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Indian Journal of Dental Research :... 2015The purpose of this paper was to review various dosimeters used in dentistry and the cumulative results of various studies done with various dosimeters. (Review)
Review
AIM
The purpose of this paper was to review various dosimeters used in dentistry and the cumulative results of various studies done with various dosimeters.
MATERIALS AND METHODS
Several relevant PubMed indexed articles from 1999 to 2013 were electronically searched by typing "dosimeters", "dosimeters in dentistry", "properties of dosimeters", "thermoluminescent and optically stimulated dosimeters", "recent advancements in dosimetry in dentistry." The searches were limited to articles in English to prepare a concise review on dental dosimetry. Titles and abstracts were screened, and articles that fulfilled the criteria of use of dosimeters in dental applications were selected for a full-text reading. Article was divided into four groups: (1) Biological effects of radiation, (2) properties of dosimeters, (3) types of dosimeters and (4) results of various studies using different dosimeters.
CONCLUSION
The present review on dosimetry based on various studies done with dosimeters revealed that, with the advent of radiographic technique the effective dose delivered is low. Therefore, selection of radiological technique plays an important role in dental dose delivery.
Topics: Dentistry; Equipment Design; Humans; Occupational Exposure; Radiation Dosage; Radiometry
PubMed: 26096102
DOI: 10.4103/0970-9290.159133 -
The British Journal of Radiology Sep 2014Dosimetric audit is required for the improvement of patient safety in radiotherapy and to aid optimization of treatment. The reassurance that treatment is being... (Review)
Review
Dosimetric audit is required for the improvement of patient safety in radiotherapy and to aid optimization of treatment. The reassurance that treatment is being delivered in line with accepted standards, that delivered doses are as prescribed and that quality improvement is enabled is as essential for brachytherapy as it is for the more commonly audited external beam radiotherapy. Dose measurement in brachytherapy is challenging owing to steep dose gradients and small scales, especially in the context of an audit. Several different approaches have been taken for audit measurement to date: thimble and well-type ionization chambers, thermoluminescent detectors, optically stimulated luminescence detectors, radiochromic film and alanine. In this work, we review all of the dosimetric brachytherapy audits that have been conducted in recent years, look at current audits in progress and propose required directions for brachytherapy dosimetric audit in the future. The concern over accurate source strength measurement may be essentially resolved with modern equipment and calibration methods, but brachytherapy is a rapidly developing field and dosimetric audit must keep pace.
Topics: Brachytherapy; Calibration; Humans; Medical Audit; Radiometry; Radiotherapy Dosage; Thermoluminescent Dosimetry
PubMed: 24807068
DOI: 10.1259/bjr.20140105 -
Molecules (Basel, Switzerland) Apr 2021Electrochemical biosensors are an increasingly attractive option for the development of a novel analyte detection method, especially when integration within a... (Review)
Review
Electrochemical biosensors are an increasingly attractive option for the development of a novel analyte detection method, especially when integration within a point-of-use device is the overall objective. In this context, accuracy and sensitivity are not compromised when working with opaque samples as the electrical readout signal can be directly read by a device without the need for any signal transduction. However, electrochemical detection can be susceptible to substantial signal drift and increased signal error. This is most apparent when analysing complex mixtures and when using small, single-use, screen-printed electrodes. Over recent years, analytical scientists have taken inspiration from self-referencing ratiometric fluorescence methods to counteract these problems and have begun to develop ratiometric electrochemical protocols to improve sensor accuracy and reliability. This review will provide coverage of key developments in ratiometric electrochemical (bio)sensors, highlighting innovative assay design, and the experiments performed that challenge assay robustness and reliability.
Topics: Biosensing Techniques; Catalysis; Electrochemical Techniques; Electrochemistry; Electrodes; Metal Nanoparticles; Oxidation-Reduction; Radiometry; Reproducibility of Results; Sensitivity and Specificity
PubMed: 33917231
DOI: 10.3390/molecules26082130 -
Molecules (Basel, Switzerland) Jul 2022The determination of Am in the environment is of importance in monitoring its release and assessing its environmental impact and radiological risk. This paper aims to... (Review)
Review
The determination of Am in the environment is of importance in monitoring its release and assessing its environmental impact and radiological risk. This paper aims to give an overview about the recent developments and the state-of-art analytical methods for Am determination in environmental samples. Thorough discussions are given in this paper covering a wide range of aspects, including sample pre-treatment and pre-concentration methods, chemical separation techniques, source preparation, radiometric and mass spectrometric measurement techniques, speciation analyses, and tracer applications. The paper focuses on some hyphenated separation methods based on different chromatographic resins, which have been developed to achieve high analytical efficiency and sample throughput for the determination of Am. The performances of different radiometric and mass spectrometric measurement techniques for Am are evaluated and compared. Tracer applications of Am in the environment, including speciation analyses of Am, and applications in nuclear forensics are also discussed.
Topics: Mass Spectrometry; Radiometry
PubMed: 35889408
DOI: 10.3390/molecules27144536 -
PloS One 2021This study investigated the accuracy of sixteen models of commercial dental radiometers (DR) in measuring the output of thirty-eight LED light curing units (LCUs)... (Comparative Study)
Comparative Study
This study investigated the accuracy of sixteen models of commercial dental radiometers (DR) in measuring the output of thirty-eight LED light curing units (LCUs) compared with a 'gold standard' laboratory-grade spectrometer integrating-sphere (IS) assembly. Nineteen Type I (fiber-bundle light guide) and nineteen Type II (light source in head) LED LCUs were tested, some using different output modes and light guides, resulting in 61 test subsets per radiometer. Gold standard (GS) output measurements (n = 3) were taken using the IS and confirmed with two types of laboratory-grade power meter (PowerMax-Pro 150 HD and PM10-19C; Coherent). One DR (Bluephase Meter II, Ivoclar; BM II) allowed power (mW) as well as irradiance (mW/cm2) recordings. Irradiance readings (n = 3) for each DR/LCU were compared with the IS derived irradiance. Individual LCU irradiance values were normalized against IS data. The GS method yielded reproducible data with a 0.4% pooled coefficient of variation for the LCUs. Mean power values ranged from 0.19 W to 2.40 W. Overall power values for the laboratory-grade power meters were within 5% of GS values. Individual LCU/DR normalized irradiance values ranged from 7% to 535% of the GS; an order of magnitude greater than previous reports. BM II was the only radiometer to average within 20% of normalized pooled GS irradiance values, whereas other radiometers differed by up to 85%. Ten radiometers failed to provide any reading for 1 LCU. When tested with the PowerMax-Pro in high speed (20 kHz) mode, eight LCUs demonstrated pulsing outputs undetectable at the standard (10 Hz) data acquisition rate. Sufficient light exposure is critical for the successful curing of dental resin-based materials. Substantial discrepancies may occur between actual and estimated radiometric data using current DRs. More accurate DRs need to be developed. Manufacturers' accuracy claims for DRs should specify compatible LCUs and testing parameters.
Topics: Curing Lights, Dental; Radiometry; Reproducibility of Results
PubMed: 33513153
DOI: 10.1371/journal.pone.0245830 -
ACS Applied Materials & Interfaces May 2020Radiation dosimeters are critical for accurately assessing the levels of radiation exposure of tumor sites and surrounding tissues and for optimizing therapeutic...
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.
Topics: Animals; Color; Colorimetry; DNA Damage; Fibroblasts; Gold; Metal Nanoparticles; Mice; Nanotubes; Paper; Radiation, Ionizing; Radiometry; Silver
PubMed: 32337977
DOI: 10.1021/acsami.0c03001 -
PloS One 2021We developed a compact and lightweight time-resolved mirrorless scintillation detector (TRMLSD) employing image processing techniques and a convolutional neural network...
PURPOSE
We developed a compact and lightweight time-resolved mirrorless scintillation detector (TRMLSD) employing image processing techniques and a convolutional neural network (CNN) for high-resolution two-dimensional (2D) dosimetry.
METHODS
The TRMLSD comprises a camera and an inorganic scintillator plate without a mirror. The camera was installed at a certain angle from the horizontal plane to collect scintillation from the scintillator plate. The geometric distortion due to the absence of a mirror and camera lens was corrected using a projective transform. Variations in brightness due to the distance between the image sensor and each point on the scintillator plate and the inhomogeneity of the material constituting the scintillator were corrected using a 20.0 × 20.0 cm2 radiation field. Hot pixels were removed using a frame-based noise-reduction technique. Finally, a CNN-based 2D dose distribution deconvolution model was applied to compensate for the dose error in the penumbra region and a lack of backscatter. The linearity, reproducibility, dose rate dependency, and dose profile were tested for a 6 MV X-ray beam to verify dosimeter characteristics. Gamma analysis was performed for two simple and 10 clinical intensity-modulated radiation therapy (IMRT) plans.
RESULTS
The dose linearity with brightness ranging from 0.0 cGy to 200.0 cGy was 0.9998 (R-squared value), and the root-mean-square error value was 1.010. For five consecutive measurements, the reproducibility was within 3% error, and the dose rate dependency was within 1%. The depth dose distribution and lateral dose profile coincided with the ionization chamber data with a 1% mean error. In 2D dosimetry for IMRT plans, the mean gamma passing rates with a 3%/3 mm gamma criterion for the two simple and ten clinical IMRT plans were 96.77% and 95.75%, respectively.
CONCLUSION
The verified accuracy and time-resolved characteristics of the dosimeter may be useful for the quality assurance of machines and patient-specific quality assurance for clinical step-and-shoot IMRT plans.
Topics: Gamma Cameras; Humans; Image Processing, Computer-Assisted; Neural Networks, Computer; Radiometry; Radiotherapy Dosage; Radiotherapy, Intensity-Modulated; Reproducibility of Results; Scintillation Counting; X-Rays
PubMed: 33577602
DOI: 10.1371/journal.pone.0246742 -
Scientific Reports Nov 2019Optical fibers hold promise for accurate dosimetry in small field proton therapy due to their superior spatial resolution and the lack of significant Cerenkov...
Optical fibers hold promise for accurate dosimetry in small field proton therapy due to their superior spatial resolution and the lack of significant Cerenkov contamination in proton beams. One known drawback for most scintillation detectors is signal quenching in areas of high linear energy transfer, as is the case in the Bragg peak region of a proton beam. In this study, we investigated the potential of innovative optical fiber bulk materials using the sol-gel technique for dosimetry in proton therapy. This type of glass is made of amorphous silica (SiO[Formula: see text]) and is doped with Gd[Formula: see text] ions and possesses very interesting light emission properties with a luminescence band around 314 nm when exposed to protons. The fibers were manufactured at the University of Lille and tested at the TRIUMF Proton Therapy facility with 8.2-62.9 MeV protons and 2-6 nA of extracted beam current. Dose-rate dependence and quenching were measured and compared to other silica-based fibers also made by sol-gel techniques and doped with Ce[Formula: see text] and Cu[Formula: see text]. The three fibers present strong luminescence in the UV (Gd) or visible (Cu,Ce) under irradiation, with the emission intensities related directly to the proton flux. In addition, the 0.5 mm diameter Gd[Formula: see text]-doped fiber shows superior resolution of the Bragg peak, indicating significantly reduced quenching in comparison to the Ce[Formula: see text] and Cu[Formula: see text] fibers with a Birks' constant, k[Formula: see text], of (0.0162 [Formula: see text] 0.0003) cm/MeV in comparison to (0.0333 [Formula: see text] 0.0006) cm/MeV and (0.0352 [Formula: see text] 0.0003) cm/MeV, respectively. To our knowledge, this is the first report of such an interesting k[Formula: see text] for a silica-based optical fiber material, showing clearly that this fiber presents lower quenching than common plastic scintillators. This result demonstrates the high potential of this inorganic fiber material for proton therapy dosimetry.
Topics: Gadolinium; Humans; Linear Energy Transfer; Luminescence; Optical Fibers; Phantoms, Imaging; Proton Therapy; Protons; Radiometry; Silicon Dioxide
PubMed: 31704964
DOI: 10.1038/s41598-019-52608-5 -
Medical Physics Jul 2022The clinical translation of FLASH radiotherapy (RT) requires challenges related to dosimetry and beam monitoring of ultra-high dose rate (UHDR) beams to be addressed....
The clinical translation of FLASH radiotherapy (RT) requires challenges related to dosimetry and beam monitoring of ultra-high dose rate (UHDR) beams to be addressed. Detectors currently in use suffer from saturation effects under UHDR regimes, requiring the introduction of correction factors. There is significant interest from the scientific community to identify the most reliable solutions and suitable experimental approaches for UHDR dosimetry. This interest is manifested through the increasing number of national and international projects recently proposed concerning UHDR dosimetry. Attaining the desired solutions and approaches requires further optimization of already established technologies as well as the investigation of novel radiation detection and dosimetry methods. New knowledge will also emerge to fill the gap in terms of validated protocols, assessing new dosimetric procedures and standardized methods. In this paper, we discuss the main challenges coming from the peculiar beam parameters characterizing UHDR beams for FLASH RT. These challenges vary considerably depending on the accelerator type and technique used to produce the relevant UHDR radiation environment. We also introduce some general considerations on how the different time structure in the production of the radiation beams, as well as the dose and dose-rate per pulse, can affect the detector response. Finally, we discuss the requirements that must characterize any proposed dosimeters for use in UDHR radiation environments. A detailed status of the current technology is provided, with the aim of discussing the detector features and their performance characteristics and/or limitations in UHDR regimes. We report on further developments for established detectors and novel approaches currently under investigation with a view to predict future directions in terms of dosimetry approaches, practical procedures, and protocols. Due to several on-going detector and dosimetry developments associated with UHDR radiation environment for FLASH RT it is not possible to provide a simple list of recommendations for the most suitable detectors for FLASH RT dosimetry. However, this article does provide the reader with a detailed description of the most up-to-date dosimetric approaches, and describes the behavior of the detectors operated under UHDR irradiation conditions and offers expert discussion on the current challenges which we believe are important and still need to be addressed in the clinical translation of FLASH RT.
Topics: Radiometry; Radiotherapy Dosage
PubMed: 35404484
DOI: 10.1002/mp.15649 -
Progress in Biophysics and Molecular... 2007This paper provides a review of current metrological capability applied to the characterisation of the acoustic output of equipment used within medical ultrasonic... (Review)
Review
This paper provides a review of current metrological capability applied to the characterisation of the acoustic output of equipment used within medical ultrasonic applications. Key measurement devices, developed to underpin metrology in this area, are the radiation force balance, used to determine total output power, and the piezo-electric hydrophone, used to resolve the spatial and temporal distribution of acoustic pressure. The measurement infrastructure in place within the United Kingdom ensuring users are able to carry out traceable measurements of these quantities in a meaningful way, is described. This includes the relevant primary standards, the way international equivalence of national standards is demonstrated and the routes by which the standards are disseminated to the user community. Emerging measurement techniques that may in future lead to improved measurement capability, are also briefly discussed.
Topics: Calibration; Equipment Design; Equipment Failure Analysis; Guidelines as Topic; Internationality; Radiation Dosage; Radiometry; Reference Values; Transducers; Ultrasonography
PubMed: 17081597
DOI: 10.1016/j.pbiomolbio.2006.07.023