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Radiation Protection and Safety in Radiotherapy
Published in Kwan Hoong Ng, Ngie Min Ung, Robin Hill, Problems and Solutions in Medical Physics, 2023
Kwan Hoong Ng, Ngie Min Ung, Robin Hill
Solution:Primary radiation is the radiation that is directly emitted from the linear accelerator through the collimator/MLC.Scatter radiation is generated by scattering of the primary radiation beam as it interacts with the different materials such as the beam collimation, the patient, the treatment couch and the air.Leakage radiation is the radiation that escapes through the head of the gantry of the linear accelerator.Neutron radiation is created for photon beams when the energy is greater than 10 MV. These are mainly created in materials with high atomic number such as the target and collimation systems.
Principles and Basic Concepts in Radiation Dosimetry
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
Many situations involve measuring the dose from photon (or neutron) radiation using detectors that fall into neither of these categories (Figure 5.26). In such cases, there is no exact expression for the dose ratio, Dmed/Ddet. ‘General' cavity theory was developed by Burlin (1966); the detector-to-medium dose ratio was approximated by a weighted mean of the stopping-power ratio and the mass–energy absorption coefficient ratio:
Area and Individual Radiation Monitoring
Published in Arash Darafsheh, Radiation Therapy Dosimetry: A Practical Handbook, 2021
Thermo Scientific™6 EPDs measure ionizing radiation in real time [26]. They are equipped with both audible and visual alarms; and can be used to measure gamma radiation, beta radiation, neutron radiation, and x-rays. Various models are available.The EPD-TruDoseTM measures Hp(10) within ±5% for 137Cs and Hp(0.07) within ±15% for 90Sr/90Y. It can measure photons in the energy range of 16 keV to 10 MeV. It has a dose rate range of 1 µSv/h to 10 Sv/h and a dose range of 1 µSv–10 Sv.
Response of murine neural stem/progenitor cells to gamma-neutron radiation
Published in International Journal of Radiation Biology, 2022
Galina A. Posypanova, Marya G. Ratushnyak, Yuliya P. Semochkina, Alexander N. Strepetov
The aim of this work was to study the sensitivity of cultured murine NSCs/NPCs to the reactor gamma-neutron irradiation (γ,n-irradiation) in a wide dose range (from 25 mGy to 2 Gy) and the features of the formation and repair of DNA DSB in these cells. Neutrons are electrically neutral high-energy particles that produce more severe damage to DNA than photons do; therefore they are more efficient in the therapy of radioresistant tumors. Neutron relative biological effectiveness (RBE) varies from 1 to 10 depending on the kind of tissue, neutron energy, and the parameter explored (Scott and Pandita 2006). The advantage of using fast neutron to eliminate radioresistant cells lies partially in the lesser dependency on cell oxygenation, cell cycle parameters, and proliferation rate (Rockhill and Laramore 2016; Goodhead 2019; Jones 2020). The effective use of neutrons in radiation therapy increases interest in the study of the mechanisms of action of neutron radiation to develop the methods of protection for normal tissues and optimize radiotherapy regimens (Goodhead 2019) since neutron therapy significantly increases the risks of long-term post-radiation complications.
Retrospective physical dosimetry in the Czech Republic: an overview of already established methods and recent research
Published in International Journal of Radiation Biology, 2022
Daniela Ekendahl, Zina Čemusová, Dan Reimitz, Jakub Vávra
Neutron activation techniques are specific for neutron radiation exposure. They were used for dose assessment in severe criticality accidents (e.g. Delafield 1985; IAEA 2001; Momose et al. 2001). They are based on the measurement of radioactivity induced by neutron interaction with biological tissues, such as blood, hair or nails or metallic elements such as coins or jewelry worn by the victims (Ekendahl, Rubovič, et al. 2019; ICRU 2019). The activity is directly proportional to neutron fluence. Taking into account neutron spectrum, a specific relationship between neutron dose and activity can be derived for the material used.
Boron phenyl alanine targeted chitosan–PNIPAAm core–shell thermo-responsive nanoparticles: boosting drug delivery to glioblastoma in BNCT
Published in Drug Development and Industrial Pharmacy, 2021
Monireh Soleimanbeigi, Fatemeh Dousti, Farshid Hassanzadeh, Mina Mirian, Jaleh Varshosaz, Yaser Kasesaz, Mahboubeh Rostami
Since BNCT is one of the leading therapies for glioma, in this study, we sought to achieve an efficient and intelligent drug delivery system for use in this treatment. As the temperature of cancer cells is higher than the normal cells, we used a temperature-sensitive system to control the release of the drug into target cells. Combining chitosan with thermo-responsive residues provides an excellent possibility to develop NPs with improved properties for use in controlled release [34]. In 2011, Rejinold et al. have reported a biocompatible and biodegradable poly(N-isopropyl acrylamide)–chitosan NPs for targeted delivery of curcumin in vitro (PC3 and L929 cell lines) [35], Different other studies are available on the advantages of this combination [36,37]. This study was designed for practical purposes and therefore attention to cost and simplicity has been one of the parameters considered in the design and therefore simple and relatively inexpensive polymers comprising chitosan and PNIPAAm were used. A wide range of target groups has been used for many years in targeted drug delivery, and the use of small molecule targeting groups has always received more attention. Boronic acid derivatives can selectively attach to sialic acid (SA) receptors on the cancer cell surface, and so could be an excellent candidate for use in targeted drug delivery [38]. Using the association of target groups (l-BPA), we modified the temperature-sensitive system for drug release into glioma cells. We evaluated the behavior of MTX and BPA separately in this system, and according to the results, this system has a dual capability in the field of drug delivery. In addition, MTX was used to confirm the proper functioning of the prepared NPs to enter the cell and induce cytotoxicity due to the MTX. Complementary in vitro studies in the presence of thermal neutron radiation is underway.