Monte-Carlo dosimetry on a realistic cell monolayer geometry exposed to alpha particles

The energy and specific energy absorbed in the main cell compartments (nucleus and cytoplasm) in typical radiobiology experiments are usually estimated by calculations as they are not accessible for a direct measurement. In most of the work, the cell geometry is modelled using the combination of simple mathematical volumes. We propose a method based on high resolution confocal imaging and ion beam analysis (IBA) in order to import realistic cell nuclei geometries in Monte-Carlo simulations and thus take into account the variety of different geometries encountered in a typical cell population. Seventy-six cell nuclei have been imaged using confocal microscopy and their chemical composition has been measured using IBA. A cellular phantom was created from these data using the ImageJ image analysis software and imported in the Geant4 Monte-Carlo simulation toolkit. Total energy and specific energy distributions in the 76 cell nuclei have been calculated for two types of irradiation protocols: a 3 MeV alpha particle microbeam used for targeted irradiation and a 239Pu alpha source used for large angle random irradiation. Qualitative images of the energy deposited along the particle tracks have been produced and show good agreement with images of DNA double strand break signalling proteins obtained experimentally. The methodology presented in this paper provides microdosimetric quantities calculated from realistic cellular volumes. It is based on open-source oriented software that is publicly available

Microdosimetry of alpha particles for simple and 3d voxelised geometries using MCNPX and Geant4 monte carlo codes

International audienceMicrodosimetry using Monte Carlo simulation is a suitable technique to describe the stochastic nature of energy deposition by alpha particle at cellular level. Because of its short range, the energy imparted by this particle to the targets is highly non-uniform. Thus, to achieve accurate dosimetric results, the modelling of the geometry should be as realistic as possible. The objectives of the present study were to validate the use of the MCNPX and Geant4 Monte Carlo codes for microdosimetric studies using simple and three-dimensional voxelised geometry and to study their limit of validity in this last case. To that aim, the specific energy (z) deposited in the cell nucleus, the single-hit density of specific energy f 1(z) and the mean-specific energy 〈z 1〉 were calculated. Results show a good agreement when compared with the literature using simple geometry. The maximum percentage difference found is andlt;6 %. For voxelised phantom, the study of the voxel size highlighted that the shape of the curve f 1(z) obtained with MCNPX for andlt;1 μ m voxel size presents a significant difference with the shape of non-voxelised geometry. When using Geant4, little differences are observed whatever the voxel size is. Below 1 μ m, the use of Geant4 is required. However, the calculation time is 10 times higher with Geant4 than MCNPX code in the same conditions. © The Author 2011. Published by Oxford University Press. All rights reserved

Comparison Between Non-obstructive Versus Obstructive Coronary Artery Disease Patients with Acute Coronary Syndrome

Background and aim: Differences in prognosis and baseline clinical presentation have been documented among patient with acute coronary syndrome and coronary artery disease with obstructive (ObCAD) or nonobstructive arteries (NObCAD), but the rates of events largely varied across single studies, the present study aimed to compare the clinical  profile, in-hospital and 3-month outcomes major adverse cardiovascular events (MACEs) of  Acute  Coronary Syndrome (ACS) patients with Non – Obstructive Coronary Diseases (NOCAD), versus Obstructive Coronary Diseases (OCAD). Patients and methods: This prospective observational study included 200 consecutive patients admitted with the diagnosis of ACS to Coronary Care Unit (CCU) at Al- Azhar University hospital Assiut and Sohag Specialized Cardiac and Digestive System Center. Results: There was statistically significant increase in patients suffered from common complication of ACS during 3 months follow up in group B (CAD) than group A (NOCAD).There was statistically significant between number of vessels in both groups with heart failure, and recurrent angina pain complications. Conclusion: Female sex, young age, less diabetic patients, less smoking, less ST segment changes,  elevations in peak troponin  levels were  all associated with coronary angiography showing no significant stenosis

Quality of primary care referral letters and feedback reports in buraidah, Qassim region, Saudi Arabia

Objective: To evaluate the quality of referral letters and feedback reports written according to the standards of Quality Assurance Manual of Ministry of Health from primary health care centers (PHCC′s) in Buraidah. Methodology: This study was conducted during October and November 2004. A total of 330 referral letters and feedback reports were randomly selected from six PHCCs (20% from PHCCs in Buraidah City). About 55 referral and feedback letters were selected from each PHCC by systematic sampling method. The referral letters and feedback reports were reviewed thoroughly for the main items required in ideal referral letters and feedback reports according to the standard of Quality Assurance Manual of Ministry of Health, and a scoring system was used Result: Many of the referral letters lacked such important information as the history in 36%, vital signs in 30%, results of clinical examination in 45%, results of basic investigations in 52%, provisional diagnosis in 50%, and treatment given in PHCCs in 47%. The legibility of referral letters and feedback reports was good in 75%, and 63% respectively, and the quality of referral letters and feedback reports was good in 63% and 39% respectively. The rate of feedback reports received by PHCCs was 30% of total number of referrals to the hospitals. The referral rate was (4%) from total number of patients seen in PHCCs. The most frequent reasons for referrals were for general treatment 36.7%, for general diagnostic evaluation 28%, and for laboratory investigation 18.8%. Conclusion: The referral rate from PHCCs in Buraidah fell within the standard set in Quality Assurance Manual. However, the quality of referral letters and feedback reports was poor in 17.6% and 29.7% respectively. The quality of both referral letters and feedback reports should improve to guarantee the quality of patient care.