PURPOSE To quantify the clinically observed dose enhancement adjacent to cranial titanium fixation plates during post-operative radiotherapy. METHODS Irradiation of a titanium burr hole cover was simulated using Monte Carlo code MCNPX for a 6 MV photon spectrum to investigate backscatter dose enhancement due to increased production of secondary electrons within the titanium plate. The simulat...

Introduction: Interventional angiography procedures are increasingly used today. These techniques require a long time of standing near the patient and x-ray tube which lead to increase the radiation-dose of the staff and interventionists. This may also, in turn, lead to the occurrence of radiation deterministic effects. Since a large number of interventional radiology were perf...

This study investigated radiation dose variations in pre-clinical irradiation due to the photon beam energy and presence of tissue heterogeneity. Based on the same mouse computed tomography image dataset, three phantoms namely, heterogeneous, homogeneous and bone homogeneous were used. These phantoms were generated by overriding the relative electron density of no voxel (heterogeneous), all vox...

introduction: occupational exposure to ionizing radiation due to medical activities (both diagnostic and therapeutic procedures) has increased sharply in recent years. among the occupationally exposed workers in these fields, those most affected by this increased exposure to ionizing radiation are nuclear medicine workers. in this study, annual average effective dose, annual collective effectiv...

background: the exposure of human being to ionize radiation from natural sources is a continuing, inescapable feature of life on earth. direct measurement of absorbed dose rates in air has been carried out in many countries of the world during the last few decades. such investigations can be useful for assessment of public dose rates, the performance of epidemiological studies, and keeping refe...

introduction radioactive materials naturally exist in the world. indeed, approximately 82% of human-absorbed radiation doses, which are out of human control, arise from natural sources of radiation including cosmic, terrestrial, and exposure through inhalation or ingestion. thus, the aim of the present study was to estimate health risk, as well as the effective and organ doses from naturally oc...

There is considerable interest in the use of heavy atom nanoparticles as theranostic contrast agents due to their high radiation cross-section compared to soft tissue. However, published studies have primarily focused on applications of gold nanoparticles. This study applies Monte Carlo radiation transport modelling using Geant4 to evaluate the macro- and micro-scale radiation dose enhancement ...

Light reflectors are widely used to enhance scintillation light collection. Their enhancement level depends on the reflector’s reflectance at scintillator’s emission wavelength. We report UV–Visible spectra, relative BaSO4, for several common reflectors. Also reported is their radiation hardness against an ionization dose up 100 Mrad. The results of this investigation provide a reference applic...

Cyclooxygenase-2 (COX-2), an inducible isoform of cyclooxygenase, is overexpressed in many types of malignant tumors, where it mediates production of prostaglandins (PGs), which in turn may stimulate tumor growth and protect against damage by cytotoxic agents. This study investigated whether SC-'236, a selective inhibitor of COX-2, potentiates antitumor efficacy of radiation without increasing ...

Background: Ionizing radiation is present in all environment of the Earth’s surface, beneath the Earth and in the atmosphere. Human beings are exposed to external radiation from their surroundings naturally and also to internal radiation from food, water and air they consume. Then, it is important to measure and develop knowledge about radiation. Objective: This study is designed to evalu...