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Multiple Choice Questions (MCQs)
Published in Ken Addley, MCQs, MEQs and OSPEs in Occupational Medicine, 2023
Non-ionising radiation includes all radiations and fields of the electromagnetic spectrum that do not normally have sufficient energy to produce ionisation in matter. As such it does not break bonds that hold molecules in cells together. Which one of the following types of radiation is NOT a type of non-ionising radiation?
Influence of medication on typical exercise response
Published in R. C. Richard Davison, Paul M. Smith, James Hopker, Michael J. Price, Florentina Hettinga, Garry Tew, Lindsay Bottoms, Sport and Exercise Physiology Testing Guidelines: Volume II – Exercise and Clinical Testing, 2022
For a drug to remain in the stomach longer has other implications, especially for medications that are pH sensitive. Gastric pH is around a value of 3.0, so any medication designed with a gastro-protective coating maybe affected by a longer resident time in the stomach, given that the rate of gastric secretions is reduced during exercise (Ritter et al., 2019). This describes the phenomenon of ionisation.
Radiotherapy Physics
Published in Debbie Peet, Emma Chung, Practical Medical Physics, 2021
Andrea Wynn-Jones, Caroline Reddy, John Gittins, Philip Baker, Anna Mason, Greg Jolliffe
One use for sealed sources in radiotherapy is for performing constancy checks (QC) on radiation monitoring equipment (such as ionisation chambers). When performing QC on a linear accelerator, it is essential to know that the variation measured is a result of fluctuation in the output of the linear accelerator and not due to changes in the sensitivity of the chamber. As the activity of the Strontium-90 source decays at a predictable rate (with a half-life of 29.1 years), it can be used to ensure a consistent response from the measurement equipment over many years. Typical strontium sources used for radiation monitoring QC have activities in the range of 10–900 MBq, and so to use sources in this way the HSE must be notified as they are more radioactive than the notification quantity of 10 kBq.
Hematological parameters and X-ray exposure among medical radiation workers: a systematic review and meta-analysis
Published in Expert Review of Hematology, 2022
Siavash Vaziri, Maryam Mirzaei, Fakhredin Saba, Kharaman Salehi Zahabi, Saleh Salehi Zahabi, Morteza Arab-Zozani
Investigation of 1392 radiation workers from public hospitals of the city of Tangshan indicated that the frequencies of micronuclei and chromosome aberrations are significantly higher in workers exposed to ionizing radiation than the healthy controls, implying that ionizing radiation exposure may cause a higher incidence of micronuclei and chromosome aberrations in radiation workers [36]. Previous studies have shown that ionizing radiation results in macromolecular ionization and dissociation and can induce DNA damage [2]. Moreover, the exposure time and higher doses of ionizing radiation lead to a higher frequency of DNA damage [37]. Hence, it is necessary to consider new molecular analysis methods such as centromere staining and the application of modern hematology tests to assess the health status of radiation workers.
FLASH ultra-high dose rates in radiotherapy: preclinical and radiobiological evidence
Published in International Journal of Radiation Biology, 2022
Andrea Borghini, Cecilia Vecoli, Luca Labate, Daniele Panetta, Maria Grazia Andreassi, Leonida A. Gizzi
The linear energy transfer (LET) for a particular radiation influences its effectiveness in evoking a biological response (i.e. relative biological effectiveness, RBE). DNA represents the most critical target for radiation-induced lethal damage, but other cellular sites such as membranes and organelles may be crucial (Hall and Giaccia 2012). Low LET radiation (X-rays, gamma rays and beta particles) induces lower concentrations of ionization events and deposits a relatively small amount of energy in a highly dispersed manner (Hall and Giaccia 2012; Phillips and Griffin 1999). Hadrons (protons, alpha rays, and other heavier ions) have an increased ionization density and deposit more energy on the biological target, inducing more effects than the low LET radiations (Figure 1). Radiation-induced ionizations may operate directly on the DNA molecule or indirectly on water, causing the production of reactive species, including the aqueous electron (e−aq), the highly reactive hydroxyl radical (OH•) and the radical H• (Ward 1988).
A Study on the Effect of Vitamins A and C to Modulate the Expression of NKG2D Ligands in Hepatic and Colon Cancer Cells
Published in Nutrition and Cancer, 2021
Mazin A. Zamzami, Mohammad Nasrullah, Hani Choudhry, Mohammad Imran Khan
A TSQ Endura™ Triple Quadrupole Mass Spectrometer (Thermo scientific) with electrospray ion source (ESI) was coupled with Thermo Scientific™ UltiMate™ 3000 UHPLC system. The analyses were carried out on C18 (2.7 × 50 mm, 4.6 μm, UHPLC columns, (3.0 × 5.0 mm, 2.7 μm) maintained at 20 °C. The mobile phases were 5 mM ammonium acetate in 0.1% aqueous formic acid (A) and 0.1% formic acid in methanol (B). The flow rate was 0.3 ml/min. The mobile phase system was using a gradient system consisted of the following steps; mobile phase B was adjusted from 20% to 80% from 0.0 to 5.0 min. The ionization mode of the mass spectrometer was positive ESI with 5500 V ionization. The heater probe was set 400 °C. Ionization was achieved as positive ions. The mass spectrometer was operated in the multiple reaction monitoring (MRM) modes with the transition MRM-multiple Reaction monitoring was developed for SAM 399 → 250 and SAH 385 → 135 and their retention time was between 0.7 and 1.5 min. The MS/MS conditions, that is, ion fragments, declustering potential (DP), entrance potential (EP), collision energy (CE), cell entrance potential (CEP), cell exit potential (CXP) for SAM and SAH were optimized. The determination concentrations and integration of peak areas were done using XcaliburTM software.