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Medical and Biological Applications of Low Energy Accelerators
Published in Vlado Valković, Low Energy Particle Accelerator-Based Technologies and Their Applications, 2022
Ionizing radiation damages the DNA of the malignant cells, most commonly by causing double-strand breaks, which may be misrepaired and disrupt the integrity of the chromosome. The effects of this damage become manifest during mitosis, at which point the cells cannot successfully replicate. Other consequences of irradiation include changes in growth factors and signal transduction pathways, apoptosis and the regulation of the cell cycle. Damage to cells, particularly those that rarely divide and are highly differentiated may also occur secondary to disruptions in their vascular supply.
Radiobiology of Normal Tissues
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
When stem cells begin to differentiate, they usually proliferate faster, tend to be more sensitive to proliferation-dependent cytotoxic agents and may be more radiosensitive. Irradiation tends to stop cell proliferation, and if the dose is high enough, the production of new cells may fail to keep up with cell loss. The parenchymal cell population will, therefore, decline, and the tissue may eventually break down. In the epidermis, this leads to the loss of the superficial layers of the skin, moist desquamation, and even ulceration. Skin that has been damaged in this way may heal (if the dose is not too high), but problems may develop later as a result of the radiation damage to connective tissues underlying the epidermis. Damaged blood vessels may become permanently swollen and visible to the eye as the disfiguring appearance of telangiectasia. The skin may become hard and less flexible. In an extreme case, the tissue may break down into a ‘deep' ulcer (i.e. necrosis), a serious clinical problem. In tissues other than the skin, more than one manifestation of radiation injury may also develop, again attributable to damage to the various cell types that are present.
Radiation protection and safety
Published in Ken Holmes, Marcus Elkington, Phil Harris, Clark's Essential Physics in Imaging for Radiographers, 2021
The risk of developing a cancer from a medical irradiation is related to the dose of radiation received as we have said previously. However, the general risk is very small across all examinations. It is clear from research data that some tissues are more sensitive and therefore at greater risk of developing a malignancy than others. This can be helpful in that most cancer cells develop more quickly than their surrounding tissues and therefore may respond to the use of ionising radiation as a treatment to destroy or shrink the tumour.
Improvement of irradiation-induced fibroblast damage by α2-macroglobulin through alleviating mitochondrial dysfunction
Published in Pharmaceutical Biology, 2022
Chaoji Huangfu, Nan Tang, Xiaokun Yang, Zhanwei Gong, Junzheng Li, Junting Jia, Jingang Zhang, Yan Huang, Yuyuan Ma
Radiation therapy has been widely used in the field of tumour treatment. However, during the process of radiation therapy, normal tissues and cells along with cancers cells are also eliminated by irradiation. Therefore, safe and effective agents with anti-radiation function need to be explored. Several studies have confirmed the effect of α2-M on radiation protection. Remarkable lower concentration of α2-M was observed in the serum of jaws osteoradionecrosis patients (Liu et al. 2018). Significant increase of rat survival rate from 50 to 100% was achieved by α2-M treatment intraperitoneally after radiation (Bogojevic et al. 2011). Amifostine is a type of anti-radiation agent, and amifostine could markedly increase the α2-M level in the rat after irradiation. Therefore, α2-M might act an important role in the amifostine-induced anti-irradiation effect (Mirjana et al. 2010). The DNA injury caused by irradiation is viewed to be the trigger of subsequent cell dysfunction events. Proliferating cell nuclear antigen (PCNA) plays a vital role during DNA repair process (Seelinger and Otterlei 2020), and α2-M could significantly promote the expression of PCNA and suppress DNA damage in the irradiation-treated rats (Bogojevic et al. 2011).
Determination of Micropulse Modes with Targeted Damage to the Retinal Pigment Epithelium Using Computer Modeling for the Development of Selective Individual Micropulse Retinal Therapy
Published in Current Eye Research, 2022
Elena V. Ivanova, Pavel L. Volodin, Alexey V. Guskov
The computer simulation of laser impact on eye tissues was performed in two stages. In the first stage, the temperature distribution was calculated as a function of time after exposure with different micropulse power. The corresponding dependence for the center of the spot is presented in Figure 3a. In the second stage, the Arrhenius integral was calculated in order to estimate a concentration of denatured protein. The fraction of native protein at the center of the exposure spot, as a function of penetration depth with respect to the center of the RPE layer, is shown in Figure 3b. Three quantities were introduced to characterize the results of the irradiation process. The quantity, A1, reflects the extent of damage to adjacent structures outside the RPE (harmful effect). The quantities, A2 and A3, are the fractions of denatured and native protein in RPE, respectively. The corresponding regions are shown in red (1), orange (2), and green (3).
Targeting USP11 may alleviate radiation-induced pulmonary fibrosis by regulating endothelium tight junction
Published in International Journal of Radiation Biology, 2022
Yiting Tang, Qian Yuan, Congzhao Zhao, Ying Xu, Qi Zhang, Lili Wang, Zhiqiang Sun, Jianping Cao, Judong Luo, Yang Jiao
A 160 Kev X-ray linear accelerator (Rad Source Technologies Inc., USA) was utilized for cellular irradiation, which was set at a fixed dose rate of 120 cGy/min. For the RIPF mouse model construction, the right lungs of both Usp11−/− and Usp11+/+ mice were exposed to a cone-beam Computed tomography (CT)-guided precision irradiation system (X-RAD 225Cx; Precision X-ray, North Branford, CT, Figure S1) at a single dose of 30 Gy (with a dose rate of 250 cGy/min, source bed distance = 30.6 cm) after the mice were anesthetized with 1% sodium pentobarbital (7 mL/kg intraperitoneally). After irradiation, CT scanning of the lung was performed at certain time intervals by the same precision irradiation X-ray apparatus as described above. For histological analysis, we collected the tissues after performing pulmonary circulation perfusion until the lungs became white.