ct.scan examinations cause high patient absorbed dose from x-ray ionizing radiation. therefore it is necessary to obtain superficial dose profile in z-line. in this research 11 thermoluminecent dosimeter (tld), after calibration were located on z line perpendicular to slice thickness. ct.scan machines did x-ray exposures. the resultant dose profiles showed gussian shape apperience, which has se...

background: a study has been conducted to assess two useful radiation protection indices, the annual per-capita effective dose equivalent (aed) and the genetically significant dose (gsd), from conventional diagnostic radiography in 10 counties with more than 1,886,000 inhabitants in khorasan province in iran. materials and methods: the health centre authorities of khorasan province were asked t...

background: radiation dose knowledge through xray examinations and their distribution in iran provides useful guidance on patient dose reduction. the results of the entrance skin dose (esds) of five common radiographies in all radiology centers in yazd province were reported in our previous study (2003). in the present study we have evaluated the collective effective dose of conventional x-ray ...

background: with the introduction of computed tomography in diagnostic radiology a new and fundamentally different imaging modality has become available. meanwhile, it is clear that the absorbed doses by the patients during ct were relatively high in comparison with those of other diagnostic radiology techniques. the aim of this survey was to determine the average absorbed dose in yazd province...

background: for an effective treatment planning in brachytherapy, it is necessary to know the accurate source dosimetric information such as air kerma strength, exposure rate constant, dose rate constant and redial dose distribution. the usual method to determine these factors is thermo luminescent dosimeter (tld) dosimetry. nowadays, another more accurate method is known to be the monte carlo ...

The controversial use of a linear, no threshold extrapolation model for low dose risk assessment has become even more so in light of the recent reports on the bystander phenomenon. The answer to the question as to which of the two phenomena, bystander versus adaptive response, is more important has practical implication in terms of low dose radiation risk assessment. In this review, genotoxicit...

BACKGROUND When chemical health hazards have been identified, probabilistic dose-response assessment ("hazard characterization") quantifies uncertainty and/or variability in toxicity as a function of human exposure. Existing probabilistic approaches differ for different types of endpoints or modes-of-action, lacking a unifying framework. OBJECTIVES We developed a unified framework for probabi...

Objective: Assessment of myocardial function can be performed at higher noise levels than necessary for coronary arterial evaluation. We evaluated image quality and radiation exposure of a dose-conserving functiononly acquisition vs retrospectively electrocardiogram (ECG)-gated coronary CTA with automatic tube current modulation. Methods: Of 26 patients who underwent clinically indicated corona...

Models generally consider risk to be a function of the hazard (toxicity) and exposure (dose). That function is best described by the dose response of the toxic effect. For any risk assessment system to be effective, it should consider that dose-response relationship. Saturation phenomena often produce nonlinear dose curves, and any risk assessment system should be able to address such effects. ...