved problems of real-time fiber RPL glass dosimetry are discussed.
关键词： X-ray exposure,real-time fiber dosimetry,build-up phenomena,radiophotoluminescent glasses,Ag-activated phosphate glasses
更新于2025-09-09 09:28:46