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Radiation and Environmental Biophysics Aug 2020Many experimental studies are carried out to compare biological effectiveness of high dose rate (HDR) with that of low dose rate (LDR). The rational for this is the...
Many experimental studies are carried out to compare biological effectiveness of high dose rate (HDR) with that of low dose rate (LDR). The rational for this is the uncertainty regarding the value of the dose rate effectiveness factor (DREF) used in radiological protection. While a LDR is defined as 0.1 mGy/min or lower, anything above that is seen as HDR. In cell and animal experiments, a dose rate around 1 Gy/min is usually used as representative for HDR. However, atomic bomb survivors, the reference cohort for radiological protection, were exposed to tens of Gy/min. The important question is whether gamma radiation delivered at very high dose rate (VHDR-several Gy/min) is more effective in inducing DNA damage than that delivered at HDR. The aim of this investigation was to compare the biological effectiveness of gamma radiation delivered at VHDR (8.25 Gy/min) with that of HDR (0.38 Gy/min or 0.79 Gy/min). Experiments were carried out with human peripheral mononuclear cells (PBMC) and the human osteosarcoma cell line U2OS. Endpoints related to DNA damage response were analysed. The results show that in PBMC, VHDR is more effective than HDR in inducing gene expression and micronuclei. In U2OS cells, the repair of 53BP1 foci was delayed after VHDR indicating a higher level of damage complexity, but no VHDR effect was observed at the level of micronuclei and clonogenic cell survival. We suggest that the DREF value may be underestimated when the biological effectiveness of HDR and LDR is compared.
Topics: Adult; Cell Line; Cesium Radioisotopes; DNA Damage; Dose-Response Relationship, Radiation; Female; Gamma Rays; Humans; Leukocytes, Mononuclear; Micronuclei, Chromosome-Defective; Radiation Protection; Relative Biological Effectiveness; Young Adult
PubMed: 32488310
DOI: 10.1007/s00411-020-00852-z -
Physics in Medicine and Biology Jun 2021Cancer radiotherapy (RT) with the irradiation at ultra-high dose rates, namely FLASH-RT, can substantially reduce radiation-induced normal tissue toxicities while...
Cancer radiotherapy (RT) with the irradiation at ultra-high dose rates, namely FLASH-RT, can substantially reduce radiation-induced normal tissue toxicities while maintaining tumor response. Currently, clinical FLASH-RT on deep-seated tumors can only be performed with proton beams. One way to achieve ultra-high dose rates at depth is through the use of high-energy transmission beams (TB), where the Bragg peaks (BP) fall outside the body. However, planning with TB alone does not fully leverage the degrees of freedom for dose shaping as traditional intensity modulated proton therapy (IMPT) which uses the BP of multi-energy proton beams at the tumor target. This work will develop a simultaneous dose and dose rate optimization (SDDRO) method with the joint use of TB and BP, namely SDDRO-Joint. Specifically, BP are placed inside tumor targets to improve the target dose conformality and sparse the normal-tissue dose, while TB primarily cover the tumor boundary to achieve ultra-high dose rate coverage of organs-at-risk (OAR) close to tumor targets. The sparing of OAR and other normal tissues via SDDRO-Joint is jointly by TB and BP, i.e. the FLASH sparing by TB and the dose sparing by BP. The results suggest that the addition of BP substantially increased the target dose conformality for SDDRO. Noticeably SDDRO-Joint also provided slightly higher conformal index values than the conventional IMPT method with BP alone.
Topics: Organs at Risk; Proton Therapy; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted; Radiotherapy, Intensity-Modulated
PubMed: 34010818
DOI: 10.1088/1361-6560/ac02d8 -
Medicine Sep 2022Aim of the study was to evaluate the effect of high and irregular heart rate on the image quality and on the radiation exposure using a 256-row, 16-cm wide detector...
Aim of the study was to evaluate the effect of high and irregular heart rate on the image quality and on the radiation exposure using a 256-row, 16-cm wide detector computed tomography (CT) system. Between March and December 2019, 349 patients undergoing CT coronary angiography (CTCA) were prospectively enrolled. Patients were divided into 2 study groups; Group 1 included patients with a regular heart rate of ≤70 bpm, while Group 2 included patients with an irregular heart rhythm or heart rate of >70 bpm. In all patients, image quality score and radiation dose were analyzed and recorded. In Group 1, there were a total of 195 patients, while in Group 2, there were 154 patients. Of the 349 patients, 299 of them had a regular heart rhythm (85.7%) and 50 (14.3%) had an irregular heart rhythm. Mean heart rate during scanning was 59 ± 7 bpm in Group 1 and 80 ± 12 bpm in Group 2. Mean effective dose of CTCA in Group 1 (1.2 ± 0.8 mSv) was lower than in Group 2 (1.9 ± 1.2 mSv, P < .001). Mean image quality (Likert score) of Group 1 was significantly higher than in Group 2 (4.1 vs 3.4, P < .001). CT scanner with 16-cm wide detector enables low-radiation exposure during CTCA even at high heart rate or irregular heart rhythm. Good CTCA image quality and low dose are related to low heart rate.
Topics: Coronary Angiography; Heart Rate; Humans; Radiation Dosage; Tomography Scanners, X-Ray Computed; Tomography, X-Ray Computed
PubMed: 36123855
DOI: 10.1097/MD.0000000000030583 -
Cancers May 2024To explore the most suitable dosage regimen for limited-stage small cell lung cancer (LS-SCLC) and provide references for clinical selection, strict inclusion criteria... (Review)
Review
To explore the most suitable dosage regimen for limited-stage small cell lung cancer (LS-SCLC) and provide references for clinical selection, strict inclusion criteria were applied, and studies were screened from Pubmed, Embase, and Web of Science. Subsequently, data on two-year overall survival rates and dosage regimens were collected, and scatter plots were constructed to provide a comprehensive perspective. The survival benefits of various dosage regimens were evaluated, and a linear quadratic equation was utilized to fit the relationship between the biologically effective dose (BED10) and the two-year overall survival rate. Among the five randomized controlled trials, the two-year overall survival rate of ConvTRT regimens with BED10 > 60 Gy (rough value) was only at or below the median of all ConvTRT regimens or all included study regimens, indicating that increasing the number and total dose of ConvTRT does not necessarily lead to better prognosis. In the exploration of HypoTRT regimens, there was a linear positive correlation between BED10 and the two-year overall survival rate ( < 0.0001), while the exploration of HyperTRT regimens was relatively limited, with the majority focused on the 45 Gy/30 F regimen. However, the current 45 Gy/30 F regimen is not sufficient to control LS-SCLC, resulting in a high local recurrence rate. High-dose ConvTRT regimens have long treatment durations and may induce tumor regrowth which may cause reduced efficacy. Under reasonable toxicity reactions, HyperTRT or HypoTRT with higher radiotherapy doses is recommended for treating LS-SCLC.
PubMed: 38791986
DOI: 10.3390/cancers16101908 -
Journal of Dairy Science Nov 2021Transition dairy cows experience a decline in immune function that increases the risk of peripartum disease. One strategy to improve peripartum immune function involves...
Transition dairy cows experience a decline in immune function that increases the risk of peripartum disease. One strategy to improve peripartum immune function involves the use of a commercially available cytokine: bovine granulocyte-colony stimulating factor, with the addition of polyethylene glycol to increase duration of effectiveness. Treatment with Imrestor (15 mg pegbovigrastim; Elanco) one week before expected calving date (d -7) and again on the day of calving (d 0) was previously reported to increase the neutrophil number and improve neutrophil function; as a result, the incidence of clinical mastitis was reduced. We conducted 2 experiments over consecutive years to investigate the effect of a lower dose rate (half or quarter dose rate) of Imrestor in grazing dairy cattle and reduced administration frequency: one dose instead of the recommended 2. White blood cell counts were measured to determine changes in relative cell populations in response to treatment. Neutrophil function was assessed by measuring myeloperoxidase activity. Imrestor treatment increased the numbers of neutrophils, band cells, lymphocytes, and monocytes until 14 d postcalving in a dose-dependent manner; it also increased neutrophil myeloperoxidase activity. One dose of Imrestor increased white blood cell counts and myeloperoxidase activity, but the timing, degree, and duration of the response were different relative to the recommended 2 doses and were also dependent upon when Imrestor treatment was given. One dose at d -7 relative to expected calving date did not have a lasting effect postcalving, whereas one dose only on d 0 caused a delayed effect relative to cows that received 2 doses. There was no effect of Imrestor on milk yield or on blood indicators of transition cow health. A lower dose rate of Imrestor or a single dose of Imrestor on the day of calving may be sufficient to improve neutrophil function during the early postpartum in grazing dairy cows. Large-scale field studies are required to determine whether the smaller response from lower dose rates or the timing of the immunological response to drug delivery affect animal health in early lactation.
Topics: Animals; Cattle; Female; Granulocyte Colony-Stimulating Factor; Lactation; Milk; Neutrophils; Recombinant Proteins
PubMed: 34419282
DOI: 10.3168/jds.2021-20630 -
Journal of Contemporary Brachytherapy Jun 2021The aim of this study was to evaluate the efficacy and vision-threatening complications of brachytherapy with ruthenium-106 (Ru) plaque to treat uveal melanoma. (Review)
Review
PURPOSE
The aim of this study was to evaluate the efficacy and vision-threatening complications of brachytherapy with ruthenium-106 (Ru) plaque to treat uveal melanoma.
MATERIAL AND METHODS
A literature review was performed based on results from searching PubMed, Embase, Web of Science, Scopus, and Cochrane databases, using the following key words: "choroidal melanoma", "uveal melanoma", "brachytherapy", and "ruthenium-106". We included studies performed on more than 30 patients since 1986, reporting on local control rate, complications rate, mean radiation dose, and mean tumor thickness. The cumulative analysis was performed using Metaprop command of Stata v.16, and meta-regression was conducted based on mean tumor thickness and mean radiation dose to tumor's apex.
RESULTS
Twenty-one retrospective studies were selected, involving 3,913 patients treated primarily with Ru plaque brachytherapy. The range of radiation dose to tumor apex was from 70 Gy to 250 Gy. The local control rate following brachytherapy ranged from 59% to 98%, and the overall weighted mean of local control was 84%. However, the heterogeneity between studies' reports was remarkable ( = 95.40%). Meta-regression based on tumor thickness and mean dose of radiation to the apex showed that the studies' heterogeneity was minimally related to the difference in mean tumor size ( = 92%). The correlation between larger tumor size and lower local control rate was statistically significant (-value = 0.024). There was no significant correlation between the mean radiation dose and local control rate (-value = 0.679). The most commonly reported complications were cataract and radiation-related retinopathy.
CONCLUSIONS
Although the studies' heterogeneity was high, in a prescription dose ranging from 70 Gy to 250 Gy to the tumor apex, Ru brachytherapy seems to be successful in local control of uveal melanoma. The efficacy of Ru in controlling uveal melanomas decreased with the increase in tumor thickness. However, these outcomes should be verified in randomized comparative studies.
PubMed: 34122577
DOI: 10.5114/jcb.2021.106191 -
Clinical Infectious Diseases : An... Feb 2023Growing evidence indicates a causal relationship between SARS-CoV-2 infection and myocarditis. Post-authorization safety data have also identified myocarditis as a rare...
BACKGROUND
Growing evidence indicates a causal relationship between SARS-CoV-2 infection and myocarditis. Post-authorization safety data have also identified myocarditis as a rare safety event following mRNA COVID-19 vaccination, particularly among adolescent and young-adult males after dose 2. We further evaluated the potential risk by querying the Moderna global safety database for myocarditis/myopericarditis reports among mRNA-1273 recipients worldwide.
METHODS
Myocarditis/myopericarditis reports from 18 December 2020 to 15 February 2022 were reviewed and classified. The reported rate after any known mRNA-1273 dose was calculated according to age and sex, then compared with a population-based incidence rate to calculate observed-to-expected rate ratios (RRs).
RESULTS
During the study period, 3017 myocarditis/myopericarditis cases among 252 million mRNA-1273 recipients who received at least 1 dose were reported to the Moderna global safety database. The overall reporting rate was 9.23 per 100 000 person-years, which was similar to the expected reference rate (9.0 cases per 100 000 person-years; RR [95% confidence interval (CI)], 1.03 [.97-1.08]). When stratified by sex and age, observed rates were highest for males aged <40 years, particularly those 18-24 years (53.76 per 100 000 person-years), which was higher than expected (RR [95% CI], 3.10 [2.68-3.58]). When considering only cases occurring within 7 days of a known dose, the observed rate was highest for males aged 18-24 years after dose 2 (4.23 per 100 000 doses administered).
CONCLUSIONS
Myocarditis/myopericarditis rates were not higher than expected for the overall population of mRNA-1273 recipients but were higher than expected in males aged 18-24 years, with most cases occurring 7 days after dose 2.
Topics: Adolescent; Adult; Male; Humans; 2019-nCoV Vaccine mRNA-1273; COVID-19; COVID-19 Vaccines; Myocarditis; SARS-CoV-2; Vaccination
PubMed: 35666513
DOI: 10.1093/cid/ciac446 -
Clinical Ophthalmology (Auckland, N.Z.) 2023The combination between sedatives and opioids is one of the recommended anesthetic options in ophthalmic procedures and regimens are more advantageous as smaller amounts...
BACKGROUND
The combination between sedatives and opioids is one of the recommended anesthetic options in ophthalmic procedures and regimens are more advantageous as smaller amounts of each drug can be administered to reduce side effects and have proper outcomes due to the synergistic effects. This study aims to observe the use of low-dose propofol and fentanyl for patients undergoing phacoemulsification surgery.
MATERIAL AND METHODS
This observational study involves a sample of 125 adult patients who underwent elective cataract procedures using the phacoemulsification technique and had an American Society of Anesthesiologists (ASA) physical status of 1 to 3. Dose amount of fentanyl and propofol, Ramsay score, hemodynamic parameter, side effects, and patient satisfaction were evaluated, recorded, and analyzed using a 5-point Likert scale.
RESULTS
The result showed the mean absolute dose of propofol was 12.46±4.376 mg, with a range between 10 and 30 mg, while the mean per body weight was 0.21±0.075 mg. Similarly, the mean absolute dose for fentanyl was 25.04±3.012 mcg within the range of 10-50 mcg, and the per-body weight dose was 0.43±0.080 mcg. About 90.4% and 9.6% of the patients reached Ramsay 2 and 3, respectively. The analysis of systolic, diastolic blood pressure, mean arterial pressure, and pulse rate showed that the combination of low-dose fentanyl and propofol was significantly lower than before therapy administration in all four values (p < 0.05).
CONCLUSION
The combination of low-dose propofol and fentanyl in cataract surgery using phacoemulsification successfully reached the targeted sedation level and a significant decrease in blood pressure, MAP, pulse rate, minimal side effects, and high satisfaction rate.
PubMed: 37431431
DOI: 10.2147/OPTH.S415852 -
Journal of Medical Virology Jun 2022We analyzed published studies on the efficacy and safety of the third dose of the COVID-19 vaccine in various general population settings. We conducted systematic...
We analyzed published studies on the efficacy and safety of the third dose of the COVID-19 vaccine in various general population settings. We conducted systematic searches of PubMed and EMBASE for series published in the English language through November 15, 2021, using the search terms "third" or "booster" or "three" and "dose" and "COVID-19" or "SARS-CoV-2." All articles were selected according to the MOOSE guidelines. The seroconversion risk after third doses was descriptively expressed as a pooled rate ratio ([seroconversion rate after the third dose]/[seroconversion rate after the second dose]). The search returned 30 studies that included a total of 2 734 437 vaccinated subjects. In more than 2 700 000 Israeli patients extracted from the general population, the reduction in the risk of infection ranged from 88% to 92%. Conversion rates for IgG anti-spike ranged from 95% to 100%. In cancer or immunocompromised patients, mean IgG seroconversion was 39.4% before and 66.6% after third doses. A third dose seems necessary to protect against all COVID-19 infection, severe disease, and death risk.
Topics: Antibodies, Viral; COVID-19; COVID-19 Vaccines; Humans; Immunoglobulin G; SARS-CoV-2; Seroconversion
PubMed: 35118680
DOI: 10.1002/jmv.27644 -
Journal of Environmental Radioactivity Oct 2022In this paper, we have developed a methodology to estimate the spatiotemporal distribution of radiation air dose rates around the Fukushima Daiichi Nuclear Power Plant...
In this paper, we have developed a methodology to estimate the spatiotemporal distribution of radiation air dose rates around the Fukushima Daiichi Nuclear Power Plant (FDNPP). In our exploratory data analysis, we found that (1) the temporal evolution of dose rates is composed of a log-linear decay trend and fluctuations of air dose rates that are spatially correlated among adjacent monitoring posts; and (2) the slope of the log-linear environmental decay trend can be represented as a function of the apparent initial dose rates, coordinate position, land-use type, and soil type. From these observations, we first estimated the log-linear decay trend at each location based on these predictors, using the random forest method. We then developed a modified Kalman filter coupled with a Gaussian process model to estimate the dose-rate time series at a given location and time. We applied this method to the Fukushima evacuation zone (as of March 2017), which included 17 monitoring post locations (with monitoring datasets collected between 2014 and 2018) and generated a time series of dose-rate maps. Our results show that this approach allows us to produce accurate spatial and temporal predictions of radiation dose-rate maps using limited spatiotemporal measurements.
Topics: Air Pollutants, Radioactive; Cesium Radioisotopes; Fukushima Nuclear Accident; Japan; Nuclear Power Plants; Radiation Dosage; Radiation Monitoring
PubMed: 35752033
DOI: 10.1016/j.jenvrad.2022.106946