Background: In treating patients with radiation, the degree of accuracy for the delivery of tumor dose is recommended to be within ± 5% by ICRU in report 24. The experimental studies have shown that the presence of low-density inhomogeneity in areas such as the lung can lead to a greater than 30% change in the water dose data. Therefore, inhomogeneity corrections should be used in treatment pla...

Background: Prostate cancer is considered as the second leading cause of cancer related death in men worldwide and the third frequent cancer among Iranian men. Despite the use of PSA as the only biomarker for early diagnosis of prostate cancer, its application in clinical settings is under debate. Therefore, the introduction of new molecular markers for early detection of prostate cancer is nee...

An α-particle irradiator, enabling high-precision irradiation of cells for in vitro studies, has been constructed. The irradiation source was a (241)Am source, on which well inserts containing cancer cells growing in monolayer were placed. The total radioactivity, uniformity, and α-particle spectrum were determined by use of HPGe detector, Gafchromic dosimetry film, and PIPS detector measuremen...

BACKGROUND Joint models of longitudinal and time-to-event data are increasingly used to perform individual dynamic prediction of a risk of event. However the difficulty to perform inference in nonlinear models and to calculate the distribution of individual parameters has long limited this approach to linear mixed-effect models for the longitudinal part. Here we use a Bayesian algorithm and a n...

abstract prostate cancer is one of the life threatening disorders of male. although, over the last two decades, a high rate of overdiagnosis, and overtreatment has lowered the incidence rate of prostate cancer, the treatment or prevention strategies are not enough to control the high rate of disease related mortality. current medical treatment approaches include surgery, radiation therapy, chem...

introduction lead-based shields are the most widely used attenuators in x-ray and gamma ray fields. the heavy weight, toxicity and corrosion of lead have led researchers towards the development of non-lead shields. materials and methods the purpose of this study was to design multi-layered shields for protection against x-rays and gamma rays in diagnostic radiology and nuclear medicine. in this...

introduction: nowadays new radiochromic films have an essential role in radiotherapy dosimetry. properties such as high sensitivity, good reproducibility, high spatial resolution, easy readout and portability have made them attractive for dosimetry, especially in high-dose-gradient regions. material and methods: in this study, electron-beam dose distributions in homogenous and heterogeneous pha...

in the present study, the kinetics of biodiesel production through transesterification of brassica carinata oil with methanol in the presence of potassium hydroxide is investigated by kinetic monte carlo simulation. the obtained results from simulation agree qualitatively with the existing experimental data. the kinetics data for each step of suggested mechanism are confirmed by simulation. by ...

introduction: monte carlo (mc) is the most common method for simulating virtual spect projections. it is useful for optimizing procedures, evaluating correction algorithms and more recently image reconstruction as a forward projector in iterative algorithms; however, the main drawback of mc is its long run time. we introduced a model based method considering the effect of body attenuation and i...