Phototherapy Using Nanomaterials
D. Sakthi Kumar, Aswathy Ravindran Girija in Bionanotechnology in Cancer, 2023
X-rays can be used as efficient energy sources for initiating effective PDT. For this, scintillation nanoparticles (ScNps) with attached photosensitizers are employed, which serves the purpose of self-lighting photodynamic therapy (SLPDT) [208]. These materials can convert X-rays to UV-visible light and this concept improved the efficiency of PDT without employing an external light source. X-rays will be irradiated to the tumor site where the nano sensitizer systems have been accumulated. Upon irradiation, the encapsulated nanoparticles will emit light and this can be collected to activate the nearby PS. The scintillation process involves the conversion of incoming radiation into a large number of electron-hole pair and transfer of this electron-hole pair energy to the luminescent ions. Upon interaction with high energy photons with the lattice of ScNPs, many electron-hole pairs will be created and thermalized in the conduction and valence band respectively. Photoelectric effect and Compton Effect account for this interaction. Afterwards, these electron-hole pairs will migrate through the materials and repeated trapping at defects of these materials cause energy losses mainly due to non-radiative recombination. This will be followed by the final stage, which is luminescence, and here the energy from the SCNPs will excite the nearby PS causing 1O2 generation [209, 210].
Radiation Protection of Staff and the Public
W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald in Handbook of Radiotherapy Physics, 2021
It is important that after installation, a full survey is conducted to verify the design calculations and to ensure that builders have followed instructions.* The first step in this process is to choose the correct survey instrument. In the case of linear accelerators*, the pulsed nature of the radiation can give erroneous results with equipment such as Geiger–Müller tubes that count photons, in contrast to ionisation-based instruments that measure charge (see Section 16.2.2). Scintillation detectors can be used, provided that their response to pulsed radiation is verified. Radiation monitoring badges using thermoluminescent dosimeters (TLDs) (see Section 17.2) or Al2O3 (see Section 17.5) can be used for longer-term environmental surveys. Neutron measurements will be needed if the energy of the machine is above 8 MeV.
Cherenkov and Scintillation Imaging Dosimetry
Arash Darafsheh in Radiation Therapy Dosimetry: A Practical Handbook, 2021
Scintillation is a luminescence process – molecular excitation caused by absorption of ionizing radiation results in emission of light during material electronic relaxation. Numerous studies have shown that under appropriate conditions, scintillation signal can be directly proportional to dose [9]. Plastic scintillators used for dosimetry purposes are often composed of a bulk medium and organic fluorophores, where light production is enabled through fluorescence resonance energy transfer between these two components, with the medium being the conduit for radiation interaction and electron liberation, and the fluorophore being the electron/energy acceptor. A secondary fluorophore (a material that will absorb light at the lower end of the visible light spectrum) is sometimes added to shift the emission spectra to higher wavelengths [10]. Specifically, scintillators emit light when the excited organic fluorophore de-excites via a fluorescence, phosphorescence, or some alternate delayed fluorescence pathway [11].
Prostate-specific membrane antigen-directed imaging and radioguided surgery with single-photon emission computed tomography: state of the art and future outlook
Published in Expert Review of Medical Devices, 2022
Luca Filippi, Barbara Palumbo, Viviana Frantellizzi, Susanna Nuvoli, Giuseppe De Vincentis, Angela Spanu, Orazio Schillaci
As the present paper is focused on gamma-emitting PSMA-targeting tracers, we briefly describe the main characteristics of the two types of handheld devices employed as gamma-probes: the scintillation and the semiconductor-ionization detectors [28]. Scintillation probes are made up of some components: scintillation crystal – most commonly, thallium-activated sodium iodide/NaI(Tl) -, a light guide, a photomultiplier tube (PMT) and associated electronic: incident photon is absorbed by the scintillator crystal, producing visible light that, in its turn, is converted into electric pulse by the PMT. In the semiconductor-ionization detector-based probes, the main components are: semiconductor crystal, a pre-amplifier and its associated electronic; in this type of gamma-probes, incident photons determine ionization in the semiconductor crystal producing free electrons that are collected as electric pulse. It is still an open debate which type of intraoperative probe (scintillation vs semiconductor ones) performs better: while semiconductor probes, in fact, are generally characterized by higher energy and spatial resolution, scintillation detectors present higher sensitivity, especially for high and medium-energy photons [29,30].
Disposition of tris(4-chlorophenyl)methanol and tris(4-chlorophenyl)methane in male and female Harlan Sprague Dawley rats and B6C3F1/N mice following oral and intravenous administration
Published in Xenobiotica, 2019
Natasha R. Catlin, Suramya Waidyanatha, Sherry R. Black, James M. Mathews, Rodney W. Snyder, Purvi R. Patel, Scott L. Watson, Timothy R. Fennell
Duplicate aliquots of bile, urine and triplicate aliquots of cage rinse and plasma were added directly to vials containing Ultima Gold™ scintillation cocktail. GI tract tissues, GI contents, skin, and carcass where applicable, were digested in 2 N ethanolic NaOH and added to vials containing Ultima Gold™ scintillation cocktail. Triplicate weighed aliquots of fecal homogenate samples and all other tissues were combusted using a Model 307 sample oxidizer (PerkinElmer Life and Analytical Sciences, Waltham, MA, USA), absorbed on Carbo-Sorb E® and Permafluor® E+ scintillation cocktail added prior to analysis. All samples were analyzed for radioactivity content by liquid scintillation spectroscopy (LSS) using a Packard 1900CA Tri-Carb Liquid Scintillation Analyzer (PerkinElmer, Waltham, MA, USA). A Debra™ data collection and reporting system (LabLogic Systems Ltd., Sheffield, England) was used for calculation of radiolabel disposition data. The percent dose reported for individual dispersed tissues (blood, adipose, muscle, and skin) was based on that found in the measured aliquots and not based on the whole tissue. The dose remaining in the rest of the dispersed tissues were accounted for in the carcass digest and hence disposition data for tissues are presented as the percent dose in tissues and carcass.
Design and optimization of crocetin loaded PLGA nanoparticles against diabetic nephropathy via suppression of inflammatory biomarkers: a formulation approach to preclinical study
Published in Drug Delivery, 2019
In brief, the renal tissue sample was homogenized in the ice-cold medium of HEPES. The glomeruls was successfully isolated from the renal tissue by removing the capsules and step by step passed through the various numbers of sieves. After washing with RPMI1640 medium (containing HEPES 20 mM, pH = 7.4) and mixing with salt solution (0.4 mM potassium phosphate, 137 mM NaCl, 0.3 mM sodium phosphate, 5.4 mM KCl, 5.5 mM glucose, 25 mM β-glycerophosphate, 5.5 mM glucose, 2.5 mM CaCl2, 5 mM EGTA, 10 mM MgCl2 and HEPES 20 mM), glomerulus was again incubated with salt solution for 15 min in the presence and absence of PKC-specific substrate (100 μM) and also adding the digitonin (5 mg/mL) and ATP (1 mM) with γ-[32P]ATP (<1500 ppm/pmol) and trichloroacetic acid (5%) was used for terminate the reaction. The sample was transferred onto the P81 phosphocellulose paper and washed 4 times with phosphoric acid (1%) and one time with acetone. Scintillation counting was used for the determination of radioactivity incorporated into the substrate. Glomerular PKC activity was estimated in correspond to protein estimation.
Related Knowledge Centers
- Alpha Particle
- Compton Scattering
- Gamma Ray
- Photoelectric Effect
- Ultraviolet
- Scintillator
- X-Ray
- Ion
- Scintillation Counter
- Attenuation Coefficient