Evaluation of MLC Thickness and Composite Effects on Collimation Parameters using EGSnrc and IAEA Phase Space Data.

Background: Recently, multileaf collimators (MLC) have become an important part of any LINAC collimation system because they reduce the treatment planning time and improve the conformity. Important factors that affect MLCs collimation performance are leaves material composition and their thickness.

Objective: In this study, we investigate main dosimetric parameters of a typical MLC including dose in the buildup point, physical penumbra as well as average and end leaf leakages.

Portal venous pressure as a predictor of mortality in cirrhotic patients undergoing emergency surgery.

Objective: Emergency surgery is a risk factor for mortality in cirrhotic patients. Portal hypertension is an essential feature of decompensated cirrhosis. This study aimed to assess the value of portal venous pressure (PVP) measurement in prediction of 1-month mortality in cirrhotic patients undergoing emergency laparotomy.

Endoscopic ultrasound (EUS) elastography and strain ratio, could it help in differentiating malignant from benign pancreatic lesions?

Evaluating the role of endoscopic ultrasound (EUS) elastography and strain ratio in differentiation between malignant and benign pancreatic lesions.Three hundred twenty-five patients with solid pancreatic lesions were enrolled in this prospective study from 2014 to 2017. EUS real-time elastography scoring and strain ratio were done to all patients and compared to the final diagnosis to assess its sensitivity, specificity, positive and negative predictive values (PPV and NPV) in differentiating malignant from benign lesions.

Limitations and opportunities of whole blood bilirubin measurements by GEM premier 4000®.

Background: Neonatal hyperbilirubinemia has traditionally been screened by either total serum bilirubin or transcutaneous bilirubin. Whole blood bilirubin (TwB) by the GEM Premier 4000® blood gas analyzer (GEM) is a relatively new technology and it provides fast bilirubin results with a small sample volume and can measure co-oximetry and other analytes. Our clinical study was to evaluate the reliability of TwB measured by the GEM and identify analytical and clinical factors that may contribute to possible bias.

Revision of orthovoltage chest wall treatment using Monte Carlo simulations.

Purpose: Given the high local control rates observed in breast cancer patients undergoing chest wall irradiation by kilovoltage x-rays, we aimed to revisit this treatment modality by accurate calculation of dose distributions using Monte Carlo simulation.

Methods And Material: The machine components were simulated using the MCNPX code. This model was used to assess the dose distribution of chest wall kilovoltage treatment in different chest wall thicknesses and larger contour or fat patients in standard and mid sternum treatment plans.

Voxel dosimetry: Comparison of MCNPX and DOSXYZnrc Monte Carlo codes in patient specific phantom calculations.

Introduction: Dose evaluation with two Monte Carlo codes using patient specific voxel phantom is presented in this paper. We employ both MCNPX and DOSXYZnrc to perform dosimetry for mathematical voxel phantoms generated by our in-house developed voxel phantom generator and EGSnrc/CTCreate respectively.

Material And Method: Our case study was a 2.

Accuracy Evaluation of Oncentra™ TPS in HDR Brachytherapy of Nasopharynx Cancer Using EGSnrc Monte Carlo Code.

Background: HDR brachytherapy is one of the commonest methods of nasopharyngeal cancer treatment. In this method, depending on how advanced one tumor is, 2 to 6 Gy dose as intracavitary brachytherapy is prescribed. Due to high dose rate and tumor location, accuracy evaluation of treatment planning system (TPS) is particularly important.

Application of polystyrene films for indoor radon dosimetry as SSNTD.

In this study, the sensitivities and calibration factors of polystyrene (PS) to (220)Rn and (222)Rn have been investigated. The sensitivity of compact disks (CD/DVD) as thick polycarbonates (PC) to (220)Rn and (222)Rn has been also obtained by applying a new etching condition. Five different brands of X-ray radiology and MRI films with polystyrene base and four brands of CD/DVDs have been studied to assess their applicability as a passive detector for indoor radon monitoring.

EchoSeed Model 6733 Iodine-125 brachytherapy source: improved dosimetric characterization using the MCNP5 Monte Carlo code.

This study primarily aimed to obtain the dosimetric characteristics of the Model 6733 (125)I seed (EchoSeed) with improved precision and accuracy using a more up-to-date Monte-Carlo code and data (MCNP5) compared to previously published results, including an uncertainty analysis. Its secondary aim was to compare the results obtained using the MCNP5, MCNP4c2, and PTRAN codes for simulation of this low-energy photon-emitting source. The EchoSeed geometry and chemical compositions together with a published (125)I spectrum were used to perform dosimetric characterization of this source as per the updated AAPM TG-43 protocol.

Wavelet transform-based artificial neural networks (WT-ANN) in PM10 pollution level estimation, based on circular variables.

Introduction: In this paper, a novel method in the estimation and prediction of PM(10) is introduced using wavelet transform-based artificial neural networks (WT-ANN).

Discussion: First, the application of wavelet transform, selected for its temporal shift properties and multiresolution analysis characteristics enabling it to reduce disturbing perturbations in input training set data, is presented. Afterward, the circular statistical indices which are used in this method are formally introduced in order to investigate the relation between PM(10) levels and circular meteorological variables.

The design of long-term air quality monitoring networks in urban areas using a spatiotemporal approach.

The implementation and maintenance of an air pollution monitoring program can be expensive and time consuming, especially when the aim is for long-term monitoring over a significant area. Consequently, it is essential that sites are optimized to provide the best representative cover while minimizing costs. In the past, there has been a tendency to locate sampling stations at pollution hot-spots.

U-series concentration in surface and ground water resources of Ardabil province.

Hundred and sixteen water resources including springs, wells, rivers and lakes in Ardabil province, northwest of Iran, were sampled and analyzed. The analysis included chemical analyses, (222)Rn and (226)Ra levels as well as total Uranium contents. (222)Rn levels were determined only for hot springs.

Indoor radon monitoring in Northern Iran using passive and active measurements.

In this work we present the results of a 2-year survey of indoor radon variations in four cities of Lahijan, Ardabil, Sar-Ein and Namin in North and Northwest Iran. We used both passive and active measurements by solid state nuclear track detectors (SSNTDs) with CR-39 polycarbonate and PRASSI Portable radon Gas Surveyor. A total of 1124 samplers in Lahijan, Ardabil, Sar-Ein and Namin were installed.

Impact of different pollutant sources on Shiraz air pollution using SPM elemental analysis.

Weekly average suspended particulate matter (SPM) concentrations were measured in four locations in Shiraz, Iran. Sampling was carried out from July 1999 and continued until July 2000. Instrumental neutron activation analysis (INAA) and atomic absorption spectrometry (AAS) methods were employed to obtain the weekly concentrations of Pb, Br, V, Ca, Al, Fe, Cu, Cr, Mn, Sc and Zn.

Selection of treatment of cefaclor-associated urticarial, serum sickness-like reactions and erythema multiforme by emergency pediatricians: lack of a uniform standard of care.

Background: Serum sickness-like reactions (SSLR) and erythema multiforme are common adverse effects of cefaclor therapy and can be associated with significant morbidity. No standardized evidence-based protocol for the optimal treatment of drug-induced SSLR exists.

Objectives: To define the standard of care used by physicians treating adverse reactions associated with cefaclor.