Comparison of Dose–Response Curves between EBT-XD and EBT3 Radiochromic Films at High Dose Range (2000–4500 cGy) for a 175 MeV Proton Beam

2021 ◽  
Vol 18 (6) ◽  
pp. 691-699
Author(s):  
D. M. Borowicz ◽  
M. Kruszyna-Mochalska ◽  
K. Shipulin ◽  
A. Molokanov ◽  
G. Mytsin ◽  
...  
2018 ◽  
Vol 45 (1) ◽  
pp. 146-159 ◽  
Author(s):  
Valentina Anechitei-Deacu ◽  
Alida Timar-Gabor ◽  
Daniela Constantin ◽  
Oana Trandafir-Antohi ◽  
Laura Del Valle ◽  
...  

Abstract SAR-OSL dating studies of Romanian, Serbian and Chinese loess using fine and coarse quartz have previously resulted in a series of controversial issues. We extend here the investigations using fine (4–11 μm) and different coarse quartz (>63 μm) grains extracted from aeolianites from a site on Eivissa Island (southwestern Mediterranean). Aeolianites were chosen since they contain quartz from a different geological context and have significantly lower environmental dose rates. The dose response curves of the OSL signals for fine and coarse quartz are similar to those for loess and are also represented by the sum of two saturating exponential functions. For doses up to ~200 Gy, the dose response curves of fine and coarse grains from aeolianites can be superimposed and the ages obtained for the different grain sizes are in agreement up to ~250 ka, increasing our confidence in the accuracy of the ages obtained for samples with such doses, irrespective of the magnitude of the environmental dose rate. Particularly for the fine quartz fraction, a mismatch between the SAR dose response curve and the dose response curve obtained when doses are added to the natural is reported, indicating that the application of the SAR protocol in the high dose range is problematic. This dose dependent deviation is much less pronounced for coarse grains. Thus, it seems reasonable to infer that the dose response curves for the coarse grains, although saturating earlier can be regarded as more reliable for equivalent dose calculation than those for the fine grains.


2015 ◽  
Vol 81 ◽  
pp. 150-156 ◽  
Author(s):  
A. Timar-Gabor ◽  
D. Constantin ◽  
J.P. Buylaert ◽  
M. Jain ◽  
A.S. Murray ◽  
...  

Dose-Response ◽  
2018 ◽  
Vol 16 (3) ◽  
pp. 155932581879828 ◽  
Author(s):  
Corinne E. Hill ◽  
J. P. Myers ◽  
Laura N. Vandenberg

Non-monotonic dose response curves (NMDRCs) occur in cells, tissues, animals and human populations in response to nutrients, vitamins, pharmacological compounds, hormones and endocrine disrupting chemicals (EDCs). Yet, regulatory agencies have argued that NMDRCs are not common, are not found for adverse outcomes, and are not relevant for regulation of EDCs. Under the linear dose response model, high dose testing is used to extrapolate to lower doses that are anticipated to be ‘safe’ for human exposures. NMDRCs that occur below the toxicological no-observed-adverse-effect level (NOAEL) would falsify a fundamental assumption, that high dose hazards can be used to predict low dose safety. In this commentary, we provide examples of NMDRCs and discuss how their presence in different portions of the dose response curve might affect regulatory decisions. We provide evidence that NMDRCs do occur below the NOAEL dose, and even below the ‘safe’ reference dose, for chemicals such as resveratrol, permethrin, chlorothalonil, and phthalates such as DEHP. We also briefly discuss the recent CLARITY-BPA study, which reported mammary adenocarcinomas only in rats exposed to the lowest BPA dose. We conclude our commentary with suggestions for how NMDRCs should be acknowledged and utilized to improve regulatory toxicity testing and in the calculation of reference doses that are public health protective.


2017 ◽  
Author(s):  
◽  
E. Y. León-Marroquín

To analyze the net absorption spectra of EBT2 and EBT3 radiochromic films to describe their influenceon the behavior of dose-response curves. The films were irradiated in a linear accelerator of 6 MV. The net absorption spectra were obtained with a UV / VIS spectrophotometer. Dose-response curves were obtained with a scanner, a He-Ne laser and a spectrophotometer. The absorption spectrum of the EBT2 shows three focused absorption bands that retain position and increase their intensity as a function of dose, however, this behavior is not observed in EBT3 films. The dose-response curve shows maximum sensitivity using the spectrophotometer, but does not show a defined behavior. Generation of new knowledge for the creation of new optical systems capable of amplifying the responsiveness of the films. Show the correlation between net absorption spectra and their influence on dose-response curves in three different optical systems. The behavior of absorption spectra combined with the behavior of the dose-response curves helps to discard the use of optical systems that do not guarantee a reliable clinical use.


2015 ◽  
Vol 32 (10) ◽  
pp. 971-982 ◽  
Author(s):  
Salvatore Paterna ◽  
Francesca Di Gaudio ◽  
Vincenzo La Rocca ◽  
Fabio Balistreri ◽  
Massimiliano Greco ◽  
...  

2005 ◽  
Vol 29 (3) ◽  
pp. 104-107 ◽  
Author(s):  
David Taylor

Aims and MethodThe aim of this literature analysis was to establish the range of doses of haloperidol decanoate effective in preventing relapse in schizophrenia. Studies reporting relapse rates in patients treated for longer than 6 months were included. Relapse rate was then plotted against dose or log dose to allow drawing of dose–response curves.ResultsFifteen publications reporting 13 individual studies were identified. of these, 6 studies met inclusion criteria and were analysed. Dose–response curves indicated limited effect at 25 mg/4 weeks but near maximal effect at doses of 50 mg/4 weeks. There was no clear evidence that increasing the dose above 100 mg/4 weeks provided additional benefit in preventing relapse.Clinical ImplicationsThe recommended dose range for haloperidol decanoate (50–300 mg/ 4 weeks) does not reflect the findings of this study. Optimally effective doses appear to be around 50–100 mg/4 weeks. The use of doses above 100 mg/4 weeks is difficult to support given data available.


2016 ◽  
Vol 124 (2) ◽  
pp. 387-395 ◽  
Author(s):  
Daniel J. Johnson ◽  
Andrew V. Scott ◽  
Viachaslau M. Barodka ◽  
Sunhee Park ◽  
Jack O. Wasey ◽  
...  

Abstract Background It is well recognized that increased transfusion volumes are associated with increased morbidity and mortality, but dose–response relations between high- and very-high-dose transfusion and clinical outcomes have not been described previously. In this study, the authors assessed (1) the dose–response relation over a wide range of transfusion volumes for morbidity and mortality and (2) other clinical predictors of adverse outcomes. Methods The authors retrospectively analyzed electronic medical records for 272,592 medical and surgical patients (excluding those with hematologic malignancies), 3,523 of whom received transfusion (10 or greater erythrocyte units throughout the hospital stay), to create dose–response curves for transfusion volumes and in-hospital morbidity and mortality. Prehospital comorbidities were assessed in a risk-adjusted manner to identify the correlation with clinical outcomes. Results For patients receiving high- or very-high-dose transfusion, infections and thrombotic events were four to five times more prevalent than renal, respiratory, and ischemic events. Mortality increased linearly over the entire dose range, with a 10% increase for each 10 units of erythrocytes transfused and 50% mortality after 50 erythrocyte units. Independent predictors of mortality were transfusion dose (odds ratio [OR], 1.037; 95% CI, 1.029 to 1.044), the Charlson comorbidity index (OR, 1.209; 95% CI, 1.141 to 1.276), and a history of congestive heart failure (OR, 1.482; 95% CI, 1.062 to 2.063). Conclusions Patients receiving high- or very-high-dose transfusion are at especially high risk for hospital-acquired infections and thrombotic events. Mortality increased linearly over the entire dose range and exceeded 50% after 50 erythrocyte units.


1974 ◽  
Vol 32 (02/03) ◽  
pp. 356-365 ◽  
Author(s):  
F Haverkate ◽  
D. W Traas

SummaryIn the fibrin plate assay different types of relationships between the dose of applied proteolytic enzyme and the response have been previously reported. This study was undertaken to determine whether a generally valid relationship might exist.Trypsin, chymotrypsin, papain, the plasminogen activator urokinase and all of the microbial proteases investigated, including brinase gave a linear relationship between the logarithm of the enzyme concentration and the diameter of the circular lysed zone. A similar linearity of dose-response curves has frequently been found by investigators who used enzyme plate assays with substrates different from fibrin incorporated in an agar gel. Consequently, it seems that this linearity of dose-response curves is generally valid for the fibrin plate assay as well as for other enzyme plate bioassays.Both human plasmin and porcine tissue activator of plasminogen showed deviations from linearity of semi-logarithmic dose-response curves in the fibrin plate assay.


1962 ◽  
Vol 41 (1) ◽  
pp. 143-153 ◽  
Author(s):  
U. Henriques

ABSTRACT A bioassay of thyroid hormone has been developed using Xenopus larvae made hypothyroid by the administration of thiourea. Only tadpoles of uniform developmental rate were used. Thiourea was given just before the metamorphotic climax in concentrations that produced neoteni in an early metamorphotic stage. During maintained thiourea neotoni, 1-thyroxine and 1-triiodothyronine were added as sodium salts to the water for three days and at the end of one week the stage of metamorphosis produced was determined. In this way identical dose-response curves were obtained for the two compounds. No qualitative differences between their effects were noted except that triiodothyronine seemed more toxic than thyroxine in equivalent doses. Triiodothyronine was found to be 7–12 times as active as thyroxine.


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