Monte Carlo Determination of Dosimetric Parameters of a New I-125 Brachytherapy Source According to AAPM TG-43 (U1) Protocol

Background: I-125 is one of the important sources frequently used in brachytherapy. Up to now, several different commercial models of this source type have been introduced to the clinical radiation oncology applications. Recently, a new source model, IrSeed-125, has been added to this list. The aim of the present study is to determine the dosimetric parameters of this new source model based on the recommendations of TG-43 (U1) protocol using Monte Carlo simulation. Methods: The dosimetric characteristics of Ir-125 including dose rate constant, radial dose function, 2D anisotropy function and 1D anisotropy function were determined inside liquid water using MCNPX code and compared to those of other commercially available iodine sources. Results: The dose rate constant of this new source was found to be 0.983+0.015 cGyh(-1)U(-1) that was in good agreement with the TLD measured data (0.965 cGyh(-1)U(-1)). The 10 anisotropy function at 3, 5, and 7 cm radial distances were obtained as 0.954, 0.953 and 0.959, respectively. Conclusion: The results of this study showed that the dosimetric characteristics of this new brachytherapy source are comparable with those of other commercially available sources. Furthermore, the simulated parameters were in accordance with the previously measured ones. Therefore, the Monte Carlo calculated dosimetric parameters could be employed to obtain the dose distribution around this new brachytherapy source based on TG-43 (U1) protocol

Evaluation Methods of the Academic Achievement of Students Ilam University of Medical Sciences

Aims: Academic achievement exams have long played an important role in education and so have been always judged, reviewed and restudied. The aim of this study was to investigate the use of different types of academic achievement exams (evaluation methods) by faculty of Ilam University of Medical Sciences. Instrument & Methods: In this descriptive and cross-sectional study, faculty members of Ilam University of Medical Sciences in the second semester of 2013-14 academic year (N=90) were studied by total counting. Data were gathered by a researcher made questionnaire by 29 questions that was assessing the application level of educational progress evaluation methods by faculty members. For data analysis, SPSS 16 software was used and descriptive and inferential statistics (Student T test and one-way ANOVA) were performed. Findings: 76 of participants (93.8%) placed a greater emphasis on the final exam. The most widely used methods for students' progress evaluation was multiple-choice questions (93.8% n=76), and low used assessment method was 360 degree evaluation (4.9% n=4). Comparing of mean scores of participants based on gender and academic degree, were not showed a significant differences, but comparison of the mean scores of participants based on faculty showed a significant difference (p<0.05). Conclusion: With respect to faculty member's emphasis on use and application of the final evaluation results and preferably less effort and common procedures, as well as less variety of evaluation methods of students' progress, paying attention to the new methods of educational achievement evaluation and implementation training courses for teachers is essential

Determination of dosimetric characteristics of irseed 125I brachytherapy source

Introduction: Low dose rate brachytherapy sources have been widely used for interstitial implants in tumor sites, particularly in prostate. Dosimetric characteristics of a new IrSeed 125I brachytherapy source have been determined using the LiF thermoluminescent dosimeter (TLD) chips. Materials and Methods: Dose rate constant, radial dose function, and anisotropy function around the IrSeed 125I source were measured in a plexiglass phantom using TLD-100 chips. A plexiglass slab phantom with dimensions of 30×30×7.3 cm3 was used to measure dose distribution around the source. Results: Dose rate constant was measured to be equal to 0.965±0.006 cGyh-1U-1. Radial dose function, anisotropy function, and geometry function have been presented as tabulated data for the IrSeed source. Conclusion: Basically, the dosimetric parameters presented here for this new IrSeed source have clinical and treatment planning applications