A systematic review of clinical applications of polymer gel dosimeters in radiotherapy

Abstract: Radiotherapy has rapidly improved because of the use of new equipment and techniques. Hence, the appeal for a feasible and accurate three-dimensional (3D) dosimetry system has increased. In this regard, gel dosimetry systems are accurate 3D dosimeters with high resolution. This systematic review evaluates the clinical applications of polymer gel dosimeters in radiotherapy. To find the clinical applications of polymer gel dosimeters in radiotherapy, a full systematic literature search was performed on the basis of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines in electronic databases up to January 31, 2017, with use of search-related terms in the titles and abstracts of articles. A total of 765 articles were screened in accordance with our inclusion and exclusion criteria. Eventually, 53 articles were included in the study. The findings show that most clinical applications of polymer gel dosimeters relate to external radiotherapy. Most of the gel dosimeters studied have acceptable dose accuracy as a 3D dosimeter with high resolution. It is difficult to judge which is the best polymer gel dosimeter to use in a clinical setting, because each gel dosimeter has advantages and limitations. For example, methacrylic acid–based gel dosimeters have high dose sensitivity and low toxicity, while their dose response is beam energy dependent; in contrast, N-isopropylacrylamide gel dosimeters have low dose resolution, but their sensitivity is lower and they are relatively toxic. Keywords: Polymer gel dosimetry Clinical application Radiotherapy Brachytherapy Neutron capture therap

Measurement of the photon and thermal neutron doses of contralateral breast surface in breast cancer radiotherapy

Introduction and purpose:During the radiation therapy of tumoral breast, the contralateral breast (CB) will receive scattered doses. In the present study, the photon and thermal neutron dose values received by CB surface during breast cancer radiation therapy were measured.Materials and methods:The right breast region of RANDO phantom was considered as CB, and the measurements of photon and thermal neutron dose values were carried out on this region surface. The phantom was irradiated with 18 MV photon beams, and the dose values were measured with thermoluminescent dosimeter (TLD-600 and TLD-700) chips for 11 � 13, 11 � 17 and 11 � 21 cm2 field sizes in the presence of physical and dynamic wedges.Results:The total dose values (photon + thermal neutron) received by the CB surface in the presence of physical wedge were 12·06, 15·75 and 33·40 of the prescribed dose, respectively, for 11 � 13, 11 � 17 and 11 � 21 cm2 field sizes. The corresponding dose values for dynamic wedge were 9·18, 12·92 and 29·26 of the prescribed dose, respectively. Moreover, the results showed that treatment field size and wedge type affect the received photon and thermal neutron doses at CB surface.Conclusion:According to our results, the total dose values received at CB surface during breast cancer radiotherapy with high-energy photon beams are remarkable. In addition, the dose values received at CB surface when using a physical wedge were greater than when using a dynamic wedge, especially for medial tangential fields. © Cambridge University Press 2019

Different Methods of Measuring Neutron Dose/Fluence Generated During Radiation Therapy with Megavoltage Beams

Medical linear accelerators (linacs) are the most frequently applied radiation therapy machines in the locoregional treatment of cancers by producing either high-energy electron or photon beams. However, with high-energy photons (>8 MeV), interaction of these photons with different high-Z nuclei of materials in components of the linac head unavoidably generates neutrons. On the other hand, the average energy of these generated neutrons has almost the highest radiation-weighting factor. Therefore, the produced neutrons should not be neglected. There are various tools for the measurement of neutron dose/fluence generated in a megavoltage linac, including thermoluminescent dosimeters, solid-state nuclear track detectors, bubble detectors, activation foils, Bonner sphere systems, and ionization chamber pairs. In this review article, each of the above-mentioned dosimetric methods will be described in detail

Measuring the dose�width product and proposing the local diagnostic reference level in panoramic dental radiography: a multi-center study from Iran

Objective: Although radiation exposure associated with dental radiography is relatively low, patient exposure must be kept practically low. Therefore, it is necessary for each country to establish its own diagnostic reference levels (DRLs) suitable for its equipment and practice. In the present study, dose-width product (DWP) values for panoramic dental radiography were measured and a local DRL was established. Methods: Five panoramic devices from five radiology clinics of Kashan, Iran were selected to measure the DWP values of panoramic dental radiography. To investigate the DWP values, the parameters of each patient�s exposure (e.g., tube voltage, tube current, and exposure time) at these five radiology clinics were extracted. Then, the dose value received by each patient was measured based on a CT pencil chamber. Finally, the overall median DWP values for the patients with small, medium, and large sizes were obtained, and these values were considered as the local DRLs for panoramic dental radiography. Results: A total of 99 adult patients were included in the present study. The findings demonstrated that the median and third-quartile DWP values for these five radiology clinics ranged from 42.3 to 94.3 and 49.7 to 142.8 mGy mm, respectively. The local DRL values, which were established as the overall median DWP values, were 43.4, 52.0, and 80.3 mGy mm for the adults with small, medium, and large sizes, respectively. Conclusion: The local DRL proposed in this study for the adult with standard/medium size was lower than those proposed by other reports and seemed acceptable for panoramic radiography in Kashan, Iran. © 2020, Japanese Society for Oral and Maxillofacial Radiology and Springer Nature Singapore Pte Ltd

Heme oxygenase-1 induction in hepatocytes and non-parenchymal cells protects against liver injury during endotoxemia

INTRODUCTION:Heme oxygenase-1 (HO-1) is a stress response enzyme, which catalyses the breakdown of heme into biliverdin-IX alpha, carbon monoxide and ferrous iron. Under situations of oxidative stress, heat stress, ischemia/reperfusion injury or endotoxemia, HO-1 has been shown to be induced and to elicit a protective effect. The mechanism of how this protective effect is executed is unknown.RESULTS:HO-1 induction with cobalt protoporphorin (Co-PP) dose-dependently protected against apoptotic cell death as well as neutrophil-mediated oncosis in the galactosamine/endotoxin (Gal/ET) shock model. Induction of HO-1 with Co-PP dose-dependently protected against neutrophil-mediated oncosis as indicated by attenuated ALT release and TNF-mediated apoptotic cell death as indicated by reduced caspase-3 activation. HO-1 induction did not attenuate Gal/ET-induced TNF-alpha formation. Furthermore, a similar protective effect with the high dose of Co-PP was observed when animals were treated with Gal/TNF-alpha.CONCLUSIONS:HO-1 induction attenuates apoptosis and neutrophil-mediated oncosis in the Gal/ET shock model. However, the protective effect is not due to the reduction of TNF-alpha release or the attenuation of neutrophil accumulation in the liver sinusoids.This item is part of the UA Faculty Publications collection. For more information this item or other items in the UA Campus Repository, contact the University of Arizona Libraries at [email protected]

Cancer stem cells (CSCs) in cancer progression and therapy

Cancer stem cells (CSCs) are self-renewable cell types that are identified in most types of liquid and solid cancers and contributed to tumor onset, expansion, resistance, recurrence, and metastasis after therapy. CSCs are identified from the expression of cell surface markers, which is tumor-type dependent. The transition between CSCs with cancer cells and other non-CSCs occurs in cancers, which is possibly under the control of signals from CSCs and tumor microenvironment (TME), including CSC niche. Cancer-associated fibroblasts are among the most influential cells for promoting both differentiation of CSCs and dedifferentiation of non-CSCs toward attaining a CSC-like phenotype. WNT/β-catenin, transforming growth factor-β, Hedgehog, and Notch are important signals for maintaining self-renewal in CSCs. An effective therapeutic strategy relies on targeting both CSCs and non-CSCs to remove a possible chance of tumor relapse. There are multiple ways to target CSCs, including immunotherapy, hormone therapy, (mi)siRNA delivery, and gene knockout. Such approaches can be designed for suppressing CSC stemness, tumorigenic cues from TME, CSC extrinsic and/or intrinsic signaling, hypoxia or for promoting differentiation in the cells. Because of sharing a range of characteristics to normal stem/progenitor cells, CSCs must be targeted based on their unique markers and their preferential expression of antigens. © 2018 Wiley Periodicals, Inc

Chest CT findings of COVID-19-infected patients, are there differences between pediatric and adult patients? A systematic review

Background: Purpose of this study was to deliver a report of chest CT findings of COVID-19-infected pediatric and adult patients and to make an age-based comparison. A systematic search was conducted in accordance with PRISMA guidelines to identify relevant studies in the electronic databases of PubMed, Scopus, ProQuest, ScienceDirect, and Web of Sciences from January 1, 2020 to March 27, 2020 using search terms in the titles and abstracts. Based on our inclusion and exclusion criteria, 762 articles were screened. Finally, 15 eligible articles which had adequate data on chest CT findings of COVID-19-infected patients were enrolled in this systematic review. Results: In pediatric patients (15 years old or younger), peripheral distribution was found in 100 of cases, ground glass opacities (GGO) in 55.2, bilateral involvement in 50, halo sign in 50, unilateral involvement in 30, consolidation in 22.2, crazy paving pattern in 20, nodular opacities in 15, pleural effusion in 4.2, lymphadenopathy in none, and normal imaging in 20.8 of cases. On the other hand, in adult patients, bilateral involvement was reported in 76.8, GGO in 68.4, peripheral distribution in 62.2, mixed GGO and consolidation in 48.7, consolidation in 33.7, crazy paving pattern in 27.7, mixed central and peripheral distribution in 25.0, unilateral involvement in 15.2, nodular opacities in 9.2, pleural effusion in 5.5, central distribution of lesions in 5.4, lymphadenopathy in 2.4, and normal imaging in 9.8 of cases. Conclusion: According to the findings of this systematic review, children infected with COVID-19 can present with normal or atypical findings (nodular opacities/unilateral involvement) in chest imaging more frequently than adult patients. Therefore, more caution should be taken to avoid misdiagnosis or missed diagnosis in infected children. Besides, clinical and laboratory findings need to be considered more decision-making for pediatric patients with normal or atypical chest CT scan but high suspicion of COVID-19. © 2020, The Author(s)

Oxidant-Antioxidant Status and Some Related Parameters in Hypertension Diabetic (Type 1&2) Patients - in Thi-Qar /Iraq

Hyperglycemia is considered a major initiator  of oxidative stress which lead to the formation of free radicals and consequently lipid peroxidation occurs that which lead to tissue damage and diabetes mellitus development. Therefore, the present study aims to investigate the relationship between antioxidant status and lipid peroxidation end products (malondialdehyde; MDA) and some trace elements in the plasma of 30 type 1 DM patients and 30 type 2 DM patients and 40 hypertension DM patients (20 type1 and 20 type2) and 30 non hypertension DM patients (15 type1 and15 type2) and 40 non diabetic healthy control subjects.Plasma MDA, chromium and ceruloplasmin  concentrations was measured by manual methods, whereas glucose, iron, copper, transferrin and albumin concentrations were analyzed spectrophotometrically by kits in all patients with DM as well as in the control subjects. The results of type1DM were compared with type2DM and hypertension-DM were compared with a non- hypertension DM and control group using One way ANOVA-test to compare parameters in different studied groups.The results show a significant elevation (P ≤ 0.05) in levels of glucose, MDA, iron, copper and ceruloplasmin of type 2- diabetic patients in comparison type 1-diabetic patients and healthy subjects, also, it has been found a significant decrease (P ≤ 0.05) in chromium, transferrin and albumin levels in type 2- diabetic patients in comparison with type 1- diabetic patients and control group. Also the results show a significant elevation (P ≤ 0.05) in levels of glucose, MDA, chromium, iron, copper and ceruloplasmin of (type1 and type 2) hypertension- diabetic patients in comparison (type 1and type2) non hypertension-diabetic patients and healthy subjects, also, it has been found a significant decrease (P ≤ 0.05) in transferrin and albumin levels (type1 and type 2) hypertension- diabetic patients in comparison (type1and type2) non hypertension-diabetic patients and healthy subjects