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Proceedings of the Japan Academy.... 2018Scintillation materials and detectors that are used in many applications, such as medical imaging, security, oil-logging, high energy physics and non-destructive... (Review)
Review
Scintillation materials and detectors that are used in many applications, such as medical imaging, security, oil-logging, high energy physics and non-destructive inspection, are reviewed. The fundamental physics understood today is explained, and common scintillators and scintillation detectors are introduced. The properties explained here are light yield, energy non-proportionality, emission wavelength, energy resolution, decay time, effective atomic number and timing resolution. For further understanding, the emission mechanisms of scintillator materials are also introduced. Furthermore, unresolved problems in scintillation phenomenon are considered, and my recent interpretations are discussed. These topics include positive hysteresis, the co-doping of non-luminescent ions, the introduction of an aimed impurity phase, the excitation density effect and the complementary relationship between scintillators and storage phosphors.
Topics: Luminescent Agents; Luminescent Measurements; Materials Testing; Physical Phenomena; Scintillation Counting; Semiconductors
PubMed: 29434081
DOI: 10.2183/pjab.94.007 -
Journal of Nuclear Medicine Technology Sep 1999Design features of intraoperative probes are presented. A brief discussion of the sentinel node concept and relevant radiopharmaceuticals is given. The importance of the... (Review)
Review
Design features of intraoperative probes are presented. A brief discussion of the sentinel node concept and relevant radiopharmaceuticals is given. The importance of the injection technique and the necessity of imaging in radiotracer techniques for sentinel node detection are explained. Probe calibration, procedural precautions, intraoperative techniques, and radiation dosimetry relevant to the successful use of intraoperative probes are discussed. Intraoperative use of gamma probes requires a team effort involving surgery and nuclear medicine personnel and requires that team members understand the fundamentals of probe use. After reading this paper, the nuclear medicine technologist will be able to: (a) describe present day and future potential use of intraoperative probes; (b) define the sentinel lymph node (SLN) concept; (c) state the radiopharmaceuticals and injection techniques used for SLN evaluation; (d) name several SLN detection procedures; and (e) discuss the design features and care of currently available probes.
Topics: Calibration; Equipment Design; Gamma Rays; Humans; Intraoperative Care; Lymph Nodes; Lymphatic Metastasis; Neoplasms; Radiation Dosage; Radionuclide Imaging; Radiopharmaceuticals; Scintillation Counting
PubMed: 10512473
DOI: No ID Found -
Applied Radiation and Isotopes :... Aug 2021We report here on the primary activity standardisation of aRa dichloride solution in equilibrium with its decay daughters. Both the triple-to-double-coincidence-ratio...
We report here on the primary activity standardisation of aRa dichloride solution in equilibrium with its decay daughters. Both the triple-to-double-coincidence-ratio (TDCR) method with an in-house TDCR detector and the CIEMAT-NIST efficiency tracing (CNET) technique with a commercial counter were used. The liquid scintillation efficiencies for both methods are about 6 while the activities they predict with about 0.4% relative standard uncertainty agree within 0.15%. For backup, the solution was also standardised with 4πγ NaI(Tl) integral counting with a well-type NaI(Tl) detector, and efficiencies computed by Monte Carlo simulations using the GEANT code. This simple technique, unused previously for this nuclide, yielded an activity concentration compatible with, but 1% lower than, the one determined by liquid scintillation counting.
PubMed: 34051527
DOI: 10.1016/j.apradiso.2021.109788 -
Physics in Medicine and Biology Jul 2019The goal of this study was to test the utility of time-gated optical imaging of head and neck (HN) radiotherapy treatments to measure surface dosimetry in real-time and...
The goal of this study was to test the utility of time-gated optical imaging of head and neck (HN) radiotherapy treatments to measure surface dosimetry in real-time and inform possible interfraction replanning decisions. The benefit of both Cherenkov and scintillator imaging in HN treatments is direct daily feedback on dose, with no change to the clinical workflow. Emission from treatment materials was characterized by measuring radioluminescence spectra during irradiation and comparing emission intensities relative to Cherenkov emission produced in phantoms and scintillation from small plastic targets. HN treatment plans were delivered to a phantom with bolus and mask present to measure impact on signal quality. Interfraction superficial tumor reduction was simulated on a HN phantom, and cumulative Cherenkov images were analyzed in the region of interest (ROI). HN human patient treatment was imaged through the mask and compared with the dose distribution calculated by the treatment planning system. The relative intensity of radioluminescence from the mask was found to be within 30% of the Cherenkov emission intensity from tissue-colored clay. A strong linear relationship between normalized cumulative Cherenkov intensity and tumor size was established ([Formula: see text]). The presence of a mask above a scintillator ROI was found to decrease mean pixel intensity by >40% and increase distribution spread. Cherenkov imaging through mask material is shown to have potential for surface field verification and tracking of superficial anatomy changes between treatment fractions. Imaging of scintillating targets provides a direct imaging of surface dose on the patient and through transparent bolus material. The first imaging of a patient receiving HN radiotherapy was achieved with a signal map which qualitatively matches the surface dose plan.
Topics: Algorithms; Electrons; Head and Neck Neoplasms; Humans; Image Processing, Computer-Assisted; Optical Imaging; Phantoms, Imaging; Radiometry; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted; Scintillation Counting
PubMed: 31146269
DOI: 10.1088/1361-6560/ab25a3 -
Sensors (Basel, Switzerland) Sep 2022In nuclear power plants, particle accelerators, and other nuclear facilities, measuring the level of ionising gamma radiation is critical for the safety and management...
In nuclear power plants, particle accelerators, and other nuclear facilities, measuring the level of ionising gamma radiation is critical for the safety and management of the operation and the environment's protection. However, in many cases, it is impossible to monitor ionising radiation directly at the required location continuously. This is typically either due to the lack of space to accommodate the entire dosimeter or in environments with high ionising radiation activity, electromagnetic radiation, and temperature, which significantly shorten electronics' lifetime. To allow for radiation measurement in such scenarios, we designed a fibre optic dosimeter that introduces an optical fibre link to deliver the scintillation radiation between the ionising radiation sensor and the detectors. The sensors can thus be placed in space-constrained and electronically hostile locations. We used silica optical fibres that withstand high radiation doses, high temperatures, and electromagnetic interference. We use a single photon counter and a photomultiplier to detect the transmitted scintillation radiation. We have shown that selected optical fibres, combined with different scintillation materials, are suitable for measuring gamma radiation levels in hundreds of kBq. We present the architecture of the dosimeter and its experimental characterisation with several combinations of optical fibres, detectors, and scintillation crystals.
Topics: Optical Fibers; Physical Phenomena; Radiation Dosimeters; Radiometry; Scintillation Counting; Silicon Dioxide
PubMed: 36236411
DOI: 10.3390/s22197312 -
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 -
Optical and x-ray technology synergies enabling diagnostic and therapeutic applications in medicine.Journal of Biomedical Optics Oct 2018X-ray and optical technologies are the two central pillars for human imaging and therapy. The strengths of x-rays are deep tissue penetration, effective cytotoxicity,... (Review)
Review
X-ray and optical technologies are the two central pillars for human imaging and therapy. The strengths of x-rays are deep tissue penetration, effective cytotoxicity, and the ability to image with robust projection and computed-tomography methods. The major limitations of x-ray use are the lack of molecular specificity and the carcinogenic risk. In comparison, optical interactions with tissue are strongly scatter dominated, leading to limited tissue penetration, making imaging and therapy largely restricted to superficial or endoscopically directed tissues. However, optical photon energies are comparable with molecular energy levels, thereby providing the strength of intrinsic molecular specificity. Additionally, optical technologies are highly advanced and diversified, being ubiquitously used throughout medicine as the single largest technology sector. Both have dominant spatial localization value, achieved with optical surface scanning or x-ray internal visualization, where one often is used with the other. Therapeutic delivery can also be enhanced by their synergy, where radio-optical and optical-radio interactions can inform about dose or amplify the clinical therapeutic value. An emerging trend is the integration of nanoparticles to serve as molecular intermediates or energy transducers for imaging and therapy, requiring careful design for the interaction either by scintillation or Cherenkov light, and the nanoscale design is impacted by the choices of optical interaction mechanism. The enhancement of optical molecular sensing or sensitization of tissue using x-rays as the energy source is an important emerging field combining x-ray tissue penetration in radiation oncology with the molecular specificity and packaging of optical probes or molecular localization. The ways in which x-rays can enable optical procedures, or optics can enable x-ray procedures, provide a range of new opportunities in both diagnostic and therapeutic medicine. Taken together, these two technologies form the basis for the vast majority of diagnostics and therapeutics in use in clinical medicine.
Topics: Animals; Diagnostic Imaging; Humans; Imaging, Three-Dimensional; Light; Nanoparticles; Optics and Photonics; Oxygen; Photons; Radiation Oncology; Radiography; Scintillation Counting; X-Rays
PubMed: 30350489
DOI: 10.1117/1.JBO.23.12.121610 -
Journal of Food Protection Apr 2023This study was carried out to validate the liquid scintillation counter method (Charm II) for the detection of tetracyclines, beta-lactams, and sulfonamides (Sulfa...
This study was carried out to validate the liquid scintillation counter method (Charm II) for the detection of tetracyclines, beta-lactams, and sulfonamides (Sulfa drugs) in a range of Aquaculture Products. This method of validation followed primary validation performed in Belgium and was therefore transferred to Nigeria but further validation was required, and this was performed according to the European Commission Decision 2002/657/EC. Method performance was based on the detection capability (CCβ), specificity (cross-reactivity), robustness, repeatability, and reproducibility for the detection of antimicrobial residues. Seafood and aquaculture samples used for the validation process included tilapia (Oreochromis niloctus), catfish (Siluriformes), African threadfin (Galeoides decadactylus), common carp (Cyprinus carpio), and shrimps (penaeidae). These were spiked with varying concentrations of tetracyclines, beta-lactams, and sulfonamides standards to determine the validation parameters. Results of the validation showed tetracyclines had detection capabilities of 50 µg/kg, while beta-lactams and sulphonamides had detection capabilities of 25 µg/kg. The relative standard deviation for both repeatability and reproducibility studies ranged between 1.36% and 10.50%. Results of this study are suitable and comparable to the initial validation reports from the primary validation ofCharm II tests forthedetection ofantimicrobial residues inarange ofaquaculture fish conducted in Belgium. The results also prove the specificity, ruggedness, and reliability of the radio receptor assay tests for detection of the various antimicrobials in aquaculture products. This could be used in seafood/aquaculture products monitoring in Nigeria.
Topics: Animals; beta-Lactams; Reproducibility of Results; Sulfonamides; Tetracyclines; Carps; Scintillation Counting; Anti-Bacterial Agents; Sulfanilamide; Seafood; Aquaculture; Drug Residues
PubMed: 37005035
DOI: 10.1016/j.jfp.2023.100055 -
Physics in Medicine and Biology Sep 2011The development of radiation detectors capable of delivering spatial information about gamma-ray interactions was one of the key enabling technologies for nuclear... (Review)
Review
The development of radiation detectors capable of delivering spatial information about gamma-ray interactions was one of the key enabling technologies for nuclear medicine imaging and, eventually, single-photon emission computed tomography (SPECT). The continuous sodium iodide scintillator crystal coupled to an array of photomultiplier tubes, almost universally referred to as the Anger Camera after its inventor, has long been the dominant SPECT detector system. Nevertheless, many alternative materials and configurations have been investigated over the years. Technological advances as well as the emerging importance of specialized applications, such as cardiac and preclinical imaging, have spurred innovation such that alternatives to the Anger Camera are now part of commercial imaging systems. Increased computing power has made it practical to apply advanced signal processing and estimation schemes to make better use of the information contained in the detector signals. In this review we discuss the key performance properties of SPECT detectors and survey developments in both scintillator and semiconductor detectors and their readouts with an eye toward some of the practical issues at least in part responsible for the continuing prevalence of the Anger Camera in the clinic.
Topics: Equipment Design; Gamma Cameras; Humans; Nuclear Medicine; Radiation Monitoring; Radionuclide Imaging; Scintillation Counting; Semiconductors; Sensitivity and Specificity; Signal Processing, Computer-Assisted; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed
PubMed: 21828904
DOI: 10.1088/0031-9155/56/17/R01 -
Medical Physics Oct 2013Photon counting detectors (PCDs) with energy discrimination capabilities have been developed for medical x-ray computed tomography (CT) and x-ray (XR) imaging. Using... (Review)
Review
Photon counting detectors (PCDs) with energy discrimination capabilities have been developed for medical x-ray computed tomography (CT) and x-ray (XR) imaging. Using detection mechanisms that are completely different from the current energy integrating detectors and measuring the material information of the object to be imaged, these PCDs have the potential not only to improve the current CT and XR images, such as dose reduction, but also to open revolutionary novel applications such as molecular CT and XR imaging. The performance of PCDs is not flawless, however, and it seems extremely challenging to develop PCDs with close to ideal characteristics. In this paper, the authors offer our vision for the future of PCD-CT and PCD-XR with the review of the current status and the prediction of (1) detector technologies, (2) imaging technologies, (3) system technologies, and (4) potential clinical benefits with PCDs.
Topics: Diagnostic Imaging; Humans; Image Processing, Computer-Assisted; Photons; Radiation Dosage; Scintillation Counting; X-Rays
PubMed: 24089889
DOI: 10.1118/1.4820371