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Radionuclides and heavy metals
Published in Rym Salah-Tazdaït, Djaber Tazdaït, Phyto and Microbial Remediation of Heavy Metals and Radionuclides in the Environment, 2022
Rym Salah-Tazdaït, Djaber Tazdaït
Lastly, given that the quantity of absorbed radiation is in no case an indication of its hazardous health effect on living beings, it would be useful to convert the dose of absorbed radiation into radiation dose equivalent, allowing the estimation of the health risk inherent to the absorbed radiation. The SI unit of radiation dose equivalent is the sievert (Sv), which measures the adverse health effect exerted by ionizing radiation on the biological system of the human being (Abe, Fuchigami, Hatamura, and Kasahara 2015, 140). It is the product of the absorbed dose measured in the unit gray by a corrective factor called radiation weighting (Wr) that depends on three parameters: the radiation type, radiation energy, and tissue being targeted (IARC 2001, 34).
The Medical Implications of Nuclear Power Plant Accidents
Published in W.A. Crosbie, J.H. Gittus, Medical Response to Effects of Ionising Radiation, 2003
For example, a single dose of 4 Gray to the whole body, delivered as an instantaneous exposure, would result in a serious illness with the probability of 50% of those exposed dying within 30 days. However, if the same dose of 4 Gray was delivered in four separate exposures of 1 Gray, with an interval of a few days between, it is likely that no deaths would occur and the subsequent illness would be much less severe. If however, the dose of 4 Gray was received over a working life time, no acute illness would develop, although populations exposed to this level of radiation would be expected to show an increased incidence of late effects, such as leukaemia and other malignancies.
Radiation—ionising and non-ionising
Published in Sue Reed, Dino Pisaniello, Geza Benke, Principles of Occupational Health & Hygiene, 2020
Absorbed dose (D) is a measure of the energy absorbed per unit mass of any matter. For a given type of ionising radiation of defined energy, the absorbed dose increases with the density of the absorbing matter. The SI unit is joule per kilogram (J/kg), or gray (Gy). The gray is a large unit, so normally milligray (mGy), microgray (µGy) and nanogray (nGy) are used.
Effects of X-ray application on infertility in new-born rats
Published in Radiation Effects and Defects in Solids, 2023
Salih Çibuk, Handan Mert, Nihat Mert, Oğuz Tuncer, Fikret Altındağ, Kamuran Karaman, Uğur Özdek, İsmet Meydan
It has been reported that X-ray causes oxidative stress by increasing malondialdehit and decreasing Glutathione (GSH), super oxide dismutase (SOD) and catalse (CAT) (9). In a study conducted in cell culture, it was revealed that the application of ionizing radiation causes DNA damage and oxidative stress (10). It has been demonstrated that the application of 9 Gray doses of radiation increases the MDA level in the liver, kidney and brain tissues (11). It is well known that ionizing radiation causes oxidative stress in the testicles and induces apoptosis in germ cells (3). Scientists have revealed in their study that radiation causes epigenetic changes in normal tissues (12). Cihan et al. (13) in their study, showed that radiation caused an increase in malon dialdehyde (MDA) levels and a decrease in CAT and SOD activities in rat brain tissue (13). While sensitivity to radiation-induced apoptosis is higher in spermatocytes, Sertoli and Leydig cells are relatively more resistant (1, 2).
Affinely adjustable robust optimization for radiation therapy under evolving data uncertainty via semi-definite programming
Published in Optimization, 2023
V. Jeyakumar, G. Li, D. Woolnough, H. Wu
Patient and Source Data. For our study, we use a dataset provided by [6] for a liver cancer case. We set a lower threshold on the tumour of 55 Gy based on a prescribed dose of 60 Gy to the tumour. Note that Gray (Gy) is the unit used to measure the amount of radiation. We set the sole OAR to be the heart, with a limiting dose of 70 Gy in line with the recommendations in [34]. The number of voxels in the tumour and heart are 6954 and 33021, respectively, with a total voxel count of 7910952. All three models follow a treatment plan, where T = 3 and the observation of the hypoxia value is taken at . To reduce computational complexity, following [35], we eliminate the set of voxels in the liver cancer data set which, by prior knowledge, will never receive a dose greater than zero. Rather than enforcing a fractionated approach with dose limits , we utilize the parameter with , to allow the optimization program to instead select the optimal dosage distribution over the treatment period.