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Dento Maxillo Facial Radiology May 2021This study was conducted to assess the impact of tube voltage on ambient dose during intraoral radiography, specifically remnant-beam transmission and scattered...
OBJECTIVES
This study was conducted to assess the impact of tube voltage on ambient dose during intraoral radiography, specifically remnant-beam transmission and scattered radiation.
METHODS AND MATERIALS
Remnant-beam and scattered radiation doses were recorded using a phantom at tube voltages of 60, 63, 66 and 70 kV. Mathematical equations depicting their relations were then formulated, and reference values were calculated at the various voltages tested. Total ambient doses per exposure at 60 kV and at 70 kV were compared.
RESULTS
Both remnant-beam transmission and scattered radiation increased ~40% by increasing tube voltage from 60 kV to 70 kV, and the relation was linear. A remnant beam transmission reference value of 7.5% was established at 70 kV, as well as a conversion factor of 0.035 µSv/mAs at 1 m for scattered radiation at 60 kV. Given longer exposure times at 60 kV, total ambient dose proved higher at 60 kV than at 70 kV.
CONCLUSION
Higher tube voltage results in higher remnant-beam transmission and more scattered radiation per workload. The relation is linear in the range between 60kV and 70 kV. Remnant-beam transmission at 70 kV is safely assessed at 7.5%. A conversion factor at 60 kV of 0.035 µSv/mAs at 1 m for the scattered radiation dose can be proposed. Total ambient dose per exposure was higher at 60kV than at 70 kV.
Topics: Humans; Phantoms, Imaging; Radiation Dosage; Radiography
PubMed: 33180551
DOI: 10.1259/dmfr.20190362 -
International Journal of Radiation... Jul 2021
Topics: Humans; Organs at Risk; Radiation Dosage; Radiobiology; Radiotherapy Dosage; Technology
PubMed: 33548337
DOI: 10.1016/j.ijrobp.2021.01.053 -
Chemico-biological Interactions Mar 2019The linear no-threshold (LNT) model is currently used to estimate low dose radiation (LDR) induced health risks. This model lacks safety thresholds and postulates that... (Review)
Review
The linear no-threshold (LNT) model is currently used to estimate low dose radiation (LDR) induced health risks. This model lacks safety thresholds and postulates that health risks caused by ionizing radiation is directly proportional to dose. Therefore even the smallest radiation dose has the potential to cause an increase in cancer risk. Advances in LDR biology and cell molecular techniques demonstrate that the LNT model does not appropriately reflect the biology or the health effects at the low dose range. The main pitfall of the LNT model is due to the extrapolation of mutation and DNA damage studies that were conducted at high radiation doses delivered at a high dose-rate. These studies formed the basis of several outdated paradigms that are either incorrect or do not hold for LDR doses. Thus, the goal of this review is to summarize the modern cellular and molecular literature in LDR biology and provide new paradigms that better represent the biological effects in the low dose range. We demonstrate that LDR activates a variety of cellular defense mechanisms including DNA repair systems, programmed cell death (apoptosis), cell cycle arrest, senescence, adaptive memory, bystander effects, epigenetics, immune stimulation, and tumor suppression. The evidence presented in this review reveals that there are minimal health risks (cancer) with LDR exposure, and that a dose higher than some threshold value is necessary to achieve the harmful effects classically observed with high doses of radiation. Knowledge gained from this review can help the radiation protection community in making informed decisions regarding radiation policy and limits.
Topics: Dose-Response Relationship, Radiation; Humans; Linear Models; Models, Statistical; Radiation Dosage; Risk Assessment
PubMed: 30763548
DOI: 10.1016/j.cbi.2018.11.013 -
Radiography (London, England : 1995) Jul 2023As weights among neonates can vary from <900 g to >2.5 kg, weight-based Diagnostic Reference Levels (DRLs) specific to the neonatal intensive care unit (NICU) are...
INTRODUCTION
As weights among neonates can vary from <900 g to >2.5 kg, weight-based Diagnostic Reference Levels (DRLs) specific to the neonatal intensive care unit (NICU) are essential. Repeated radiation exposure to this sensitive patient group raises concerns regarding high cumulative radiation doses and the potential for long-term health detriment. This study aimed to establish weight-based DRLs for neonates undergoing mobile chest radiography (CXR) in the NICU.
METHODS
Neonates were classified into three discrete groups; <1000, 1000-2500 and >2500 g. Data were collected prospectively over three months; 95 DAP values were collected, and five were excluded due to poor technique, leaving 90 patients that met the inclusion criteria for mobile CXR in the NICU. Dose-area-product (DAP) in mGycm, the peak kilovoltage (kVp) and the product of tube current and exposure time (mAs) were retrieved from the Picture Archiving and Communication System (PACS). Images and radiological reports were also analysed to confirm diagnostic image quality (IQ). Local DRLs (LDRLs) were derived using the median DAP, and national DRLs were suggested using the 3rd quartile value.
RESULTS
The proposed LDRLs for neonates weighing <1000 g was 2.7 mGycm, for neonates weighing between 1000 g and 2500 g, it was 3.7 mGycm, and for neonates weighing >2500 g it was 6.6 mGycm. The radiation dose received by the 90 (100%) neonates included in the study fell below 11.4 mGycm; of these, 82% of the DAP values fell below the study institution's existing LDRL of 7.25 mGycm.
CONCLUSION
Weight-based DRLs provide crucial information on doses to this specific radiation-sensitive group. This work recommends using weight-based categories for DRLs and serves as a benchmark for neonatal CXR standardisation and optimisation.
IMPLICATIONS FOR PRACTICE
The proposed weight-based DRLs can be adopted for neonates' locally, nationally and internationally.
Topics: Infant, Newborn; Humans; Diagnostic Reference Levels; Radiation Dosage; X-Rays; Radiography; Reference Standards
PubMed: 37276688
DOI: 10.1016/j.radi.2023.05.012 -
Environmental Health Perspectives Jun 1997The health effects of radiation have been a focus for research since early in the 20th century. As the century ends, extensive experimental and epidemiologic evidence... (Review)
Review
The health effects of radiation have been a focus for research since early in the 20th century. As the century ends, extensive experimental and epidemiologic evidence has been accumulated that addresses the adverse consequences of radiation exposure; epidemiologic studies of radiation-exposed groups from the general population and specific occupational groups provide quantitative estimates of the cancer risks associated with exposure. This report provides a perspective on the extensive epidemiologic evidence on the health effects of ionizing radiation and on likely needs for further epidemiologic research on radiation and health. Epidemiologic studies have proved informative on the quantitative risks of radiation-caused cancer but we now face the challenges of more precisely characterizing risks at lower levels of exposure and also of assessing modifiers of the risks, including dose rate, genetic susceptibility, and other environmental exposures. This report considers investigative approaches, such as pooled analysis of multiple data sets, that can be used to address these complex questions and the limitations of these approaches for addressing societal concerns about the risks of radiation exposure.
Topics: Dose-Response Relationship, Radiation; Humans; Neoplasms, Radiation-Induced; Radiation Dosage; Risk
PubMed: 9255575
DOI: 10.1289/ehp.97105s4883 -
Journal of Radiation Research 2011Exposure to radiation is one of the main concerns for space exploration by humans. By focusing deliberately on the works performed on human cells, we endeavored to... (Review)
Review
Exposure to radiation is one of the main concerns for space exploration by humans. By focusing deliberately on the works performed on human cells, we endeavored to review, decade by decade, the technological developments and conceptual advances of space radiation biology. Despite considerable efforts, the cancer and the toxicity risks remain to be quantified: 1) the nature and the frequency of secondary heavy ions need to be better characterized in order to estimate their contribution to the dose and to the final biological response; 2) the diversity of radiation history of each astronaut and the impact of individual susceptibility make very difficult any epidemiological analysis for estimating hazards specifically due to space radiation exposure. 3) Cytogenetic data undoubtedly revealed that space radiation exposure produce significant damage in cells. However, our knowledge of the basic mechanisms specific to low-dose, to repeated doses and to adaptive response is still poor. The application of new radiobiological techniques, like immunofluorescence, and the use of human tissue models different from blood, like skin fibroblasts, may help in clarifying all the above items.
Topics: Astronauts; Cosmic Radiation; Cytogenetics; DNA Damage; Fibroblasts; Heavy Ions; History, 20th Century; History, 21st Century; Humans; Microscopy, Fluorescence; Radiation Dosage; Radiobiology; Relative Biological Effectiveness; Space Flight
PubMed: 21436608
DOI: 10.1269/jrr.10128 -
Journal of Radiation Research Mar 2009The prevailing dogma for radiation biology is that genotoxic effects of ionizing radiation such as mutations and carcinogenesis are attributed mainly to direct damage to... (Review)
Review
The prevailing dogma for radiation biology is that genotoxic effects of ionizing radiation such as mutations and carcinogenesis are attributed mainly to direct damage to the nucleus. However, with the development of microbeam that can target precise positions inside the cells, accumulating evidences have shown that energy deposit by radiation in nuclear DNA is not required to trigger the damage, extra-nuclear or extra-cellular radiation could induce the similar biological effects as well. This review will summarize the biological responses after cytoplasm irradiated by microbeam, and the possible mechanisms involved in cytoplasmic irradiation.
Topics: Animals; Bystander Effect; Cytoplasm; Dose-Response Relationship, Radiation; Humans; Radiation Dosage
PubMed: 19346686
DOI: 10.1269/jrr.08120s -
Journal of Radiation Research Apr 2018In order to quantify radiation risks at exposure scenarios relevant for radiation protection, often extrapolation of data obtained at high doses and high dose rates down... (Review)
Review
In order to quantify radiation risks at exposure scenarios relevant for radiation protection, often extrapolation of data obtained at high doses and high dose rates down to low doses and low dose rates is needed. Task Group TG91 on 'Radiation Risk Inference at Low-dose and Low-dose Rate Exposure for Radiological Protection Purposes' of the International Commission on Radiological Protection is currently reviewing the relevant cellular, animal and human studies that could be used for that purpose. This paper provides an overview of dose rates and doses typically used or present in those studies, and compares them with doses and dose rates typical of those received by the A-bomb survivors in Japan.
Topics: Animals; Dose-Response Relationship, Radiation; Humans; Occupational Exposure; Radiation Dosage; Radioactive Pollutants; Risk Factors
PubMed: 29432579
DOI: 10.1093/jrr/rrx093 -
Practical Radiation Oncology 2024
Topics: Humans; Radiation Dosage; Radiotherapy
PubMed: 37657504
DOI: 10.1016/j.prro.2023.08.009 -
Journal of Nuclear Medicine : Official... Oct 2023
Topics: Pamphlets; Radiation Dosage; Radiometry
PubMed: 37562805
DOI: 10.2967/jnumed.123.266325