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Journal of Radiation Research Nov 2016The calculated risk of cancer in humans due to radiation exposure is based primarily on long-term follow-up studies, e.g. the life-span study (LSS) on atomic bomb... (Review)
Review
The calculated risk of cancer in humans due to radiation exposure is based primarily on long-term follow-up studies, e.g. the life-span study (LSS) on atomic bomb (A-bomb) survivors in Hiroshima and Nagasaki. Since A-bomb radiation consists of a mixture of γ-rays and neutrons, it is essential that the relative biological effectiveness (RBE) of neutrons is adequately evaluated if a study is to serve as a reference for cancer risk. However, the relatively small neutron component hampered the direct estimation of RBE in LSS data. To circumvent this problem, several strategies have been attempted, including dose-independent constant RBE, dose-dependent variable RBE, and dependence on the degrees of dominance of intermingled γ-rays. By surveying the available literature, we tested the chromosomal RBE of neutrons as the biological endpoint for its equivalence to the microdosimetric quantities obtained using a tissue-equivalent proportional counter (TEPC) in various neutron fields. The radiation weighting factor, or quality factor, Q, of neutrons as expressed in terms of the energy dependence of the maximum RBE, RBE, was consistent with that predicted by the TEPC data, indicating that the chromosomally measured RBE was independent of the magnitude of coexisting γ-rays. The obtained neutron RBE, which varied with neutron dose, was confirmed to be the most adequate RBE system in terms of agreement with the cancer incidence in A-bomb survivors, using chromosome aberrations as surrogate markers. With this RBE system, the cancer risk in A-bomb survivors as expressed in unit dose of reference radiation is equally compatible with Hiroshima and Nagasaki cities, and may be potentially applicable in other cases of human radiation exposure.
Topics: Chromosomes; Dose-Response Relationship, Radiation; Humans; Japan; Leukemia, Radiation-Induced; Neoplasms, Radiation-Induced; Neutrons; Nuclear Warfare; Radiation Dosage; Radiometry; Relative Biological Effectiveness; Risk; Treatment Outcome; World War II
PubMed: 27614201
DOI: 10.1093/jrr/rrw079 -
Journal of Radiation Research Mar 2022Intestinal organoids are an in vitro cultured tissue model generated from intestinal stem cells, and they contain a mixture of epithelial cell types. We previously...
Intestinal organoids are an in vitro cultured tissue model generated from intestinal stem cells, and they contain a mixture of epithelial cell types. We previously established an efficient 'one cell/well' sorting method, and defined organoid-forming potential (OFP) as a useful index to evaluate the stemness of individual cells. In this study, we assessed the response to radiation dose and dose-rate by measuring both OFP and the percentage of stem cells in the crypts. After high-dose-rate (HDR, 0.5 Gy/min) irradiation in vivo, the percentage of stem cells in the harvested crypt cells decreased, and the replenishment of cycling stem cells originating from dormant cells was enhanced, but OFP increased in cells irradiated with a total dose of >1 Gy. In contrast, at a total dose of 0.1 Gy the percentage of stem cells reduced slightly, but neither replenishment rate nor OFP changed. Furthermore, the response to 1 Gy of low-dose-rate (LDR) irradiation was similar to the response to 0.1 Gy HDR irradiation. These results suggest that 0.1 Gy HDR irradiation or 1 Gy LDR irradiation does not alter stemness. Additionally, the OFP increase in the colon in response to irradiation was smaller than that in the duodenum, similar to the percentage of stem cells. Understanding the differences in the response of stem cells between the colon and the duodenum to radiation is important to clarify the mechanisms underlying the development of radiation-associated intestinal cancers.
Topics: Dose-Response Relationship, Radiation; Intestines; Organoids; Radiation Dosage; Radiation, Ionizing; Stem Cells
PubMed: 34977948
DOI: 10.1093/jrr/rrab120 -
Journal of Interventional Cardiac... Jun 2022
Topics: Cardiac Electrophysiology; Fluoroscopy; Humans; Radiation Dosage
PubMed: 35258751
DOI: 10.1007/s10840-022-01173-5 -
JACC. Cardiovascular Interventions Oct 2016
Topics: Coronary Artery Disease; Endovascular Procedures; Humans; Occupational Exposure; Radiation Dosage; Radiography, Interventional
PubMed: 27639900
DOI: 10.1016/j.jcin.2016.08.001 -
Radiation Research Apr 1992The transfer of energy from ionizing radiation to matter involves a series of steps. In wide ranges of their energy spectra photons and neutrons transfer energy to an...
The transfer of energy from ionizing radiation to matter involves a series of steps. In wide ranges of their energy spectra photons and neutrons transfer energy to an irradiated medium almost exclusively by the production of charged particles which ionize and thereby produce electrons that can ionize in turn. The examination of these processes leads to a series of intermediate quantities. One of these is kerma, which has long been employed as a measure of the energy imparted in the first of the interactions. It depends only on the fluence of uncharged particles and is therefore--unlike absorbed dose and electron fluence--insensitive to local differences of receptor geometry and composition. An analogous quantity for charged-particle fields, cema (converted energy per unit mass), is defined, which quantifies the energy imparted in terms of the interactions of charged particles, disregarding energy dissipation by secondary electrons. Cema can be expressed as an integral over the fluence of ions times their stopping power. However, complications arise when the charged particles are electrons, and when their fluence cannot be separated from that of the secondaries. The resulting difficulty can be circumvented by the definition of reduced cema. This quantity corresponds largely to the concept employed in the cavity theory of Spencer and Attix. In reduced cema not all secondary electrons but all electrons below a chosen cutoff energy, delta, are considered to be absorbed locally. When the cutoff energy is reduced, cema approaches absorbed dose and thereby becomes sensitive to highly local differences in geometry or composition. With larger values of delta, reduced cema is a useful parameter to specify the dose-generating potential of a charged-particle field 'free in air' or in vacuo. It is nearly equal to the mean absorbed dose in a sphere with radius equal to the range of electrons of energy delta. Reduced cema is a function of the fluence at the specified location at and above the chosen cutoff energy. Its definition requires a modification of restricted linear collision stopping power, L delta, and it is recommended that the definition of L delta be so changed.
Topics: Models, Theoretical; Radiation Dosage; Radiometry
PubMed: 1561314
DOI: No ID Found -
Journal of Medical Radiation Sciences Dec 2018This editorial is discussing about the indiscriminate use of abdominal radiographs in the emergency department in general, with focus on value of the erect abdominal...
This editorial is discussing about the indiscriminate use of abdominal radiographs in the emergency department in general, with focus on value of the erect abdominal radiograph for the diagnosis of mechanical bowel obstruction and paralytic ileus.
Topics: Emergency Service, Hospital; Humans; Radiation Dosage; Radiography, Abdominal
PubMed: 30506851
DOI: 10.1002/jmrs.307 -
Journal of Medical Radiation Sciences Mar 2023This editorial examines current collimation and cropping practices in general radiography. We critically reflect on whether we are concerned by the practice of...
This editorial examines current collimation and cropping practices in general radiography. We critically reflect on whether we are concerned by the practice of collimation creep amongst radiographers. Discussions around policy, evidence‐based practice and potential hypocrisies are outlined in this editorial piece.
Topics: Radiography; Phantoms, Imaging; Radiation Dosage
PubMed: 36608354
DOI: 10.1002/jmrs.648 -
Journal of the American Heart... Feb 2021
Topics: Cardiologists; Cardiology; Female; Humans; Radiation Dosage
PubMed: 33618547
DOI: 10.1161/JAHA.120.019431 -
Journal of Radiological Protection :... May 2024The aim of this study is to propose diagnostic reference levels (DRLs) values for mammography in Switzerland. For the data collection, a survey was conducted among a...
The aim of this study is to propose diagnostic reference levels (DRLs) values for mammography in Switzerland. For the data collection, a survey was conducted among a sufficient number of centres, including five University hospitals, several cantonal hospitals, and large private clinics, covering all linguistic regions of Switzerland to be representative of the clinical practice. The data gathered contained the mean glandular dose (MGD), the compressed breast thickness (CBT), the mammography model and the examination parameters for each acquisition. The data collected was sorted into the following categories: 2D or digital breast tomosynthesis (DBT) examination, craniocaudal (CC) or mediolateral oblique (MLO) projection, and eight categories of CBT ranging from 20 mm to 100 mm in 10 mm intervals. A total of 24 762 acquisitions were gathered in 31 centres on 36 mammography units from six manufacturers. The analysis showed that the data reflects the practice in Switzerland. The results revealed that the MGD is larger for DBT than for 2D acquisitions for the same CBT. From 20-30 mm to 90-100 mm of CBT, the 75th percentile of the MGD values obtained increased from 0.81 mGy to 2.55 mGy for 2D CC acquisitions, from 0.83 mGy to 2.96 mGy for 2D MLO acquisitions, from 1.22 mGy to 3.66 mGy for DBT CC acquisitions and from 1.33 mGy to 4.04 mGy for DBT MLO acquisitions. The results of the survey allow us to propose Swiss DRLs for mammography according to the examination type (2D/DBT), projection (CC/MLO) and CBT. The proposed values are very satisfactory in comparison with other studies.
Topics: Mammography; Switzerland; Humans; Female; Radiation Dosage; Diagnostic Reference Levels; Breast Neoplasms; Reference Values
PubMed: 38530290
DOI: 10.1088/1361-6498/ad37c8 -
Journal of Nuclear Medicine : Official... May 1992
Topics: Animals; Blood Platelets; Humans; Indium Radioisotopes; Models, Theoretical; Radiation Dosage; Radiation Protection
PubMed: 1569491
DOI: No ID Found