Background: In this work investigation of the normoxic PAGAT polymer gel dosimeter such as sensitivity, the R2-dose response with post time and the percentage depth dose (PDD) of PAGAT polymer gel dosimeter have been undertaken. Materials and Methods: Using MRI, the formulation to give the maximum change in the transverse relaxation rate R2 was determined to be 4.5% N,N'-methylenbis- ...

Carcinogenesis data for 315 chemicals were obtained from the National Cancer Institute-National Toxicology Program (NCI-NTP) bioassay programs and were analyzed to examine the shape of carcinogenesis dose-response curves. Tumor site data were more often consistent with a quadratic response than with a linear response, suggesting that the routine use of linear dose-response models will often ove...

BACKGROUND It is important to quantify the dose response for a drug in phase 2a clinical trials so the optimal doses can then be selected for subsequent late phase trials. In a phase 2a clinical trial of new lead drug being developed for the treatment of rheumatoid arthritis (RA), a U-shaped dose response curve was observed. In the light of this result further research was undertaken to design ...

In dose response studies, the dose range is often restricted due to concerns over drug toxicity and/or efficacy. We present restricted and unrestricted interval locally optimal designs with respect to a very general class of optimality criteria for estimating the underlying dose response curve. The underlying curve belongs to a diversified set of link functions suitable for the dose response st...

Designs for nonlinear regression models depend on some prior information about the unknown parameters. There are three primary methods for accounting for this: The locally optimal designs, globally optimal Bayesian designs, and sequential procedures. If prior knowledge about the parameters is available from former experiments, Bayesian designs integrate this information most eeciently. If the e...

In the estimation of a dose-response curve, parametric models are straightforward and efficient but subject to model misspecifications; nonparametric methods are robust but less efficient. As a compromise, we propose a semiparametric approach that combines the advantages of parametric and nonparametric curve estimates. In a mixture form, our estimator takes a weighted average of the parametric ...

The motor endplate of frog sartorius muscle was voltage clamped and the peak current to different concentrations of acetylcholine and carbachol applied in the perfusing fluid was measured. Perfusing fluid was hypertonic in order to suppress contractions. Current responses were smooth and reached a peak value within 2-5 s. The dose-response curve was usually linear even with concentrations of 10...

Dose-response curves are widely used to assess pharmacological, radiological, or toxicological effects in medical research and clinical applications. A dose-response design can provide evidence of causal effects between exposure/treatment and responses; however, such conclusions heavily rely on the quality of the dose-response curves. Thus there is considerable interest in developing analytical...