ABSTRACT
Background: Field-in-field [FIF] technique for treatment of breast cancer has become a widely performed method over the recent years. However, there was no study in the application of FIF technique in patients with breast cancer undergoing mastectomy and lumpectomy. This study is an attempt to compare dosimetric outcomes after applying the FIF technique in these patients
Materials and Methods: Twenty-four patients with right and left breast cancer participated in this study. The FIF planning technique was carried out for patients undergoing mastectomy and lumpectomy using the TiGRT treatment planning system [TPS]. For the comparison purpose, we used two main indices, i.e. dose homogeneity index [HI] and conformity index [CI], the number of subfields, as well as mean, maximum, and minimum doses, doses received by 2% [D2] and 98% [D98] of the target volume, volumes received greater than 107% [V>107%] and less than 95% [V<95%] of the prescribed dose, doses to organs at risk [OARs], and total monitor units [MUs]
Results: The results indicated that CI and HI are better in patients with right and left breast lumpectomy surgery [p<0.038 and p<0.047] relative to mastectomy patients [p<0.037 and p<0.029], respectively. Other parameters mentioned in Materials and Methods did not show any significant difference between the two groups of patients [p>0.05]
Conclusion: The use of alternative subfields resulted in better dose distribution in target volume with the increase in breast volume. Moreover, to disappear the hot spot areas in isodose curves, it is essential to elevate the number of subfields
ABSTRACT
Understanding of the incident electron energy and angular distributions from clinical electron accelerators [linacs] is important for dosimetry and treatment planning. The most important goals of this study were to evaluate the energy fluence and angular distributions of electron beams from a Neptun 10PC linac using the Monte Carlo [MC] code. The linac electron beams [6, 8, and 10 MeV] were modeled, using the BEAMnrc MC system based on the Electron- Gamma-Shower [EGSnrc] code. Central axis depthdose curves and dose profiles of the electron beams were measured experimentally, and calculated with the MC for three field sizes. In order to benchmarking the simulated models, the calculated and measured dose distributions were compared with Kolmogorov- Smirnov [KS] statistical test. The KS test indicated that the calculated percent depth dose [PDD] and dose profile values for the three electron beam energies well agree with measured data [within 2% everywhere]. The results also showed good agreement [discrepancies smaller than 1%] between the simulated electron energy parameters and those calculated from energy-range relationships using equations for the reference field size. The results showed that there was no significant difference between energy fluence curves of each electron beam energy at different field sizes. In addition, the results of the calculated angular distributions showed that the direction of the electron emerged from the treatment head and trimmer applicators were in forward direction
Subject(s)
Particle Accelerators , Monte Carlo Method , Statistics, NonparametricABSTRACT
The main goal of medical education is preparing experts in health care fields. Medical education should answer the population needs and develop in accordance with technology changes. The aim of this study was to evaluate the effect of active education on knowledge of health care workers of Golestan University of Medical Sciences about avian influenza. In 2005-2006, this semi experimental study was conducted through before-after design. At the beginning, knowledge of the samples regarding to avian influenza was evaluated with self-administered questionnaire. After intervention [active participation in lectures and group workshops] the questionnaires were distributed once again. Data were analysed by non-parametric tests [Wilcoxon, Mann- Whitney, Kruskal-Wallis] to evaluate the effect of active education on knowledge about Avian Influenza. The mean score of knowledge increased significantly after educational intervention [P-value < 0.001]. Previous information was significantly related to pretest scores. The mean score of knowledge was not significantly related to gender and age. Educational workshops are effective in increasing knowledge of healthcare workers about avian influanza. While educational programs of the mass media are effective knowledge, it doesn't meet the special educational needs in the field of health